edgefirst_egl/

lib.rs

//! This crate provides a binding for the Khronos EGL 1.4/1.5 API.
//!
//! It is a trimmed, maintained fork of the [`khronos-egl`](https://crates.io/crates/khronos-egl)
//! crate (itself a fork of the unmaintained `egl` crate), kept current for the
//! EdgeFirst HAL. Only runtime (dynamic) loading of `libEGL` is supported; the
//! upstream static-linking path has been removed.
//!
//! ## Usage
//!
//! Enable the `dynamic` feature and load the EGL API at runtime via
//! [`libloading`](https://crates.io/crates/libloading) into an
//! `Instance<Dynamic<libloading::Library>>`:
//!
//! ```toml
//! edgefirst-egl = { version = ..., features = ["dynamic"] }
//! ```
//!
//! ```no_run
//! # extern crate edgefirst_egl as egl;
//! let lib = unsafe { libloading::Library::new("libEGL.so.1") }.expect("unable to find libEGL.so.1");
//! let egl = unsafe { egl::DynamicInstance::<egl::EGL1_4>::load_required_from(lib) }.expect("unable to load libEGL.so.1");
//! ```
//!
//! `egl::EGL1_4` specifies the minimum required EGL version. When `libEGL.so.1`
//! provides a newer version you can upcast for version-specific features:
//!
//! ```no_run
//! # extern crate edgefirst_egl as egl;
//! # let lib = unsafe { libloading::Library::new("libEGL.so.1") }.expect("unable to find libEGL.so.1");
//! # let egl = unsafe { egl::DynamicInstance::<egl::EGL1_4>::load_required_from(lib) }.expect("unable to load libEGL.so.1");
//! match egl.upcast::<egl::EGL1_5>() {
//!   Some(egl1_5) => {
//!     // do something with EGL 1.5
//!   }
//!   None => {
//!     // do something with EGL 1.4 instead.
//!   }
//! };
//! ```
#![allow(non_upper_case_globals)]
#![allow(non_snake_case)]
// Vendored upstream FFI bindings: the `# Safety` docs and explicit transmute
// type annotations these pedantic lints want are not present in the original
// khronos-egl source, and adding them across the generated API would diverge
// us from upstream for no functional gain.
#![allow(clippy::missing_safety_doc)]
#![allow(clippy::missing_transmute_annotations)]

extern crate libc;

use std::convert::{TryFrom, TryInto};
use std::ffi::CStr;
use std::ffi::CString;
use std::fmt;
use std::ptr;

use libc::{c_char, c_uint, c_void};

/// EGL API provider.
pub trait Api {
    /// Version of the provided EGL API.
    fn version(&self) -> Version;
}

pub trait Downcast<V> {
    fn downcast(&self) -> &V;
}

impl<T> Downcast<T> for T {
    fn downcast(&self) -> &T {
        self
    }
}

pub trait Upcast<V> {
    fn upcast(&self) -> Option<&V>;
}

impl<T> Upcast<T> for T {
    fn upcast(&self) -> Option<&T> {
        Some(self)
    }
}

/// EGL API instance.
///
/// An instance wraps an interface to the EGL API and provide
/// rust-friendly access to it.
pub struct Instance<T> {
    api: T,
}

impl<T> Instance<T> {
    /// Cast the API.
    #[inline(always)]
    pub fn cast_into<U: From<T>>(self) -> Instance<U> {
        Instance {
            api: self.api.into(),
        }
    }

    /// Try to cast the API.
    #[inline(always)]
    pub fn try_cast_into<U: TryFrom<T>>(self) -> Result<Instance<U>, Instance<U::Error>> {
        match self.api.try_into() {
            Ok(t) => Ok(Instance { api: t }),
            Err(e) => Err(Instance { api: e }),
        }
    }

    /// Returns the version of the provided EGL API.
    #[inline(always)]
    pub fn version(&self) -> Version
    where
        T: Api,
    {
        self.api.version()
    }
}

impl<T> Instance<T> {
    #[inline(always)]
    pub const fn new(api: T) -> Instance<T> {
        Instance { api }
    }
}

impl<T: fmt::Debug> fmt::Debug for Instance<T> {
    #[inline(always)]
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Instance({:?})", self.api)
    }
}

impl<T> From<T> for Instance<T> {
    #[inline(always)]
    fn from(t: T) -> Instance<T> {
        Instance::new(t)
    }
}

// ------------------------------------------------------------------------------------------------
// EGL 1.0
// ------------------------------------------------------------------------------------------------

#[cfg(feature = "1_0")]
mod egl1_0 {
    use super::*;

    pub type Boolean = c_uint;
    pub type Int = i32;
    pub type Attrib = usize;
    pub type EGLDisplay = *mut c_void;
    pub type EGLConfig = *mut c_void;
    pub type EGLContext = *mut c_void;
    pub type EGLSurface = *mut c_void;
    pub type NativeDisplayType = *mut c_void;

    #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
    pub struct Display(EGLDisplay);

    impl Display {
        /// Creates a new display from its EGL pointer.
        ///
        /// # Safety
        ///
        /// `ptr` must be a valid `EGLDisplay` pointer.
        #[inline]
        pub unsafe fn from_ptr(ptr: EGLDisplay) -> Display {
            Display(ptr)
        }

        #[inline]
        pub fn as_ptr(&self) -> EGLDisplay {
            self.0
        }
    }

    #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
    pub struct Config(pub(crate) EGLConfig);

    impl Config {
        /// Creates a new configuration form its EGL pointer.
        ///
        /// # Safety
        ///
        /// `ptr` must be a valid `EGLConfig` pointer.
        #[inline]
        pub unsafe fn from_ptr(ptr: EGLConfig) -> Config {
            Config(ptr)
        }

        #[inline]
        pub fn as_ptr(&self) -> EGLConfig {
            self.0
        }
    }

    #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
    pub struct Context(pub(crate) EGLContext);

    impl Context {
        /// Creates a new context form its EGL pointer.
        ///
        /// # Safety
        ///
        /// `ptr` must be a valid `EGLContext` pointer.
        #[inline]
        pub unsafe fn from_ptr(ptr: EGLContext) -> Context {
            Context(ptr)
        }

        #[inline]
        pub fn as_ptr(&self) -> EGLContext {
            self.0
        }
    }

    #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
    pub struct Surface(EGLSurface);

    impl Surface {
        /// Creates a new surface form its EGL pointer.
        ///
        /// # Safety
        ///
        /// `ptr` must be a valid `EGLSurface` pointer.
        #[inline]
        pub unsafe fn from_ptr(ptr: EGLSurface) -> Surface {
            Surface(ptr)
        }

        #[inline]
        pub fn as_ptr(&self) -> EGLSurface {
            self.0
        }
    }

    #[cfg(not(target_os = "android"))]
    pub type NativePixmapType = *mut c_void;

    #[cfg(not(target_os = "android"))]
    pub type NativeWindowType = *mut c_void;

    // On Android, EGL's native window/pixmap types are opaque pointers that
    // the C EGL API treats as `void*`. We keep them as `*mut c_void` (not a
    // distinct opaque struct) so the FFI signatures in the `EGL1_5` trait
    // (which use `*mut c_void`) type-check. The Android NDK headers define
    // `struct ANativeWindow` / `struct egl_native_pixmap_t` as opaque, but
    // passing the pointer through `void*` is the documented Khronos contract.
    #[cfg(target_os = "android")]
    pub type NativePixmapType = *mut c_void;

    #[cfg(target_os = "android")]
    pub type NativeWindowType = *mut c_void;

    pub const ALPHA_SIZE: Int = 0x3021;
    pub const BAD_ACCESS: Int = 0x3002;
    pub const BAD_ALLOC: Int = 0x3003;
    pub const BAD_ATTRIBUTE: Int = 0x3004;
    pub const BAD_CONFIG: Int = 0x3005;
    pub const BAD_CONTEXT: Int = 0x3006;
    pub const BAD_CURRENT_SURFACE: Int = 0x3007;
    pub const BAD_DISPLAY: Int = 0x3008;
    pub const BAD_MATCH: Int = 0x3009;
    pub const BAD_NATIVE_PIXMAP: Int = 0x300A;
    pub const BAD_NATIVE_WINDOW: Int = 0x300B;
    pub const BAD_PARAMETER: Int = 0x300C;
    pub const BAD_SURFACE: Int = 0x300D;
    pub const BLUE_SIZE: Int = 0x3022;
    pub const BUFFER_SIZE: Int = 0x3020;
    pub const CONFIG_CAVEAT: Int = 0x3027;
    pub const CONFIG_ID: Int = 0x3028;
    pub const CORE_NATIVE_ENGINE: Int = 0x305B;
    pub const DEPTH_SIZE: Int = 0x3025;
    pub const DONT_CARE: Int = -1;
    pub const DRAW: Int = 0x3059;
    pub const EXTENSIONS: Int = 0x3055;
    pub const FALSE: Boolean = 0;
    pub const GREEN_SIZE: Int = 0x3023;
    pub const HEIGHT: Int = 0x3056;
    pub const LARGEST_PBUFFER: Int = 0x3058;
    pub const LEVEL: Int = 0x3029;
    pub const MAX_PBUFFER_HEIGHT: Int = 0x302A;
    pub const MAX_PBUFFER_PIXELS: Int = 0x302B;
    pub const MAX_PBUFFER_WIDTH: Int = 0x302C;
    pub const NATIVE_RENDERABLE: Int = 0x302D;
    pub const NATIVE_VISUAL_ID: Int = 0x302E;
    pub const NATIVE_VISUAL_TYPE: Int = 0x302F;
    pub const NONE: Int = 0x3038;
    pub const ATTRIB_NONE: Attrib = 0x3038;
    pub const NON_CONFORMANT_CONFIG: Int = 0x3051;
    pub const NOT_INITIALIZED: Int = 0x3001;
    pub const NO_CONTEXT: EGLContext = 0 as EGLContext;
    pub const NO_DISPLAY: EGLDisplay = 0 as EGLDisplay;
    pub const NO_SURFACE: EGLSurface = 0 as EGLSurface;
    pub const PBUFFER_BIT: Int = 0x0001;
    pub const PIXMAP_BIT: Int = 0x0002;
    pub const READ: Int = 0x305A;
    pub const RED_SIZE: Int = 0x3024;
    pub const SAMPLES: Int = 0x3031;
    pub const SAMPLE_BUFFERS: Int = 0x3032;
    pub const SLOW_CONFIG: Int = 0x3050;
    pub const STENCIL_SIZE: Int = 0x3026;
    pub const SUCCESS: Int = 0x3000;
    pub const SURFACE_TYPE: Int = 0x3033;
    pub const TRANSPARENT_BLUE_VALUE: Int = 0x3035;
    pub const TRANSPARENT_GREEN_VALUE: Int = 0x3036;
    pub const TRANSPARENT_RED_VALUE: Int = 0x3037;
    pub const TRANSPARENT_RGB: Int = 0x3052;
    pub const TRANSPARENT_TYPE: Int = 0x3034;
    pub const TRUE: Boolean = 1;
    pub const VENDOR: Int = 0x3053;
    pub const VERSION: Int = 0x3054;
    pub const WIDTH: Int = 0x3057;
    pub const WINDOW_BIT: Int = 0x0004;

    /// EGL errors.
    #[derive(Clone, Copy, PartialEq, Eq, Debug)]
    pub enum Error {
        /// EGL is not initialized, or could not be initialized, for the specified
        /// EGL display connection.
        NotInitialized,

        /// EGL cannot access a requested resource (for example a context is bound
        /// in another thread).
        BadAccess,

        /// EGL failed to allocate resources for the requested operation.
        BadAlloc,

        /// An unrecognized attribute or attribute value was passed in the attribute
        /// list.
        BadAttribute,

        /// An Context argument does not name a valid EGL rendering context.
        BadContext,

        /// An Config argument does not name a valid EGL frame buffer configuration.
        BadConfig,

        /// The current surface of the calling thread is a window, pixel buffer or
        /// pixmap that is no longer valid.
        BadCurrentSurface,

        /// An Display argument does not name a valid EGL display connection.
        BadDisplay,

        /// An Surface argument does not name a valid surface (window, pixel buffer
        /// or pixmap) configured for GL rendering.
        BadSurface,

        /// Arguments are inconsistent (for example, a valid context requires
        /// buffers not supplied by a valid surface).
        BadMatch,

        /// One or more argument values are invalid.
        BadParameter,

        /// A NativePixmapType argument does not refer to a valid native pixmap.
        BadNativePixmap,

        /// A NativeWindowType argument does not refer to a valid native window.
        BadNativeWindow,

        /// A power management event has occurred. The application must destroy all
        /// contexts and reinitialise OpenGL ES state and objects to continue
        /// rendering.
        ContextLost,
    }

    impl std::error::Error for Error {
        fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
            None
        }
    }

    impl Error {
        pub fn native(&self) -> Int {
            use Error::*;
            match self {
                NotInitialized => NOT_INITIALIZED,
                BadAccess => BAD_ACCESS,
                BadAlloc => BAD_ALLOC,
                BadAttribute => BAD_ATTRIBUTE,
                BadContext => BAD_CONTEXT,
                BadConfig => BAD_CONFIG,
                BadCurrentSurface => BAD_CURRENT_SURFACE,
                BadDisplay => BAD_DISPLAY,
                BadSurface => BAD_SURFACE,
                BadMatch => BAD_MATCH,
                BadParameter => BAD_PARAMETER,
                BadNativePixmap => BAD_NATIVE_PIXMAP,
                BadNativeWindow => BAD_NATIVE_WINDOW,
                ContextLost => CONTEXT_LOST,
            }
        }

        fn message(&self) -> &'static str {
            use Error::*;
            match self {
				NotInitialized => "EGL is not initialized, or could not be initialized, for the specified EGL display connection.",
				BadAccess => "EGL cannot access a requested resource (for example a context is bound in another thread.",
				BadAlloc => "EGL failed to allocate resources for the requested operation.",
				BadAttribute => "An unrecognized attribute or attribute value was passed in the attribute list.",
				BadContext => "An Context argument does not name a valid EGL rendering context.",
				BadConfig => "An Config argument does not name a valid EGL frame buffer configuration.",
				BadCurrentSurface => "The current surface of the calling thread is a window, pixel buffer or pixmap that is no longer valid.",
				BadDisplay => "An Display argument does not name a valid EGL display connection.",
				BadSurface => "An Surface argument does not name a valid surface (window, pixel buffer or pixmap) configured for GL rendering.",
				BadMatch => "Arguments are inconsistent (for example, a valid context requires buffers not supplied by a valid surface.",
				BadParameter => "One or more argument values are invalid.",
				BadNativePixmap => "A NativePixmapType argument does not refer to a valid native pixmap.",
				BadNativeWindow => "A NativeWindowType argument does not refer to a valid native window.",
				ContextLost => "A power management event has occurred. The application must destroy all contexts and reinitialise OpenGL ES state and objects to continue rendering."
			}
        }
    }

    impl From<Error> for Int {
        fn from(e: Error) -> Int {
            e.native()
        }
    }

    impl TryFrom<Int> for Error {
        type Error = Int;

        fn try_from(e: Int) -> Result<Error, Int> {
            use Error::*;
            match e {
                NOT_INITIALIZED => Ok(NotInitialized),
                BAD_ACCESS => Ok(BadAccess),
                BAD_ALLOC => Ok(BadAlloc),
                BAD_ATTRIBUTE => Ok(BadAttribute),
                BAD_CONTEXT => Ok(BadContext),
                BAD_CONFIG => Ok(BadConfig),
                BAD_CURRENT_SURFACE => Ok(BadCurrentSurface),
                BAD_DISPLAY => Ok(BadDisplay),
                BAD_SURFACE => Ok(BadSurface),
                BAD_MATCH => Ok(BadMatch),
                BAD_PARAMETER => Ok(BadParameter),
                BAD_NATIVE_PIXMAP => Ok(BadNativePixmap),
                BAD_NATIVE_WINDOW => Ok(BadNativeWindow),
                CONTEXT_LOST => Ok(ContextLost),
                _ => Err(e),
            }
        }
    }

    impl fmt::Display for Error {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            self.message().fmt(f)
        }
    }

    pub fn check_int_list(attrib_list: &[Int]) -> Result<(), Error> {
        if attrib_list.last() == Some(&NONE) {
            Ok(())
        } else {
            Err(Error::BadParameter)
        }
    }

    pub fn check_attrib_list(attrib_list: &[Attrib]) -> Result<(), Error> {
        if attrib_list.last() == Some(&ATTRIB_NONE) {
            Ok(())
        } else {
            Err(Error::BadParameter)
        }
    }

    impl<T: api::EGL1_0> Instance<T> {
        /// Return the number of EGL frame buffer configurations that atch specified
        /// attributes.
        ///
        /// This will call `eglChooseConfig` without `null` as `configs` to get the
        /// number of matching configurations.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `NONE`).
        pub fn matching_config_count(
            &self,
            display: Display,
            attrib_list: &[Int],
        ) -> Result<usize, Error> {
            check_int_list(attrib_list)?;
            unsafe {
                let mut count = 0;

                if self.api.eglChooseConfig(
                    display.as_ptr(),
                    attrib_list.as_ptr(),
                    ptr::null_mut(),
                    0,
                    &mut count,
                ) == TRUE
                {
                    Ok(count as usize)
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Return a list of EGL frame buffer configurations that match specified
        /// attributes.
        ///
        /// This will write as many matching configurations in `configs` up to its
        /// capacity. You can use the function [`matching_config_count`](Self::matching_config_count) to get the
        /// exact number of configurations matching the specified attributes.
        ///
        /// ## Example
        ///
        /// ```no_run
        /// # extern crate edgefirst_egl as egl;
        /// # fn main() -> Result<(), egl::Error> {
        /// # let lib = unsafe { libloading::Library::new("libEGL.so.1") }.unwrap();
        /// # let egl = unsafe { egl::DynamicInstance::<egl::EGL1_4>::load_required_from(lib) }.unwrap();
        /// # let display = unsafe { egl.get_display(egl::DEFAULT_DISPLAY) }.unwrap();
        /// # egl.initialize(display)?;
        /// # let attrib_list = [egl::RED_SIZE, 8, egl::GREEN_SIZE, 8, egl::BLUE_SIZE, 8, egl::NONE];
        /// // Get the number of matching configurations.
        /// let count = egl.matching_config_count(display, &attrib_list)?;
        ///
        /// // Get the matching configurations.
        /// let mut configs = Vec::with_capacity(count);
        /// egl.choose_config(display, &attrib_list, &mut configs)?;
        /// # Ok(())
        /// # }
        /// ```
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `NONE`).
        pub fn choose_config(
            &self,
            display: Display,
            attrib_list: &[Int],
            configs: &mut Vec<Config>,
        ) -> Result<(), Error> {
            check_int_list(attrib_list)?;

            let capacity = configs.capacity();
            if capacity == 0 {
                // When the input ptr is null (when capacity is 0),
                // eglChooseConfig behaves differently and returns the number
                // of configurations.
                Ok(())
            } else {
                unsafe {
                    let mut count = 0;

                    if self.api.eglChooseConfig(
                        display.as_ptr(),
                        attrib_list.as_ptr(),
                        configs.as_mut_ptr() as *mut EGLConfig,
                        capacity.try_into().unwrap(),
                        &mut count,
                    ) == TRUE
                    {
                        configs.set_len(count as usize);
                        Ok(())
                    } else {
                        Err(self.get_error().unwrap())
                    }
                }
            }
        }

        /// Return the first EGL frame buffer configuration that match specified
        /// attributes.
        ///
        /// This is an helper function that will call `choose_config` with a buffer of
        /// size 1, which is equivalent to:
        /// ```no_run
        /// # extern crate edgefirst_egl as egl;
        /// # fn main() -> Result<(), egl::Error> {
        /// # let lib = unsafe { libloading::Library::new("libEGL.so.1") }.unwrap();
        /// # let egl = unsafe { egl::DynamicInstance::<egl::EGL1_4>::load_required_from(lib) }.unwrap();
        /// # let display = unsafe { egl.get_display(egl::DEFAULT_DISPLAY) }.unwrap();
        /// # egl.initialize(display)?;
        /// # let attrib_list = [egl::RED_SIZE, 8, egl::GREEN_SIZE, 8, egl::BLUE_SIZE, 8, egl::NONE];
        /// let mut configs = Vec::with_capacity(1);
        /// egl.choose_config(display, &attrib_list, &mut configs)?;
        /// configs.first();
        /// # Ok(())
        /// # }
        /// ```
        pub fn choose_first_config(
            &self,
            display: Display,
            attrib_list: &[Int],
        ) -> Result<Option<Config>, Error> {
            let mut configs = Vec::with_capacity(1);
            self.choose_config(display, attrib_list, &mut configs)?;
            Ok(configs.first().copied())
        }

        /// Copy EGL surface color buffer to a native pixmap.
        ///
        /// # Safety
        ///
        /// `target` must be a valid pointer to a native pixmap that belongs
        /// to the same platform as `display` and `surface`.
        pub unsafe fn copy_buffers(
            &self,
            display: Display,
            surface: Surface,
            target: NativePixmapType,
        ) -> Result<(), Error> {
            unsafe {
                if self
                    .api
                    .eglCopyBuffers(display.as_ptr(), surface.as_ptr(), target)
                    == TRUE
                {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Create a new EGL rendering context.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `NONE`).
        pub fn create_context(
            &self,
            display: Display,
            config: Config,
            share_context: Option<Context>,
            attrib_list: &[Int],
        ) -> Result<Context, Error> {
            check_int_list(attrib_list)?;
            unsafe {
                let share_context = match share_context {
                    Some(share_context) => share_context.as_ptr(),
                    None => NO_CONTEXT,
                };

                let context = self.api.eglCreateContext(
                    display.as_ptr(),
                    config.as_ptr(),
                    share_context,
                    attrib_list.as_ptr(),
                );

                if context != NO_CONTEXT {
                    Ok(Context(context))
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Create a new EGL pixel buffer surface.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `NONE`).
        pub fn create_pbuffer_surface(
            &self,
            display: Display,
            config: Config,
            attrib_list: &[Int],
        ) -> Result<Surface, Error> {
            check_int_list(attrib_list)?;
            unsafe {
                let surface = self.api.eglCreatePbufferSurface(
                    display.as_ptr(),
                    config.as_ptr(),
                    attrib_list.as_ptr(),
                );

                if surface != NO_SURFACE {
                    Ok(Surface(surface))
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Create a new EGL offscreen surface.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `NONE`).
        ///
        /// # Safety
        ///
        /// This function may raise undefined behavior if the display and native
        /// pixmap do not belong to the same platform.
        pub unsafe fn create_pixmap_surface(
            &self,
            display: Display,
            config: Config,
            pixmap: NativePixmapType,
            attrib_list: &[Int],
        ) -> Result<Surface, Error> {
            check_int_list(attrib_list)?;
            let surface = self.api.eglCreatePixmapSurface(
                display.as_ptr(),
                config.as_ptr(),
                pixmap,
                attrib_list.as_ptr(),
            );

            if surface != NO_SURFACE {
                Ok(Surface(surface))
            } else {
                Err(self.get_error().unwrap())
            }
        }

        /// Create a new EGL window surface.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `NONE`).
        ///
        /// # Safety
        ///
        /// This function may raise undefined behavior if the display and native
        /// window do not belong to the same platform.
        pub unsafe fn create_window_surface(
            &self,
            display: Display,
            config: Config,
            window: NativeWindowType,
            attrib_list: Option<&[Int]>,
        ) -> Result<Surface, Error> {
            let attrib_list = match attrib_list {
                Some(attrib_list) => {
                    check_int_list(attrib_list)?;
                    attrib_list.as_ptr()
                }
                None => ptr::null(),
            };

            let surface = self.api.eglCreateWindowSurface(
                display.as_ptr(),
                config.as_ptr(),
                window,
                attrib_list,
            );

            if surface != NO_SURFACE {
                Ok(Surface(surface))
            } else {
                Err(self.get_error().unwrap())
            }
        }

        /// Destroy an EGL rendering context.
        pub fn destroy_context(&self, display: Display, ctx: Context) -> Result<(), Error> {
            unsafe {
                if self.api.eglDestroyContext(display.as_ptr(), ctx.as_ptr()) == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Destroy an EGL surface.
        pub fn destroy_surface(&self, display: Display, surface: Surface) -> Result<(), Error> {
            unsafe {
                if self
                    .api
                    .eglDestroySurface(display.as_ptr(), surface.as_ptr())
                    == TRUE
                {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Return information about an EGL frame buffer configuration.
        pub fn get_config_attrib(
            &self,
            display: Display,
            config: Config,
            attribute: Int,
        ) -> Result<Int, Error> {
            unsafe {
                let mut value: Int = 0;
                if self.api.eglGetConfigAttrib(
                    display.as_ptr(),
                    config.as_ptr(),
                    attribute,
                    &mut value,
                ) == TRUE
                {
                    Ok(value)
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Return the number of all frame buffer configurations.
        ///
        /// You can use it to setup the correct capacity for the configurations buffer in [`get_configs`](Self::get_configs).
        ///
        /// ## Example
        /// ```no_run
        /// # extern crate edgefirst_egl as egl;
        /// # fn main() -> Result<(), egl::Error> {
        /// # let lib = unsafe { libloading::Library::new("libEGL.so.1") }.unwrap();
        /// # let egl = unsafe { egl::DynamicInstance::<egl::EGL1_4>::load_required_from(lib) }.unwrap();
        /// # let display = unsafe { egl.get_display(egl::DEFAULT_DISPLAY) }.unwrap();
        /// # egl.initialize(display)?;
        /// let mut configs = Vec::with_capacity(egl.get_config_count(display)?);
        /// egl.get_configs(display, &mut configs);
        /// assert!(configs.len() > 0);
        /// # Ok(())
        /// # }
        /// ```
        pub fn get_config_count(&self, display: Display) -> Result<usize, Error> {
            unsafe {
                let mut count = 0;

                if self
                    .api
                    .eglGetConfigs(display.as_ptr(), std::ptr::null_mut(), 0, &mut count)
                    == TRUE
                {
                    Ok(count as usize)
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Get the list of all EGL frame buffer configurations for a display.
        ///
        /// The configurations are added to the `configs` buffer, up to the buffer's capacity.
        /// You can use [`get_config_count`](Self::get_config_count) to get the total number of available frame buffer configurations,
        /// and setup the buffer's capacity accordingly.
        ///
        /// ## Example
        /// ```no_run
        /// # extern crate edgefirst_egl as egl;
        /// # fn main() -> Result<(), egl::Error> {
        /// # let lib = unsafe { libloading::Library::new("libEGL.so.1") }.unwrap();
        /// # let egl = unsafe { egl::DynamicInstance::<egl::EGL1_4>::load_required_from(lib) }.unwrap();
        /// # let display = unsafe { egl.get_display(egl::DEFAULT_DISPLAY) }.unwrap();
        /// # egl.initialize(display)?;
        /// let mut configs = Vec::with_capacity(egl.get_config_count(display)?);
        /// egl.get_configs(display, &mut configs);
        /// # Ok(())
        /// # }
        /// ```
        pub fn get_configs(
            &self,
            display: Display,
            configs: &mut Vec<Config>,
        ) -> Result<(), Error> {
            let capacity = configs.capacity();
            if capacity == 0 {
                // When the input ptr is null (when capacity is 0),
                // eglGetConfig behaves differently and returns the number
                // of configurations.
                Ok(())
            } else {
                unsafe {
                    let mut count = 0;

                    if self.api.eglGetConfigs(
                        display.as_ptr(),
                        configs.as_mut_ptr() as *mut EGLConfig,
                        capacity.try_into().unwrap(),
                        &mut count,
                    ) == TRUE
                    {
                        configs.set_len(count as usize);
                        Ok(())
                    } else {
                        Err(self.get_error().unwrap())
                    }
                }
            }
        }

        /// Return the display for the current EGL rendering context.
        pub fn get_current_display(&self) -> Option<Display> {
            unsafe {
                let display = self.api.eglGetCurrentDisplay();

                if display != NO_DISPLAY {
                    Some(Display(display))
                } else {
                    None
                }
            }
        }

        /// Return the read or draw surface for the current EGL rendering context.
        pub fn get_current_surface(&self, readdraw: Int) -> Option<Surface> {
            unsafe {
                let surface = self.api.eglGetCurrentSurface(readdraw);

                if surface != NO_SURFACE {
                    Some(Surface(surface))
                } else {
                    None
                }
            }
        }

        /// Return an EGL display connection.
        ///
        /// # Safety
        ///
        /// The `native_display` must be a valid pointer to the native display.
        /// Valid values for platform are defined by EGL extensions, as are
        /// requirements for native_display. For example, an extension
        /// specification that defines support for the X11 platform may require
        /// that native_display be a pointer to an X11 Display, and an extension
        /// specification that defines support for the Microsoft Windows
        /// platform may require that native_display be a pointer to a Windows
        /// Device Context.
        pub unsafe fn get_display(&self, display_id: NativeDisplayType) -> Option<Display> {
            let display = self.api.eglGetDisplay(display_id);

            if display != NO_DISPLAY {
                Some(Display(display))
            } else {
                None
            }
        }

        /// Return error information.
        ///
        /// Return the error of the last called EGL function in the current thread, or
        /// `None` if the error is set to `SUCCESS`.
        ///
        /// Note that since a call to `eglGetError` sets the error to `SUCCESS`, and
        /// since this function is automatically called by any wrapper function
        /// returning a `Result` when necessary, this function may only return `None`
        /// from the point of view of a user.
        pub fn get_error(&self) -> Option<Error> {
            unsafe {
                let e = self.api.eglGetError();
                if e == SUCCESS {
                    None
                } else {
                    Some(e.try_into().unwrap())
                }
            }
        }

        /// Return a GL or an EGL extension function.
        pub fn get_proc_address(&self, procname: &str) -> Option<extern "system" fn()> {
            unsafe {
                let string = CString::new(procname).unwrap();

                let addr = self.api.eglGetProcAddress(string.as_ptr());
                // `eglGetProcAddress` returns a null pointer for unknown names even
                // though the FFI type is a non-nullable fn pointer; compare the raw
                // address to sidestep a `useless_ptr_null_checks` false positive.
                if addr as usize != 0 {
                    Some(addr)
                } else {
                    None
                }
            }
        }

        /// Initialize an EGL display connection.
        pub fn initialize(&self, display: Display) -> Result<(Int, Int), Error> {
            unsafe {
                let mut major = 0;
                let mut minor = 0;

                if self
                    .api
                    .eglInitialize(display.as_ptr(), &mut major, &mut minor)
                    == TRUE
                {
                    Ok((major, minor))
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Attach an EGL rendering context to EGL surfaces.
        pub fn make_current(
            &self,
            display: Display,
            draw: Option<Surface>,
            read: Option<Surface>,
            ctx: Option<Context>,
        ) -> Result<(), Error> {
            unsafe {
                let draw = match draw {
                    Some(draw) => draw.as_ptr(),
                    None => NO_SURFACE,
                };
                let read = match read {
                    Some(read) => read.as_ptr(),
                    None => NO_SURFACE,
                };
                let ctx = match ctx {
                    Some(ctx) => ctx.as_ptr(),
                    None => NO_CONTEXT,
                };

                if self.api.eglMakeCurrent(display.as_ptr(), draw, read, ctx) == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Return EGL rendering context information.
        pub fn query_context(
            &self,
            display: Display,
            ctx: Context,
            attribute: Int,
        ) -> Result<Int, Error> {
            unsafe {
                let mut value = 0;
                if self
                    .api
                    .eglQueryContext(display.as_ptr(), ctx.as_ptr(), attribute, &mut value)
                    == TRUE
                {
                    Ok(value)
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Return a string describing properties of the EGL client or of an EGL display
        /// connection.
        pub fn query_string(
            &self,
            display: Option<Display>,
            name: Int,
        ) -> Result<&'static CStr, Error> {
            unsafe {
                let display_ptr = match display {
                    Some(display) => display.as_ptr(),
                    None => NO_DISPLAY,
                };

                let c_str = self.api.eglQueryString(display_ptr, name);

                if !c_str.is_null() {
                    Ok(CStr::from_ptr(c_str))
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Return EGL surface information.
        pub fn query_surface(
            &self,
            display: Display,
            surface: Surface,
            attribute: Int,
        ) -> Result<Int, Error> {
            unsafe {
                let mut value = 0;
                if self.api.eglQuerySurface(
                    display.as_ptr(),
                    surface.as_ptr(),
                    attribute,
                    &mut value,
                ) == TRUE
                {
                    Ok(value)
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Post EGL surface color buffer to a native window.
        pub fn swap_buffers(&self, display: Display, surface: Surface) -> Result<(), Error> {
            unsafe {
                if self.api.eglSwapBuffers(display.as_ptr(), surface.as_ptr()) == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Terminate an EGL display connection.
        pub fn terminate(&self, display: Display) -> Result<(), Error> {
            unsafe {
                if self.api.eglTerminate(display.as_ptr()) == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Complete GL execution prior to subsequent native rendering calls.
        pub fn wait_gl(&self) -> Result<(), Error> {
            unsafe {
                if self.api.eglWaitGL() == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Complete native execution prior to subsequent GL rendering calls.
        pub fn wait_native(&self, engine: Int) -> Result<(), Error> {
            unsafe {
                if self.api.eglWaitNative(engine) == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }
    }
}

#[cfg(feature = "1_0")]
pub use egl1_0::*;

// ------------------------------------------------------------------------------------------------
// EGL 1.1
// ------------------------------------------------------------------------------------------------

#[cfg(feature = "1_1")]
mod egl1_1 {
    use super::*;

    pub const BACK_BUFFER: Int = 0x3084;
    pub const BIND_TO_TEXTURE_RGB: Int = 0x3039;
    pub const BIND_TO_TEXTURE_RGBA: Int = 0x303A;
    pub const CONTEXT_LOST: Int = 0x300E;
    pub const MIN_SWAP_INTERVAL: Int = 0x303B;
    pub const MAX_SWAP_INTERVAL: Int = 0x303C;
    pub const MIPMAP_TEXTURE: Int = 0x3082;
    pub const MIPMAP_LEVEL: Int = 0x3083;
    pub const NO_TEXTURE: Int = 0x305C;
    pub const TEXTURE_2D: Int = 0x305F;
    pub const TEXTURE_FORMAT: Int = 0x3080;
    pub const TEXTURE_RGB: Int = 0x305D;
    pub const TEXTURE_RGBA: Int = 0x305E;
    pub const TEXTURE_TARGET: Int = 0x3081;

    impl<T: api::EGL1_1> Instance<T> {
        /// Defines a two-dimensional texture image.
        pub fn bind_tex_image(
            &self,
            display: Display,
            surface: Surface,
            buffer: Int,
        ) -> Result<(), Error> {
            unsafe {
                if self
                    .api
                    .eglBindTexImage(display.as_ptr(), surface.as_ptr(), buffer)
                    == TRUE
                {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        ///  Releases a color buffer that is being used as a texture.
        pub fn release_tex_image(
            &self,
            display: Display,
            surface: Surface,
            buffer: Int,
        ) -> Result<(), Error> {
            unsafe {
                if self
                    .api
                    .eglReleaseTexImage(display.as_ptr(), surface.as_ptr(), buffer)
                    == TRUE
                {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Set an EGL surface attribute.
        pub fn surface_attrib(
            &self,
            display: Display,
            surface: Surface,
            attribute: Int,
            value: Int,
        ) -> Result<(), Error> {
            unsafe {
                if self
                    .api
                    .eglSurfaceAttrib(display.as_ptr(), surface.as_ptr(), attribute, value)
                    == TRUE
                {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Specifies the minimum number of video frame periods per buffer swap for the
        /// window associated with the current context.
        pub fn swap_interval(&self, display: Display, interval: Int) -> Result<(), Error> {
            unsafe {
                if self.api.eglSwapInterval(display.as_ptr(), interval) == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }
    }
}

#[cfg(feature = "1_1")]
pub use egl1_1::*;

// ------------------------------------------------------------------------------------------------
// EGL 1.2
// ------------------------------------------------------------------------------------------------

#[cfg(feature = "1_2")]
mod egl1_2 {
    use super::*;

    pub type Enum = c_uint;
    pub type EGLClientBuffer = *mut c_void;

    #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
    pub struct ClientBuffer(EGLClientBuffer);

    impl ClientBuffer {
        /// Creates a new client buffer form its EGL pointer.
        ///
        /// # Safety
        ///
        /// `ptr` must be a valid `EGLClientBuffer` pointer.
        #[inline]
        pub unsafe fn from_ptr(ptr: EGLClientBuffer) -> ClientBuffer {
            ClientBuffer(ptr)
        }

        #[inline]
        pub fn as_ptr(&self) -> EGLClientBuffer {
            self.0
        }
    }

    pub const ALPHA_FORMAT: Int = 0x3088;
    pub const ALPHA_FORMAT_NONPRE: Int = 0x308B;
    pub const ALPHA_FORMAT_PRE: Int = 0x308C;
    pub const ALPHA_MASK_SIZE: Int = 0x303E;
    pub const BUFFER_PRESERVED: Int = 0x3094;
    pub const BUFFER_DESTROYED: Int = 0x3095;
    pub const CLIENT_APIS: Int = 0x308D;
    pub const COLORSPACE: Int = 0x3087;
    pub const COLORSPACE_sRGB: Int = 0x3089;
    pub const COLORSPACE_LINEAR: Int = 0x308A;
    pub const COLOR_BUFFER_TYPE: Int = 0x303F;
    pub const CONTEXT_CLIENT_TYPE: Int = 0x3097;
    pub const DISPLAY_SCALING: Int = 10000;
    pub const HORIZONTAL_RESOLUTION: Int = 0x3090;
    pub const LUMINANCE_BUFFER: Int = 0x308F;
    pub const LUMINANCE_SIZE: Int = 0x303D;
    pub const OPENGL_ES_BIT: Int = 0x0001;
    pub const OPENVG_BIT: Int = 0x0002;
    pub const OPENGL_ES_API: Enum = 0x30A0;
    pub const OPENVG_API: Enum = 0x30A1;
    pub const OPENVG_IMAGE: Int = 0x3096;
    pub const PIXEL_ASPECT_RATIO: Int = 0x3092;
    pub const RENDERABLE_TYPE: Int = 0x3040;
    pub const RENDER_BUFFER: Int = 0x3086;
    pub const RGB_BUFFER: Int = 0x308E;
    pub const SINGLE_BUFFER: Int = 0x3085;
    pub const SWAP_BEHAVIOR: Int = 0x3093;
    pub const UNKNOWN: Int = -1;
    pub const VERTICAL_RESOLUTION: Int = 0x3091;

    impl<T: api::EGL1_2> Instance<T> {
        /// Set the current rendering API.
        pub fn bind_api(&self, api: Enum) -> Result<(), Error> {
            unsafe {
                if self.api.eglBindAPI(api) == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Query the current rendering API.
        pub fn query_api(&self) -> Enum {
            unsafe { self.api.eglQueryAPI() }
        }

        /// Create a new EGL pixel buffer surface bound to an OpenVG image.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `NONE`).
        pub fn create_pbuffer_from_client_buffer(
            &self,
            display: Display,
            buffer_type: Enum,
            buffer: ClientBuffer,
            config: Config,
            attrib_list: &[Int],
        ) -> Result<Surface, Error> {
            check_int_list(attrib_list)?;
            unsafe {
                let surface = self.api.eglCreatePbufferFromClientBuffer(
                    display.as_ptr(),
                    buffer_type,
                    buffer.as_ptr(),
                    config.as_ptr(),
                    attrib_list.as_ptr(),
                );

                if surface != NO_SURFACE {
                    Ok(Surface::from_ptr(surface))
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Release EGL per-thread state.
        pub fn release_thread(&self) -> Result<(), Error> {
            unsafe {
                if self.api.eglReleaseThread() == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Complete client API execution prior to subsequent native rendering calls.
        pub fn wait_client(&self) -> Result<(), Error> {
            unsafe {
                if self.api.eglWaitClient() == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }
    }
}

#[cfg(feature = "1_2")]
pub use egl1_2::*;

// ------------------------------------------------------------------------------------------------
// EGL 1.3
// ------------------------------------------------------------------------------------------------

#[cfg(feature = "1_3")]
mod egl1_3 {
    use super::*;

    pub const CONFORMANT: Int = 0x3042;
    pub const CONTEXT_CLIENT_VERSION: Int = 0x3098;
    pub const MATCH_NATIVE_PIXMAP: Int = 0x3041;
    pub const OPENGL_ES2_BIT: Int = 0x0004;
    pub const VG_ALPHA_FORMAT: Int = 0x3088;
    pub const VG_ALPHA_FORMAT_NONPRE: Int = 0x308B;
    pub const VG_ALPHA_FORMAT_PRE: Int = 0x308C;
    pub const VG_ALPHA_FORMAT_PRE_BIT: Int = 0x0040;
    pub const VG_COLORSPACE: Int = 0x3087;
    pub const VG_COLORSPACE_sRGB: Int = 0x3089;
    pub const VG_COLORSPACE_LINEAR: Int = 0x308A;
    pub const VG_COLORSPACE_LINEAR_BIT: Int = 0x0020;
}

#[cfg(feature = "1_3")]
pub use egl1_3::*;

// ------------------------------------------------------------------------------------------------
// EGL 1.4
// ------------------------------------------------------------------------------------------------

#[cfg(feature = "1_4")]
mod egl1_4 {
    use super::*;

    pub const DEFAULT_DISPLAY: NativeDisplayType = 0 as NativeDisplayType;
    pub const MULTISAMPLE_RESOLVE_BOX_BIT: Int = 0x0200;
    pub const MULTISAMPLE_RESOLVE: Int = 0x3099;
    pub const MULTISAMPLE_RESOLVE_DEFAULT: Int = 0x309A;
    pub const MULTISAMPLE_RESOLVE_BOX: Int = 0x309B;
    pub const OPENGL_API: Enum = 0x30A2;
    pub const OPENGL_BIT: Int = 0x0008;
    pub const SWAP_BEHAVIOR_PRESERVED_BIT: Int = 0x0400;

    impl<T: api::EGL1_4> Instance<T> {
        /// Return the current EGL rendering context.
        pub fn get_current_context(&self) -> Option<Context> {
            unsafe {
                let context = self.api.eglGetCurrentContext();

                if context != NO_CONTEXT {
                    Some(Context(context))
                } else {
                    None
                }
            }
        }
    }
}

#[cfg(feature = "1_4")]
pub use egl1_4::*;

// ------------------------------------------------------------------------------------------------
// EGL 1.5
// ------------------------------------------------------------------------------------------------

#[cfg(feature = "1_5")]
mod egl1_5 {
    use super::*;

    pub type Time = u64;
    pub type EGLSync = *mut c_void;
    pub type EGLImage = *mut c_void;

    #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
    pub struct Sync(EGLSync);

    impl Sync {
        /// Creates a new sync form its EGL pointer.
        ///
        /// # Safety
        ///
        /// `ptr` must be a valid `EGLSync` pointer.
        #[inline]
        pub unsafe fn from_ptr(ptr: EGLSync) -> Sync {
            Sync(ptr)
        }

        #[inline]
        pub fn as_ptr(&self) -> EGLSync {
            self.0
        }
    }

    #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
    pub struct Image(EGLImage);

    impl Image {
        /// Creates a new image form its EGL pointer.
        ///
        /// # Safety
        ///
        /// `ptr` must be a valid `EGLImage` pointer.
        #[inline]
        pub unsafe fn from_ptr(ptr: EGLImage) -> Image {
            Image(ptr)
        }

        #[inline]
        pub fn as_ptr(&self) -> EGLImage {
            self.0
        }
    }

    pub const CONTEXT_MAJOR_VERSION: Int = 0x3098;
    pub const CONTEXT_MINOR_VERSION: Int = 0x30FB;
    pub const CONTEXT_OPENGL_PROFILE_MASK: Int = 0x30FD;
    pub const CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY: Int = 0x31BD;
    pub const NO_RESET_NOTIFICATION: Int = 0x31BE;
    pub const LOSE_CONTEXT_ON_RESET: Int = 0x31BF;
    pub const CONTEXT_OPENGL_CORE_PROFILE_BIT: Int = 0x00000001;
    pub const CONTEXT_OPENGL_COMPATIBILITY_PROFILE_BIT: Int = 0x00000002;
    pub const CONTEXT_OPENGL_DEBUG: Int = 0x31B0;
    pub const CONTEXT_OPENGL_FORWARD_COMPATIBLE: Int = 0x31B1;
    pub const CONTEXT_OPENGL_ROBUST_ACCESS: Int = 0x31B2;
    pub const OPENGL_ES3_BIT: Int = 0x00000040;
    pub const CL_EVENT_HANDLE: Int = 0x309C;
    pub const SYNC_CL_EVENT: Int = 0x30FE;
    pub const SYNC_CL_EVENT_COMPLETE: Int = 0x30FF;
    pub const SYNC_PRIOR_COMMANDS_COMPLETE: Int = 0x30F0;
    pub const SYNC_TYPE: Int = 0x30F7;
    pub const SYNC_STATUS: Int = 0x30F1;
    pub const SYNC_CONDITION: Int = 0x30F8;
    pub const SIGNALED: Int = 0x30F2;
    pub const UNSIGNALED: Int = 0x30F3;
    pub const SYNC_FLUSH_COMMANDS_BIT: Int = 0x0001;
    pub const FOREVER: u64 = 0xFFFFFFFFFFFFFFFFu64;
    pub const TIMEOUT_EXPIRED: Int = 0x30F5;
    pub const CONDITION_SATISFIED: Int = 0x30F6;
    pub const NO_SYNC: EGLSync = 0 as EGLSync;
    pub const SYNC_FENCE: Int = 0x30F9;
    pub const GL_COLORSPACE: Int = 0x309D;
    pub const GL_COLORSPACE_SRGB: Int = 0x3089;
    pub const GL_COLORSPACE_LINEAR: Int = 0x308A;
    pub const GL_RENDERBUFFER: Int = 0x30B9;
    pub const GL_TEXTURE_2D: Int = 0x30B1;
    pub const GL_TEXTURE_LEVEL: Int = 0x30BC;
    pub const GL_TEXTURE_3D: Int = 0x30B2;
    pub const GL_TEXTURE_ZOFFSET: Int = 0x30BD;
    pub const GL_TEXTURE_CUBE_MAP_POSITIVE_X: Int = 0x30B3;
    pub const GL_TEXTURE_CUBE_MAP_NEGATIVE_X: Int = 0x30B4;
    pub const GL_TEXTURE_CUBE_MAP_POSITIVE_Y: Int = 0x30B5;
    pub const GL_TEXTURE_CUBE_MAP_NEGATIVE_Y: Int = 0x30B6;
    pub const GL_TEXTURE_CUBE_MAP_POSITIVE_Z: Int = 0x30B7;
    pub const GL_TEXTURE_CUBE_MAP_NEGATIVE_Z: Int = 0x30B8;
    pub const IMAGE_PRESERVED: Int = 0x30D2;
    pub const NO_IMAGE: EGLImage = 0 as EGLImage;

    impl<T: api::EGL1_5> Instance<T> {
        /// Create a new EGL sync object.
        ///
        /// Note that the constant `ATTRIB_NONE` which has the type `Attrib` can be used
        /// instead of `NONE` to terminate the attribute list.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `ATTRIB_NONE`).
        ///
        /// # Safety
        ///
        /// When creating an OpenCL Event Sync Object, passing an invalid event
        /// handle in `attrib_list` may result in undefined behavior up to and including program
        /// termination.
        pub unsafe fn create_sync(
            &self,
            display: Display,
            ty: Enum,
            attrib_list: &[Attrib],
        ) -> Result<Sync, Error> {
            check_attrib_list(attrib_list)?;
            let sync = self
                .api
                .eglCreateSync(display.as_ptr(), ty, attrib_list.as_ptr());
            if sync != NO_SYNC {
                Ok(Sync(sync))
            } else {
                Err(self.get_error().unwrap())
            }
        }

        /// Destroy a sync object.
        ///
        /// # Safety
        ///
        /// If display does not match the display passed to eglCreateSync when
        /// sync was created, the behaviour is undefined.
        pub unsafe fn destroy_sync(&self, display: Display, sync: Sync) -> Result<(), Error> {
            if self.api.eglDestroySync(display.as_ptr(), sync.as_ptr()) == TRUE {
                Ok(())
            } else {
                Err(self.get_error().unwrap())
            }
        }

        /// Wait in the client for a sync object to be signalled.
        ///
        /// # Safety
        ///
        /// If `display` does not match the [`Display`] passed to [`create_sync`](Self::create_sync)
        /// when `sync` was created, the behaviour is undefined.
        pub unsafe fn client_wait_sync(
            &self,
            display: Display,
            sync: Sync,
            flags: Int,
            timeout: Time,
        ) -> Result<Int, Error> {
            let status =
                self.api
                    .eglClientWaitSync(display.as_ptr(), sync.as_ptr(), flags, timeout);
            if status != FALSE as Int {
                Ok(status)
            } else {
                Err(self.get_error().unwrap())
            }
        }

        /// Return an attribute of a sync object.
        ///
        /// # Safety
        ///
        /// If `display` does not match the [`Display`] passed to [`create_sync`](Self::create_sync)
        /// when `sync` was created, behavior is undefined.
        pub unsafe fn get_sync_attrib(
            &self,
            display: Display,
            sync: Sync,
            attribute: Int,
        ) -> Result<Attrib, Error> {
            let mut value = 0;
            if self.api.eglGetSyncAttrib(
                display.as_ptr(),
                sync.as_ptr(),
                attribute,
                &mut value as *mut Attrib,
            ) == TRUE
            {
                Ok(value)
            } else {
                Err(self.get_error().unwrap())
            }
        }

        /// Create a new Image object.
        ///
        /// Note that the constant `ATTRIB_NONE` which has the type `Attrib` can be used
        /// instead of `NONE` to terminate the attribute list.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `ATTRIB_NONE`).
        pub fn create_image(
            &self,
            display: Display,
            ctx: Context,
            target: Enum,
            buffer: ClientBuffer,
            attrib_list: &[Attrib],
        ) -> Result<Image, Error> {
            check_attrib_list(attrib_list)?;
            unsafe {
                let image = self.api.eglCreateImage(
                    display.as_ptr(),
                    ctx.as_ptr(),
                    target,
                    buffer.as_ptr(),
                    attrib_list.as_ptr(),
                );
                if image != NO_IMAGE {
                    Ok(Image(image))
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Destroy an Image object.
        pub fn destroy_image(&self, display: Display, image: Image) -> Result<(), Error> {
            unsafe {
                if self.api.eglDestroyImage(display.as_ptr(), image.as_ptr()) == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }

        /// Return an EGL display connection.
        ///
        /// Note that the constant `ATTRIB_NONE` which has the type `Attrib` can be used
        /// instead of `NONE` to terminate the attribute list.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `ATTRIB_NONE`).
        ///
        /// # Safety
        ///
        /// The `native_display` must be a valid pointer to the native display.
        /// Valid values for platform are defined by EGL extensions, as are
        /// requirements for native_display. For example, an extension
        /// specification that defines support for the X11 platform may require
        /// that native_display be a pointer to an X11 Display, and an extension
        /// specification that defines support for the Microsoft Windows
        /// platform may require that native_display be a pointer to a Windows
        /// Device Context.
        pub unsafe fn get_platform_display(
            &self,
            platform: Enum,
            native_display: NativeDisplayType,
            attrib_list: &[Attrib],
        ) -> Result<Display, Error> {
            check_attrib_list(attrib_list)?;

            let display =
                self.api
                    .eglGetPlatformDisplay(platform, native_display, attrib_list.as_ptr());
            if display != NO_DISPLAY {
                Ok(Display::from_ptr(display))
            } else {
                Err(self.get_error().unwrap())
            }
        }

        /// Create a new EGL on-screen rendering surface.
        ///
        /// Note that the constant `ATTRIB_NONE` which has the type `Attrib` can be used
        /// instead of `NONE` to terminate the attribute list.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `ATTRIB_NONE`).
        ///
        /// # Safety
        ///
        /// The `native_window` must be a valid pointer to the native window
        /// and must belong to the same platform as `display`.
        /// EGL considers the returned EGLSurface as belonging to that same platform.
        /// The EGL extension that defines the platform to which display belongs
        /// also defines the requirements for the `native_window` parameter.
        pub unsafe fn create_platform_window_surface(
            &self,
            display: Display,
            config: Config,
            native_window: NativeWindowType,
            attrib_list: &[Attrib],
        ) -> Result<Surface, Error> {
            check_attrib_list(attrib_list)?;

            let surface = self.api.eglCreatePlatformWindowSurface(
                display.as_ptr(),
                config.as_ptr(),
                native_window,
                attrib_list.as_ptr(),
            );
            if surface != NO_SURFACE {
                Ok(Surface::from_ptr(surface))
            } else {
                Err(self.get_error().unwrap())
            }
        }

        /// Create a new EGL offscreen surface.
        ///
        /// Note that the constant `ATTRIB_NONE` which has the type `Attrib` can be used
        /// instead of `NONE` to terminate the attribute list.
        ///
        /// This will return a `BadParameter` error if `attrib_list` is not a valid
        /// attributes list (if it does not terminate with `ATTRIB_NONE`).
        ///
        /// # Safety
        ///
        /// The `native_pixmap` must be a valid pointer to a native pixmap.
        /// and must belong to the same platform as `display`.
        /// EGL considers the returned EGLSurface as belonging to that same platform.
        /// The EGL extension that defines the platform to which display belongs
        /// also defines the requirements for the `native_pixmap` parameter.
        pub unsafe fn create_platform_pixmap_surface(
            &self,
            display: Display,
            config: Config,
            native_pixmap: NativePixmapType,
            attrib_list: &[Attrib],
        ) -> Result<Surface, Error> {
            check_attrib_list(attrib_list)?;

            let surface = self.api.eglCreatePlatformPixmapSurface(
                display.as_ptr(),
                config.as_ptr(),
                native_pixmap,
                attrib_list.as_ptr(),
            );
            if surface != NO_SURFACE {
                Ok(Surface::from_ptr(surface))
            } else {
                Err(self.get_error().unwrap())
            }
        }

        /// Wait in the server for a sync object to be signalled.
        ///
        /// This function is unsafe: if `display` does not match the [`Display`] passed to [`create_sync`](Self::create_sync)
        /// when `sync` was created, the behavior is undefined.
        pub fn wait_sync(&self, display: Display, sync: Sync, flags: Int) -> Result<(), Error> {
            unsafe {
                if self.api.eglWaitSync(display.as_ptr(), sync.as_ptr(), flags) == TRUE {
                    Ok(())
                } else {
                    Err(self.get_error().unwrap())
                }
            }
        }
    }
}

#[cfg(feature = "1_5")]
pub use egl1_5::*;

// -------------------------------------------------------------------------------------------------
// FFI
// -------------------------------------------------------------------------------------------------

macro_rules! api {
	($($id:ident : $version:literal { $(fn $name:ident ($($arg:ident : $atype:ty ),* ) -> $rtype:ty ;)* }),*) => {
		#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
		pub enum Version {
			$(
				#[cfg(feature=$version)]
				$id,
			)*
		}

		impl std::fmt::Display for Version {
			fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
				match self {
					$(
						#[cfg(feature=$version)]
						Version::$id => write!(f, $version),
					)*
				}
			}
		}

		pub mod api {
			use super::*;

			api!(@api_traits () () $($id : $version { $(fn $name ($($arg : $atype ),* ) -> $rtype ;)* })*);
		}

		#[cfg(feature="dynamic")]
		extern crate libloading;

		api!(@dynamic_struct $($id : $version { $(fn $name ($($arg : $atype ),* ) -> $rtype ;)* })*);
		api!(@api_types () $($id : $version { $(fn $name ($($arg : $atype ),* ) -> $rtype ;)* })*);
	};
	(@dynamic_struct $($id:ident : $version:literal { $(fn $name:ident ($($arg:ident : $atype:ty ),* ) -> $rtype:ty ;)* })*) => {
		#[cfg(feature="dynamic")]
		#[derive(Debug)]
		pub enum LoadError<L> {
			/// Something wrong happend while loading the library.
			Library(L),

			/// The provided version does not meet the requirements.
			InvalidVersion {
				provided: Version,
				required: Version
			}
		}

		#[cfg(feature="dynamic")]
		impl<L: std::error::Error + 'static> std::error::Error for LoadError<L> {
			fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
				match self {
					LoadError::Library(l) => Some(l),
					_ => None
				}
			}
		}

		#[cfg(feature="dynamic")]
		impl<L: std::fmt::Display> std::fmt::Display for LoadError<L> {
			fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
				match self {
					LoadError::Library(l) => write!(f, "Load error: {}", l),
					LoadError::InvalidVersion { provided, required } => write!(f, "Invalid EGL API version (required {}, provided {})", required, provided)
				}
			}
		}

		#[cfg(feature="dynamic")]
		struct RawDynamic<L> {
			lib: L,
			version: Version,
			$(
				$(
					#[cfg(feature=$version)]
					$name : std::mem::MaybeUninit<unsafe extern "system" fn($($atype ),*) -> $rtype>,
				)*
			)*
		}

		#[cfg(feature="dynamic")]
		impl<L> RawDynamic<L> {
			#[inline(always)]
			/// Returns the underlying EGL library.
			pub fn library(&self) -> &L {
				&self.lib
			}

			#[inline(always)]
			/// Returns the EGL version.
			pub fn version(&self) -> Version {
				self.version
			}

			#[inline(always)]
			/// Sets the EGL version.
			pub unsafe fn set_version(&mut self, version: Version) {
				self.version = version
			}

			/// Wraps the given library but does not load the symbols.
			pub unsafe fn unloaded(lib: L, version: Version) -> Self {
				RawDynamic {
					lib,
					version,
					$(
						$(
							#[cfg(feature=$version)]
							$name : std::mem::MaybeUninit::uninit(),
						)*
					)*
				}
			}
		}

		#[cfg(feature="dynamic")]
		/// Dynamic EGL API interface.
		///
		/// The first type parameter is the type of the underlying library handle.
		/// The second `Dynamic` type parameter gives the EGL API version provided by the library.
		///
		/// This type is only available when the `dynamic` feature is enabled.
		/// In most cases, you may prefer to directly use the `DynamicInstance` type.
		pub struct Dynamic<L, A> {
			raw: RawDynamic<L>,
			_api_version: std::marker::PhantomData<A>
		}

		#[cfg(feature="dynamic")]
		impl<L, A> Dynamic<L, A> {
			#[inline(always)]
			/// Return the underlying EGL library.
			pub fn library(&self) -> &L {
				self.raw.library()
			}

			/// Returns the provided EGL version.
			pub fn version(&self) -> Version {
				self.raw.version()
			}

			/// Wraps the given library but does not load the symbols.
			pub(crate) unsafe fn unloaded(lib: L, version: Version) -> Self {
				Dynamic {
					raw: RawDynamic::unloaded(lib, version),
					_api_version: std::marker::PhantomData
				}
			}
		}

		#[cfg(feature="dynamic")]
		impl<L, A> Api for Dynamic<L, A> {
			/// Returns the provided EGL version.
			#[inline(always)]
			fn version(&self) -> Version {
				self.version()
			}
		}

		#[cfg(feature="dynamic")]
		#[cfg(feature="1_0")]
		impl<L: std::borrow::Borrow<libloading::Library>> Dynamic<L, EGL1_0> {
			#[inline]
			/// Load the EGL API symbols from the given library.
			///
			/// This will load the most recent API provided by the library,
			/// which is at least EGL 1.0.
			/// You can check what version has actually been loaded using [`Dynamic::version`],
			/// and/or convert to a more recent version using [`try_into`](TryInto::try_into).
			///
			/// ## Safety
			/// This is fundamentally unsafe since there are no guaranties the input library complies to the EGL API.
			pub unsafe fn load_from(lib: L) -> Result<Dynamic<L, EGL1_0>, libloading::Error> {
				let mut result = Dynamic::unloaded(lib, Version::EGL1_0);

				$(
					match $id::load_from(&mut result.raw) {
						Ok(()) => result.raw.set_version(Version::$id),
						Err(libloading::Error::DlSymUnknown) => {
							if Version::$id == Version::EGL1_0 {
								return Err(libloading::Error::DlSymUnknown) // we require at least EGL 1.0.
							} else {
								return Ok(result)
							}
						},
						Err(e @ libloading::Error::DlSym { .. }) => {
							if Version::$id == Version::EGL1_0 {
								return Err(e) // we require at least EGL 1.0.
							} else {
								return Ok(result)
							}
						},
						Err(e) => return Err(e)
					}
				)*

				Ok(result)
			}
		}

		#[cfg(feature="dynamic")]
		#[cfg(feature="1_0")]
		impl<L: std::borrow::Borrow<libloading::Library>> Instance<Dynamic<L, EGL1_0>> {
			#[inline(always)]
			/// Create an EGL instance using the symbols provided by the given library.
			///
			/// The most recent version of EGL provided by the given library is loaded.
			/// You can check what version has actually been loaded using [`Instance::version`],
			/// and/or convert to a more recent version using [`try_into`](TryInto::try_into).
			///
			/// ## Safety
			/// This is fundamentally unsafe since there are no guaranties the input library complies to the EGL API.
			pub unsafe fn load_from(lib: L) -> Result<Instance<Dynamic<L, EGL1_0>>, libloading::Error> {
				Ok(Instance::new(Dynamic::<L, EGL1_0>::load_from(lib)?))
			}
		}

		#[cfg(feature="dynamic")]
		impl<L, V> Instance<Dynamic<L, V>> {
			/// Cast the API.
			#[inline(always)]
			pub fn downcast<W>(&self) -> &Instance<Dynamic<L, W>> where Instance<Dynamic<L, V>>: Downcast<Instance<Dynamic<L, W>>> {
				Downcast::downcast(self)
			}

			/// Cast the API.
			#[inline(always)]
			pub fn upcast<W>(&self) -> Option<&Instance<Dynamic<L, W>>> where Instance<Dynamic<L, V>>: Upcast<Instance<Dynamic<L, W>>> {
				Upcast::upcast(self)
			}
		}

		#[cfg(feature="dynamic")]
		unsafe impl<L: std::borrow::Borrow<libloading::Library> + Send, A: Send> Send for Dynamic<L, A> {}

		#[cfg(feature="dynamic")]
		unsafe impl<L: std::borrow::Borrow<libloading::Library> + std::marker::Sync, A: std::marker::Sync> std::marker::Sync for Dynamic<L, A> {}

		#[cfg(feature="dynamic")]
		impl<L: std::borrow::Borrow<libloading::Library> + fmt::Debug, A> fmt::Debug for Dynamic<L, A> {
			fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
				write!(f, "Dynamic({:?})", self.library())
			}
		}
	};
	(@api_traits ( ) ( ) $id:ident : $version:literal { $(fn $name:ident ($($arg:ident : $atype:ty ),* ) -> $rtype:ty ;)* } $($t_id:ident : $t_version:literal { $(fn $t_name:ident ($($t_arg:ident : $t_atype:ty ),* ) -> $t_rtype:ty ;)* })*) => {
		api!(@api_trait ( ) ( ) $id : $version { $(fn $name ($($arg : $atype ),* ) -> $rtype ;)* });
		api!(@api_traits ( $id : $version ) ( : $id ) $($t_id : $t_version { $(fn $t_name ($($t_arg : $t_atype ),* ) -> $t_rtype ;)* })*);
	};
	(@api_traits ( $($pred:ident : $p_version:literal)+ ) ( $($deps:tt)+ ) $id:ident : $version:literal { $(fn $name:ident ($($arg:ident : $atype:ty ),* ) -> $rtype:ty ;)* } $($t_id:ident : $t_version:literal { $(fn $t_name:ident ($($t_arg:ident : $t_atype:ty ),* ) -> $t_rtype:ty ;)* })*) => {
		api!(@api_trait ( $($pred : $p_version)* ) ( $($deps)* ) $id : $version { $(fn $name ($($arg : $atype ),* ) -> $rtype ;)* });
		api!(@api_traits ( $($pred : $version)* $id : $version ) ( $($deps)* + $id ) $($t_id : $t_version { $(fn $t_name ($($t_arg : $t_atype ),* ) -> $t_rtype ;)* })*);
	};
	(@api_traits ( $($pred:ident : $p_version:literal)* ) ( $($deps:tt)* )) => {
		// nothing
	};
	(@api_trait ( $($pred:ident : $p_version:literal)* ) ( $($deps:tt)* ) $id:ident : $version:literal { $(fn $name:ident ($($arg:ident : $atype:ty ),* ) -> $rtype:ty ;)* }) => {
		/// EGL API interface.
		///
		/// An implementation of this trait can be used to create an [`Instance`].
		///
		/// This crate provides one implementation of this trait:
		///  - [`Dynamic`] which is available with the `dynamic` feature enabled,
		///    defined by dynamically linking to the EGL library at runtime.
		///    In this case, you may prefer to directly use the `DynamicInstance` type.
		#[cfg(feature=$version)]
		pub unsafe trait $id $($deps)* {
			$(
				unsafe fn $name (&self, $($arg : $atype ),* ) -> $rtype ;
			)*
		}
	};
	(@api_types ( ) $id:ident : $version:literal { $(fn $name:ident ($($arg:ident : $atype:ty ),* ) -> $rtype:ty ;)* } $($t_id:ident : $t_version:literal { $(fn $t_name:ident ($($t_arg:ident : $t_atype:ty ),* ) -> $t_rtype:ty ;)* })*) => {
		#[cfg(feature="dynamic")]
		$(
			#[cfg(not(feature=$t_version))]
		)*
		#[cfg(feature=$version)]
		/// Latest available EGL version.
		pub type Latest = $id;

		$(
			#[cfg(not(feature=$t_version))]
		)*
		#[cfg(feature=$version)]
		/// Latest available EGL version.
		pub const LATEST: Version = Version::$id;

		api!(@api_type ( ) $id : $version { $(fn $name ($($arg : $atype ),* ) -> $rtype ;)* });
		api!(@api_types ( $id : $version { $(fn $name ($($arg : $atype ),* ) -> $rtype ;)* } ) $($t_id : $t_version { $(fn $t_name ($($t_arg : $t_atype ),* ) -> $t_rtype ;)* })*);
	};
	(@api_types ( $($pred:ident : $p_version:literal { $(fn $p_name:ident ($($p_arg:ident : $p_atype:ty ),* ) -> $p_rtype:ty ;)* })+ ) $id:ident : $version:literal { $(fn $name:ident ($($arg:ident : $atype:ty ),* ) -> $rtype:ty ;)* } $($t_id:ident : $t_version:literal { $(fn $t_name:ident ($($t_arg:ident : $t_atype:ty ),* ) -> $t_rtype:ty ;)* })*) => {
		#[cfg(feature="dynamic")]
		$(
			#[cfg(not(feature=$t_version))]
		)*
		#[cfg(feature=$version)]
		/// Latest available EGL version.
		pub type Latest = $id;

		$(
			#[cfg(not(feature=$t_version))]
		)*
		#[cfg(feature=$version)]
		/// Latest available EGL version.
		pub const LATEST: Version = Version::$id;

		api!(@api_type ( $($pred : $p_version { $(fn $p_name ($($p_arg : $p_atype ),* ) -> $p_rtype ;)* })* ) $id : $version { $(fn $name ($($arg : $atype ),* ) -> $rtype ;)* });
		api!(@api_types ( $($pred : $p_version { $(fn $p_name ($($p_arg : $p_atype ),* ) -> $p_rtype ;)* })* $id : $version { $(fn $name ($($arg : $atype ),* ) -> $rtype ;)* } ) $($t_id : $t_version { $(fn $t_name ($($t_arg : $t_atype ),* ) -> $t_rtype ;)* })*);
	};
	(@api_types ( $($pred:ident : $p_version:literal { $(fn $p_name:ident ($($p_arg:ident : $p_atype:ty ),* ) -> $p_rtype:ty ;)* })+ ) ) => {
		#[cfg(feature="dynamic")]
		#[cfg(feature="1_0")]
		/// Alias for dynamically linked instances with the latest handled version of EGL.
		pub type DynamicInstance<V = Latest> = Instance<Dynamic<libloading::Library, V>>;

		#[cfg(feature="dynamic")]
		#[cfg(feature="1_0")]
		impl DynamicInstance<EGL1_0> {
			#[inline(always)]
			/// Create an EGL instance by finding and loading a dynamic library with the given filename.
			///
			/// See [`Library::new`](libloading::Library::new)
			/// for more details on how the `filename` argument is used.
			///
			/// On Linux plateforms, the library is loaded with the `RTLD_NODELETE` flag.
			/// See [#14](https://github.com/timothee-haudebourg/khronos-egl/issues/14) for more details.
			///
			/// ## Safety
			/// This is fundamentally unsafe since there are no guaranties the input library complies to the EGL API.
			pub unsafe fn load_from_filename<P: libloading::AsFilename>(filename: P) -> Result<DynamicInstance<EGL1_0>, libloading::Error> {
				#[cfg(target_os = "linux")]
				let lib: libloading::Library = {
					// On Linux, load library with `RTLD_NOW | RTLD_NODELETE` to fix a SIGSEGV
					// See https://github.com/timothee-haudebourg/khronos-egl/issues/14 for more details.
					libloading::os::unix::Library::open(Some(filename), 0x2 | 0x1000)?.into()
				};
				#[cfg(not(target_os = "linux"))]
				let lib = libloading::Library::new(filename)?;
				Self::load_from(lib)
			}

			#[inline(always)]
			/// Create an EGL instance by finding and loading the `libEGL.so.1` or `libEGL.so` library.
			///
			/// This is equivalent to `DynamicInstance::load_from_filename("libEGL.so.1")`.
			///
			/// ## Safety
			/// This is fundamentally unsafe since there are no guaranties the found library complies to the EGL API.
			pub unsafe fn load() -> Result<DynamicInstance<EGL1_0>, libloading::Error> {
				Self::load_from_filename("libEGL.so.1").or(Self::load_from_filename("libEGL.so"))
			}
		}
	};
	(@api_type ( $($pred:ident : $p_version:literal { $(fn $p_name:ident ($($p_arg:ident : $p_atype:ty ),* ) -> $p_rtype:ty ;)* })* ) $id:ident : $version:literal { $(fn $name:ident ($($arg:ident : $atype:ty ),* ) -> $rtype:ty ;)* }) => {
		#[cfg(feature="dynamic")]
		#[cfg(feature=$version)]
		/// EGL version type.
		///
		/// Used by [`Dynamic`] to statically know the EGL API version provided by the library.
		pub struct $id;

		#[cfg(feature="dynamic")]
		#[cfg(feature=$version)]
		impl $id {
			#[allow(unused_variables)]
			unsafe fn load_from<L: std::borrow::Borrow<libloading::Library>>(raw: &mut RawDynamic<L>) -> Result<(), libloading::Error> {
				let lib = raw.lib.borrow();

				$(
					let name = stringify!($name).as_bytes();
					let symbol = lib.get::<unsafe extern "system" fn($($atype ),*) -> $rtype>(name)?;
					#[cfg(unix)]
					let ptr = (&symbol.into_raw().into_raw()) as *const *mut _ as *const unsafe extern "system" fn($($atype ),*) -> $rtype;
					#[cfg(windows)]
					let ptr = (&symbol.into_raw().into_raw()) as *const _ as *const unsafe extern "system" fn($($atype ),*) -> $rtype;
					assert!(!ptr.is_null());
					raw.$name = std::mem::MaybeUninit::new(*ptr);
				)*

				Ok(())
			}
		}

		$(
			#[cfg(feature="dynamic")]
			#[cfg(feature=$version)]
			unsafe impl<L: std::borrow::Borrow<libloading::Library>> api::$pred for Dynamic<L, $id> {
				$(
					#[inline(always)]
					unsafe fn $p_name(&self, $($p_arg : $p_atype),*) -> $p_rtype {
						(self.raw.$p_name.assume_init())($($p_arg),*)
					}
				)*
			}
		)*

		#[cfg(feature="dynamic")]
		#[cfg(feature=$version)]
		unsafe impl<L: std::borrow::Borrow<libloading::Library>> api::$id for Dynamic<L, $id> {
			$(
				#[inline(always)]
				unsafe fn $name(&self, $($arg : $atype),*) -> $rtype {
					(self.raw.$name.assume_init())($($arg),*)
				}
			)*
		}

		$(
			#[cfg(feature="dynamic")]
			#[cfg(feature=$version)]
			impl<L: std::borrow::Borrow<libloading::Library>> TryFrom<Dynamic<L, $pred>> for Dynamic<L, $id> {
				type Error = Dynamic<L, $pred>;

				fn try_from(other: Dynamic<L, $pred>) -> Result<Self, Dynamic<L, $pred>> {
					if other.version() >= Version::$id {
						Ok(Dynamic {
							raw: other.raw,
							_api_version: std::marker::PhantomData
						})
					} else {
						Err(other)
					}
				}
			}

			#[cfg(feature="dynamic")]
			#[cfg(feature=$version)]
			impl<L: std::borrow::Borrow<libloading::Library>> From<Dynamic<L, $id>> for Dynamic<L, $pred> {
				fn from(other: Dynamic<L, $id>) -> Self {
					Dynamic {
						raw: other.raw,
						_api_version: std::marker::PhantomData
					}
				}
			}

			#[cfg(feature="dynamic")]
			#[cfg(feature=$version)]
			impl<L: std::borrow::Borrow<libloading::Library>> AsRef<Dynamic<L, $pred>> for Dynamic<L, $id> {
				fn as_ref(&self) -> &Dynamic<L, $pred> {
					unsafe { std::mem::transmute(self) } // this is safe because both types have the same repr.
				}
			}

			#[cfg(feature="dynamic")]
			#[cfg(feature=$version)]
			impl<L: std::borrow::Borrow<libloading::Library>> Downcast<Dynamic<L, $pred>> for Dynamic<L, $id> {
				fn downcast(&self) -> &Dynamic<L, $pred> {
					unsafe { std::mem::transmute(self) } // this is safe because both types have the same repr.
				}
			}

			#[cfg(feature="dynamic")]
			#[cfg(feature=$version)]
			impl<L: std::borrow::Borrow<libloading::Library>> Downcast<Instance<Dynamic<L, $pred>>> for Instance<Dynamic<L, $id>> {
				fn downcast(&self) -> &Instance<Dynamic<L, $pred>> {
					unsafe { std::mem::transmute(self) } // this is safe because both types have the same repr.
				}
			}

			#[cfg(feature="dynamic")]
			#[cfg(feature=$version)]
			impl<L: std::borrow::Borrow<libloading::Library>> Upcast<Dynamic<L, $id>> for Dynamic<L, $pred> {
				fn upcast(&self) -> Option<&Dynamic<L, $id>> {
					if self.version() >= Version::$id {
						Some(unsafe { std::mem::transmute(self) }) // this is safe because both types have the same repr.
					} else {
						None
					}
				}
			}

			#[cfg(feature="dynamic")]
			#[cfg(feature=$version)]
			impl<L: std::borrow::Borrow<libloading::Library>> Upcast<Instance<Dynamic<L, $id>>> for Instance<Dynamic<L, $pred>> {
				fn upcast(&self) -> Option<&Instance<Dynamic<L, $id>>> {
					if self.version() >= Version::$id {
						Some(unsafe { std::mem::transmute(self) }) // this is safe because both types have the same repr.
					} else {
						None
					}
				}
			}
		)*

		#[cfg(feature="dynamic")]
		#[cfg(feature=$version)]
		impl<L: std::borrow::Borrow<libloading::Library>> Dynamic<L, $id> {
			#[inline]
			/// Load the EGL API symbols from the given library.
			///
			/// The second `Dynamic` type parameter gives the EGL API version expected to be provided by the library.
			///
			/// ## Safety
			/// This is fundamentally unsafe since there are no guaranties the input library complies to the EGL API.
			pub unsafe fn load_required(lib: L) -> Result<Dynamic<L, $id>, LoadError<libloading::Error>> {
				match Dynamic::<L, EGL1_0>::load_from(lib) {
					Ok(dynamic) => {
						let provided = dynamic.version();
						match dynamic.try_into() {
							Ok(t) => Ok(t),
							Err(_) => Err(LoadError::InvalidVersion {
								provided,
								required: Version::$id
							})
						}
					},
					Err(e) => Err(LoadError::Library(e))
				}
			}
		}

		#[cfg(feature="dynamic")]
		#[cfg(feature=$version)]
		impl<L: std::borrow::Borrow<libloading::Library>> Instance<Dynamic<L, $id>> {
			#[inline(always)]
			/// Create an EGL instance using the symbols provided by the given library.
			/// This function fails if the EGL library does not provide the minimum required version given by the type parameter.
			///
			/// ## Safety
			/// This is fundamentally unsafe since there are no guaranties the input library complies to the EGL API.
			pub unsafe fn load_required_from(lib: L) -> Result<Instance<Dynamic<L, $id>>, LoadError<libloading::Error>> {
				Ok(Instance::new(Dynamic::<L, $id>::load_required(lib)?))
			}
		}

		#[cfg(feature="dynamic")]
		#[cfg(feature=$version)]
		impl DynamicInstance<$id> {
			#[inline(always)]
			/// Create an EGL instance by finding and loading a dynamic library with the given filename.
			/// This function fails if the EGL library does not provide the minimum required version given by the type parameter.
			///
			/// See [`Library::new`](libloading::Library::new)
			/// for more details on how the `filename` argument is used.
			///
			/// On Linux plateforms, the library is loaded with the `RTLD_NODELETE` flag.
			/// See [#14](https://github.com/timothee-haudebourg/khronos-egl/issues/14) for more details.
			///
			/// ## Safety
			/// This is fundamentally unsafe since there are no guaranties the input library complies to the EGL API.
			pub unsafe fn load_required_from_filename<P: libloading::AsFilename>(filename: P) -> Result<DynamicInstance<$id>, LoadError<libloading::Error>> {
				#[cfg(target_os = "linux")]
				let lib: libloading::Library = {
					// On Linux, load library with `RTLD_NOW | RTLD_NODELETE` to fix a SIGSEGV
					// See https://github.com/timothee-haudebourg/khronos-egl/issues/14 for more details.
					libloading::os::unix::Library::open(Some(filename), 0x2 | 0x1000).map_err(LoadError::Library)?.into()
				};
				#[cfg(not(target_os = "linux"))]
				let lib = libloading::Library::new(filename).map_err(LoadError::Library)?;
				Self::load_required_from(lib)
			}

			#[inline(always)]
			/// Create an EGL instance by finding and loading the `libEGL.so.1` or `libEGL.so` library.
			/// This function fails if the EGL library does not provide the minimum required version given by the type parameter.
			///
			/// This is equivalent to `DynamicInstance::load_required_from_filename("libEGL.so.1")`.
			///
			/// ## Safety
			/// This is fundamentally unsafe since there are no guaranties the found library complies to the EGL API.
			pub unsafe fn load_required() -> Result<DynamicInstance<$id>, LoadError<libloading::Error>> {
			    Self::load_required_from_filename("libEGL.so.1").or(Self::load_required_from_filename("libEGL.so"))
			}
		}
	}
}

api! {
    EGL1_0 : "1_0" {
        fn eglChooseConfig(
            display: EGLDisplay,
            attrib_list: *const Int,
            configs: *mut EGLConfig,
            config_size: Int,
            num_config: *mut Int
        ) -> Boolean;
        fn eglCopyBuffers(
            display: EGLDisplay,
            surface: EGLSurface,
            target: NativePixmapType
        ) -> Boolean;
        fn eglCreateContext(
            display: EGLDisplay,
            config: EGLConfig,
            share_context: EGLContext,
            attrib_list: *const Int
        ) -> EGLContext;
        fn eglCreatePbufferSurface(
            display: EGLDisplay,
            config: EGLConfig,
            attrib_list: *const Int
        ) -> EGLSurface;
        fn eglCreatePixmapSurface(
            display: EGLDisplay,
            config: EGLConfig,
            pixmap: NativePixmapType,
            attrib_list: *const Int
        ) -> EGLSurface;
        fn eglCreateWindowSurface(
            display: EGLDisplay,
            config: EGLConfig,
            win: NativeWindowType,
            attrib_list: *const Int
        ) -> EGLSurface;
        fn eglDestroyContext(display: EGLDisplay, ctx: EGLContext) -> Boolean;
        fn eglDestroySurface(display: EGLDisplay, surface: EGLSurface) -> Boolean;
        fn eglGetConfigAttrib(
            display: EGLDisplay,
            config: EGLConfig,
            attribute: Int,
            value: *mut Int
        ) -> Boolean;
        fn eglGetConfigs(
            display: EGLDisplay,
            configs: *mut EGLConfig,
            config_size: Int,
            num_config: *mut Int
        ) -> Boolean;
        fn eglGetCurrentDisplay() -> EGLDisplay;
        fn eglGetCurrentSurface(readdraw: Int) -> EGLSurface;
        fn eglGetDisplay(display_id: NativeDisplayType) -> EGLDisplay;
        fn eglGetError() -> Int;
        fn eglGetProcAddress(procname: *const c_char) -> extern "system" fn();
        fn eglInitialize(display: EGLDisplay, major: *mut Int, minor: *mut Int) -> Boolean;
        fn eglMakeCurrent(
            display: EGLDisplay,
            draw: EGLSurface,
            read: EGLSurface,
            ctx: EGLContext
        ) -> Boolean;
        fn eglQueryContext(
            display: EGLDisplay,
            ctx: EGLContext,
            attribute: Int,
            value: *mut Int
        ) -> Boolean;
        fn eglQueryString(display: EGLDisplay, name: Int) -> *const c_char;
        fn eglQuerySurface(
            display: EGLDisplay,
            surface: EGLSurface,
            attribute: Int,
            value: *mut Int
        ) -> Boolean;
        fn eglSwapBuffers(display: EGLDisplay, surface: EGLSurface) -> Boolean;
        fn eglTerminate(display: EGLDisplay) -> Boolean;
        fn eglWaitGL() -> Boolean;
        fn eglWaitNative(engine: Int) -> Boolean;
    },

    EGL1_1 : "1_1" {
        fn eglBindTexImage(display: EGLDisplay, surface: EGLSurface, buffer: Int) -> Boolean;
        fn eglReleaseTexImage(display: EGLDisplay, surface: EGLSurface, buffer: Int) -> Boolean;
        fn eglSurfaceAttrib(
            display: EGLDisplay,
            surface: EGLSurface,
            attribute: Int,
            value: Int
        ) -> Boolean;
        fn eglSwapInterval(display: EGLDisplay, interval: Int) -> Boolean;
    },

    EGL1_2 : "1_2" {
        fn eglBindAPI(api: Enum) -> Boolean;
        fn eglQueryAPI() -> Enum;
        fn eglCreatePbufferFromClientBuffer(
            display: EGLDisplay,
            buftype: Enum,
            buffer: EGLClientBuffer,
            config: EGLConfig,
            attrib_list: *const Int
        ) -> EGLSurface;
        fn eglReleaseThread() -> Boolean;
        fn eglWaitClient() -> Boolean;
    },

    EGL1_3 : "1_3" {
        // nothing.
    },

    EGL1_4 : "1_4" {
        fn eglGetCurrentContext() -> EGLContext;
    },

    EGL1_5 : "1_5" {
        fn eglCreateSync(display: EGLDisplay, type_: Enum, attrib_list: *const Attrib) -> EGLSync;
        fn eglDestroySync(display: EGLDisplay, sync: EGLSync) -> Boolean;
        fn eglClientWaitSync(display: EGLDisplay, sync: EGLSync, flags: Int, timeout: Time) -> Int;
        fn eglGetSyncAttrib(
            display: EGLDisplay,
            sync: EGLSync,
            attribute: Int,
            value: *mut Attrib
        ) -> Boolean;
        fn eglCreateImage(
            display: EGLDisplay,
            ctx: EGLContext,
            target: Enum,
            buffer: EGLClientBuffer,
            attrib_list: *const Attrib
        ) -> EGLImage;
        fn eglDestroyImage(display: EGLDisplay, image: EGLImage) -> Boolean;
        fn eglGetPlatformDisplay(
            platform: Enum,
            native_display: *mut c_void,
            attrib_list: *const Attrib
        ) -> EGLDisplay;
        fn eglCreatePlatformWindowSurface(
            display: EGLDisplay,
            config: EGLConfig,
            native_window: *mut c_void,
            attrib_list: *const Attrib
        ) -> EGLSurface;
        fn eglCreatePlatformPixmapSurface(
            display: EGLDisplay,
            config: EGLConfig,
            native_pixmap: *mut c_void,
            attrib_list: *const Attrib
        ) -> EGLSurface;
        fn eglWaitSync(display: EGLDisplay, sync: EGLSync, flags: Int) -> Boolean;
    }
}