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//! Windowing system interoperability
//!
//! Screen presentation (fullscreen or window) of images requires two objects:
//!
//! * [`Surface`] is the host abstraction of the native screen
//! * [`Swapchain`] is the device abstraction for a surface, containing multiple presentable images
//!
//! ## Window
//!
//! // DOC TODO
//!
//! ## Surface
//!
//! // DOC TODO
//!
//! ## Swapchain
//!
//! The most interesting part of a swapchain are the contained presentable images/backbuffers.
//! Presentable images are specialized images, which can be presented on the screen. They are
//! 2D color images with optionally associated depth-stencil images.
//!
//! The common steps for presentation of a frame are acquisition and presentation:
//!
//! ```no_run
//! # extern crate gfx_backend_empty as empty;
//! # extern crate gfx_hal;
//! # fn main() {
//! use gfx_hal::{Device, FrameSync};
//! # use gfx_hal::{CommandQueue, Graphics, Swapchain};
//!
//! # let mut swapchain: empty::Swapchain = return;
//! # let device: empty::Device = return;
//! # let mut present_queue: CommandQueue<empty::Backend, Graphics> = return;
//! # unsafe {
//! let acquisition_semaphore = device.create_semaphore().unwrap();
//! let render_semaphore = device.create_semaphore().unwrap();
//!
//! let frame = swapchain.acquire_image(!0, FrameSync::Semaphore(&acquisition_semaphore));
//! // render the scene..
//! // `render_semaphore` will be signalled once rendering has been finished
//! swapchain.present(&mut present_queue, 0, &[render_semaphore]);
//! # }}
//! ```
//!
//! Queues need to synchronize with the presentation engine, usually done via signalling a semaphore
//! once a frame is available for rendering and waiting on a separate semaphore until scene rendering
//! has finished.
//!
//! ### Recreation
//!
//! DOC TODO
use device;
use format::Format;
use image;
use queue::{Capability, CommandQueue};
use Backend;
use std::iter;
use std::any::Any;
use std::borrow::Borrow;
use std::cmp::{max, min};
use std::ops::Range;
/// Error occurred during swapchain creation.
#[derive(Clone, Copy, Debug, Fail, PartialEq, Eq)]
pub enum CreationError {
/// Out of either host or device memory.
#[fail(display = "{}", _0)]
OutOfMemory(device::OutOfMemory),
/// Device is lost
#[fail(display = "{}", _0)]
DeviceLost(device::DeviceLost),
/// Surface is lost
#[fail(display = "{}", _0)]
SurfaceLost(device::SurfaceLost),
/// Window in use
#[fail(display = "{}", _0)]
WindowInUse(device::WindowInUse),
}
impl From<device::OutOfMemory> for CreationError {
fn from(error: device::OutOfMemory) -> Self {
CreationError::OutOfMemory(error)
}
}
impl From<device::DeviceLost> for CreationError {
fn from(error: device::DeviceLost) -> Self {
CreationError::DeviceLost(error)
}
}
impl From<device::SurfaceLost> for CreationError {
fn from(error: device::SurfaceLost) -> Self {
CreationError::SurfaceLost(error)
}
}
impl From<device::WindowInUse> for CreationError {
fn from(error: device::WindowInUse) -> Self {
CreationError::WindowInUse(error)
}
}
/// An extent describes the size of a rectangle, such as
/// a window or texture. It is not used for referring to a
/// sub-rectangle; for that see `command::Rect`.
#[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct Extent2D {
/// Width
pub width: image::Size,
/// Height
pub height: image::Size,
}
impl From<image::Extent> for Extent2D {
fn from(ex: image::Extent) -> Self {
Extent2D {
width: ex.width,
height: ex.height,
}
}
}
impl Extent2D {
/// Convert into a regular image extent.
pub fn to_extent(&self) -> image::Extent {
image::Extent {
width: self.width,
height: self.height,
depth: 1,
}
}
}
/// Describes information about what a `Surface`'s properties are.
/// Fetch this with `surface.capabilities_and_formats(device)`.
#[derive(Debug, Clone)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct SurfaceCapabilities {
/// Number of presentable images supported by the adapter for a swapchain
/// created from this surface.
///
/// - `image_count.start` must be at least 1.
/// - `image_count.end` must be larger of equal to `image_count.start`.
pub image_count: Range<SwapImageIndex>,
/// Current extent of the surface.
///
/// `None` if the surface has no explicit size, depending on the swapchain extent.
pub current_extent: Option<Extent2D>,
/// Range of supported extents.
///
/// `current_extent` must be inside this range.
pub extents: Range<Extent2D>,
/// Maximum number of layers supported for presentable images.
///
/// Must be at least 1.
pub max_image_layers: image::Layer,
/// Supported image usage flags.
pub usage: image::Usage,
}
/// A `Surface` abstracts the surface of a native window, which will be presented
/// on the display.
pub trait Surface<B: Backend>: Any + Send + Sync {
/// Retrieve the surface image kind.
fn kind(&self) -> image::Kind;
/// Check if the queue family supports presentation to this surface.
///
/// # Examples
///
/// ```no_run
///
/// ```
fn supports_queue_family(&self, family: &B::QueueFamily) -> bool;
/// Query surface capabilities, formats, and present modes for this physical device.
///
/// Use this function for configuring swapchain creation.
///
/// Returns a tuple of surface capabilities and formats.
/// If formats is `None` than the surface has no preferred format and the
/// application may use any desired format.
fn compatibility(
&self,
physical_device: &B::PhysicalDevice,
) -> (SurfaceCapabilities, Option<Vec<Format>>, Vec<PresentMode>, Vec<CompositeAlpha>);
}
/// Index of an image in the swapchain.
///
/// The swapchain is a series of one or more images, usually
/// with one being drawn on while the other is displayed by
/// the GPU (aka double-buffering). A `SwapImageIndex` refers
/// to a particular image in the swapchain.
pub type SwapImageIndex = u32;
/// Synchronization primitives which will be signalled once a frame got retrieved.
///
/// The semaphore or fence _must_ be unsignalled.
pub enum FrameSync<'a, B: Backend> {
/// Semaphore used for synchronization.
///
/// Will be signaled once the frame backbuffer is available.
Semaphore(&'a B::Semaphore),
/// Fence used for synchronization.
///
/// Will be signaled once the frame backbuffer is available.
Fence(&'a B::Fence),
}
/// Specifies the mode regulating how a swapchain presents frames.
#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum PresentMode {
/// Don't ever wait for v-sync.
Immediate = 0,
/// Wait for v-sync, overwrite the last rendered frame.
Mailbox = 1,
/// Present frames in the same order they are rendered.
Fifo = 2,
/// Don't wait for the next v-sync if we just missed it.
Relaxed = 3,
}
/// Specifies the composition of the swapchain with regards to alpha component.
#[repr(C)]
#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
pub enum CompositeAlpha {
/// Ignore alpha and treat it as 1.0 at all times.
Opaque = 0,
/// Use the alpha, expect the color to already be multiplied by it.
PreMultiplied = 1,
/// Use the alpha, let the compositor multiply the color by it.
PostMultiplied = 2,
/// Default to native system settings.
Inherit = 3,
}
/// Contains all the data necessary to create a new `Swapchain`:
/// color, depth, and number of images.
///
/// # Examples
///
/// This type implements the builder pattern, method calls can be
/// easily chained.
///
/// ```no_run
/// # extern crate gfx_hal;
/// # fn main() {
/// # use gfx_hal::{SwapchainConfig};
/// # use gfx_hal::format::Format;
/// let config = SwapchainConfig::new(100, 100, Format::Bgra8Unorm, 2);
/// # }
/// ```
#[derive(Debug, Clone)]
pub struct SwapchainConfig {
/// Presentation mode.
pub present_mode: PresentMode,
/// Alpha composition mode.
pub composite_alpha: CompositeAlpha,
/// Format of the backbuffer images.
pub format: Format,
/// Requested image extent. Must be in
/// `SurfaceCapabilities::extents` range.
pub extent: Extent2D,
/// Number of images in the swapchain. Must be in
/// `SurfaceCapabilities::image_count` range.
pub image_count: SwapImageIndex,
/// Number of image layers. Must be lower or equal to
/// `SurfaceCapabilities::max_image_layers`.
pub image_layers: image::Layer,
/// Image usage of the backbuffer images.
pub image_usage: image::Usage,
}
impl SwapchainConfig {
/// Create a new default configuration (color images only).
///
/// # Examples
///
/// ```no_run
///
/// ```
pub fn new(width: u32, height: u32, format: Format, image_count: SwapImageIndex) -> Self {
SwapchainConfig {
present_mode: PresentMode::Fifo,
composite_alpha: CompositeAlpha::Inherit,
format,
extent: Extent2D { width, height },
image_count,
image_layers: 1,
image_usage: image::Usage::COLOR_ATTACHMENT,
}
}
/// Create a swapchain configuration based on the capabilities
/// returned from a physical device query. If the surface does not
/// specify a current size, default_extent is clamped and used instead.
pub fn from_caps(caps: &SurfaceCapabilities, format: Format, default_extent: Extent2D) -> Self {
let clamped_extent = match caps.current_extent {
Some(current) => current,
None => {
let (min_width, max_width) = (caps.extents.start.width, caps.extents.end.width - 1);
let (min_height, max_height) =
(caps.extents.start.height, caps.extents.end.height - 1);
// clamp the default_extent to within the allowed surface sizes
let width = min(max_width, max(default_extent.width, min_width));
let height = min(max_height, max(default_extent.height, min_height));
Extent2D { width, height }
}
};
SwapchainConfig {
present_mode: PresentMode::Fifo,
composite_alpha: CompositeAlpha::Inherit,
format,
extent: clamped_extent,
image_count: caps.image_count.start,
image_layers: 1,
image_usage: image::Usage::COLOR_ATTACHMENT,
}
}
/// Specify the presentation mode.
///
/// # Examples
///
/// ```no_run
///
/// ```
pub fn with_mode(mut self, mode: PresentMode) -> Self {
self.present_mode = mode;
self
}
/// Specify the usage of backbuffer images.
///
/// # Examples
///
/// ```no_run
///
/// ```
pub fn with_image_usage(mut self, usage: image::Usage) -> Self {
self.image_usage = usage;
self
}
// TODO: depth-only, stencil-only, swapchain size, present modes, etc.
}
/// Swapchain backbuffer type
#[derive(Debug)]
pub enum Backbuffer<B: Backend> {
/// Color image chain
Images(Vec<B::Image>),
/// A single opaque framebuffer
Framebuffer(B::Framebuffer),
}
/// Error on acquiring the next image from a swapchain.
#[derive(Debug)]
pub enum AcquireError {
/// No image was ready after the specified timeout expired.
NotReady,
/// The swapchain is no longer in sync with the surface, needs to be re-created.
OutOfDate,
/// The surface was lost, and the swapchain is no longer usable.
SurfaceLost(device::SurfaceLost),
}
/// The `Swapchain` is the backend representation of the surface.
/// It consists of multiple buffers, which will be presented on the surface.
pub trait Swapchain<B: Backend>: Any + Send + Sync {
/// Acquire a new swapchain image for rendering. This needs to be called before presenting.
///
/// May fail according to one of the reasons indicated in `AcquireError` enum.
///
/// # Synchronization
///
/// The acquired image will not be immediately available when the function returns.
/// Once available the underlying primitive of `sync` will be signaled.
/// This can either be a [`Semaphore`](../trait.Resources.html#associatedtype.Semaphore)
/// or a [`Fence`](../trait.Resources.html#associatedtype.Fence).
///
/// # Examples
///
/// ```no_run
///
/// ```
unsafe fn acquire_image(
&mut self,
timeout_ns: u64,
sync: FrameSync<B>,
) -> Result<SwapImageIndex, AcquireError>;
/// Present one acquired image.
///
/// # Safety
///
/// The passed queue _must_ support presentation on the surface, which is
/// used for creating this swapchain.
///
/// # Examples
///
/// ```no_run
///
/// ```
unsafe fn present<'a, C, S, Iw>(
&'a self,
present_queue: &mut CommandQueue<B, C>,
image_index: SwapImageIndex,
wait_semaphores: Iw,
) -> Result<(), ()>
where
Self: 'a + Sized + Borrow<B::Swapchain>,
C: Capability,
S: 'a + Borrow<B::Semaphore>,
Iw: IntoIterator<Item = &'a S>,
{
present_queue.present(iter::once((self, image_index)), wait_semaphores)
}
/// Present one acquired image without any semaphore synchronization.
unsafe fn present_nosemaphores<'a, C>(
&'a self,
present_queue: &mut CommandQueue<B, C>,
image_index: SwapImageIndex,
) -> Result<(), ()>
where
Self: 'a + Sized + Borrow<B::Swapchain>,
C: Capability,
{
self.present::<_, B::Semaphore, _>(present_queue, image_index, iter::empty())
}
}