Struct Context

pub struct Context { /* private fields */ }

A struct storing the global state which is used for all operations which require access to the GPU.

Examples

use crow::{
    glutin::{
        event::{Event, WindowEvent},
        event_loop::{ControlFlow, EventLoop},
        window::WindowBuilder,
    },
    Context, DrawConfig, Texture,
};

fn main() -> Result<(), crow::Error> {
    let event_loop = EventLoop::new();
    let mut ctx = Context::new(WindowBuilder::new(), &event_loop)?;

    let texture = Texture::load(&mut ctx, "./textures/player.png")?;

    event_loop.run(
        move |event: Event<()>, _window_target: _, control_flow: &mut ControlFlow| match event {
            Event::WindowEvent {
                event: WindowEvent::CloseRequested,
                ..
            } => *control_flow = ControlFlow::Exit,
            Event::MainEventsCleared => ctx.window().request_redraw(),
            Event::RedrawRequested(_) => {
                let mut surface = ctx.surface();
                ctx.clear_color(&mut surface, (0.4, 0.4, 0.8, 1.0));
                ctx.draw(&mut surface, &texture, (100, 150), &DrawConfig::default());
                ctx.present(surface).unwrap();
            }
            _ => (),
        },
    )
}

Implementations

impl Context

pub fn new<T>( window: WindowBuilder, event_loop: &EventLoop<T>, ) -> Result<Self, NewContextError>

Creates a new Context. It is not possible to have more than one Context in a program.

To create a new Context after a previous context was used, The previous context has to be dropped using the method Context::unlock_unchecked(). This is a workaround and will probably be fixed in a future release.

pub fn window_dimensions(&self) -> (u32, u32)

Returns the dimensions of the used window.

pub fn window_width(&self) -> u32

Returns the width of the used window.

pub fn window_height(&self) -> u32

Returns the height of the used window.

pub fn resize_window(&mut self, width: u32, height: u32)

Sets the dimensions of the used window.

pub fn maximum_texture_size(&self) -> (u32, u32)

Returns the size of the biggest supported texture.

Trying to create a texture with a size greater than maximum_texture_size results in an InvalidTextureSize error.

use crow::{Context, glutin::{window::WindowBuilder, event_loop::EventLoop}};

let mut ctx = Context::new(WindowBuilder::new(), &EventLoop::new()).unwrap();
println!("maximum supported texture size: {:?}", ctx.maximum_texture_size());

pub fn draw<T>( &mut self, target: &mut T, source: &Texture, position: (i32, i32), config: &DrawConfig, )

where T: DrawTarget,

Draws the source onto target.

To draw to the window, use Context::window_surface as a target.

pub fn debug_line<T>( &mut self, target: &mut T, from: (i32, i32), to: (i32, i32), color: (f32, f32, f32, f32), )

where T: DrawTarget,

Draws the a line going from from to to onto target with the given color.

To draw this line to the window, use Context::window_surface as a target.

pub fn debug_rectangle<T>( &mut self, target: &mut T, lower_left: (i32, i32), upper_right: (i32, i32), color: (f32, f32, f32, f32), )

where T: DrawTarget,

Draws the bounding box of an axis-aligned rectangle specified by its lower_left and upper_right corner.

In case lower_left is to the right or above upper_right, the two points will be flipped.

To draw this rectangle to the window, use Context::window_surface as a target.

pub fn clear_color<T>(&mut self, target: &mut T, color: (f32, f32, f32, f32))

where T: DrawTarget,

Clears the color of the given DrawTarget, setting each pixel to color

pub fn clear_depth<T>(&mut self, target: &mut T)

where T: DrawTarget,

Resets the depth buffer of the given DrawTarget to 1.0.

pub fn image_data<T>(&mut self, image: &T) -> RgbaImage

where T: DrawTarget,

Loads the current state of a DrawTarget into an image.

pub fn window(&self) -> &Window

Returns the inner window.

Examples

use crow::{
    glutin::{event_loop::EventLoop, window::WindowBuilder},
    Context,
};

let context = Context::new(
    WindowBuilder::new().with_title("Starting"),
    &EventLoop::new(),
)?;

context.window().set_title("Running");

pub fn surface(&mut self) -> WindowSurface

Returns a handle to the window surface.

This handle implements DrawTarget and can be used to draw to the window.

Use fn Context::present to actually display the resulting image.

pub fn present(&mut self, surface: WindowSurface) -> Result<(), FinalizeError>

Presents the current frame to the screen.

pub unsafe fn unlock_unchecked(self)

Drops this context while allowing the initialization of a new one afterwards.

Safety

This method may lead to undefined behavior if a struct, for example a Texture, which was created using the current context, is used with the new context.

Trait Implementations

impl Debug for Context

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.