Trait Renderer

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pub trait Renderer: Send + 'static {
    // Required methods
    fn attach(&mut self, target: FrameTarget) -> Result<(), RenderError>;
    fn resize(&mut self, width: u32, height: u32) -> bool;
    fn wants_present(
        &mut self,
        render_world: &mut World,
        request: FrameRequest,
    ) -> bool;
    fn present(&mut self, render_world: &mut World) -> Result<(), RenderError>;
    fn detach(&mut self);
}

Expand description

A render backend’s renderer: everything between the retained scene and the pixels.

The renderer owns scene assembly, encoding caches, damage tracking, and whatever its target needs (a swap chain, a window buffer, an offscreen image). No graphics-API type crosses the boundary, so a caller compiles without naming one. Frames are driven from the render world, which already holds the retained scene, the viewport, the text shaper, and the screenshot channel.

Construction does no work. Self::attach binds the renderer to a FrameTarget: a window backend attaches a window once it exists, and a headless launch attaches an offscreen image and hands the renderer to crate::render_backend::install_offscreen, whose render-world system drives it each frame. A pending crate::render_world::SurfaceCapture request is answered from the frame Self::present puts up, on either kind of target.

Required Methods§

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fn attach(&mut self, target: FrameTarget) -> Result<(), RenderError>

Bind to target. Calling it again rebinds the renderer. A RenderError::Init failure is what lets a launch try the next backend.

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fn resize(&mut self, width: u32, height: u32) -> bool

Reconfigure for a new physical size. Returns true when the size actually changed, so callers can drop the relayout and repaint a duplicate resize event would otherwise force.

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fn wants_present( &mut self, render_world: &mut World, request: FrameRequest, ) -> bool

Whether Self::present would put anything new up. The renderer answers, because only it knows what its buffers still hold and how precisely it can compare this scene against the last one it painted.

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fn present(&mut self, render_world: &mut World) -> Result<(), RenderError>

Paint, submit, and present one frame from the render world.

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fn detach(&mut self)

Release the target and everything behind it. A window backend calls this while the platform connection is still alive, because tearing a surface down after the display connection closes crashes some drivers.