Trait Canvas

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pub trait Canvas: Sized {
    type Pixel: Sized;
    type Image: Sized;

    // Required methods
    fn new(
        width: u32,
        height: u32,
        dark_pixel: Self::Pixel,
        light_pixel: Self::Pixel,
    ) -> Self;
    fn draw_dark_pixel(&mut self, x: u32, y: u32);
    fn into_image(self) -> Self::Image;

    // Provided methods
    fn validate_dimensions(
        _width: u32,
        _height: u32,
        _dark_pixel: &Self::Pixel,
        _light_pixel: &Self::Pixel,
    ) -> Result<(), RenderError> { ... }
    fn draw_dark_rect(&mut self, left: u32, top: u32, width: u32, height: u32) { ... }
}

Expand description

Rendering canvas of a QR code image.

Required Associated Types§

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type Pixel: Sized

The pixel type stored in this canvas.

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type Image: Sized

The finalized image type produced from this canvas.

Required Methods§

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fn new( width: u32, height: u32, dark_pixel: Self::Pixel, light_pixel: Self::Pixel, ) -> Self

Constructs a new canvas of the given dimensions.

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fn draw_dark_pixel(&mut self, x: u32, y: u32)

Draws a single dark pixel at the (x, y) coordinate.

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fn into_image(self) -> Self::Image

Finalize the canvas to a real image.

Provided Methods§

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fn validate_dimensions( _width: u32, _height: u32, _dark_pixel: &Self::Pixel, _light_pixel: &Self::Pixel, ) -> Result<(), RenderError>

Checks dimensions and pixel-dependent resource limits before allocation.

The default accepts all dimensions, preserving existing custom and vector canvases. Buffered backends override this to reject requests that exceed their allocation budget. Renderer::try_build calls this before Canvas::new.