ladybird/Tests/LibWeb/Text/input/HTML/CanvasRenderingContext2D-get-image-data-correctness.html

<!DOCTYPE html>
<script src="../include.js"></script>
<script>
    test(() => {
        let area = document.createElement("canvas");
        let areaCtx = area.getContext("2d");

        area.width = 1;
        area.height = 1;

        areaCtx.fillStyle = "#ff8040";
        areaCtx.fillRect(0, 0, 1, 1);

        let imageData = areaCtx.getImageData(0, 0, area.width, area.height);

        if (imageData.data[0] == 0xff && imageData.data[1] == 0x80 && imageData.data[2] == 0x40 && imageData.data[3] == 0xff)
            println("PASS");
        else
            println("FAIL");
    });
</script>
Meta: Add DOCTYPEs to most text tests 2025-03-18 19:28:35 +01:00			`<!DOCTYPE html>`
Tests/LibWeb: Add test to verify correctness of getImageData 2024-06-14 15:22:25 +02:00			`<script src="../include.js"></script>`
			`<script>`
			`test(() => {`
			`let area = document.createElement("canvas");`
			`let areaCtx = area.getContext("2d");`

			`area.width = 1;`
			`area.height = 1;`

			`areaCtx.fillStyle = "#ff8040";`
			`areaCtx.fillRect(0, 0, 1, 1);`

			`let imageData = areaCtx.getImageData(0, 0, area.width, area.height);`

LibWeb: Use bitmap's alpha type instead of assuming unpremultiplied When converting a `Gfx::Bitmap` to a Skia bitmap, we cannot assume the color data is unpremultiplied. For example, everything canvas-related uses premultiplied color data: https://html.spec.whatwg.org/multipage/canvas.html#premultiplied-alpha-and-the-2d-rendering-context We were probably assuming unpremultiplied since that is what the PNG decoder gives us. Since we now make `Gfx::Bitmap` identify what alpha type is being used, we can instruct Skia a bit better :^) Update our `EdgeFlagPathRasterizer` to use premultiplied alpha instead of unpremultiplied so we can apply alpha correctly for path masks. This fixes the dark borders sometimes visible when SVGs are blended with a colored background. This also exposed an issue with our `CanvasRenderingContext2D`, which is supposed to hold a bitmap with premultiplied alpha internally but expose a bitmap with unpremultiplied alpha in `CanvasImageData`. Expand our C2D test to include the alpha channel as well. Finally, this also exposed an off-by-one issue in `EdgeFlagPathRasterizer` which caused the last scanlines for edges to render incorrectly. We had some reference images which included these corruptions (they were almost unnoticeable), so update them as well. 2024-08-02 13:15:45 +02:00			`if (imageData.data[0] == 0xff && imageData.data[1] == 0x80 && imageData.data[2] == 0x40 && imageData.data[3] == 0xff)`
Tests/LibWeb: Add test to verify correctness of getImageData 2024-06-14 15:22:25 +02:00			`println("PASS");`
			`else`
			`println("FAIL");`
			`});`
			`</script>`