Improve canvas text

[eXecutable]

getImageData forces the browser to copy the pixels drawn by the canvas to JS world. By using ImageBitmap instead the pixels can be drawn on the GPU and stay there.

[Copilot]

Pull request overview

This PR updates the canvas text rendering path to avoid getImageData pixel readback by using GPU-friendly sources (ImageBitmap via transferToImageBitmap on OffscreenCanvas, or passing an HTMLCanvasElement directly) as texture inputs.

Changes:

• Extend texture source typing to allow HTMLCanvasElement (and broaden internal image sources in ImageTexture).
• Update the canvas text renderer to capture output as ImageBitmap/HTMLCanvasElement instead of ImageData.
• Update WebGL and Canvas texture upload paths to accept HTMLCanvasElement as a valid source type.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/core/textures/Texture.ts	Adds HTMLCanvasElement to the core TextureData union.
src/core/textures/ImageTexture.ts	Broadens src typing to include ImageBitmap/HTMLCanvasElement and unifies non-string load handling.
src/core/text-rendering/TextRenderer.ts	Updates CanvasRenderInfo.imageData to `ImageBitmap
src/core/text-rendering/CanvasTextRenderer.ts	Switches capture from getImageData to transferToImageBitmap/direct-canvas source.
src/core/renderers/webgl/WebGlCtxTexture.ts	Allows uploading textures from HTMLCanvasElement in the WebGL path.
src/core/renderers/webgl/WebGlCtxSubTexture.ts	Extends subtexture data union to include HTMLCanvasElement.
src/core/renderers/canvas/CanvasTexture.ts	Allows HTMLCanvasElement as a direct image source in the Canvas renderer path.
src/core/CoreTextNode.ts	Passes through the new canvas text image source type to ImageTexture.

Comments suppressed due to low confidence (1)

src/core/renderers/webgl/WebGlCtxTexture.ts:209

• HTMLCanvasElement support was added to the WebGL upload path, but there’s no unit test to ensure this new branch is exercised (and that upload + UNPACK_PREMULTIPLY_ALPHA_WEBGL behavior matches the ImageData/HTMLImageElement path). Consider extending WebGlCtxTexture.test.ts with a stubbed HTMLCanvasElement and asserting it goes through the same upload branch.

    const memoryPadding = 1.1; // Add padding to account for GPU Padding
    const isImageBitmap =
      typeof ImageBitmap !== 'undefined' && tdata instanceof ImageBitmap;
    const isHTMLCanvas =
      typeof HTMLCanvasElement !== 'undefined' &&
      tdata instanceof HTMLCanvasElement;

    // If textureData is null, the texture is empty (0, 0) and we don't need to
    // upload any data to the GPU.
    if (
      isImageBitmap ||
      isHTMLCanvas ||
      tdata instanceof ImageData ||
      // not using typeof HTMLI mageElement due to web worker
      isHTMLImageElement(tdata) === true
    ) {

[wouterlucas]

Nice thanks!! we should also add support for this in the Platform layers right? else we would never utilize offscreen canvas properly unless you have your own custom platform.

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[eXecutable]

Nice thanks!! we should also add support for this in the Platform layers right? else we would never utilize offscreen canvas properly unless you have your own custom platform.

Updated WebPlatform, not sure that is what you meant.