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
    ) {