Improve canvas text

[jfboeve]

This pull request refactors the text rendering pipeline to improve performance and flexibility by allowing the use of ImageBitmap and HTMLCanvasElement as texture sources, in addition to ImageData. The changes optimize how text is rendered and transferred to GPU textures, reduce unnecessary pixel readbacks and copies, and add support for offscreen and onscreen canvas workflows. The most important changes are grouped below:

Text rendering pipeline improvements

• The text renderer now uses ImageBitmap (for OffscreenCanvas) or a dedicated HTMLCanvasElement (for onscreen rendering) as the texture source, instead of always using ImageData. This enables zero-copy transfers to the GPU and avoids unnecessary pixel readbacks. (src/core/text-rendering/CanvasTextRenderer.ts, src/core/text-rendering/TextRenderer.ts) [1] [2] [3]
• The renderer distinguishes between offscreen and onscreen canvases, using transferToImageBitmap() for OffscreenCanvas and allocating a new HTMLCanvasElement per text node otherwise. (src/core/text-rendering/CanvasTextRenderer.ts) [1] [2] [3]

Texture and image source handling

• The ImageTexture and TextureData types now support ImageBitmap and HTMLCanvasElement as valid texture sources, in addition to ImageData. (src/core/textures/ImageTexture.ts, src/core/textures/Texture.ts) [1] [2] [3]
• The texture uploaders in both Canvas and WebGL renderers are updated to handle HTMLCanvasElement as a valid image source for textures. (src/core/renderers/canvas/CanvasTexture.ts, src/core/renderers/webgl/WebGlCtxTexture.ts, src/core/renderers/webgl/WebGlCtxSubTexture.ts) [1] [2] [3]

Platform and canvas management

• The platform abstraction is updated to provide both createCanvas() (for onscreen) and createOffscreenCanvas() (for offscreen or worker rendering), and the web platform implements both methods. The renderer now uses these appropriately. (src/core/platforms/Platform.ts, src/core/platforms/web/WebPlatform.ts) [1] [2]

These changes collectively make the text rendering pipeline more efficient, flexible, and compatible with modern browser features.

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❌ jorge-graca-sky
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[eXecutable]

Suggested change

	canvas = stage.platform.createOffscreenCanvas();
	isOffscreen =
	typeof OffscreenCanvas !== 'undefined' && canvas instanceof OffscreenCanvas;
	if (canvas === null) {
	canvas = stage.platform.createCanvas();
	}
	canvas = stage.platform.createOffscreenCanvas();
	if (canvas) {
	isOffscreen = true;
	} else {
	isOffscreen = false;
	canvas = stage.platform.createCanvas();
	}

[eXecutable]

Suggested change

	this.canvas = settings.canvas || document.createElement('canvas');
	this.canvas = settings.canvas || this.createCanvas();

[eXecutable]

Suggested change

	* Creates a new canvas.
	* Creates a new canvas element.