[Feature]: rive integration on a single canvas

[ShaMan123]

Description

I would like to integrate Rive with other canvas features using the canvas-advanced package.
Rive forces me to call renderer.clear() at the beginning of each frame because it does something under the hood, registering the renderer:

rive-wasm/wasm/js/renderer.js

Lines 900 to 913 in f860745

	"clear": function () {
	// Add ourselves to the list of deferred canvases. This works here because clear aways
	// gets called first.
	_pendingCanvasRenderers.add(this);
	this._drawList.push(
	this._ctx["clearRect"].bind(
	this._ctx,
	0,
	0,
	this._canvas["width"],
	this._canvas["height"]
	)
	);
	},

That is not desirable in case the canvas is used to render other visuals, not allowing to share the same canvas/context.
I am aware that I can add the ctx.fillRect call to the render loop but I do not wish to do that due to performance and other considerations (such as having a background etc.).

related #336

Provide a Repro

I've reused the basketball demo and added a simple ctx.fillRect that I want to persist however renderer.clear() clears it.
https://codesandbox.io/p/sandbox/rive-canvas-integration-8xx7lx

Screen.Recording.2024-12-20.at.9.56.29.mov

Expected behavior

The clear call shoud be decoupled from the registration call.
clear should be optional and/or accept optional x, y, width, height params.
The under the hood registration call should be exposed so that the caller can decide if/how to clear the canvas.

rive.prepareAnimationFrame(); // registers the canvas
// frame logic
// rive.clear();
...
rive.resolveAnimationFrame();

Browser & Versions (please complete the following information)

• Browser: Chrome 131
• OS: macOS 15.2
• NPM Version: 10.2.4
• @rive-app/canvas-advanced@2.25.1

[sims11tz]

I would also benefit greatly from this change!