webcanvas: multi-threaded rendering support

[tinyjin]

Added a thread preset build, compiled with Emscripten pthread support.

usage:

import ThorVG from '@thorvg/webcanvas/thread';

const TVG = await ThorVG.init({
    renderer: 'sw',
    threads: navigator.hardwareConcurrency,
});
const canvas = new TVG.Canvas('#canvas', { width: 800, height: 600 });

issue: #286

[Copilot]

Pull request overview

Copilot reviewed 8 out of 11 changed files in this pull request and generated 2 comments.

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packages/webcanvas/src/index.ts:227

• The thread preset currently won’t reliably load the pthread WASM on unpkg because the default locateFile override always returns .../dist/thorvg.wasm for any .wasm request. With @thorvg/webcanvas/thread, the WASM lives under dist/thread/, so this will fetch the single-threaded WASM unless the caller provides locateFile manually.

  // Load WASM module
  Module = await ThorVGModuleFactory({
    locateFile: locateFile ?? ((path: string) => path.endsWith('.wasm') ? THORVG_WASM_URL : path),
  }) as unknown as ThorVGModule;