skia2/modules/canvaskit/tests/canvaskitinit.js
Elliot Evans 2879619a29 Added CanvasKit.MakeImageFromCanvasImageSource which is useful as an alternative to
CanvasKit.MakeImageFromEncoded, when used with Browser APIs for loading/decoding images.

 - `CanvasKit.MakeImageFromCanvasImageSource` takes either an HTMLImageElement,
   SVGImageElement, HTMLVideoElement, HTMLCanvasElement, ImageBitmap, or OffscreenCanvas and returns
   an SkImage. This function is an alternative to `CanvasKit.MakeImageFromEncoded` for creating
   SkImages when loading and decoding images. In the future, codesize of CanvasKit may be able to be
   reduced by removing image codecs in wasm, if browser APIs for decoding images are used along with
   `CanvasKit.MakeImageFromCanvasImageSource` instead of `CanvasKit.MakeImageFromEncoded`.
-  Three usage examples of `CanvasKit.MakeImageFromCanvasImageSource` in core.spec.ts. These 
   examples use browser APIs to decode images including 2d canvas, bitmaprenderer canvas, 
   HTMLImageElement and Blob.
-  Added support for asynchronous callbacks in perfs and tests.

Here are notes on the image decoding approaches we tested and perfed in the process of finding ways 
to use Browser APIs to decode images:

1. pipeline:
  ArrayBuffer → ImageData → ctx.putImageData →
  context.getImageData → Uint8Array → CanvasKit.MakeImage
 Problem: ImageData constructor expects decoded bytes already.

2. interface.js - CanvasKit.ExperimentalCanvas2DMakeImageFromEncoded (async function)
pipeline:
  ArrayBuffer → Blob -> HTMLImageElement ->
  draw on Canvas2d -> context.getImageData → Uint8Array →
  CanvasKit.MakeImage
 Works
⏱ Performance: 3rd place (in my testing locally)

3. interface.js - CanvasKit.ExperimentalCanvas2DMakeImageFromEncoded2 (async function)
  ArrayBuffer → Blob → ImageBitmap → draw on Canvas2d →
  context.getImageData → Uint8Array → CanvasKit.MakeImage
 Works
⏱ Performance: 2nd place (in my testing locally)

4. interface.js - CanvasKit.ExperimentalCanvas2DMakeImageFromEncoded3 (async function)
  ArrayBuffer → Blob → ImageBitmap →
  draw on canvas 1 using bitmaprenderer context →
  draw canvas 1 on canvas 2 using drawImage → context2d.getImageData →
  Uint8Array → CanvasKit.MakeImage
 Works
⏱ Performance: 1st place (in my testing locally) - quite surprising, this in some ways seems to be a more roundabout way of CanvasKit.ExperimentalCanvas2DMakeImageFromEncoded2, but it seems bitmaprenderer context is fairly fast.

Bug: skia:10360
Change-Id: I6fe94b8196dfd1ad0d8929f04bb1697da537ca18
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/295390
Reviewed-by: Kevin Lubick <kjlubick@google.com>
2020-06-15 19:35:09 +00:00

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584 B
JavaScript

// The increased timeout is especially needed with larger binaries
// like in the debug/gpu build
jasmine.DEFAULT_TIMEOUT_INTERVAL = 60000;
let CanvasKit = null;
const LoadCanvasKit = new Promise((resolve, reject) => {
console.log('canvaskit loading', new Date());
CanvasKitInit({
locateFile: (file) => '/canvaskit/'+file,
}).then((loaded) => {
console.log('canvaskit loaded', new Date());
CanvasKit = loaded;
resolve();
}).catch((e) => {
console.error('canvaskit failed to load', new Date(), e);
reject();
});
});