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Merge pull request #1970 from mzgoddard/image-bitmap
Use Promise.all, createImageBitmap, and one canvas in `load-costume.js`
This commit is contained in:
Michael "Z" Goddard
GitHub
commit
a791a1e64e
1 changed files with 141 additions and 97 deletions
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@ -32,6 +32,53 @@ const loadVector_ = function (costume, runtime, rotationCenter, optVersion) {
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});
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};
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const canvasPool = (function () {
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/**
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* A pool of canvas objects that can be reused to reduce memory
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* allocations. And time spent in those allocations and the later garbage
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* collection.
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*/
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class CanvasPool {
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constructor () {
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this.pool = [];
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this.clearSoon = null;
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}
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/**
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* After a short wait period clear the pool to let the VM collect
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* garbage.
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*/
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clear () {
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if (!this.clearSoon) {
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this.clearSoon = new Promise(resolve => setTimeout(resolve, 1000))
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.then(() => {
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this.pool.length = 0;
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this.clearSoon = null;
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});
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}
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}
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/**
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* Return a canvas. Create the canvas if the pool is empty.
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* @returns {HTMLCanvasElement} A canvas element.
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*/
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create () {
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return this.pool.pop() || document.createElement('canvas');
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}
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/**
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* Release the canvas to be reused.
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* @param {HTMLCanvasElement} canvas A canvas element.
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*/
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release (canvas) {
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this.clear();
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this.pool.push(canvas);
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}
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}
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return new CanvasPool();
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}());
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/**
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* Return a promise to fetch a bitmap from storage and return it as a canvas
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* If the costume has bitmapResolution 1, it will be converted to bitmapResolution 2 here (the standard for Scratch 3)
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@ -54,64 +101,53 @@ const fetchBitmapCanvas_ = function (costume, runtime, rotationCenter) {
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return Promise.reject('No V2 Bitmap adapter present.');
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}
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return Promise.all([costume.asset, costume.textLayerAsset].map(asset => {
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if (!asset) {
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return null;
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}
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if (typeof createImageBitmap !== 'undefined') {
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return createImageBitmap(
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new Blob([asset.data], {type: asset.assetType.contentType})
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);
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}
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return new Promise((resolve, reject) => {
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const baseImageElement = new Image();
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let textImageElement;
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// We need to wait for 2 images total to load. loadedOne will be true when one
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// is done, and we are just waiting for one more.
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let loadedOne = false;
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const onError = function () {
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// eslint-disable-next-line no-use-before-define
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removeEventListeners();
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const image = new Image();
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image.onload = function () {
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resolve(image);
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image.onload = null;
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image.onerror = null;
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};
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image.onerror = function () {
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reject('Costume load failed. Asset could not be read.');
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image.onload = null;
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image.onerror = null;
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};
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const onLoad = function () {
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if (loadedOne) {
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// eslint-disable-next-line no-use-before-define
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removeEventListeners();
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resolve([baseImageElement, textImageElement]);
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} else {
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loadedOne = true;
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}
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};
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image.src = asset.encodeDataURI();
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});
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}))
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.then(([baseImageElement, textImageElement]) => {
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const mergeCanvas = canvasPool.create();
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const removeEventListeners = function () {
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baseImageElement.removeEventListener('error', onError);
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baseImageElement.removeEventListener('load', onLoad);
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if (textImageElement) {
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textImageElement.removeEventListener('error', onError);
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textImageElement.removeEventListener('load', onLoad);
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}
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};
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baseImageElement.addEventListener('load', onLoad);
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baseImageElement.addEventListener('error', onError);
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if (costume.textLayerAsset) {
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textImageElement = new Image();
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textImageElement.addEventListener('load', onLoad);
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textImageElement.addEventListener('error', onError);
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textImageElement.src = costume.textLayerAsset.encodeDataURI();
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} else {
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loadedOne = true;
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}
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baseImageElement.src = costume.asset.encodeDataURI();
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}).then(imageElements => {
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const [baseImageElement, textImageElement] = imageElements;
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let canvas = document.createElement('canvas');
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const scale = costume.bitmapResolution === 1 ? 2 : 1;
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canvas.width = baseImageElement.width;
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canvas.height = baseImageElement.height;
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mergeCanvas.width = baseImageElement.width;
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mergeCanvas.height = baseImageElement.height;
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const ctx = canvas.getContext('2d');
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const ctx = mergeCanvas.getContext('2d');
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ctx.drawImage(baseImageElement, 0, 0);
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if (textImageElement) {
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ctx.drawImage(textImageElement, 0, 0);
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}
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// Track the canvas we merged the bitmaps onto separately from the
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// canvas that we receive from resize if scale is not 1. We know
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// resize treats mergeCanvas as read only data. We don't know when
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// resize may use or modify the canvas. So we'll only release the
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// mergeCanvas back into the canvas pool. Reusing the canvas from
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// resize may cause errors.
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let canvas = mergeCanvas;
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if (scale !== 1) {
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canvas = runtime.v2BitmapAdapter.resize(canvas, canvas.width * scale, canvas.height * scale);
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canvas = runtime.v2BitmapAdapter.resize(mergeCanvas, canvas.width * scale, canvas.height * scale);
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}
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// By scaling, we've converted it to bitmap resolution 2
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@ -128,8 +164,9 @@ const fetchBitmapCanvas_ = function (costume, runtime, rotationCenter) {
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delete costume.textLayerAsset;
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return {
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canvas: canvas,
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rotationCenter: rotationCenter,
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canvas,
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mergeCanvas,
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rotationCenter,
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// True if the asset matches the base layer; false if it required adjustment
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assetMatchesBase: scale === 1 && !textImageElement
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};
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@ -141,12 +178,17 @@ const fetchBitmapCanvas_ = function (costume, runtime, rotationCenter) {
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});
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};
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const loadBitmap_ = function (costume, runtime, rotationCenter) {
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return fetchBitmapCanvas_(costume, runtime, rotationCenter).then(fetched => new Promise(resolve => {
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rotationCenter = fetched.rotationCenter;
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const loadBitmap_ = function (costume, runtime, _rotationCenter) {
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return fetchBitmapCanvas_(costume, runtime, _rotationCenter)
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.then(fetched => {
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const updateCostumeAsset = function (dataURI) {
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if (!runtime.v2BitmapAdapter) {
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// TODO: This might be a bad practice since the returned
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// promise isn't acted on. If this is something we should be
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// creating a rejected promise for we should also catch it
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// somewhere and act on that error (like logging).
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//
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// Return a rejection to stop executing updateCostumeAsset.
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return Promise.reject('No V2 Bitmap adapter present.');
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}
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@ -166,11 +208,13 @@ const loadBitmap_ = function (costume, runtime, rotationCenter) {
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if (!fetched.assetMatchesBase) {
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updateCostumeAsset(fetched.canvas.toDataURL());
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}
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resolve(fetched.canvas);
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}))
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.then(canvas => {
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return fetched;
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})
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.then(({canvas, mergeCanvas, rotationCenter}) => {
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// createBitmapSkin does the right thing if costume.bitmapResolution or rotationCenter are undefined...
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costume.skinId = runtime.renderer.createBitmapSkin(canvas, costume.bitmapResolution, rotationCenter);
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canvasPool.release(mergeCanvas);
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const renderSize = runtime.renderer.getSkinSize(costume.skinId);
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costume.size = [renderSize[0] * 2, renderSize[1] * 2]; // Actual size, since all bitmaps are resolution 2
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