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88 lines
3.8 KiB
88 lines
3.8 KiB
// Adds compile-time JS functions to augment the CanvasKit interface.
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// Specifically, anything that should only be on the GPU version of canvaskit.
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(function(CanvasKit){
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CanvasKit._extraInitializations = CanvasKit._extraInitializations || [];
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CanvasKit._extraInitializations.push(function() {
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function get(obj, attr, defaultValue) {
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if (obj && obj.hasOwnProperty(attr)) {
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return obj[attr];
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}
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return defaultValue;
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}
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function makeWebGLContext(canvas, attrs) {
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// These defaults come from the emscripten _emscripten_webgl_create_context
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var contextAttributes = {
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'alpha': get(attrs, 'alpha', 1),
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'depth': get(attrs, 'depth', 1),
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'stencil': get(attrs, 'stencil', 0),
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'antialias': get(attrs, 'antialias', 1),
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'premultipliedAlpha': get(attrs, 'premultipliedAlpha', 1),
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'preserveDrawingBuffer': get(attrs, 'preserveDrawingBuffer', 0),
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'preferLowPowerToHighPerformance': get(attrs, 'preferLowPowerToHighPerformance', 0),
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'failIfMajorPerformanceCaveat': get(attrs, 'failIfMajorPerformanceCaveat', 0),
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'majorVersion': get(attrs, 'majorVersion', 1),
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'minorVersion': get(attrs, 'minorVersion', 0),
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'enableExtensionsByDefault': get(attrs, 'enableExtensionsByDefault', 1),
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'explicitSwapControl': get(attrs, 'explicitSwapControl', 0),
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'renderViaOffscreenBackBuffer': get(attrs, 'renderViaOffscreenBackBuffer', 0),
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};
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if (!canvas) {
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SkDebug('null canvas passed into makeWebGLContext');
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return 0;
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}
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// This check is from the emscripten version
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if (contextAttributes['explicitSwapControl']) {
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SkDebug('explicitSwapControl is not supported');
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return 0;
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}
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return GL.createContext(canvas, contextAttributes);
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}
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// arg can be of types:
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// - String - in which case it is interpreted as an id of a
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// canvas element.
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// - HTMLCanvasElement - in which the provided canvas element will
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// be used directly.
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// - int - in which case it will be used as a WebGLContext. Only 1.0
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// contexts are known to work for now.
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// Width and height can be provided to override those on the canvas
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// element, or specify a height for when a context is provided.
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CanvasKit.MakeWebGLCanvasSurface = function(arg, width, height) {
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var ctx = arg;
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// ctx is only > 0 if it's an int, and thus a valid context
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if (!(ctx > 0)) {
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var canvas = arg;
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if (canvas.tagName !== 'CANVAS') {
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canvas = document.getElementById(arg);
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if (!canvas) {
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throw 'Canvas with id ' + arg + ' was not found';
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}
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}
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// we are ok with all the defaults
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ctx = makeWebGLContext(canvas);
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}
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if (!ctx || ctx < 0) {
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throw 'failed to create webgl context: err ' + ctx;
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}
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if (!canvas && (!width || !height)) {
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throw 'height and width must be provided with context';
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}
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// Maybe better to use clientWidth/height. See:
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// https://webglfundamentals.org/webgl/lessons/webgl-anti-patterns.html
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var surface = this._getWebGLSurface(ctx, width || canvas.width,
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height || canvas.height);
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if (!surface) {
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SkDebug('falling back from GPU implementation to a SW based one');
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return CanvasKit.MakeSWCanvasSurface(arg);
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}
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return surface;
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};
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// Default to trying WebGL first.
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CanvasKit.MakeCanvasSurface = CanvasKit.MakeWebGLCanvasSurface;
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});
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}(Module)); // When this file is loaded in, the high level object is "Module";
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