skia2/modules/canvaskit/gpu.js

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// Adds compile-time JS functions to augment the CanvasKit interface.
// Specifically, anything that should only be on the GPU version of canvaskit.
(function(CanvasKit){
CanvasKit._extraInitializations = CanvasKit._extraInitializations || [];
CanvasKit._extraInitializations.push(function() {
function get(obj, attr, defaultValue) {
if (obj && obj.hasOwnProperty(attr)) {
return obj[attr];
}
return defaultValue;
}
CanvasKit.makeWebGLContextAsCurrent = function(canvas, attrs) {
if (!canvas) {
throw 'null canvas passed into makeWebGLContext';
}
var contextAttributes = {
'alpha': get(attrs, 'alpha', 1),
'depth': get(attrs, 'depth', 1),
'stencil': get(attrs, 'stencil', 8),
'antialias': get(attrs, 'antialias', 0),
'premultipliedAlpha': get(attrs, 'premultipliedAlpha', 1),
'preserveDrawingBuffer': get(attrs, 'preserveDrawingBuffer', 0),
'preferLowPowerToHighPerformance': get(attrs, 'preferLowPowerToHighPerformance', 0),
'failIfMajorPerformanceCaveat': get(attrs, 'failIfMajorPerformanceCaveat', 0),
'enableExtensionsByDefault': get(attrs, 'enableExtensionsByDefault', 1),
'explicitSwapControl': get(attrs, 'explicitSwapControl', 0),
'renderViaOffscreenBackBuffer': get(attrs, 'renderViaOffscreenBackBuffer', 0),
};
// This check is from the emscripten version
if (contextAttributes['explicitSwapControl']) {
throw 'explicitSwapControl is not supported';
}
// Creates a WebGL context and sets it to be the current context.
this.createContext(canvas, true, true, contextAttributes);
}
CanvasKit.GetWebGLContext = function(canvas, attrs) {
this.makeWebGLContextAsCurrent(canvas, attrs);
return CanvasKit.currentContext() || 0;
};
// arg can be of types:
// - String - in which case it is interpreted as an id of a
// canvas element.
// - HTMLCanvasElement - in which the provided canvas element will
// be used directly.
// Width and height can be provided to override those on the canvas
// element, or specify a height for when a context is provided.
CanvasKit.MakeWebGLCanvasSurface = function(arg, width, height) {
var canvas = arg;
if (canvas.tagName !== 'CANVAS') {
canvas = document.getElementById(arg);
if (!canvas) {
throw 'Canvas with id ' + arg + ' was not found';
}
}
// we are ok with all the other defaults.
var ctx = this.GetWebGLContext(canvas);
if (!ctx || ctx < 0) {
throw 'failed to create webgl context: err ' + ctx;
}
if (!canvas && (!width || !height)) {
throw 'height and width must be provided with context';
}
var grcontext = this.MakeGrContext(ctx);
if (grcontext) {
// Bump the default resource cache limit.
var RESOURCE_CACHE_BYTES = 256 * 1024 * 1024;
grcontext.setResourceCacheLimitBytes(RESOURCE_CACHE_BYTES);
}
// Maybe better to use clientWidth/height. See:
// https://webglfundamentals.org/webgl/lessons/webgl-anti-patterns.html
var surface = this.MakeOnScreenGLSurface(grcontext,
width || canvas.width,
height || canvas.height);
if (!surface) {
SkDebug('falling back from GPU implementation to a SW based one');
// we need to throw away the old canvas (which was locked to
// a webGL context) and create a new one so we can
var newCanvas = canvas.cloneNode(true);
var parent = canvas.parentNode;
parent.replaceChild(newCanvas, canvas);
// add a class so the user can detect that it was replaced.
newCanvas.classList.add('ck-replaced');
return CanvasKit.MakeSWCanvasSurface(newCanvas);
}
surface._context = ctx;
surface.grContext = grcontext;
return surface;
};
// Default to trying WebGL first.
CanvasKit.MakeCanvasSurface = CanvasKit.MakeWebGLCanvasSurface;
});
}(Module)); // When this file is loaded in, the high level object is "Module";