| // 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; |
| } |
| |
| function makeWebGLContext(canvas, attrs) { |
| // These defaults come from the emscripten _emscripten_webgl_create_context |
| var contextAttributes = { |
| 'alpha': get(attrs, 'alpha', 1), |
| 'depth': get(attrs, 'depth', 1), |
| 'stencil': get(attrs, 'stencil', 0), |
| 'antialias': get(attrs, 'antialias', 1), |
| 'premultipliedAlpha': get(attrs, 'premultipliedAlpha', 1), |
| 'preserveDrawingBuffer': get(attrs, 'preserveDrawingBuffer', 0), |
| 'preferLowPowerToHighPerformance': get(attrs, 'preferLowPowerToHighPerformance', 0), |
| 'failIfMajorPerformanceCaveat': get(attrs, 'failIfMajorPerformanceCaveat', 0), |
| 'majorVersion': get(attrs, 'majorVersion', 1), |
| 'minorVersion': get(attrs, 'minorVersion', 0), |
| 'enableExtensionsByDefault': get(attrs, 'enableExtensionsByDefault', 1), |
| 'explicitSwapControl': get(attrs, 'explicitSwapControl', 0), |
| 'renderViaOffscreenBackBuffer': get(attrs, 'renderViaOffscreenBackBuffer', 0), |
| }; |
| if (!canvas) { |
| SkDebug('null canvas passed into makeWebGLContext'); |
| return 0; |
| } |
| // This check is from the emscripten version |
| if (contextAttributes['explicitSwapControl']) { |
| SkDebug('explicitSwapControl is not supported'); |
| return 0; |
| } |
| return GL.createContext(canvas, contextAttributes); |
| } |
| |
| // 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. |
| // - int - in which case it will be used as a WebGLContext. Only 1.0 |
| // contexts are known to work for now. |
| // 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 ctx = arg; |
| // ctx is only > 0 if it's an int, and thus a valid context |
| if (!(ctx > 0)) { |
| 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 defaults |
| ctx = makeWebGLContext(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'; |
| } |
| |
| // Maybe better to use clientWidth/height. See: |
| // https://webglfundamentals.org/webgl/lessons/webgl-anti-patterns.html |
| var surface = this._getWebGLSurface(ctx, width || canvas.width, |
| height || canvas.height); |
| if (!surface) { |
| SkDebug('falling back from GPU implementation to a SW based one'); |
| return CanvasKit.MakeSWCanvasSurface(arg); |
| } |
| return surface; |
| }; |
| // Default to trying WebGL first. |
| CanvasKit.MakeCanvasSurface = CanvasKit.MakeWebGLCanvasSurface; |
| }); |
| }(Module)); // When this file is loaded in, the high level object is "Module"; |