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function makeCanvas() {
return new Promise(resolve => {
var testCanvas = document.createElement("canvas");
testCanvas.width = 20;
testCanvas.height = 20;
var testCtx = testCanvas.getContext("2d");
testCtx.fillStyle = "rgb(255, 0, 0)";
testCtx.fillRect(0, 0, 10, 10);
testCtx.fillStyle = "rgb(0, 255, 0)";
testCtx.fillRect(10, 0, 10, 10);
testCtx.fillStyle = "rgb(0, 0, 255)";
testCtx.fillRect(0, 10, 10, 10);
testCtx.fillStyle = "rgb(0, 0, 0)";
testCtx.fillRect(10, 10, 10, 10);
resolve(testCanvas);
});
}
function makeOffscreenCanvas() {
return new Promise(resolve => {
let canvas = new OffscreenCanvas(20, 20);
var testCtx = canvas.getContext("2d");
testCtx.fillStyle = "rgb(255, 0, 0)";
testCtx.fillRect(0, 0, 10, 10);
testCtx.fillStyle = "rgb(0, 255, 0)";
testCtx.fillRect(10, 0, 10, 10);
testCtx.fillStyle = "rgb(0, 0, 255)";
testCtx.fillRect(0, 10, 10, 10);
testCtx.fillStyle = "rgb(0, 0, 0)";
testCtx.fillRect(10, 10, 10, 10);
resolve(canvas);
});
}
var imageBitmapVideoPromise = new Promise(function(resolve, reject) {
var video = document.createElement("video");
video.oncanplaythrough = function() {
resolve(video);
};
video.onerror = reject;
// preload=auto is required to ensure a frame is available once
// canplaythrough is fired. The default of preload=metadata does not
// gaurantee this.
video.preload = "auto";
video.src = getVideoURI("/images/pattern");
// Prevent WebKit from garbage collecting event handlers.
window._video = video;
});
function makeVideo() {
return imageBitmapVideoPromise;
}
var imageBitmapDataUrlVideoPromise = fetch(getVideoURI("/images/pattern"))
.then(response => Promise.all([response.headers.get("Content-Type"), response.arrayBuffer()]))
.then(([type, data]) => {
return new Promise(function(resolve, reject) {
var video = document.createElement("video");
video.oncanplaythrough = function() {
resolve(video);
};
video.onerror = reject;
var encoded = btoa(String.fromCodePoint(...new Uint8Array(data)));
var dataUrl = `data:${type};base64,${encoded}`;
// preload=auto is required to ensure a frame is available once
// canplaythrough is fired. The default of preload=metadata does not
// gaurantee this.
video.preload = "auto";
video.src = dataUrl;
// Prevent WebKit from garbage collecting event handlers.
window._dataVideo = video;
});
});
function makeDataUrlVideo() {
return imageBitmapDataUrlVideoPromise;
}
function makeMakeHTMLImage(src) {
return function() {
return new Promise((resolve, reject) => {
var img = new Image();
img.onload = function() {
resolve(img);
};
img.onerror = reject;
img.src = src;
});
}
}
function makeMakeSVGImage(src) {
return function() {
return new Promise((resolve, reject) => {
image.onload = () => resolve(image);
image.onerror = reject;
image.setAttribute("externalResourcesRequired", "true");
document.body.appendChild(image);
});
}
}
function makeImageData() {
return new Promise(function(resolve, reject) {
var width = 20, height = 20;
var imgData = new ImageData(width, height);
for (var i = 0; i < width * height * 4; i += 4) {
imgData.data[i] = 0;
imgData.data[i + 1] = 0;
imgData.data[i + 2] = 0;
imgData.data[i + 3] = 255; //alpha channel: 255
}
var halfWidth = width / 2;
var halfHeight = height / 2;
// initialize to R, G, B, Black, with each one 10*10 pixels
for (var i = 0; i < halfHeight; i++)
for (var j = 0; j < halfWidth; j++)
imgData.data[i * width * 4 + j * 4] = 255;
for (var i = 0; i < halfHeight; i++)
for (var j = halfWidth; j < width; j++)
imgData.data[i * width * 4 + j * 4 + 1] = 255;
for (var i = halfHeight; i < height; i++)
for (var j = 0; j < halfWidth; j++)
imgData.data[i * width * 4 + j * 4 + 2] = 255;
resolve(imgData);
});
}
function makeImageBitmap() {
return makeCanvas().then(canvas => {
return createImageBitmap(canvas);
});
}
function makeBlob(src) {
return function () {
return new Promise(function(resolve, reject) {
var xhr = new XMLHttpRequest();
xhr.open("GET", src);
xhr.responseType = 'blob';
xhr.send();
xhr.onload = function() {
resolve(xhr.response);
};
});
}
}
var imageSourceTypes = [
{ name: 'an HTMLCanvasElement', factory: makeCanvas },
{ name: 'an HTMLVideoElement', factory: makeVideo },
{ name: 'an HTMLVideoElement from a data URL', factory: makeDataUrlVideo },
{ name: 'a bitmap HTMLImageElement', factory: makeMakeHTMLImage("/images/pattern.png") },
{ name: 'a vector HTMLImageElement', factory: makeMakeHTMLImage("/images/pattern.svg") },
{ name: 'a bitmap SVGImageElement', factory: makeMakeSVGImage("/images/pattern.png") },
{ name: 'a vector SVGImageElement', factory: makeMakeSVGImage("/images/pattern.svg") },
{ name: 'an OffscreenCanvas', factory: makeOffscreenCanvas },
{ name: 'an ImageData', factory: makeImageData },
{ name: 'an ImageBitmap', factory: makeImageBitmap },
{ name: 'a Blob', factory: makeBlob("/images/pattern.png") },
];