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// Helper to access the element, its associated loading promise, and also to
// resolve the promise.
class ElementLoadPromise {
constructor(element_id) {
this.element_id = element_id;
this.promise = new Promise((resolve, reject) => {
this.resolve = resolve
this.reject = reject
});
}
element() {
return document.getElementById(this.element_id);
}
}
// Returns if the image is complete and the lazily loaded image matches the expected image.
function is_image_fully_loaded(image, expected_image) {
if (!image.complete || !expected_image.complete) {
return false;
}
if (image.width != expected_image.width ||
image.height != expected_image.height) {
return false;
}
let canvas = document.createElement('canvas');
canvas.width = image.width;
canvas.height = image.height;
let canvasContext = canvas.getContext("2d");
canvasContext.save();
canvasContext.drawImage(image, 0, 0);
let data = canvasContext.getImageData(0, 0, canvas.width, canvas.height).data;
canvasContext.restore();
canvasContext.drawImage(expected_image, 0, 0);
let expected_data = canvasContext.getImageData(0, 0, canvas.width, canvas.height).data;
for (var i = 0; i < data.length; i++) {
if (data[i] != expected_data[i]) {
return false;
}
}
return true;
}
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