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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
/**
* Provides testing functions working with images and image URLs.
*/
export const ImageTestUtils = {
/**
* Assert that both provided image URLs are visually identical.
*/
async assertEqualImage(win, first, second, msg) {
const firstCanvas = await this.drawImageOnCanvas(win, first);
const secondCanvas = await this.drawImageOnCanvas(win, second);
Assert.equal(
firstCanvas.width,
secondCanvas.width,
`${msg} - Both images have the same width`
);
Assert.equal(
firstCanvas.height,
secondCanvas.height,
`${msg} - Both images have the same height`
);
const differences = win.windowUtils.compareCanvases(
firstCanvas,
secondCanvas,
{}
);
Assert.equal(differences, 0, `${msg} - Both images are identical`);
},
drawImageOnCanvas(win, url) {
return new Promise((resolve, reject) => {
const img = new win.Image();
img.onload = function () {
// TODO: compareCanvases only works for the HTMLCanvasElement.
const canvas = win.document.createElementNS(
"canvas"
);
canvas.width = img.naturalWidth;
canvas.height = img.naturalHeight;
const ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0);
resolve(canvas);
};
img.onerror = function () {
reject(`error loading image ${url}`);
};
// Load the src image for drawing
img.src = url;
});
},
};