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Test Info:
/* 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
"use strict";
// a blue page
const TEST_URL =
const { Screenshots } = ChromeUtils.importESModule(
);
function get_pixels(stringOrObject, width, height) {
return new Promise(resolve => {
// get the pixels out of the screenshot that we just took
let img = document.createElementNS(XHTMLNS, "img");
let imgPath;
if (typeof stringOrObject === "string") {
Assert.ok(
Services.prefs.getBoolPref(
"browser.tabs.remote.separatePrivilegedContentProcess"
),
"The privileged about content process should be enabled."
);
imgPath = stringOrObject;
Assert.ok(
imgPath.startsWith("moz-page-thumb://"),
"Thumbnails should be retrieved using moz-page-thumb://"
);
} else {
imgPath = URL.createObjectURL(stringOrObject.data);
}
img.setAttribute("src", imgPath);
img.addEventListener(
"load",
() => {
let canvas = document.createElementNS(XHTMLNS, "canvas");
canvas.setAttribute("width", width);
canvas.setAttribute("height", height);
let ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0, width, height);
const result = ctx.getImageData(0, 0, width, height).data;
URL.revokeObjectURL(imgPath);
resolve(result);
},
{ once: true }
);
});
}
add_task(async function test_screenshot() {
await SpecialPowers.pushPrefEnv({
set: [["browser.pagethumbnails.capturing_disabled", false]],
});
// take a screenshot of a blue page and save it as a blob
const screenshotAsObject = await Screenshots.getScreenshotForURL(TEST_URL);
let pixels = await get_pixels(screenshotAsObject, 10, 10);
let rgbaCount = { r: 0, g: 0, b: 0, a: 0 };
while (pixels.length) {
// break the pixels into arrays of 4 components [red, green, blue, alpha]
let [r, g, b, a, ...rest] = pixels;
pixels = rest;
// count the number of each coloured pixels
if (r === 255) {
rgbaCount.r += 1;
}
if (g === 255) {
rgbaCount.g += 1;
}
if (b === 255) {
rgbaCount.b += 1;
}
if (a === 255) {
rgbaCount.a += 1;
}
}
// in the end, we should only have 100 blue pixels (10 x 10) with full opacity
Assert.equal(rgbaCount.b, 100, "Has 100 blue pixels");
Assert.equal(rgbaCount.a, 100, "Has full opacity");
Assert.equal(rgbaCount.r, 0, "Does not have any red pixels");
Assert.equal(rgbaCount.g, 0, "Does not have any green pixels");
});