зеркало из https://github.com/mozilla/gecko-dev.git
94 строки
3.2 KiB
JavaScript
94 строки
3.2 KiB
JavaScript
/* -*- indent-tabs-mode: nil; js-indent-level: 2; js-indent-level: 2 -*- */
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/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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// This module defines the routines used when updating the graphics shown by a
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// middleman process tab. Middleman processes have their own window/document
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// which are connected to the compositor in the UI process in the usual way.
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// We need to update the contents of the document to draw the raw graphics data
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// provided by the child process.
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"use strict";
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ChromeUtils.import("resource://gre/modules/Services.jsm");
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const CC = Components.Constructor;
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// Create a sandbox with the resources we need. require() doesn't work here.
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const sandbox = Cu.Sandbox(CC("@mozilla.org/systemprincipal;1", "nsIPrincipal")());
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Cu.evalInSandbox(
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"Components.utils.import('resource://gre/modules/jsdebugger.jsm');" +
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"addDebuggerToGlobal(this);",
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sandbox
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);
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// Windows in the middleman process are initially set up as about:blank pages.
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// This method fills them in with a canvas filling the tab.
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function setupContents(window) {
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// The middlemanCanvas element fills the tab's contents.
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const canvas = window.middlemanCanvas = window.document.createElement("canvas");
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canvas.style.position = "absolute";
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window.document.body.style.margin = "0px";
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window.document.body.prepend(canvas);
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}
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function getCanvas(window) {
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if (!window.middlemanCanvas) {
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setupContents(window);
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}
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return window.middlemanCanvas;
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}
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function updateWindowCanvas(window, buffer, width, height, hadFailure) {
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// Make sure the window has a canvas filling the screen.
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const canvas = getCanvas(window);
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canvas.width = width;
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canvas.height = height;
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// If there is a scale for this window, then the graphics will already have
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// been scaled in the child process. To avoid scaling the graphics twice,
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// transform the canvas to undo the scaling.
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const scale = window.devicePixelRatio;
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if (scale != 1) {
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canvas.style.transform =
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`scale(${ 1 / scale }) translate(-${ width / scale }px, -${ height / scale }px)`;
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}
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const cx = canvas.getContext("2d");
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const graphicsData = new Uint8Array(buffer);
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const imageData = cx.getImageData(0, 0, width, height);
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imageData.data.set(graphicsData);
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cx.putImageData(imageData, 0, 0);
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// Indicate to the user when repainting failed and we are showing old painted
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// graphics instead of the most up-to-date graphics.
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if (hadFailure) {
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cx.fillStyle = "red";
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cx.font = "48px serif";
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cx.fillText("PAINT FAILURE", 10, 50);
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}
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}
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// Entry point for when we have some new graphics data from the child process
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// to draw.
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// eslint-disable-next-line no-unused-vars
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function UpdateCanvas(buffer, width, height, hadFailure) {
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try {
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// Paint to all windows we can find. Hopefully there is only one.
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for (const window of Services.ww.getWindowEnumerator()) {
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updateWindowCanvas(window, buffer, width, height, hadFailure);
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}
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} catch (e) {
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dump("Middleman Graphics UpdateCanvas Exception: " + e + "\n");
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}
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}
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// eslint-disable-next-line no-unused-vars
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var EXPORTED_SYMBOLS = [
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"UpdateCanvas",
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];
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