The Tor Browser / file comparison
comparison: toolkit/modules/sessionstore/ScrollPosition.jsm
toolkit/modules/sessionstore/ScrollPosition.jsm
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- 6474c204b198
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| -1:000000000000 | 0:4ea8324fff08 |
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| 1 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 2 * License, v. 2.0. If a copy of the MPL was not distributed with this file, | |
| 3 * You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 4 | |
| 5 "use strict"; | |
| 6 | |
| 7 this.EXPORTED_SYMBOLS = ["ScrollPosition"]; | |
| 8 | |
| 9 const Ci = Components.interfaces; | |
| 10 | |
| 11 /** | |
| 12 * It provides methods to collect and restore scroll positions for single | |
| 13 * frames and frame trees. | |
| 14 * | |
| 15 * This is a child process module. | |
| 16 */ | |
| 17 this.ScrollPosition = Object.freeze({ | |
| 18 /** | |
| 19 * Collects scroll position data for any given |frame| in the frame hierarchy. | |
| 20 * | |
| 21 * @param frame (DOMWindow) | |
| 22 * | |
| 23 * @return {scroll: "x,y"} e.g. {scroll: "100,200"} | |
| 24 * Returns null when there is no scroll data we want to store for the | |
| 25 * given |frame|. | |
| 26 */ | |
| 27 collect: function (frame) { | |
| 28 let ifreq = frame.QueryInterface(Ci.nsIInterfaceRequestor); | |
| 29 let utils = ifreq.getInterface(Ci.nsIDOMWindowUtils); | |
| 30 let scrollX = {}, scrollY = {}; | |
| 31 utils.getScrollXY(false /* no layout flush */, scrollX, scrollY); | |
| 32 | |
| 33 if (scrollX.value || scrollY.value) { | |
| 34 return {scroll: scrollX.value + "," + scrollY.value}; | |
| 35 } | |
| 36 | |
| 37 return null; | |
| 38 }, | |
| 39 | |
| 40 /** | |
| 41 * Restores scroll position data for any given |frame| in the frame hierarchy. | |
| 42 * | |
| 43 * @param frame (DOMWindow) | |
| 44 * @param value (object, see collect()) | |
| 45 */ | |
| 46 restore: function (frame, value) { | |
| 47 let match; | |
| 48 | |
| 49 if (value && (match = /(\d+),(\d+)/.exec(value))) { | |
| 50 frame.scrollTo(match[1], match[2]); | |
| 51 } | |
| 52 }, | |
| 53 | |
| 54 /** | |
| 55 * Restores scroll position data for the current frame hierarchy starting at | |
| 56 * |root| using the given scroll position |data|. | |
| 57 * | |
| 58 * If the given |root| frame's hierarchy doesn't match that of the given | |
| 59 * |data| object we will silently discard data for unreachable frames. We | |
| 60 * may as well assign scroll positions to the wrong frames if some were | |
| 61 * reordered or removed. | |
| 62 * | |
| 63 * @param root (DOMWindow) | |
| 64 * @param data (object) | |
| 65 * { | |
| 66 * scroll: "100,200", | |
| 67 * children: [ | |
| 68 * {scroll: "100,200"}, | |
| 69 * null, | |
| 70 * {scroll: "200,300", children: [ ... ]} | |
| 71 * ] | |
| 72 * } | |
| 73 */ | |
| 74 restoreTree: function (root, data) { | |
| 75 if (data.hasOwnProperty("scroll")) { | |
| 76 this.restore(root, data.scroll); | |
| 77 } | |
| 78 | |
| 79 if (!data.hasOwnProperty("children")) { | |
| 80 return; | |
| 81 } | |
| 82 | |
| 83 let frames = root.frames; | |
| 84 data.children.forEach((child, index) => { | |
| 85 if (child && index < frames.length) { | |
| 86 this.restoreTree(frames[index], child); | |
| 87 } | |
| 88 }); | |
| 89 } | |
| 90 }); |
