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Quelle WindowsPreviewPerTab.sys.mjs
Sprache: unbekannt
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/* vim: se cin sw=2 ts=2 et filetype=javascript :
* 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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
* This module implements the front end behavior for AeroPeek. Starting in
* Windows Vista, the taskbar began showing live thumbnail previews of windows
* when the user hovered over the window icon in the taskbar. Starting with
* Windows 7, the taskbar allows an application to expose its tabbed interface
* in the taskbar by showing thumbnail previews rather than the default window
* preview. Additionally, when a user hovers over a thumbnail (tab or window),
* they are shown a live preview of the window (or tab + its containing window).
*
* In Windows 7, a title, icon, close button and optional toolbar are shown for
* each preview. This feature does not make use of the toolbar. For window
* previews, the title is the window title and the icon the window icon. For
* tab previews, the title is the page title and the page's favicon. In both
* cases, the close button "does the right thing."
*
* The primary objects behind this feature are nsITaskbarTabPreview and
* nsITaskbarPreviewController. Each preview has a controller. The controller
* responds to the user's interactions on the taskbar and provides the required
* data to the preview for determining the size of the tab and thumbnail. The
* PreviewController class implements this interface. The preview will request
* the controller to provide a thumbnail or preview when the user interacts with
* the taskbar. To reduce the overhead of drawing the tab area, the controller
* implementation caches the tab's contents in a <canvas> element. If no
* previews or thumbnails have been requested for some time, the controller will
* discard its cached tab contents.
*
* Screen real estate is limited so when there are too many thumbnails to fit
* on the screen, the taskbar stops displaying thumbnails and instead displays
* just the title, icon and close button in a similar fashion to previous
* versions of the taskbar. If there are still too many previews to fit on the
* screen, the taskbar resorts to a scroll up and scroll down button pair to let
* the user scroll through the list of tabs. Since this is undoubtedly
* inconvenient for users with many tabs, the AeroPeek objects turns off all of
* the tab previews. This tells the taskbar to revert to one preview per window.
* If the number of tabs falls below this magic threshold, the preview-per-tab
* behavior returns. There is no reliable way to determine when the scroll
* buttons appear on the taskbar, so a magic pref-controlled number determines
* when this threshold has been crossed.
*/
import { NetUtil } from "resource://gre/modules/NetUtil.sys.mjs";
import { PlacesUtils } from "resource://gre/modules/PlacesUtils.sys.mjs";
import { PrivateBrowsingUtils } from "resource://gre/modules/PrivateBrowsingUtils.sys.mjs";
import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
// Pref to enable/disable preview-per-tab
const TOGGLE_PREF_NAME = "browser.taskbar.previews.enable";
// Pref to determine the magic auto-disable threshold
const DISABLE_THRESHOLD_PREF_NAME = "browser.taskbar.previews.max";
// Pref to control the time in seconds that tab contents live in the cache
const CACHE_EXPIRATION_TIME_PREF_NAME = "browser.taskbar.previews.cachetime";
const WINTASKBAR_CONTRACTID = "@mozilla.org/windows-taskbar;1";
const lazy = {};
// Various utility properties
XPCOMUtils.defineLazyServiceGetter(
lazy,
"imgTools",
"@mozilla.org/image/tools;1",
"imgITools"
);
ChromeUtils.defineESModuleGetters(lazy, {
PageThumbs: "resource://gre/modules/PageThumbs.sys.mjs",
});
// nsIURI -> imgIContainer
function _imageFromURI(uri, privateMode, callback) {
let channel = NetUtil.newChannel({
uri,
loadUsingSystemPrincipal: true,
contentPolicyType: Ci.nsIContentPolicy.TYPE_INTERNAL_IMAGE,
});
try {
channel.QueryInterface(Ci.nsIPrivateBrowsingChannel);
channel.setPrivate(privateMode);
} catch (e) {
// Ignore channels which do not support nsIPrivateBrowsingChannel
}
NetUtil.asyncFetch(channel, function (inputStream, resultCode) {
if (!Components.isSuccessCode(resultCode)) {
return;
}
const decodeCallback = {
onImageReady(image) {
if (!image) {
// We failed, so use the default favicon (only if this wasn't the
// default favicon).
let defaultURI = PlacesUtils.favicons.defaultFavicon;
if (!defaultURI.equals(uri)) {
_imageFromURI(defaultURI, privateMode, callback);
return;
}
}
callback(image);
},
};
try {
let threadManager = Cc["@mozilla.org/thread-manager;1"].getService();
lazy.imgTools.decodeImageAsync(
inputStream,
channel.contentType,
decodeCallback,
threadManager.currentThread
);
} catch (e) {
// We failed, so use the default favicon (only if this wasn't the default
// favicon).
let defaultURI = PlacesUtils.favicons.defaultFavicon;
if (!defaultURI.equals(uri)) {
_imageFromURI(defaultURI, privateMode, callback);
}
}
});
}
// string? -> imgIContainer
function getFaviconAsImage(iconurl, privateMode, callback) {
if (iconurl) {
_imageFromURI(NetUtil.newURI(iconurl), privateMode, callback);
} else {
_imageFromURI(PlacesUtils.favicons.defaultFavicon, privateMode, callback);
}
}
// PreviewController
/*
* This class manages the behavior of thumbnails and previews. It has the following
* responsibilities:
* 1) responding to requests from Windows taskbar for a thumbnail or window
* preview.
* 2) listens for dom events that result in a thumbnail or window preview needing
* to be refresh, and communicates this to the taskbar.
* 3) Handles querying and returning to the taskbar new thumbnail or window
* preview images through PageThumbs.
*
* @param win
* The TabWindow (see below) that owns the preview that this controls
* @param tab
* The <tab> that this preview is associated with
*/
function PreviewController(win, tab) {
this.win = win;
this.tab = tab;
this.linkedBrowser = tab.linkedBrowser;
this.preview = this.win.createTabPreview(this);
this.tab.addEventListener("TabAttrModified", this);
ChromeUtils.defineLazyGetter(this, "canvasPreview", function () {
let canvas = lazy.PageThumbs.createCanvas(this.win.win);
canvas.mozOpaque = true;
return canvas;
});
}
PreviewController.prototype = {
QueryInterface: ChromeUtils.generateQI(["nsITaskbarPreviewController"]),
destroy() {
this.tab.removeEventListener("TabAttrModified", this);
// Break cycles, otherwise we end up leaking the window with everything
// attached to it.
delete this.win;
delete this.preview;
},
get wrappedJSObject() {
return this;
},
// Resizes the canvasPreview to 0x0, essentially freeing its memory.
resetCanvasPreview() {
this.canvasPreview.width = 0;
this.canvasPreview.height = 0;
},
/**
* Set the canvas dimensions.
*/
resizeCanvasPreview(aRequestedWidth, aRequestedHeight) {
this.canvasPreview.width = aRequestedWidth;
this.canvasPreview.height = aRequestedHeight;
},
get browserDims() {
return this.tab.linkedBrowser.getBoundingClientRect();
},
cacheBrowserDims() {
let dims = this.browserDims;
this._cachedWidth = dims.width;
this._cachedHeight = dims.height;
},
testCacheBrowserDims() {
let dims = this.browserDims;
return this._cachedWidth == dims.width && this._cachedHeight == dims.height;
},
/**
* Capture a new thumbnail image for this preview. Called by the controller
* in response to a request for a new thumbnail image.
*/
updateCanvasPreview(aFullScale) {
// Update our cached browser dims so that delayed resize
// events don't trigger another invalidation if this tab becomes active.
this.cacheBrowserDims();
AeroPeek.resetCacheTimer();
return lazy.PageThumbs.captureToCanvas(
this.linkedBrowser,
this.canvasPreview,
{
fullScale: aFullScale,
}
).catch(console.error);
// If we're updating the canvas, then we're in the middle of a peek so
// don't discard the cache of previews.
},
updateTitleAndTooltip() {
let title = this.win.tabbrowser.getWindowTitleForBrowser(
this.linkedBrowser
);
this.preview.title = title;
this.preview.tooltip = title;
},
// nsITaskbarPreviewController
// window width and height, not browser
get width() {
return this.win.width;
},
// window width and height, not browser
get height() {
return this.win.height;
},
get thumbnailAspectRatio() {
let browserDims = this.browserDims;
// Avoid returning 0
let tabWidth = browserDims.width || 1;
// Avoid divide by 0
let tabHeight = browserDims.height || 1;
return tabWidth / tabHeight;
},
/**
* Responds to taskbar requests for window previews. Returns the results asynchronously
* through updateCanvasPreview.
*
* @param aTaskbarCallback nsITaskbarPreviewCallback results callback
*/
requestPreview(aTaskbarCallback) {
// Grab a high res content preview
this.resetCanvasPreview();
this.updateCanvasPreview(true).then(aPreviewCanvas => {
let winWidth = this.win.width;
let winHeight = this.win.height;
let composite = lazy.PageThumbs.createCanvas(this.win.win);
// Use transparency, Aero glass is drawn black without it.
composite.mozOpaque = false;
let ctx = composite.getContext("2d");
let scale = this.win.win.devicePixelRatio;
composite.width = winWidth * scale;
composite.height = winHeight * scale;
ctx.save();
ctx.scale(scale, scale);
// Draw chrome. Note we currently do not get scrollbars for remote frames
// in the image above.
ctx.drawWindow(this.win.win, 0, 0, winWidth, winHeight, "rgba(0,0,0,0)");
// Draw the content are into the composite canvas at the right location.
ctx.drawImage(
aPreviewCanvas,
this.browserDims.x,
this.browserDims.y,
aPreviewCanvas.width,
aPreviewCanvas.height
);
ctx.restore();
// Deliver the resulting composite canvas to Windows
this.win.tabbrowser.previewTab(this.tab, function () {
aTaskbarCallback.done(composite, false);
});
});
},
/**
* Responds to taskbar requests for tab thumbnails. Returns the results asynchronously
* through updateCanvasPreview.
*
* Note Windows requests a specific width and height here, if the resulting thumbnail
* does not match these dimensions thumbnail display will fail.
*
* @param aTaskbarCallback nsITaskbarPreviewCallback results callback
* @param aRequestedWidth width of the requested thumbnail
* @param aRequestedHeight height of the requested thumbnail
*/
requestThumbnail(aTaskbarCallback, aRequestedWidth, aRequestedHeight) {
this.resizeCanvasPreview(aRequestedWidth, aRequestedHeight);
this.updateCanvasPreview(false).then(aThumbnailCanvas => {
aTaskbarCallback.done(aThumbnailCanvas, false);
});
},
// Event handling
onClose() {
this.win.tabbrowser.removeTab(this.tab);
},
onActivate() {
this.win.tabbrowser.selectedTab = this.tab;
// Accept activation - this will restore the browser window
// if it's minimized
return true;
},
// EventListener
handleEvent(evt) {
switch (evt.type) {
case "TabAttrModified":
this.updateTitleAndTooltip();
break;
}
},
};
// TabWindow
/*
* This class monitors a browser window for changes to its tabs
*
* @param win
* The nsIDOMWindow browser window
*/
function TabWindow(win) {
this.win = win;
this.tabbrowser = win.gBrowser;
this.previews = new Map();
for (let i = 0; i < this.tabEvents.length; i++) {
this.tabbrowser.tabContainer.addEventListener(this.tabEvents[i], this);
}
for (let i = 0; i < this.winEvents.length; i++) {
this.win.addEventListener(this.winEvents[i], this);
}
this.tabbrowser.addTabsProgressListener(this);
AeroPeek.windows.push(this);
let tabs = this.tabbrowser.tabs;
for (let i = 0; i < tabs.length; i++) {
this.newTab(tabs[i]);
}
this.updateTabOrdering();
AeroPeek.checkPreviewCount();
}
TabWindow.prototype = {
_enabled: false,
_cachedWidth: 0,
_cachedHeight: 0,
tabEvents: ["TabOpen", "TabClose", "TabSelect", "TabMove"],
winEvents: ["resize"],
destroy() {
this._destroying = true;
let tabs = this.tabbrowser.tabs;
this.tabbrowser.removeTabsProgressListener(this);
for (let i = 0; i < this.winEvents.length; i++) {
this.win.removeEventListener(this.winEvents[i], this);
}
for (let i = 0; i < this.tabEvents.length; i++) {
this.tabbrowser.tabContainer.removeEventListener(this.tabEvents[i], this);
}
for (let i = 0; i < tabs.length; i++) {
this.removeTab(tabs[i]);
}
let idx = AeroPeek.windows.indexOf(this.win.gTaskbarTabGroup);
AeroPeek.windows.splice(idx, 1);
AeroPeek.checkPreviewCount();
},
get width() {
return this.win.innerWidth;
},
get height() {
return this.win.innerHeight;
},
cacheDims() {
this._cachedWidth = this.width;
this._cachedHeight = this.height;
},
testCacheDims() {
return this._cachedWidth == this.width && this._cachedHeight == this.height;
},
// Invoked when the given tab is added to this window
newTab(tab) {
let controller = new PreviewController(this, tab);
// It's OK to add the preview now while the favicon still loads.
this.previews.set(tab, controller.preview);
AeroPeek.addPreview(controller.preview);
// updateTitleAndTooltip relies on having controller.preview which is lazily resolved.
// Now that we've updated this.previews, it will resolve successfully.
controller.updateTitleAndTooltip();
},
createTabPreview(controller) {
let docShell = this.win.docShell;
let preview = AeroPeek.taskbar.createTaskbarTabPreview(
docShell,
controller
);
preview.visible = AeroPeek.enabled;
let { tab } = controller;
preview.active = this.tabbrowser.selectedTab == tab;
this.updateFavicon(tab, tab.getAttribute("image"));
return preview;
},
// Invoked when the given tab is closed
removeTab(tab) {
let preview = this.previewFromTab(tab);
preview.active = false;
preview.visible = false;
preview.move(null);
preview.controller.wrappedJSObject.destroy();
this.previews.delete(tab);
AeroPeek.removePreview(preview);
},
get enabled() {
return this._enabled;
},
set enabled(enable) {
this._enabled = enable;
// Because making a tab visible requires that the tab it is next to be
// visible, it is far simpler to unset the 'next' tab and recreate them all
// at once.
for (let [, preview] of this.previews) {
preview.move(null);
preview.visible = enable;
}
this.updateTabOrdering();
},
previewFromTab(tab) {
return this.previews.get(tab);
},
updateTabOrdering() {
let previews = this.previews;
let tabs = this.tabbrowser.tabs;
// Previews are internally stored using a map, so we need to iterate the
// tabbrowser's array of tabs to retrieve previews in the same order.
let inorder = [];
for (let t of tabs) {
if (previews.has(t)) {
inorder.push(previews.get(t));
}
}
// Since the internal taskbar array has not yet been updated we must force
// on it the sorting order of our local array. To do so we must walk
// the local array backwards, otherwise we would send move requests in the
// wrong order. See bug 522610 for details.
for (let i = inorder.length - 1; i >= 0; i--) {
inorder[i].move(inorder[i + 1] || null);
}
},
// EventListener
handleEvent(evt) {
let tab = evt.originalTarget;
switch (evt.type) {
case "TabOpen":
this.newTab(tab);
this.updateTabOrdering();
break;
case "TabClose":
this.removeTab(tab);
this.updateTabOrdering();
break;
case "TabSelect":
this.previewFromTab(tab).active = true;
break;
case "TabMove":
this.updateTabOrdering();
break;
case "resize":
if (!AeroPeek._prefenabled) {
return;
}
this.onResize();
break;
}
},
// Set or reset a timer that will invalidate visible thumbnails soon.
setInvalidationTimer() {
if (!this.invalidateTimer) {
this.invalidateTimer = Cc["@mozilla.org/timer;1"].createInstance(
Ci.nsITimer
);
}
this.invalidateTimer.cancel();
// delay 1 second before invalidating
this.invalidateTimer.initWithCallback(
() => {
// invalidate every preview. note the internal implementation of
// invalidate ignores thumbnails that aren't visible.
this.previews.forEach(function (aPreview) {
let controller = aPreview.controller.wrappedJSObject;
if (!controller.testCacheBrowserDims()) {
controller.cacheBrowserDims();
aPreview.invalidate();
}
});
},
1000,
Ci.nsITimer.TYPE_ONE_SHOT
);
},
onResize() {
// Specific to a window.
// Call invalidate on each tab thumbnail so that Windows will request an
// updated image. However don't do this repeatedly across multiple resize
// events triggered during window border drags.
if (this.testCacheDims()) {
return;
}
// update the window dims on our TabWindow object.
this.cacheDims();
// invalidate soon
this.setInvalidationTimer();
},
invalidateTabPreview(aBrowser) {
for (let [tab, preview] of this.previews) {
if (aBrowser == tab.linkedBrowser) {
preview.invalidate();
break;
}
}
},
// Browser progress listener
onLocationChange() {
// I'm not sure we need this, onStateChange does a really good job
// of picking up page changes.
// this.invalidateTabPreview(aBrowser);
},
onStateChange(aBrowser, aWebProgress, aRequest, aStateFlags) {
if (
aStateFlags & Ci.nsIWebProgressListener.STATE_STOP &&
aStateFlags & Ci.nsIWebProgressListener.STATE_IS_NETWORK
) {
this.invalidateTabPreview(aBrowser);
}
},
onLinkIconAvailable(aBrowser, aIconURL) {
let tab = this.win.gBrowser.getTabForBrowser(aBrowser);
this.updateFavicon(tab, aIconURL);
},
updateFavicon(aTab, aIconURL) {
let requestURL = null;
if (aIconURL) {
try {
requestURL = PlacesUtils.favicons.getFaviconLinkForIcon(
Services.io.newURI(aIconURL)
).spec;
} catch (ex) {
requestURL = aIconURL;
}
}
let isDefaultFavicon = !requestURL;
getFaviconAsImage(
requestURL,
PrivateBrowsingUtils.isWindowPrivate(this.win),
img => {
// The tab could have closed, and there's no guarantee the icons
// will have finished fetching 'in order'.
if (this.win.closed || aTab.closing || !aTab.linkedBrowser) {
return;
}
// Note that bizarrely, we can get to updateFavicon via a sync codepath
// where the new preview controller hasn't yet been added to the
// window's map of previews. So `preview` would be null here - except
// getFaviconAsImage is async so that should never happen, as we add
// the controller to the preview collection straight after creating it.
// However, if any of this code ever tries to access this
// synchronously, that won't work.
let preview = this.previews.get(aTab);
if (
aTab.getAttribute("image") == aIconURL ||
(!preview.icon && isDefaultFavicon)
) {
preview.icon = img;
}
}
);
},
};
// AeroPeek
/*
* This object acts as global storage and external interface for this feature.
* It maintains the values of the prefs.
*/
export var AeroPeek = {
available: false,
// Does the pref say we're enabled?
__prefenabled: false,
_enabled: true,
initialized: false,
// nsITaskbarTabPreview array
previews: [],
// TabWindow array
windows: [],
// nsIWinTaskbar service
taskbar: null,
// Maximum number of previews
maxpreviews: 20,
// Length of time in seconds that previews are cached
cacheLifespan: 20,
initialize() {
if (!(WINTASKBAR_CONTRACTID in Cc)) {
return;
}
this.taskbar = Cc[WINTASKBAR_CONTRACTID].getService(Ci.nsIWinTaskbar);
this.available = this.taskbar.available;
if (!this.available) {
return;
}
Services.prefs.addObserver(TOGGLE_PREF_NAME, this, true);
this.enabled = this._prefenabled =
Services.prefs.getBoolPref(TOGGLE_PREF_NAME);
this.initialized = true;
},
destroy: function destroy() {
this._enabled = false;
if (this.cacheTimer) {
this.cacheTimer.cancel();
}
},
get enabled() {
return this._enabled;
},
set enabled(enable) {
if (this._enabled == enable) {
return;
}
this._enabled = enable;
this.windows.forEach(function (win) {
win.enabled = enable;
});
},
get _prefenabled() {
return this.__prefenabled;
},
set _prefenabled(enable) {
if (enable == this.__prefenabled) {
return;
}
this.__prefenabled = enable;
if (enable) {
this.enable();
} else {
this.disable();
}
},
_observersAdded: false,
enable() {
if (!this._observersAdded) {
Services.prefs.addObserver(DISABLE_THRESHOLD_PREF_NAME, this, true);
Services.prefs.addObserver(CACHE_EXPIRATION_TIME_PREF_NAME, this, true);
this._placesListener = this.handlePlacesEvents.bind(this);
PlacesUtils.observers.addListener(
["favicon-changed"],
this._placesListener
);
this._observersAdded = true;
}
this.cacheLifespan = Services.prefs.getIntPref(
CACHE_EXPIRATION_TIME_PREF_NAME
);
this.maxpreviews = Services.prefs.getIntPref(DISABLE_THRESHOLD_PREF_NAME);
// If the user toggled us on/off while the browser was already up
// (rather than this code running on startup because the pref was
// already set to true), we must initialize previews for open windows:
if (this.initialized) {
for (let win of Services.wm.getEnumerator("navigator:browser")) {
if (!win.closed) {
this.onOpenWindow(win);
}
}
}
},
disable() {
while (this.windows.length) {
// We can't call onCloseWindow here because it'll bail if we're not
// enabled.
let tabWinObject = this.windows[0];
tabWinObject.destroy(); // This will remove us from the array.
delete tabWinObject.win.gTaskbarTabGroup; // Tidy up the window.
}
PlacesUtils.observers.removeListener(
["favicon-changed"],
this._placesListener
);
},
addPreview(preview) {
this.previews.push(preview);
this.checkPreviewCount();
},
removePreview(preview) {
let idx = this.previews.indexOf(preview);
this.previews.splice(idx, 1);
this.checkPreviewCount();
},
checkPreviewCount() {
if (!this._prefenabled) {
return;
}
this.enabled = this.previews.length <= this.maxpreviews;
},
onOpenWindow(win) {
// This occurs when the taskbar service is not available (xp, vista)
if (!this.available || !this._prefenabled) {
return;
}
win.gTaskbarTabGroup = new TabWindow(win);
},
onCloseWindow(win) {
// This occurs when the taskbar service is not available (xp, vista)
if (!this.available || !this._prefenabled) {
return;
}
win.gTaskbarTabGroup.destroy();
delete win.gTaskbarTabGroup;
if (!this.windows.length) {
this.destroy();
}
},
resetCacheTimer() {
this.cacheTimer.cancel();
this.cacheTimer.init(
this,
1000 * this.cacheLifespan,
Ci.nsITimer.TYPE_ONE_SHOT
);
},
// nsIObserver
observe(aSubject, aTopic, aData) {
if (aTopic == "nsPref:changed" && aData == TOGGLE_PREF_NAME) {
this._prefenabled = Services.prefs.getBoolPref(TOGGLE_PREF_NAME);
}
if (!this._prefenabled) {
return;
}
switch (aTopic) {
case "nsPref:changed":
if (aData == CACHE_EXPIRATION_TIME_PREF_NAME) {
break;
}
if (aData == DISABLE_THRESHOLD_PREF_NAME) {
this.maxpreviews = Services.prefs.getIntPref(
DISABLE_THRESHOLD_PREF_NAME
);
}
// Might need to enable/disable ourselves
this.checkPreviewCount();
break;
case "timer-callback":
this.previews.forEach(function (preview) {
let controller = preview.controller.wrappedJSObject;
controller.resetCanvasPreview();
});
break;
}
},
handlePlacesEvents(events) {
for (let event of events) {
switch (event.type) {
case "favicon-changed": {
for (let win of this.windows) {
for (let [tab] of win.previews) {
if (tab.getAttribute("image") == event.faviconUrl) {
win.updateFavicon(tab, event.faviconUrl);
}
}
}
}
}
}
},
QueryInterface: ChromeUtils.generateQI([
"nsISupportsWeakReference",
"nsIObserver",
]),
};
ChromeUtils.defineLazyGetter(AeroPeek, "cacheTimer", () =>
Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer)
);
AeroPeek.initialize();
[ Dauer der Verarbeitung: 0.9 Sekunden
(vorverarbeitet)
]
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2026-03-28
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