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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
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
var { classes: Cc, interfaces: Ci, utils: Cu } = Components;
Cu.importGlobalProperties(['Blob', 'FileReader']);
Cu.import("resource://gre/modules/PageThumbUtils.jsm");
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource://gre/modules/Services.jsm");
const STATE_LOADING = 1;
const STATE_CAPTURING = 2;
const STATE_CANCELED = 3;
// NOTE: Copied from nsSandboxFlags.h
/**
* This flag prevents content from creating new auxiliary browsing contexts,
* e.g. using the target attribute, the window.open() method, or the
* showModalDialog() method.
*/
const SANDBOXED_AUXILIARY_NAVIGATION = 0x2;
const backgroundPageThumbsContent = {
init: function () {
Services.obs.addObserver(this, "document-element-inserted", true);
// We want a low network priority for this service - lower than b/g tabs
// etc - so set it to the lowest priority available.
this._webNav.QueryInterface(Ci.nsIDocumentLoader).
loadGroup.QueryInterface(Ci.nsISupportsPriority).
priority = Ci.nsISupportsPriority.PRIORITY_LOWEST;
docShell.allowMedia = false;
docShell.allowPlugins = false;
docShell.allowContentRetargeting = false;
let defaultFlags = Ci.nsIRequest.LOAD_ANONYMOUS |
Ci.nsIRequest.LOAD_BYPASS_CACHE |
Ci.nsIRequest.INHIBIT_CACHING |
Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_HISTORY;
docShell.defaultLoadFlags = defaultFlags;
docShell.sandboxFlags |= SANDBOXED_AUXILIARY_NAVIGATION;
addMessageListener("BackgroundPageThumbs:capture",
this._onCapture.bind(this));
docShell.
QueryInterface(Ci.nsIInterfaceRequestor).
getInterface(Ci.nsIWebProgress).
addProgressListener(this, Ci.nsIWebProgress.NOTIFY_STATE_WINDOW);
},
observe: function (subj, topic, data) {
// Arrange to prevent (most) popup dialogs for this window - popups done
// in the parent (eg, auth) aren't prevented, but alert() etc are.
// disableDialogs only works on the current inner window, so it has
// to be called every page load, but before scripts run.
if (content && subj == content.document) {
content.
QueryInterface(Ci.nsIInterfaceRequestor).
getInterface(Ci.nsIDOMWindowUtils).
disableDialogs();
}
},
get _webNav() {
return docShell.QueryInterface(Ci.nsIWebNavigation);
},
_onCapture: function (msg) {
this._nextCapture = {
id: msg.data.id,
url: msg.data.url,
};
if (this._currentCapture) {
if (this._state == STATE_LOADING) {
// Cancel the current capture.
this._state = STATE_CANCELED;
this._loadAboutBlank();
}
// Let the current capture finish capturing, or if it was just canceled,
// wait for onStateChange due to the about:blank load.
return;
}
this._startNextCapture();
},
_startNextCapture: function () {
if (!this._nextCapture)
return;
this._currentCapture = this._nextCapture;
delete this._nextCapture;
this._state = STATE_LOADING;
this._currentCapture.pageLoadStartDate = new Date();
try {
this._webNav.loadURI(this._currentCapture.url,
Ci.nsIWebNavigation.LOAD_FLAGS_STOP_CONTENT,
null, null, null);
} catch (e) {
this._failCurrentCapture("BAD_URI");
delete this._currentCapture;
this._startNextCapture();
}
},
onStateChange: function (webProgress, req, flags, status) {
if (webProgress.isTopLevel &&
(flags & Ci.nsIWebProgressListener.STATE_STOP) &&
this._currentCapture) {
if (req.name == "about:blank") {
if (this._state == STATE_CAPTURING) {
// about:blank has loaded, ending the current capture.
this._finishCurrentCapture();
delete this._currentCapture;
this._startNextCapture();
}
else if (this._state == STATE_CANCELED) {
delete this._currentCapture;
this._startNextCapture();
}
}
else if (this._state == STATE_LOADING &&
Components.isSuccessCode(status)) {
// The requested page has loaded. Capture it.
this._state = STATE_CAPTURING;
this._captureCurrentPage();
}
else if (this._state != STATE_CANCELED) {
// Something went wrong. Cancel the capture. Loading about:blank
// while onStateChange is still on the stack does not actually stop
// the request if it redirects, so do it asyncly.
this._state = STATE_CANCELED;
if (!this._cancelTimer) {
this._cancelTimer =
Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
this._cancelTimer.init(() => {
this._loadAboutBlank();
delete this._cancelTimer;
}, 0, Ci.nsITimer.TYPE_ONE_SHOT);
}
}
}
},
_captureCurrentPage: function () {
let capture = this._currentCapture;
capture.finalURL = this._webNav.currentURI.spec;
capture.pageLoadTime = new Date() - capture.pageLoadStartDate;
let canvasDrawDate = new Date();
let finalCanvas = PageThumbUtils.createSnapshotThumbnail(content, null);
capture.canvasDrawTime = new Date() - canvasDrawDate;
finalCanvas.toBlob(blob => {
capture.imageBlob = new Blob([blob]);
// Load about:blank to finish the capture and wait for onStateChange.
this._loadAboutBlank();
});
},
_finishCurrentCapture: function () {
let capture = this._currentCapture;
let fileReader = new FileReader();
fileReader.onloadend = () => {
sendAsyncMessage("BackgroundPageThumbs:didCapture", {
id: capture.id,
imageData: fileReader.result,
finalURL: capture.finalURL,
telemetry: {
CAPTURE_PAGE_LOAD_TIME_MS: capture.pageLoadTime,
CAPTURE_CANVAS_DRAW_TIME_MS: capture.canvasDrawTime,
},
});
};
fileReader.readAsArrayBuffer(capture.imageBlob);
},
_failCurrentCapture: function (reason) {
let capture = this._currentCapture;
sendAsyncMessage("BackgroundPageThumbs:didCapture", {
id: capture.id,
failReason: reason,
});
},
// We load about:blank to finish all captures, even canceled captures. Two
// reasons: GC the captured page, and ensure it can't possibly load any more
// resources.
_loadAboutBlank: function _loadAboutBlank() {
this._webNav.loadURI("about:blank",
Ci.nsIWebNavigation.LOAD_FLAGS_STOP_CONTENT,
null, null, null);
},
QueryInterface: XPCOMUtils.generateQI([
Ci.nsIWebProgressListener,
Ci.nsISupportsWeakReference,
Ci.nsIObserver,
]),
};
backgroundPageThumbsContent.init();
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