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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/. */
"use strict";
this.EXPORTED_SYMBOLS = [ "SharedFrame" ];
const Ci = Components.interfaces;
const Cu = Components.utils;
/**
* The purpose of this module is to create and group various iframe
* elements that are meant to all display the same content and only
* one at a time. This makes it possible to have the content loaded
* only once, while the other iframes can be kept as placeholders to
* quickly move the content to them through the swapFrameLoaders function
* when another one of the placeholder is meant to be displayed.
* */
var Frames = new Map();
/**
* The Frames map is the main data structure that holds information
* about the groups being tracked. Each entry's key is the group name,
* and the object holds information about what is the URL being displayed
* on that group, and what is the active element on the group (the frame that
* holds the loaded content).
* The reference to the activeFrame is a weak reference, which allows the
* frame to go away at any time, and when that happens the module considers that
* there are no active elements in that group. The group can be reactivated
* by changing the URL, calling preload again or adding a new element.
*
*
* Frames = {
* "messages-panel": {
* url: string,
* activeFrame: weakref
* }
* }
*
* Each object on the map is called a _SharedFrameGroup, which is an internal
* class of this module which does not automatically keep track of its state. This
* object should not be used externally, and all control should be handled by the
* module's functions.
*/
function UNLOADED_URL(aStr) "data:text/html;charset=utf-8,<!-- Unloaded frame " + aStr + " -->";
this.SharedFrame = {
/**
* Creates an iframe element and track it as part of the specified group
* The module must create the iframe itself because it needs to do some special
* handling for the element's src attribute.
*
* @param aGroupName the name of the group to which this frame belongs
* @param aParent the parent element to which the frame will be appended to
* @param aFrameAttributes an object with a list of attributes to set in the iframe
* before appending it to the DOM. The "src" attribute has
* special meaning here and if it's not blank it specifies
* the URL that will be initially assigned to this group
* @param aPreload optional, tells if the URL specified in the src attribute
* should be preloaded in the frame being created, in case
* it's not yet preloaded in any other frame of the group.
* This parameter has no meaning if src is blank.
*/
createFrame: function (aGroupName, aParent, aFrameAttributes, aPreload = true) {
let frame = aParent.ownerDocument.createElement("iframe");
for (let [key, val] of Iterator(aFrameAttributes)) {
frame.setAttribute(key, val);
}
let src = aFrameAttributes.src;
if (!src) {
aPreload = false;
}
let group = Frames.get(aGroupName);
if (group) {
// If this group has already been created
if (aPreload && !group.isAlive) {
// If aPreload is set and the group is not already loaded, load it.
// This can happen if:
// - aPreload was not used while creating the previous frames of this group, or
// - the previously active frame went dead in the meantime
group.url = src;
this.preload(aGroupName, frame);
} else {
// If aPreload is not set, or the group is already loaded in a different frame,
// there's not much that we need to do here: just create this frame as an
// inactivate placeholder
frame.setAttribute("src", UNLOADED_URL(aGroupName));
}
} else {
// This is the first time we hear about this group, so let's start tracking it,
// and also preload it if the src attribute was set and aPreload = true
group = new _SharedFrameGroup(src);
Frames.set(aGroupName, group);
if (aPreload) {
this.preload(aGroupName, frame);
} else {
frame.setAttribute("src", UNLOADED_URL(aGroupName));
}
}
aParent.appendChild(frame);
return frame;
},
/**
* Function that moves the loaded content from one active frame to
* another one that is currently a placeholder. If there's no active
* frame in the group, the content is loaded/reloaded.
*
* @param aGroupName the name of the group
* @param aTargetFrame the frame element to which the content should
* be moved to.
*/
setOwner: function (aGroupName, aTargetFrame) {
let group = Frames.get(aGroupName);
let frame = group.activeFrame;
if (frame == aTargetFrame) {
// nothing to do here
return;
}
if (group.isAlive) {
// Move document ownership to the desired frame, and make it the active one
frame.QueryInterface(Ci.nsIFrameLoaderOwner).swapFrameLoaders(aTargetFrame);
group.activeFrame = aTargetFrame;
} else {
// Previous owner was dead, reload the document at the new owner and make it the active one
aTargetFrame.setAttribute("src", group.url);
group.activeFrame = aTargetFrame;
}
},
/**
* Updates the current URL in use by this group, and loads it into the active frame.
*
* @param aGroupName the name of the group
* @param aURL the new url
*/
updateURL: function (aGroupName, aURL) {
let group = Frames.get(aGroupName);
group.url = aURL;
if (group.isAlive) {
group.activeFrame.setAttribute("src", aURL);
}
},
/**
* Loads the group's url into a target frame, if the group doesn't have a currently
* active frame.
*
* @param aGroupName the name of the group
* @param aTargetFrame the frame element which should be made active and
* have the group's content loaded to
*/
preload: function (aGroupName, aTargetFrame) {
let group = Frames.get(aGroupName);
if (!group.isAlive) {
aTargetFrame.setAttribute("src", group.url);
group.activeFrame = aTargetFrame;
}
},
/**
* Tells if a group currently have an active element.
*
* @param aGroupName the name of the group
*/
isGroupAlive: function (aGroupName) {
return Frames.get(aGroupName).isAlive;
},
/**
* Forgets about this group. This function doesn't need to be used
* unless the group's name needs to be reused.
*
* @param aGroupName the name of the group
*/
forgetGroup: function (aGroupName) {
Frames.delete(aGroupName);
}
}
function _SharedFrameGroup(aURL) {
this.url = aURL;
this._activeFrame = null;
}
_SharedFrameGroup.prototype = {
get isAlive() {
let frame = this.activeFrame;
return !!(frame &&
frame.contentDocument &&
frame.contentDocument.location);
},
get activeFrame() {
return this._activeFrame &&
this._activeFrame.get();
},
set activeFrame(aActiveFrame) {
this._activeFrame = aActiveFrame
? Cu.getWeakReference(aActiveFrame)
: null;
}
}
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