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/*
* Copyright (C) 2013 University of Washington. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
WI.BackForwardEntry = class BackForwardEntry
{
constructor(contentView, cookie)
{
this._contentView = contentView;
// ContentViews may be shared across multiple ContentViewContainers.
// A BackForwardEntry containing a tombstone doesn't actually have
// the real ContentView, and so should not close it.
this._tombstone = false;
// Cookies are compared with Object.shallowEqual, so should not store objects or arrays.
this._cookie = cookie || {};
this._scrollPositions = [];
contentView.saveToCookie(this._cookie);
}
// Public
makeCopy(newCookie)
{
let copy = new WI.BackForwardEntry(this._contentView, newCookie || this.cookie);
copy._tombstone = this._tombstone;
copy._scrollPositions = this._scrollPositions.slice();
return copy;
}
get contentView()
{
return this._contentView;
}
get cookie()
{
// Cookies are immutable; they represent a specific navigation action.
return Object.shallowCopy(this._cookie);
}
get tombstone()
{
return this._tombstone;
}
set tombstone(tombstone)
{
this._tombstone = tombstone;
}
prepareToShow()
{
console.assert(!this._tombstone, "Should not be calling shown on a tombstone");
this._restoreFromCookie();
this.contentView.needsLayout();
}
prepareToHide()
{
console.assert(!this._tombstone, "Should not be calling hidden on a tombstone");
this._saveScrollPositions();
if (this._contentView.shouldSaveStateWhenHidden) {
this._cookie = {};
this._contentView.saveToCookie(this._cookie);
}
}
isEqual(other)
{
if (!other)
return false;
return this._contentView === other._contentView && Object.shallowEqual(this._cookie, other._cookie);
}
// Private
_restoreFromCookie()
{
this._restoreScrollPositions();
this.contentView.restoreFromCookie(this.cookie);
}
_restoreScrollPositions()
{
// If no scroll positions are saved, do nothing.
if (!this._scrollPositions.length)
return;
var scrollableElements = this.contentView.scrollableElements || [];
console.assert(this._scrollPositions.length === scrollableElements.length);
for (var i = 0; i < scrollableElements.length; ++i) {
var position = this._scrollPositions[i];
var element = scrollableElements[i];
if (!element)
continue;
// Restore the top scroll position by either scrolling to the bottom or to the saved position.
element.scrollTop = position.isScrolledToBottom ? element.scrollHeight : position.scrollTop;
// Don't restore the left scroll position when scrolled to the bottom. This way the when content changes
// the user won't be left in a weird horizontal position.
element.scrollLeft = position.isScrolledToBottom ? 0 : position.scrollLeft;
}
}
_saveScrollPositions()
{
var scrollableElements = this.contentView.scrollableElements || [];
var scrollPositions = [];
for (var i = 0; i < scrollableElements.length; ++i) {
var element = scrollableElements[i];
if (!element)
continue;
let position = {scrollTop: element.scrollTop, scrollLeft: element.scrollLeft};
if (this.contentView.shouldKeepElementsScrolledToBottom)
position.isScrolledToBottom = element.isScrolledToBottom();
scrollPositions.push(position);
}
this._scrollPositions = scrollPositions;
}
};
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