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