openseadragon/src/tilecache.js

114 lines
3.9 KiB
JavaScript

/*
* OpenSeadragon - TileCache
*
* Copyright (C) 2009 CodePlex Foundation
* Copyright (C) 2010-2013 OpenSeadragon contributors
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of CodePlex Foundation nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* 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
* OWNER 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.
*/
(function( $ ){
/**
* @class TileCache
* @classdesc
*/
$.TileCache = function( options ) {
options = options || {};
this._tilesLoaded = [];
this._maxImageCacheCount = options.maxImageCacheCount || $.DEFAULT_SETTINGS.maxImageCacheCount;
};
$.TileCache.prototype = /** @lends OpenSeadragon.TileCache.prototype */{
/**
* Returns the total number of tiles that have been loaded by this TileCache.
* @method
* @returns {Number} - The total number of tiles that have been loaded by
* this TileCache.
*/
numTilesLoaded: function() {
return this._tilesLoaded.length;
},
cacheTile: function( tile, cutoff ) {
cutoff = cutoff || 0;
var insertionIndex = this._tilesLoaded.length;
if ( this._tilesLoaded.length >= this._maxImageCacheCount ) {
var worstTile = null;
var worstTileIndex = -1;
var prevTile, worstTime, worstLevel, prevTime, prevLevel;
for ( var i = this._tilesLoaded.length - 1; i >= 0; i-- ) {
prevTile = this._tilesLoaded[ i ];
if ( prevTile.level <= cutoff || prevTile.beingDrawn ) {
continue;
} else if ( !worstTile ) {
worstTile = prevTile;
worstTileIndex = i;
continue;
}
prevTime = prevTile.lastTouchTime;
worstTime = worstTile.lastTouchTime;
prevLevel = prevTile.level;
worstLevel = worstTile.level;
if ( prevTime < worstTime ||
( prevTime == worstTime && prevLevel > worstLevel ) ) {
worstTile = prevTile;
worstTileIndex = i;
}
}
if ( worstTile && worstTileIndex >= 0 ) {
worstTile.unload();
insertionIndex = worstTileIndex;
}
}
this._tilesLoaded[ insertionIndex ] = tile;
},
/**
* Clears all tiles.
* @method
*/
reset: function() {
for ( var i = 0; i < this._tilesLoaded.length; ++i ) {
this._tilesLoaded[i].unload();
}
this._tilesLoaded = [];
}
};
}( OpenSeadragon ));