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Merge pull request #26 from openseadragon/memoizelevelscale

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memoize default implementation of getLevelScale
This commit is contained in:
Chris Thatcher 2013-03-01 06:18:08 -08:00
commit fc479b5ecb
1 changed files with 13 additions and 1 deletions
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14
src/tilesource.js
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@ -141,7 +141,19 @@ $.TileSource.prototype = {
* @param {Number} level
*/
getLevelScale: function( level ) {
return 1 / ( 1 << ( this.maxLevel - level ) );
// see https://github.com/openseadragon/openseadragon/issues/22
// we use the tilesources implementation of getLevelScale to generate
// a memoized re-implementation
var levelScaleCache = {},
i;
for( i = 0; i <= this.maxLevel; i++ ){
levelScaleCache[ i ] = 1 / Math.pow(2, this.maxLevel - i);
}
this.getLevelScale = function( _level ){
return levelScaleCache[ _level ];
};
return this.getLevelScale( level );
},
/**