openseadragon/src/tilesource.js

(function( $ ){


/**
 * @class
 * @param {Number} width
 * @param {Number} height
 * @param {Number} tileSize
 * @param {Number} tileOverlap
 * @param {Number} minLevel
 * @param {Number} maxLevel
 * @property {Number} aspectRatio
 * @property {Number} dimensions
 * @property {Number} tileSize
 * @property {Number} tileOverlap
 * @property {Number} minLevel
 * @property {Number} maxLevel
 */ 
$.TileSource = function( width, height, tileSize, tileOverlap, minLevel, maxLevel ) {
    this.aspectRatio = width / height;
    this.dimensions  = new $.Point( width, height );
    this.tileSize    = tileSize ? tileSize : 0;
    this.tileOverlap = tileOverlap ? tileOverlap : 0;
    this.minLevel    = minLevel ? minLevel : 0;
    this.maxLevel    = maxLevel ? maxLevel :
        Math.ceil( 
            Math.log( Math.max( width, height ) ) / 
            Math.log( 2 ) 
        );
};

$.TileSource.prototype = {
    
    /**
     * @function
     * @param {Number} level
     */
    getLevelScale: function( level ) {
        return 1 / ( 1 << ( this.maxLevel - level ) );
    },

    /**
     * @function
     * @param {Number} level
     */
    getNumTiles: function( level ) {
        var scale = this.getLevelScale( level ),
            x = Math.ceil( scale * this.dimensions.x / this.tileSize ),
            y = Math.ceil( scale * this.dimensions.y / this.tileSize );

        return new $.Point( x, y );
    },

    /**
     * @function
     * @param {Number} level
     */
    getPixelRatio: function( level ) {
        var imageSizeScaled = this.dimensions.times( this.getLevelScale( level ) ),
            rx = 1.0 / imageSizeScaled.x,
            ry = 1.0 / imageSizeScaled.y;

        return new $.Point(rx, ry);
    },

    /**
     * @function
     * @param {Number} level
     * @param {OpenSeadragon.Point} point
     */
    getTileAtPoint: function( level, point ) {
        var pixel = point.times( this.dimensions.x ).times( this.getLevelScale(level ) ),
            tx = Math.floor( pixel.x / this.tileSize ),
            ty = Math.floor( pixel.y / this.tileSize );

        return new $.Point( tx, ty );
    },

    /**
     * @function
     * @param {Number} level
     * @param {Number} x
     * @param {Number} y
     */
    getTileBounds: function( level, x, y ) {
        var dimensionsScaled = this.dimensions.times( this.getLevelScale( level ) ),
            px = ( x === 0 ) ? 0 : this.tileSize * x - this.tileOverlap,
            py = ( y === 0 ) ? 0 : this.tileSize * y - this.tileOverlap,
            sx = this.tileSize + ( x === 0 ? 1 : 2 ) * this.tileOverlap,
            sy = this.tileSize + ( y === 0 ? 1 : 2 ) * this.tileOverlap,
            scale = 1.0 / dimensionsScaled.x;

        sx = Math.min( sx, dimensionsScaled.x - px );
        sy = Math.min( sy, dimensionsScaled.y - py );

        return new $.Rect( px * scale, py * scale, sx * scale, sy * scale );
    },

    /**
     * This method is not implemented by this class other than to throw an Error
     * announcing you have to implement it.  Because of the variety of tile 
     * server technologies, and various specifications for building image
     * pyramids, this method is here to allow easy integration.
     * @function
     * @param {Number} level
     * @param {Number} x
     * @param {Number} y
     * @throws {Error}
     */
    getTileUrl: function( level, x, y ) {
        throw new Error( "Method not implemented." );
    },

    /**
     * @function
     * @param {Number} level
     * @param {Number} x
     * @param {Number} y
     */
    tileExists: function( level, x, y ) {
        var numTiles = this.getNumTiles( level );
        return  level >= this.minLevel && 
                level <= this.maxLevel &&
                x >= 0 && 
                y >= 0 && 
                x < numTiles.x && 
                y < numTiles.y;
    }
};

}( OpenSeadragon ));