openseadragon/src/rectangle.js

/*
 * OpenSeadragon - Rect
 *
 * 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( $ ){

/**
 * A Rectangle really represents a 2x2 matrix where each row represents a
 * 2 dimensional vector component, the first is (x,y) and the second is
 * (width, height).  The latter component implies the equation of a simple
 * plane.
 *
 * @class
 * @param {Number} x The vector component 'x'.
 * @param {Number} y The vector component 'y'.
 * @param {Number} width The vector component 'height'.
 * @param {Number} height The vector component 'width'.
 * @property {Number} x The vector component 'x'.
 * @property {Number} y The vector component 'y'.
 * @property {Number} width The vector component 'width'.
 * @property {Number} height The vector component 'height'.
 */
$.Rect = function( x, y, width, height ) {
    this.x = typeof ( x ) == "number" ? x : 0;
    this.y = typeof ( y ) == "number" ? y : 0;
    this.width  = typeof ( width )  == "number" ? width : 0;
    this.height = typeof ( height ) == "number" ? height : 0;
};

$.Rect.prototype = {

    /**
     * The aspect ratio is simply the ratio of width to height.
     * @function
     * @returns {Number} The ratio of width to height.
     */
    getAspectRatio: function() {
        return this.width / this.height;
    },

    /**
     * Provides the coordinates of the upper-left corner of the rectangle as a
     * point.
     * @function
     * @returns {OpenSeadragon.Point} The coordinate of the upper-left corner of
     *  the rectangle.
     */
    getTopLeft: function() {
        return new $.Point(
            this.x,
            this.y
        );
    },

    /**
     * Provides the coordinates of the bottom-right corner of the rectangle as a
     * point.
     * @function
     * @returns {OpenSeadragon.Point} The coordinate of the bottom-right corner of
     *  the rectangle.
     */
    getBottomRight: function() {
        return new $.Point(
            this.x + this.width,
            this.y + this.height
        );
    },

    /**
     * Provides the coordinates of the top-right corner of the rectangle as a
     * point.
     * @function
     * @returns {OpenSeadragon.Point} The coordinate of the top-right corner of
     *  the rectangle.
     */
    getTopRight: function() {
        return new $.Point(
            this.x + this.width,
            this.y
        );
    },

    /**
     * Provides the coordinates of the bottom-left corner of the rectangle as a
     * point.
     * @function
     * @returns {OpenSeadragon.Point} The coordinate of the bottom-left corner of
     *  the rectangle.
     */
    getBottomLeft: function() {
        return new $.Point(
            this.x,
            this.y + this.height
        );
    },

    /**
     * Computes the center of the rectangle.
     * @function
     * @returns {OpenSeadragon.Point} The center of the rectangle as represented
     *  as represented by a 2-dimensional vector (x,y)
     */
    getCenter: function() {
        return new $.Point(
            this.x + this.width / 2.0,
            this.y + this.height / 2.0
        );
    },

    /**
     * Returns the width and height component as a vector OpenSeadragon.Point
     * @function
     * @returns {OpenSeadragon.Point} The 2 dimensional vector representing the
     *  the width and height of the rectangle.
     */
    getSize: function() {
        return new $.Point( this.width, this.height );
    },

    /**
     * Determines if two Rectangles have equivalent components.
     * @function
     * @param {OpenSeadragon.Rect} rectangle The Rectangle to compare to.
     * @return {Boolean} 'true' if all components are equal, otherwise 'false'.
     */
    equals: function( other ) {
        return ( other instanceof $.Rect ) &&
            ( this.x === other.x ) &&
            ( this.y === other.y ) &&
            ( this.width === other.width ) &&
            ( this.height === other.height );
    },

    /**
     * Rotates a rectangle around a point. Currently only 90, 180, and 270
     * degrees are supported.
     * @function
     * @param {Number} degrees The angle in degrees to rotate.
     * @param {OpenSeadragon.Point} pivot The point about which to rotate.
     * Defaults to the center of the rectangle.
     * @return {OpenSeadragon.Rect}
     */
    rotate: function( degrees, pivot ) {
        // TODO support arbitrary rotation
        var width = this.width,
            height = this.height,
            newTopLeft;

        degrees = ( degrees + 360 ) % 360;
        if( degrees % 90 !== 0 ) {
            throw new Error('Currently only 0, 90, 180, and 270 degrees are supported.');
        }

        if( degrees === 0 ){
            return this;
        }

        pivot = pivot || this.getCenter();

        switch ( degrees ) {
            case 90:
                newTopLeft = this.getBottomLeft();
                width = this.height;
                height = this.width;
                break;
            case 180:
                newTopLeft = this.getBottomRight();
                break;
            case 270:
                newTopLeft = this.getTopRight();
                width = this.height;
                height = this.width;
                break;
            default:
                newTopLeft = this.getTopLeft();
                break;
        }

        newTopLeft = newTopLeft.rotate(degrees, pivot);

        return new $.Rect(newTopLeft.x, newTopLeft.y, width, height);
    },

    /**
     * Provides a string representation of the rectangle which is useful for
     * debugging.
     * @function
     * @returns {String} A string representation of the rectangle.
     */
    toString: function() {
        return "[" +
            Math.round(this.x*100) + "," +
            Math.round(this.y*100) + "," +
            Math.round(this.width*100) + "x" +
            Math.round(this.height*100) +
        "]";
    }
};


}( OpenSeadragon ));