JavaScript Documentation

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/**
 * @class A region is a representation of an object on a grid.  It is defined
 * by the top, right, bottom, left extents, so is rectangular by default.  If
 * other shapes are required, this class could be extended to support it.
 *
 * @param {int} t the top extent
 * @param {int} r the right extent
 * @param {int} b the bottom extent
 * @param {int} l the left extent
 * @constructor
 */
YAHOO.util.Region = function(t, r, b, l) {

    /**
     * The region's top extent
     * @type int
     */
    this.top = t;

    /**
     * The region's right extent
     * @type int
     */
    this.right = r;

    /**
     * The region's bottom extent
     * @type int
     */
    this.bottom = b;

    /**
     * The region's left extent
     * @type int
     */
    this.left = l;
};

/**
 * Returns true if this region contains the region passed in
 *
 * @param  {Region}  region The region to evaluate
 * @return {boolean}        True if the region is contained with this region,
 *                          else false
 */
YAHOO.util.Region.prototype.contains = function(region) {
    return ( region.left   >= this.left   &&
             region.right  <= this.right  &&
             region.top    >= this.top    &&
             region.bottom <= this.bottom    );

    // this.logger.debug("does " + this + " contain " + region + " ... " + ret);
};

/**
 * Returns the area of the region
 *
 * @return {int} the region's area
 */
YAHOO.util.Region.prototype.getArea = function() {
    return ( (this.bottom - this.top) * (this.right - this.left) );
};

/**
 * Returns the region where the passed in region overlaps with this one
 *
 * @param  {Region} region The region that intersects
 * @return {Region}        The overlap region, or null if there is no overlap
 */
YAHOO.util.Region.prototype.intersect = function(region) {
    var t = Math.max( this.top,    region.top    );
    var r = Math.min( this.right,  region.right  );
    var b = Math.min( this.bottom, region.bottom );
    var l = Math.max( this.left,   region.left   );

    if (b >= t && r >= l) {
        return new YAHOO.util.Region(t, r, b, l);
    } else {
        return null;
    }
};

/**
 * Returns the region representing the smallest region that can contain both
 * the passed in region and this region.
 *
 * @param  {Region} region The region that to create the union with
 * @return {Region}        The union region
 */
YAHOO.util.Region.prototype.union = function(region) {
    var t = Math.min( this.top,    region.top    );
    var r = Math.max( this.right,  region.right  );
    var b = Math.max( this.bottom, region.bottom );
    var l = Math.min( this.left,   region.left   );

    return new YAHOO.util.Region(t, r, b, l);
};

/**
 * toString
 * @return string the region properties
 */
YAHOO.util.Region.prototype.toString = function() {
    return ( "Region {" +
             "  t: "    + this.top    +
             ", r: "    + this.right  +
             ", b: "    + this.bottom +
             ", l: "    + this.left   +
             "}" );
}

/**
 * Returns a region that is occupied by the DOM element
 *
 * @param  {HTMLElement} el The element
 * @return {Region}         The region that the element occupies
 * @static
 */
YAHOO.util.Region.getRegion = function(el) {
    var p = YAHOO.util.Dom.getXY(el);

    var t = p[1];
    var r = p[0] + el.offsetWidth;
    var b = p[1] + el.offsetHeight;
    var l = p[0];

    return new YAHOO.util.Region(t, r, b, l);
};

/////////////////////////////////////////////////////////////////////////////


/**
 * @class
 *
 * A point is a region that is special in that it represents a single point on
 * the grid.
 *
 * @param {int} x The X position of the point
 * @param {int} y The Y position of the point
 * @constructor
 * @extends Region
 */
YAHOO.util.Point = function(x, y) {
    /**
     * The X position of the point
     * @type int
     */
    this.x      = x;

    /**
     * The Y position of the point
     * @type int
     */
    this.y      = y;

    this.top    = y;
    this.right  = x;
    this.bottom = y;
    this.left   = x;
};

YAHOO.util.Point.prototype = new YAHOO.util.Region();