Source: d:/wamp/www/phaser/src/pixi/InteractionData.js

/**
 * @author Mat Groves http://matgroves.com/ @Doormat23
 */

/**
 * Holds all information related to an Interaction event
 *
 * @class InteractionData
 * @constructor
 */
PIXI.InteractionData = function()
{
    /**
     * This point stores the global coords of where the touch/mouse event happened
     *
     * @property global
     * @type Point
     */
    this.global = new PIXI.Point();

    /**
     * The target Sprite that was interacted with
     *
     * @property target
     * @type Sprite
     */
    this.target = null;

    /**
     * When passed to an event handler, this will be the original DOM Event that was captured
     *
     * @property originalEvent
     * @type Event
     */
    this.originalEvent = null;
};

/**
 * This will return the local coordinates of the specified displayObject for this InteractionData
 *
 * @method getLocalPosition
 * @param displayObject {DisplayObject} The DisplayObject that you would like the local coords off
 * @param [point] {Point} A Point object in which to store the value, optional (otherwise will create a new point)
 * @return {Point} A point containing the coordinates of the InteractionData position relative to the DisplayObject
 */
PIXI.InteractionData.prototype.getLocalPosition = function(displayObject, point)
{
    var worldTransform = displayObject.worldTransform;
    var global = this.global;

    // do a cheeky transform to get the mouse coords;
    var a00 = worldTransform.a, a01 = worldTransform.c, a02 = worldTransform.tx,
        a10 = worldTransform.b, a11 = worldTransform.d, a12 = worldTransform.ty,
        id = 1 / (a00 * a11 + a01 * -a10);

    point = point || new PIXI.Point();

    point.x = a11 * id * global.x + -a01 * id * global.y + (a12 * a01 - a02 * a11) * id;
    point.y = a00 * id * global.y + -a10 * id * global.x + (-a12 * a00 + a02 * a10) * id;

    // set the mouse coords...
    return point;
};

// constructor
PIXI.InteractionData.prototype.constructor = PIXI.InteractionData;