Touch and drag

Two methods were added to the Sprite class to provide additional support for touch-enabled applications supporting touch-point input: Sprite.startTouchDrag() and Sprite.stopTouchDrag(). These methods behave the same as Sprite.startDrag() and Sprite.stopDrag() do for mouse events. However, notice the Sprite.startTouchDrag() and Sprite.stopTouchDrag() methods both take touchPointID values as parameters.

The runtime assigns the touchPointID value to the event object for a touch event. Use this value to respond to a specific touch point in the case the environment supports multiple, simultaneous, touch points (even if it does not handle gestures). For more information about the touchPointID property, see Touch Point ID.

The following code shows a simple start drag event handler and a stop drag event handler for a touch event. The variable bg is a display object that contains mySprite:

mySprite.addEventListener(TouchEvent.TOUCH_BEGIN, onTouchBegin);
mySprite.addEventListener(TouchEvent.TOUCH_END, onTouchEnd);

function onTouchBegin(e:TouchEvent) {
    e.target.startTouchDrag(e.touchPointID, false, bg.getRect(this));
    trace("touch begin");
}

function onTouchEnd(e:TouchEvent) {
    e.target.stopTouchDrag(e.touchPointID);
    trace("touch end");
}

And the following shows a more advanced example combining dragging with touch event phases:

Multitouch.inputMode = MultitouchInputMode.TOUCH_POINT;
var mySprite:Sprite = new Sprite();

mySprite.graphics.beginFill(0x336699);
mySprite.graphics.drawRect(0,0,40,40);
addChild(mySprite);

mySprite.addEventListener(TouchEvent.TOUCH_BEGIN, onTouchBegin);
mySprite.addEventListener(TouchEvent.TOUCH_MOVE, onTouchMove);
mySprite.addEventListener(TouchEvent.TOUCH_END, onTouchEnd);

function onTouchBegin(evt:TouchEvent) {
    evt.target.startTouchDrag(evt.touchPointID);
    evt.target.scaleX *= 1.5;
    evt.target.scaleY *= 1.5;
}

function onTouchMove(evt:TouchEvent) {
    evt.target.alpha = 0.5;
}

function onTouchEnd(evt:TouchEvent) {
    evt.target.stopTouchDrag(evt.touchPointID);
    evt.target.width = 40;
    evt.target.height = 40;
    evt.target.alpha = 1;
}