How to make a scrollable interface In Touch Flash CS5 for mobile devices (primarily iOS)

There are two ways to make a scrollable image in the AS3 mobile project: using Pan gestures (with two fingers) or using the mouse down, move and up (events with one finger are registered as mouse events on mobile devices). The example below supports both.

Note. With mouse events, you might want to add a timer to distinguish between clicks and drags (shown in the example).

// Necessary imports for this example - I use Flash Builder, so I'm not sure what CS5 requires.
import flash.display.DisplayObject;
import flash.events.MouseEvent;
import flash.events.TransformGestureEvent;
import flash.geom.Point;
import flash.ui.Multitouch;
import flash.ui.MultitouchInputMode;
import flash.utils.getTimer;


public class ScrollExample {
    // The image or other display object you want to scroll
    private var t:DisplayObject;
    // Dragging variables
    private var _prevX:Number; // Not required in this case since we're only scrolling vertically
    private var _prevY:Number;
    private var _dragging:Boolean = false;
    private var _lastMouseEvent:int;
    // Minimum touch time to permit drag (in milliseconds) - I use
    private static const MIN_DRAG_TIME:Number = 150;



    public function ScrollExample() {
        // Switch multitouch mode to support gestures (touch/mouse events are still registered)
        Multitouch.inputMode = MultitouchInputMode.GESTURE;

        // For my applications, I have found that the stage is much more responsive to touch events, but you may want to change "stage" here to "t"
        // Pan Gesture - two fingers up and down - like the scroll on a Mac
        stage.addEventListener(TransformGestureEvent.GESTURE_PAN, onPan);
        // Mouse down, move, and up - one finger drag
        stage.addEventListener(MouseEvent.MOUSE_DOWN, onStartDrag);
        stage.addEventListener(MouseEvent.MOUSE_MOVE, onMoveDrag);
        stage.addEventListener(MouseEvent.MOUSE_UP, onStopDrag);
    }


    private function onPan(e:TransformGestureEvent):void {
        // Move target display object by equivalent offset from pan object
        // For only vertical scrolling, don't use X!
        //t.x += e.offsetX;
        t.y += e.offsetY;
    }


    private function onStartDrag(e:MouseEvent):void {
        // Start timer to differentiate between click and drag
        _lastMouseEvent = getTimer();

        // Start dragging
        _dragging = true;
        // Set drag location values to track how drag is occuring
        // For only vertical scrolling, don't use X!
        //_prevX = e.stageX;
        _prevY = e.stageY;
     }


     private function onMoveDrag(e:MouseEvent):void {
         // If mouse down for less than minimum time, don't drag
         if (getTimer() > _lastMouseEvent + MIN_DRAG_TIME && _dragging) {
             // Move target display object to a valid location - prevents scrolling too far
             // Not using X...
             // t.x = ValidXDragPosition(e);
             t.y = ValidYDragPosition(e);

             // Reset drag position values
             _prevX = e.stageX;
             _prevY = e.stageY;
         }
     }


     private function onStopDrag(e:MouseEvent):void {
         // Stop dragging
         _dragging = false;

         // If mouse down time was less than min time, count as click
         if (getTimer() <= _lastMouseEvent + MIN_DRAG_TIME) {
             onClick(e);
         }
     }


     private function onClick(e:MouseEvent):void {
         // Handle your click event here...
     }


     // This function prevents your target display object from moving too far
     // In this example, it stops dragging when the display object boundary is reached
     // (Only showing Y direction)
     private function ValidYDragPosition(e:MouseEvent):Number {
         // Get the requested drag amount
         var requestedPoint:Number = _prevY - e.stageY;

         if (t.y - requestedPoint > 0) {
             // If drag will move target too far down, stop at top of object
             return 0;
         } else if (t.y - requestedPoint < stage.stageHeight - t.height) {
             // If drag will move target too far up, stop at bottom of object
             return stage.stageHeight - t.height;
         } else {
             // Otherwise, allow drag by requested amount
             return t.y - requestedPoint;
         }
     }
 }