Troubleshooting

Hardware and software support for touch input is changing, rapidly. This reference does not maintain a list of every device an operating system and software combination that supports multitouch. However, it provides guidance on using the discovery API to determine if your application is deployed on a device that supports multitouch, and provides tips for troubleshooting your ActionScript code.

Flash runtimes respond to touch events based on information the device, operating system, or containing software (such as a browser) passes to the runtime. This dependency on the software environment complicates documenting multitouch compatibility. Some devices interpret a gesture or touch motion differently than another device. Is rotation defined by two fingers rotating at the same time? Is rotation one finger drawing a circle on a screen? Depending on the hardware and software environment, the rotation gesture could be either, or something entirely different. So, the device tells the operating system the user input, then the operating system passes that information to the runtime. If the runtime is inside a browser, the browser software sometimes interprets the gesture or touch event and does not pass the input to the runtime. This behavior is similar to the behavior of "hotkeys": you try to use a specific key combination to get Flash Player to do something inside the browser and the browser keeps opening a menu instead.

Individual API and classes mention if they're not compatible with specific operating systems. You can explore individual API entries here, starting with the Multitouch class: https://airsdk.dev/reference/actionscript/3.0/flash/ui/Multitouch.html.

Here are some common gesture and touch descriptions:

Pan
Move a finger left-to-right or right-to-left. Some devices require two fingers to pan.

Rotate
Touch two fingers down, then move them around in a circle (as if they're both simultaneously tracing an imaginary circle on a surface). The pivot point is set at the midpoint between the two finger touch points.

Swipe
Move three fingers left-to-right or right-to-left, top-to-bottom, or bottom-to-top, quickly.

Zoom
Touch two fingers down, then move them away from each other to zoom in and toward each other to zoom out.

Press-and-tap
Move or press one finger, then tap the surface with another.

Each device has its own documentation about the gestures the device supports and how to perform each gesture on that device. In general, the user must remove all fingers from contact with the device between gestures, depending upon the operating system.

If you find your application is not responding to touch events or gestures, test the following:

Do you have event listeners for touch or gesture events attached to an object class that inherits from the InteractiveObject class? Only InteractiveObject instances can listen for touch and gesture events
Are you testing your application within Flash Professional CS5? If so, try publishing and testing the application, because Flash Professional can intercept the interaction.

Start simple and see what does work, first (the following code example is from the API entry for Multitouch.inputMode:

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

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

mySprite.addEventListener(TouchEvent.TOUCH_TAP, taplistener);

function taplistener(e:TouchEvent): void {
    myTextField.text = "I've been tapped";
    myTextField.y = 50;
    addChild(myTextField);
}

Tap the rectangle. If this example works, then you know your environment supports a simple tap. Then you can try more complicated handling.

Testing for gesture support is more complicated. An individual device or operating system supports any combination of gesture input, or none.

Here is a simple test for the zoom gesture:

Multitouch.inputMode = MultitouchInputMode.GESTURE;

stage.addEventListener(TransformGestureEvent.GESTURE_ZOOM , onZoom);
var myTextField = new TextField();
myTextField.y = 200;
myTextField.text = "Perform a zoom gesture";
addChild(myTextField);

function onZoom(evt:TransformGestureEvent):void {
    myTextField.text = "Zoom is supported";
}

Perform a zoom gesture on the device and see if the text field populates with the message Zoom is supported. The event listener is added to the stage so you can perform the gesture on any part of the test application.

Here is a simple test for the pan gesture:

Multitouch.inputMode = MultitouchInputMode.GESTURE;

stage.addEventListener(TransformGestureEvent.GESTURE_PAN , onPan);
var myTextField = new TextField();
myTextField.y = 200;
myTextField.text = "Perform a pan gesture";
addChild(myTextField);

function onPan(evt:TransformGestureEvent):void {
    myTextField.text = "Pan is supported";
}

Perform a pan gesture on the device and see if the text field populates with the message Pan is supported. The event listener is added to the stage so you can perform the gesture on any part of the test application.

Some operating system and device combinations support both gestures, some support only one, some none. Test your application's deployment environment to be sure.

Known Issues

The following are known issues related to touch input:

Mobile Internet Explorer on Windows Mobile operating system automatically zooms SWF file content:
This Internet Explorer zoom behavior is overridden by adding the following to the HTML page hosting the SWF file:
```
<head>
    <meta name="viewport" content="width=device-width, height=device-height, initial-scale=1.0">
</head>
```
Windows 7 (and possibly other operating systems), the user must lift the pointing device (or fingers) off the screen between gestures. For example:, to rotate and zoom an image:
- Perform the rotate gesture.
- Lift your fingers off the screen.
- Put your fingers back onto the screen and perform the zoom gesture.
Windows 7 (and possibly other operating systems), the rotate and zoom gestures don't always generate an "update" phase if the user performs the gesture very quickly.
Windows 7 Starter Edition does not support multitouch. See the AIR Labs Forum for details: http://forums.adobe.com/thread/579180?tstart=0
For Mac OS 10.5.3 and later, the Multitouch.supportsGestureEvents value is always true, even if the hardware does not support gesture events.

Troubleshooting

Known Issues​

Known Issues