ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Touch, multitouch and gesture input
Touch support discovery
Flash Player 10.1 and later, Adobe AIR 2 and later
Use the Multitouch class properties to set the scope of touch input your application handles. Then, test the
environment to ensure that support exists for the events your ActionScript handles. Specifically, first establish the type
of touch input for your application. The options are: touch point, gesture, or none (interpret all touch input as mouse
clicks and use mouse event handlers, only). Then, use the properties and methods of the Multitouch class to make sure
that the runtime is in an environment that supports the touch input your application requires. Test the runtime
environment for support of the types of touch input (such as whether it can interpret gestures), and respond
accordingly.
Note: The Multitouch class properties are static properties, and do not belong to instances of any class. Use them with the
syntax Multitouch.property, for example:
var touchSupport:Boolean = Multitouch.supportsTouchEvents;
Set the input type
The Flash runtime must know the type of touch input to interpret, because a touch event can have many elements or
phases. If a finger simply touches a touch-enabled screen, does the runtime dispatch a touch event? Or does it wait for
a gesture? Or does the runtime track the touch as a mouse-down event? An application that supports touch input must
establish the type of touch events it handles for the Flash runtime. Use the Multitouch.inputMode property to
establish the type of touch input for the runtime. The input mode can be one of three options:
None No special handling is provided for touch events. Set: Multitouch.inputMode=MultitouchInputMode.NONE
and use the MouseEvent class to handle input.
Single touch points All touch input is interpreted, individually, and all touch points can be tracked and handled. Set:
Multitouch.inputMode=MultitouchInputMode.TOUCH_POINT and use the TouchEvent class to handle input.
Gesture input The device or operating system interprets input as a complex form of finger movement across the
screen. The device or operating system collectively assigns the movement to a single gesture input event. Set:
Multitouch.inputMode=MultitouchInputMode.GESTURE and use the TransformGestureEvent,
PressAndTapGestureEvent, or GestureEvent classes to handle input.
See “Touch event handling” on page 584 for an example that uses the Multitouch.inputMode property to set the
input type before handling a touch event.
Test for touch input support
Other properties of the Multitouch class provide values for fine-tuning your application to the current environment’s
touch support. The Flash runtime populates values for the number of simultaneous touch points allowed or gestures
available. If the runtime is in an environment that does not support the touch event handling your application needs,
provide the user with an alternative. For example, provide mouse event handling or information about what features
are available, or not, in the current environment.
You can also use the API for keyboard, touch, and mouse support, see “Discovering input types” on page 557.
For more information about compatibility testing, see “Troubleshooting” on page 592.
Last updated 6/6/2012
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