Detecting Gestures on a multi-touch Screen
This topic demonstrates how to detect and use multi-touch gestures in a MonoGame game.
Overview
The code in this topic shows you the technique for detecting and using multi-touch gestures. You can download a complete code sample for this topic, including full source code and any additional supporting files required by the sample.
MonoGame supports multi-touch gesture-based input on Mobile. The primary class that provides this support is TouchPanel, which provides the ability to:
- Designate which gestures should be detected.
- Query to see if any gestures are available for processing.
Note
Gesture support is provided as a convenient subset of the features possible on a multi-touch input device. For more information about general multi-touch programming, see Working with Touch Input.
How to detect Gestures on a multi-touch Screen
Set the gestures to enable with TouchPanel.EnabledGestures. This can be one value, or a combination of values, in the GestureType enumeration. Performance can be decreased by enabling all gestures, so it is a good practice to enable only the gestures you will be using in your game.
During your game loop, check to see if any gestures are available with TouchPanel.IsGestureAvailable. When IsGestureAvailable is false, there are no more gestures in the queue.
If gestures are available, call TouchPanel.ReadGesture to get a GestureSample that contains the data for the gesture.
Some gestures will be preceded by another gesture that begins the gesture. For instance, a DoubleTap gesture is always preceded by a Tap gesture. For more information about the various gesture types supported, see GestureType.
Example
The following code illustrates the procedure for detecting gestures on a multi-touch screen.
Enabling gestures in the game's constructor:
// set up touch gesture support: make vertical drag and flick the // gestures that we are interested in. TouchPanel.EnabledGestures = GestureType.VerticalDrag | GestureType.Flick;Detecting gestures in the game's Update method:
// get any gestures that are ready. while (TouchPanel.IsGestureAvailable) { GestureSample gs = TouchPanel.ReadGesture(); switch (gs.GestureType) { case GestureType.VerticalDrag: // move the poem screen vertically by the drag delta amount. poem.offset.Y -= gs.Delta.Y; break; case GestureType.Flick: // add velocity to the poem screen (only interested in changes to Y velocity). poem.velocity.Y += gs.Delta.Y; break; } }