Qt Quick Examples - Touch Interaction

A collection of QML Touch Interaction examples.

Touch Interaction is a collection of small QML examples relating to touch interaction methods. For more information, visit Important Concepts In Qt Quick - User Input.

Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Multipoint Flames Example

Multipoint Flames demonstrates distinguishing different fingers in a MultiPointTouchArea, by assigning a different colored flame to each touch point.

The MultipointTouchArea sets up multiple touch points:

     MultiPointTouchArea {
         anchors.fill: parent
         minimumTouchPoints: 1
         maximumTouchPoints: 5
         touchPoints: [
             TouchPoint { id: touch1 },
             TouchPoint { id: touch2 },
             TouchPoint { id: touch11 },
             TouchPoint { id: touch21 },
             TouchPoint { id: touch31 }
         ]
     }

The flames are then simply bound to the coordinates of the touch point, and whether it is currently pressed, as follows:

     ParticleFlame {
         color: "red"
         emitterX: touch1.x
         emitterY: touch1.y
         emitting: touch1.pressed
     }

Bear-Whack Example

Bear-Whack demonstrates using MultiPointTouchArea to add multiple finger support to a simple game. The interaction with the game is done through a SpriteGoal that follows the TouchPoint. The TouchPoints added to the MultiPointTouchArea are a component with the relevant logic embedded into it:

 TouchPoint {
     id: container
     property ParticleSystem system
     onPressedChanged: {
         if (pressed) {
             timer.restart();
             child.enabled = true;
             system.explode(x,y);
         }
     }
     property QtObject obj: Timer {
         id: timer
         interval: 100
         running: false
         repeat: false
         onTriggered: container.child.enabled = false
     }
     property Item child: SpriteGoal {
         enabled: false
         x: container.area.x - 16
         y: container.area.y - 16
         width: container.area.width + 32
         height: container.area.height + 32 //+32 so it doesn't have to hit the exact center
         system: container.system
         parent: container.system
         goalState: "falling"
     }
 }

Flick Resize Example

Flick Resize uses a PinchArea to implement a pinch-to-resize behavior. This is easily achieved by listening to the PinchArea signals and responding to user input.

 onPinchStarted: {
     initialWidth = flick.contentWidth
     initialHeight = flick.contentHeight
 }

 onPinchUpdated: (pinch)=> {
     // adjust content pos due to drag
     flick.contentX += pinch.previousCenter.x - pinch.center.x
     flick.contentY += pinch.previousCenter.y - pinch.center.y

     // resize content
     flick.resizeContent(initialWidth * pinch.scale, initialHeight * pinch.scale, pinch.center)
 }

 onPinchFinished: {
     // Move its content within bounds.
     flick.returnToBounds()
 }

Flickable Example

Flickable is a simple example demonstrating the Flickable type.

 Rectangle {
 width: 320
 height: 480
 Flickable {
     anchors.fill: parent
     contentWidth: 1200
     contentHeight: 1200
     Rectangle {
         width: 1000
         height: 1000

Corkboards Example

Corkboards shows another use for Flickable, with QML types within the flickable object that respond to mouse and keyboard interaction. This behavior does not require special code as the Qt Quick types already cooperate with the Flickable type for accepting touch events.

Example project @ code.qt.io

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