Qt Quick Examples - Touch Interaction

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: 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: {
      // 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.

Files:

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