Android development gesture detection and method of implementing page turn function through gestures

This article describes the gesture detection and the method of page turning function through gestures in Android development. Share it for your reference, as follows:

Gestures refer to the continuous touching of the user's finger or touch pen on the touch screen. For example, a gesture is drawn from left to right on the screen, which is a gesture, and for example, drawing a circle on the screen is also a gesture. Continuous touches of gestures will form a movement trend in a certain direction and will also form an irregular geometric shape. Android supports both gesture behaviors:

1. For the first gesture behavior, Android provides gesture detection and provides corresponding listeners for gesture detection.

2. For the second gesture behavior, Android allows developers to add gestures and provides corresponding APIs to identify users' gestures.

Gesture detection

Android provides aGestureDetector class,GestrueDetector instance represents a gesture detector, createsGestureDetectorA need to be passed inAn example is a listener that is responsible for responding to user gesture behavior.

The event handling methods included are as follows.

Boolean onDown(MotionEvent e): This method is triggered when the touch event is pressed.
Boolean onFling(MotionEvent e1,MotionEvent e2,float velocitX,floatvelocity): This method is triggered when the user drags over the touch screen. Among them, velocityX and velocityY represent the speed of dragging the action in the horizontal and vertical directions.
Abstract void onLongPress(MotionEvent e): This method is triggered when the user presses and holds on the screen for a long time.
Boolean onScroll(MotionEvent e1,MotionEvent e2,float distance,float distance): When the user scrolls on the screen, this method is triggered.
Void onShowPress(MotionEvent e): This method is triggered when the user presses on the touch screen and has not been moved and released.
Boolean onSingleTapUp(MotionEvent e): The user's tap event on the touch screen will trigger this method.

Using Android's gesture detection requires only two steps:

1. Create a GestureDetector. When creating this object, you must implement aListener instance.

2. Bind the listener for the TouchEvent event of the application's Activity, and specify that the TouchEvent event on the Activity is handed over to the event processing.GestureDetectordeal with.

After the above two steps, the TouchEvent event on the Activity will be handed over to the GestureDetector to handle, and the GestureDetector will detect whether a specific gesture action has been triggered.

Example: Use gestures to achieve page turn effect

Ideas:Leave the TouchEvent of the Activity to GestureDetector for processing. The special thing about this program is that the program uses a ViewFlipper component. The ViewFlipper component is actually a container-class component. Therefore, addView (View v) can be called to addView (View v). Once multiple components are added to ViewFlipper, ViewFlipper can use animation to control the switching effect between multiple components.

This example uses GestureDetector to detect user gesture actions, and controls the switching of View components contained in ViewFlipper according to the gesture actions, thereby achieving page turnover effect.

The key code is as follows:

Public Boolean onFling(MotionEvent event1,MotionEvent event2,float velocityX,velocity)
{
  if(()-()>FLIP_DISTANCE)
  {
    (animations[0]);
    (animations[1]);
    ();
    return true;
  }
  else if(()-()>FLIP_DISTANCE)
  {
    (animations[2]);
    (animation[3]);
    ();
    return true;
  }
  return false;
}

in:

animations[0]=(this,.left_in);
animations[1]=(this,.left_out);
animations[2]=(this,.right_in);
animations[3]=(this,.right_out);

For more information about Android related content, please check out the topic of this site:Android gesture operation skills summary》、《Summary of the usage of basic Android components》、《Android development introduction and advanced tutorial》、《Android debugging skills and solutions to common problems》、《Android View View Tips Summary》、《Android layout layout tips summary"and"Android control usage summary》

I hope this article will be helpful to everyone's Android programming design.