Android slide gesture Detection Method

The Android mobile phone operating system supports various sliding gestures. Here we will introduce how these gestures can be detected on the Android platform. Next let's take a look at the specific recognition methods of Android sliding gestures.

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The Android SDK provides a listener class to detect different gestures:

SimpleOnGestureListener. You only need to implement the gestures you care about.

In android, Swipe is called Fling.

First, create your own gesture detector class:

 
 

  
  
class MyGestureDetector extends SimpleOnGestureListener {   
  
  
@Override   
  
  
public boolean onFling(MotionEvent e1, MotionEvent e2, 
float velocityX, float velocityY) {   
  
  
} 
 
 

An Android slide gesture has several features. For example, it is almost a straight line on the x or Y axis. The deviation between the midway path cannot be too large, and it requires a certain speed. Therefore, we define several quantiles:

 
 

  
  
private static final int SWIPE_MIN_DISTANCE = 120;   
  
  
private static final int SWIPE_MAX_OFF_PATH = 250;   
  
  
private static final int 
SWIPE_THRESHOLD_VELOCITY = 200;  
 
 

Then, in the onFling method, determine whether it is a reasonable swipe action:

 
 

  
  
if(e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && Math.abs
(velocityX) > SWIPE_THRESHOLD_VELOCITY) {   
  
  
viewFlipper.setInAnimation(slideLeftIn);   
  
  
viewFlipper.setOutAnimation(slideLeftOut);   
  
  
viewFlipper.showNext();   
  
  
} else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && 
Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {   
  
  
viewFlipper.setInAnimation(slideRightIn);   
  
  
viewFlipper.setOutAnimation(slideRightOut);   
  
  
viewFlipper.showPrevious();   
  
  
}   
  
  
if(e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && 
Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {  
  
  
viewFlipper.setInAnimation(slideLeftIn);  
  
  
viewFlipper.setOutAnimation(slideLeftOut);  
  
  
viewFlipper.showNext();  
  
  
} else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && 
Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {  
  
  
viewFlipper.setInAnimation(slideRightIn);  
  
  
viewFlipper.setOutAnimation(slideRightOut);  
  
  
viewFlipper.showPrevious();  
  
  
} 
 
 

ViewFlipper is a container containing multiple views. You can easily call prev/next view and add the animation to achieve some good results:

 
 

  
  
viewFlipper = (ViewFlipper)findViewById(R.id.flipper);   
  
  
slideLeftIn = AnimationUtils.loadAnimation
(this, R.anim.slide_left_in);   
  
  
slideLeftOut = AnimationUtils.loadAnimation
(this, R.anim.slide_left_out);   
  
  
slideRightIn = AnimationUtils.loadAnimation
(this, R.anim.slide_right_in);   
  
  
slideRightOut = AnimationUtils.loadAnimation
(this, R.anim.slide_right_out);  
 
 

Custom animation allows you to view specific XML, such as an animation coming in from the left:

 
 

  
  
< set xmlns:android="http://schemas.
android.com/apk/res/android">   
  
  
< translate android:fromXDelta="100%p" 
android:toXDelta="0" android:duration="800"/>   
  
  
< /set> 
 
 

Of course, do not forget to use the override onTouch method in your Activity to obtain the gesture action:

 
 

  
  
@Override   
  
  
public boolean onTouchEvent(MotionEvent event) {   
  
  
if (gestureDetector.onTouchEvent(event))   
  
  
return true;   
  
  
else   
  
  
return false;   
  
  
} 
 
 

Android sliding gesture recognition methods are described here.