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Wednesday, November 27, 2013

Using GestureDetector to detect user swipe, onFling()

Previous exercise demonstrate "Bi-direction sliding ViewFlipper" controlled by buttons. This exercise show how to implements GestureDetector.OnGestureListener to detect user swipe to update ViewFlipper.

Using GestureDetector to detect user swipe


package com.example.androidviewflipper;

import android.os.Bundle;
import android.app.Activity;
import android.support.v4.view.GestureDetectorCompat;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.Toast;
import android.widget.ViewFlipper;

public class MainActivity extends Activity implements
GestureDetector.OnGestureListener {

private GestureDetectorCompat mDetector;

Button buttonPrev, buttonNext;
ViewFlipper viewFlipper;

Animation slide_in_left, slide_out_right;
Animation slide_in_right, slide_out_left;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

mDetector = new GestureDetectorCompat(this,this);

buttonPrev = (Button) findViewById(R.id.prev);
buttonNext = (Button) findViewById(R.id.next);
viewFlipper = (ViewFlipper) findViewById(R.id.viewflipper);

slide_in_left = AnimationUtils.loadAnimation(this,
R.anim.slide_in_left);
slide_out_right = AnimationUtils.loadAnimation(this,
R.anim.slide_out_right);

slide_in_right = AnimationUtils.loadAnimation(this,
R.anim.slide_in_right);
slide_out_left = AnimationUtils.loadAnimation(this,
R.anim.slide_out_left);

//viewFlipper.setInAnimation(slide_in_left);
//viewFlipper.setOutAnimation(slide_out_right);

buttonPrev.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
viewFlipper.setInAnimation(slide_in_right);
viewFlipper.setOutAnimation(slide_out_left);
viewFlipper.showPrevious();
}
});

buttonNext.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
viewFlipper.setInAnimation(slide_in_left);
viewFlipper.setOutAnimation(slide_out_right);
viewFlipper.showNext();
}
});
;
}

@Override
public boolean onTouchEvent(MotionEvent event) {
this.mDetector.onTouchEvent(event);
return super.onTouchEvent(event);
}

@Override
public boolean onDown(MotionEvent arg0) {
// TODO Auto-generated method stub
return false;
}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
float sensitvity = 50;

if((e1.getX() - e2.getX()) > sensitvity){
viewFlipper.setInAnimation(slide_in_right);
viewFlipper.setOutAnimation(slide_out_left);
viewFlipper.showPrevious();
Toast.makeText(MainActivity.this,
"Previous", Toast.LENGTH_SHORT).show();
}else if((e2.getX() - e1.getX()) > sensitvity){
viewFlipper.setInAnimation(slide_in_left);
viewFlipper.setOutAnimation(slide_out_right);
viewFlipper.showNext();
Toast.makeText(MainActivity.this,
"Next", Toast.LENGTH_SHORT).show();
}

return true;
}

@Override
public void onLongPress(MotionEvent e) {
// TODO Auto-generated method stub

}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
float distanceY) {
// TODO Auto-generated method stub
return false;
}

@Override
public void onShowPress(MotionEvent e) {
// TODO Auto-generated method stub

}

@Override
public boolean onSingleTapUp(MotionEvent e) {
// TODO Auto-generated method stub
return false;
}

}


Keep using the layout and animation XML files in last exercise.

download filesDownload the files.


Next:
- Detect Gesture by implementing GestureDetector.SimpleOnGestureListener

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