Gestures Detector

Gestures are patterns drawn by the user on the screen. Simple gestures include tap, scroll, swipe, etc. Complex gestures are more complex patterns drawn on the screen. In Android we can detect simple gestures using GestureDetector class.

Here i am going to create a simple Gestures Detector having scroll and flip on the basis of the Double-tap. 

Create an activity -> FlipperActivity.java 


package com.samples.gesturedetectorsample;

import java.util.ArrayList;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Vibrator;
import android.view.GestureDetector;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.ViewGroup.LayoutParams;
import android.view.animation.Animation;
import android.view.animation.OvershootInterpolator;
import android.view.animation.TranslateAnimation;
import android.widget.TextView;
import android.widget.ViewFlipper;

public class FlipperActivity extends Activity 
implements GestureDetector.OnGestureListener,GestureDetector.OnDoubleTapListener{
final private int SWIPE_MIN_DISTANCE = 100;
final private int SWIPE_MIN_VELOCITY = 100;
private ViewFlipper flipper = null;
private ArrayList<TextView> views = null;
private GestureDetector gesturedetector = null;
private Vibrator vibrator = null;
int colors[] = { Color.rgb(255,128,128), Color.rgb(128,255,128), 
Color.rgb(128,128,255), Color.rgb(128,128,128) };
private Animation animleftin = null;
private Animation animleftout = null;
private Animation animrightin = null;
private Animation animrightout = null;
private Animation animupin = null;
private Animation animupout = null;
private Animation animdownin = null;
private Animation animdownout = null;
private boolean isDragMode = false;
private int currentview = 0;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        flipper = new ViewFlipper(this);
        gesturedetector = new GestureDetector(this, this);
        vibrator = (Vibrator)getSystemService(VIBRATOR_SERVICE);
        gesturedetector.setOnDoubleTapListener(this);
        flipper.setInAnimation(animleftin);
        flipper.setOutAnimation(animleftout);
        flipper.setFlipInterval(3000);
        flipper.setAnimateFirstView(true);
        prepareAnimations();
        prepareViews();
        addViews();
        setViewText();        
        setContentView(flipper);
    }
private void prepareAnimations() {
animleftin = new TranslateAnimation(
        Animation.RELATIVE_TO_PARENT,  +1.0f, Animation.RELATIVE_TO_PARENT,  0.0f,
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,   0.0f);       
        animleftout = new TranslateAnimation(
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  -1.0f,
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  0.0f);        
        animrightin = new TranslateAnimation(
        Animation.RELATIVE_TO_PARENT,  -1.0f, Animation.RELATIVE_TO_PARENT,  0.0f,
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,   0.0f);        
        animrightout = new TranslateAnimation(
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  +1.0f,
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  0.0f);       
        animupin = new TranslateAnimation(
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  0.0f,
        Animation.RELATIVE_TO_PARENT,  +1.0f, Animation.RELATIVE_TO_PARENT,   0.0f);     
        animupout = new TranslateAnimation(
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  0.0f,
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  -1.0f);        
        animdownin = new TranslateAnimation(
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  0.0f,
        Animation.RELATIVE_TO_PARENT,  -1.0f, Animation.RELATIVE_TO_PARENT,   0.0f);        
        animdownout = new TranslateAnimation(
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  0.0f,
        Animation.RELATIVE_TO_PARENT,  0.0f, Animation.RELATIVE_TO_PARENT,  +1.0f);        
        animleftin.setDuration(1000);
        animleftin.setInterpolator(new OvershootInterpolator());
        animleftout.setDuration(1000);
        animleftout.setInterpolator(new OvershootInterpolator());      
        animrightin.setDuration(1000);
        animrightin.setInterpolator(new OvershootInterpolator());
        animrightout.setDuration(1000);
        animrightout.setInterpolator(new OvershootInterpolator());       
        animupin.setDuration(1000);
        animupin.setInterpolator(new OvershootInterpolator());
        animupout.setDuration(1000);
        animupout.setInterpolator(new OvershootInterpolator());       
        animdownin.setDuration(1000);
        animdownin.setInterpolator(new OvershootInterpolator());
        animdownout.setDuration(1000);
        animdownout.setInterpolator(new OvershootInterpolator());
}
private void prepareViews(){
TextView view = null;

views = new ArrayList<TextView>();

for(int color: colors)
{
view = new TextView(this);
view.setBackgroundColor(color);
view.setTextColor(Color.BLACK);
view.setGravity(Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL);

views.add(view);
}
}

private void addViews(){
for(int index=0; index<views.size(); ++index)
{
flipper.addView(views.get(index),index,
new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
}
}

private void setViewText(){
String text = getString(isDragMode ? R.string.app_info_drag : R.string.app_info_flip);
for(int index=0; index<views.size(); ++index)
{
views.get(index).setText(text);
}
}

@Override
public boolean onTouchEvent(MotionEvent event) {
return gesturedetector.onTouchEvent(event);
}

@Override
public boolean onDown(MotionEvent e) {
return false;
}

@Override
public boolean onFling(MotionEvent event1, MotionEvent event2, float velocityX,float velocityY) {
if(isDragMode)
return false;

final float ev1x = event1.getX();
final float ev1y = event1.getY();
final float ev2x = event2.getX();
final float ev2y = event2.getY();
final float xdiff = Math.abs(ev1x - ev2x);
final float ydiff = Math.abs(ev1y - ev2y);
final float xvelocity = Math.abs(velocityX);
final float yvelocity = Math.abs(velocityY);

if(xvelocity > this.SWIPE_MIN_VELOCITY && xdiff > this.SWIPE_MIN_DISTANCE)
{
if(ev1x > ev2x) //Swipe Left
{
--currentview;

if(currentview < 0)
{
currentview = views.size() - 1;
}

flipper.setInAnimation(animleftin);
flipper.setOutAnimation(animleftout);
}
else //Swipe Right
{
++currentview;

if(currentview >= views.size())
{
currentview = 0;
}

flipper.setInAnimation(animrightin);
flipper.setOutAnimation(animrightout);
}

flipper.scrollTo(0,0);
flipper.setDisplayedChild(currentview);
}
else if(yvelocity > this.SWIPE_MIN_VELOCITY && ydiff > this.SWIPE_MIN_DISTANCE)
{
if(ev1y > ev2y) //Swipe Up
{
--currentview;

if(currentview < 0)
{
currentview = views.size() - 1;
}

flipper.setInAnimation(animupin);
flipper.setOutAnimation(animupout);
}
else //Swipe Down
{
++currentview;

if(currentview >= views.size())
{
currentview = 0;
}
flipper.setInAnimation(animdownin);
flipper.setOutAnimation(animdownout);
}

flipper.scrollTo(0,0);
flipper.setDisplayedChild(currentview);
}

return false;
}

@Override
public void onLongPress(MotionEvent e) {
vibrator.vibrate(200);
flipper.scrollTo(0,0);

isDragMode = !isDragMode;

setViewText();
}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,float distanceY) {
if(isDragMode)
flipper.scrollBy((int)distanceX, (int)distanceY);

return false;
}

@Override
public void onShowPress(MotionEvent e) {
}

@Override
public boolean onSingleTapUp(MotionEvent e) {
return false;
}

@Override
public boolean onDoubleTap(MotionEvent e) {
flipper.scrollTo(0,0);

return false;
}

@Override
public boolean onDoubleTapEvent(MotionEvent e) {
return false;
}

@Override
public boolean onSingleTapConfirmed(MotionEvent e) {
return false;
}
}

          The AndroidManifest.xml look like :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.samples.gesturedetectorsample"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".FlipperActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
<uses-permission android:name="android.permission.VIBRATE"></uses-permission>
</manifest> 




Note: Modify the above code as you requirements.