Adding Fling Gesture to an image view - Android

Question

Okay I have been referencing the code here: Fling gesture detection on grid layout

but just can not get it to work. In my main activity I have a simple image define

Answer 1

Try this

imageView.setOnTouchListener(new View.OnTouchListener() {

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            if (gestureDetector.onTouchEvent(event)) {
                return false;
            }
            return true;
        }
  });

Answer 2

some of the precondition

1) setonClick method

image.setOnClickListener(this);

2) set your gesture detection in onTouch()

image.setOnTouchListener(new OnTouchListener() {
    GestureDetector gestureDetector = new GestureDetector(new SwingGestureDetection((mContext),image,a));
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        return gestureDetector.onTouchEvent(event);
    }
});

3) create SwingGestureDetection class and implement all method

@Override
public boolean onFling(MotionEvent start, MotionEvent finish, float arg2,float arg3) {
    if (start.getRawX() < finish.getRawX()) {
        System.out.println("next...swing");
    } else {
        System.out.println("previois...swing");
    }
}

4) pass your imageview in constructor

public SwingGestureDetection(Context con,ImageView image,int pos) {
    mContext = con;
    this.image = image;
    this.position = pos;
}

This is perfect work for me.if any query then put comment.

Answer 3

Design your layout with ImageView. Add setOnTouchListenerto imageView.imageview.setOnTouchListener(this).add unimplemented method View.OnTouchListener.Then onTouch method you can implemtn your guesture logic.This sample tells you left to right and right to left guesture,

float x1,x2;
float y1, y2;

@Override
public boolean onTouch(View view, MotionEvent event) {
    switch ( event.getAction() ){

        case MotionEvent.ACTION_DOWN:{
            x1 = event.getX();
            y1 = event.getY();
            break;
        }

        case MotionEvent.ACTION_UP:{
            x2 = event.getX();
            y2 = event.getY();

            if ( x1<x2 ) {
                //implement what you need to do here
            }
            if ( x1>x2 ) {
                //implement what you need to do here
            }
            break;
        }
    }
    return false;
}

Answer 4

If you dont like to create a separate class or make code complex,
You can just create a GestureDetector variable inside OnTouchListener and make your code more easier

namVyuVar can be any name of the View on which you need to set the listner

namVyuVar.setOnTouchListener(new View.OnTouchListener()
{
    @Override
    public boolean onTouch(View view, MotionEvent MsnEvtPsgVal)
    {
        flingActionVar.onTouchEvent(MsnEvtPsgVal);
        return true;
    }

    GestureDetector flingActionVar = new GestureDetector(getApplicationContext(), new GestureDetector.SimpleOnGestureListener()
    {
        private static final int flingActionMinDstVac = 120;
        private static final int flingActionMinSpdVac = 200;

        @Override
        public boolean onFling(MotionEvent fstMsnEvtPsgVal, MotionEvent lstMsnEvtPsgVal, float flingActionXcoSpdPsgVal, float flingActionYcoSpdPsgVal)
        {
            if(fstMsnEvtPsgVal.getX() - lstMsnEvtPsgVal.getX() > flingActionMinDstVac && Math.abs(flingActionXcoSpdPsgVal) > flingActionMinSpdVac)
            {
                // TskTdo :=> On Right to Left fling

                return false;
            }
            else if (lstMsnEvtPsgVal.getX() - fstMsnEvtPsgVal.getX() > flingActionMinDstVac && Math.abs(flingActionXcoSpdPsgVal) > flingActionMinSpdVac)
            {
                // TskTdo :=> On Left to Right fling

                return false;
            }

            if(fstMsnEvtPsgVal.getY() - lstMsnEvtPsgVal.getY() > flingActionMinDstVac && Math.abs(flingActionYcoSpdPsgVal) > flingActionMinSpdVac)
            {
                // TskTdo :=> On Bottom to Top fling

                return false;
            }
            else if (lstMsnEvtPsgVal.getY() - fstMsnEvtPsgVal.getY() > flingActionMinDstVac && Math.abs(flingActionYcoSpdPsgVal) > flingActionMinSpdVac)
            {
                // TskTdo :=> On Top to Bottom fling

                return false;
            }
            return false;
        }
    });
});

Answer 5

If you're looking for a method like ImageView.setOnGestureListener, there is none. You can go look at the Android source code. Your best option is to handle it in onTouch() of the View object.

This is the simplest GestureDetector I can make.

I have a class called GenesMotionDetector.java. Here's the code for it:

package gene.com.motioneventssample;

import android.app.Activity;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class GenesMotionDetector extends Activity implements GestureDetector.OnGestureListener {
    private GestureDetector gestureScanner;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.nothing);
        gestureScanner= new GestureDetector(getBaseContext(),this);
    }

    @Override
    public boolean onTouchEvent(MotionEvent me) {
        System.out.println("Inside onTouchEvent() of GenesMotionDetector.java");
        return gestureScanner.onTouchEvent(me);
    }

    @Override
    public boolean onDown(MotionEvent e) {
        System.out.println("Inside onDown() of GenesMotionDetector.java");
        return true;
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        System.out.println("Inside onFling() of GenesMotionDetector.java");
        return true;
    }

    @Override
    public void onLongPress(MotionEvent e) {
        System.out.println("Inside onLongPress() of GenesMotionDetector.java");
    }

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
        System.out.println("Inside onScroll() of GenesMotionDetector.java");
        return true;
    }

    @Override
    public void onShowPress(MotionEvent e) {
        System.out.println("Inside onShowPress() of GenesMotionDetector.java");
    }

    @Override
    public boolean onSingleTapUp(MotionEvent e) {
        System.out.println("Inside onSingleTapUp() of GenesMotionDetector.java");
        return true;
    }
}

The corresponding XML layout file for that class is nothing.xml. Here's the code for it:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/screen"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/text"
        android:background="#17528c"
        android:text="testing"
        android:layout_width="100dp"
        android:layout_height="200dp" />

    <ImageView
        android:id="@+id/image"
        android:background="#f8af20"
        android:layout_width="100dp"
        android:layout_height="200dp" />
</LinearLayout>

Now, taking the simplest GestureDetector I can make (from above) and modifying it for what you want, I get this:

package gene.com.motioneventssample;

import android.app.Activity;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.widget.ImageView;

public class GenesMotionDetector3 extends Activity implements GestureDetector.OnGestureListener {
    private GestureDetector gestureScanner;
    ImageView mView3;

    View.OnTouchListener gestureListener;
    MotionEvent initialME, finalME;
    private VelocityTracker mVelocityTracker = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.nothing);


        mView3 = (ImageView) findViewById(R.id.image);

        // Gesture detection
        gestureScanner = new GestureDetector(getBaseContext(), this);

        gestureListener = new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                switch(event.getAction()){
                    case MotionEvent.ACTION_DOWN:
                        initialME= event;

                        if(mVelocityTracker == null) {
                            // Retrieve a new VelocityTracker object to watch the velocity of a motion.
                            mVelocityTracker = VelocityTracker.obtain();
                        }
                        else {
                            // Reset the velocity tracker back to its initial state.
                            mVelocityTracker.clear();
                        }
                        // Add a user's movement to the tracker.
                        mVelocityTracker.addMovement(event);

                        break;
                    case MotionEvent.ACTION_MOVE:
                        mVelocityTracker.addMovement(event);
                        // When you want to determine the velocity, call
                        // computeCurrentVelocity(). Then call getXVelocity()
                        // and getYVelocity() to retrieve the velocity for each pointer ID.
                        mVelocityTracker.computeCurrentVelocity(1000);
                        break;
                    case MotionEvent.ACTION_UP:
                        finalME=event;
                        break;
                    case MotionEvent.ACTION_CANCEL:
                        // Return a VelocityTracker object back to be re-used by others.
                        mVelocityTracker.recycle();
                        break;
                }
                return onFling(initialME, finalME, mVelocityTracker.getXVelocity(), mVelocityTracker.getYVelocity());
                //return false;
            }
        };

        mView3.setOnTouchListener(gestureListener);
    }

    @Override
    public boolean onTouchEvent(MotionEvent me) {
        System.out.println("Inside onTouchEvent() of GenesMotionDetector.java");

        return gestureScanner.onTouchEvent(me);
    }

    @Override
    public boolean onDown(MotionEvent e) {
        System.out.println("Inside onDown() of GenesMotionDetector.java");
        return true;
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        System.out.println("Inside onFling() of GenesMotionDetector.java");
        System.out.println("e1= "+ e1);
        System.out.println("e2= "+ e2);
        System.out.println("velocityX= "+ velocityX);
        System.out.println("velocityY= "+ velocityY);
        return true;
    }

    @Override
    public void onLongPress(MotionEvent e) {
        System.out.println("Inside onLongPress() of GenesMotionDetector.java");
    }

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
        System.out.println("Inside onScroll() of GenesMotionDetector.java");
        return true;
    }

    @Override
    public void onShowPress(MotionEvent e) {
        System.out.println("Inside onShowPress() of GenesMotionDetector.java");
    }

    @Override
    public boolean onSingleTapUp(MotionEvent e) {
        System.out.println("Inside onSingleTapUp() of GenesMotionDetector.java");
        return true;
    }
}

You might as well just handle everything in onTouch(). I'm basically getting the gestures in onTouch and passing it to onFling().

Answer 6

Try to read: http://illusionsandroid.blogspot.com/2011/05/adding-fling-gesture-listener-to-view.html

It allow you to separate your activity implementation from your custom listener. It is simply a refactoring of the solution reported by Alex Orlov