Swipe with Android / Android tutorial

You need first to create a class extended from gesturedetector.simpleongesturelistener . And inside create three variables .

private static final int SWIPE_MIN_DISTANCE = 150;

private static final int SWIPE_MAX_OFF_PATH = 100;

private static final int SWIPE_THRESHOLD_VELOCITY = 100;

SWIPE_MIN_DISTANCE is the minimal distance you need to make that will be receive by the Android device.

SWIPE_THRESHOLD_VELOCITY is the speed you need to do.

SWIPE_MAX_OFF_PATH is the error limit you can do . For example you swipe diagonally, the Android device will know if you’re trying to swipe up or right .

Now create the method onFling and put this calculs . It’s really complicated so i’m just giving you this without any explications .

This should look like this .

class MyGestureListener extends GestureDetector.SimpleOnGestureListener{

private static final int SWIPE_MIN_DISTANCE = 150;

private static final int SWIPE_MAX_OFF_PATH = 100;

private static final int SWIPE_THRESHOLD_VELOCITY = 100;

@Override

public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,

float velocityY) {

float dX = e2.getX()-e1.getX();

float dY = e1.getY()-e2.getY();

if (Math.abs(dY)<SWIPE_MAX_OFF_PATH &&

Math.abs(velocityX)>=SWIPE_THRESHOLD_VELOCITY &&

Math.abs(dX)>=SWIPE_MIN_DISTANCE ) {

if (dX>0) {

Toast.makeText(getApplicationContext(), “Right Swipe”, Toast.LENGTH_SHORT).show();

} else {

Toast.makeText(getApplicationContext(), “Left Swipe”, Toast.LENGTH_SHORT).show();

}

return true;

} else if (Math.abs(dX)<SWIPE_MAX_OFF_PATH &&

Math.abs(velocityY)>=SWIPE_THRESHOLD_VELOCITY &&

Math.abs(dY)>=SWIPE_MIN_DISTANCE ) {

if (dY>0) {

Toast.makeText(getApplicationContext(), “Up Swipe”, Toast.LENGTH_SHORT).show();

} else {

Toast.makeText(getApplicationContext(), “Down Swipe”, Toast.LENGTH_SHORT).show();

}

return true;

}

return false;

}

}

Now on the oncreate you’ll need to implement the ontouch on the view .

gesturedetector = new GestureDetector(new MyGestureListener());

Choose the root of your layout (it’s more conveniant) .

layout.setOnTouchListener(new OnTouchListener() {

@Override

public boolean onTouch(View v, MotionEvent event) {

gesturedetector.onTouchEvent(event);

return true;

}

});

But sometimes you have a ScrollView inside the layout and the gestures can’t be detected so just do .

public boolean dispatchTouchEvent(MotionEvent ev){

super.dispatchTouchEvent(ev);

return gesturedetector.onTouchEvent(ev);

}

This should look like this :

public class Test extends Activity{

private GestureDetector gesturedetector = null;

View layout;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.test);

layout = (LinearLayout)findViewById(R.id.container);

gesturedetector = new GestureDetector(new MyGestureListener());

layout.setOnTouchListener(new OnTouchListener() {

@Override

public boolean onTouch(View v, MotionEvent event) {

gesturedetector.onTouchEvent(event);

return true;

}

});

}

public boolean dispatchTouchEvent(MotionEvent ev){

super.dispatchTouchEvent(ev);

return gesturedetector.onTouchEvent(ev);

}

class MyGestureListener extends GestureDetector.SimpleOnGestureListener{

private static final int SWIPE_MIN_DISTANCE = 150;

private static final int SWIPE_MAX_OFF_PATH = 100;

private static final int SWIPE_THRESHOLD_VELOCITY = 100;

@Override

public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,

float velocityY) {

float dX = e2.getX()-e1.getX();

float dY = e1.getY()-e2.getY();

if (Math.abs(dY)<SWIPE_MAX_OFF_PATH &&

Math.abs(velocityX)>=SWIPE_THRESHOLD_VELOCITY &&

Math.abs(dX)>=SWIPE_MIN_DISTANCE ) {

if (dX>0) {

Toast.makeText(getApplicationContext(), “Right Swipe”, Toast.LENGTH_SHORT).show();

} else {

Toast.makeText(getApplicationContext(), “Left Swipe”, Toast.LENGTH_SHORT).show();

}

return true;

} else if (Math.abs(dX)<SWIPE_MAX_OFF_PATH &&

Math.abs(velocityY)>=SWIPE_THRESHOLD_VELOCITY &&

Math.abs(dY)>=SWIPE_MIN_DISTANCE ) {

if (dY>0) {

Toast.makeText(getApplicationContext(), “Up Swipe”, Toast.LENGTH_SHORT).show();

} else {

Toast.makeText(getApplicationContext(), “Down Swipe”, Toast.LENGTH_SHORT).show();

}

return true;

}

return false;

}

}

}