Hope you have gone through my previous post
Zooming a view completely
Now to apply pinch zoom we need to override the OnTouchListener.
There are many blogs and code to do pinch zoom in image view me used that logic here
So my main activity class will be like this
public class PinchZoomLayout extends Activity {
View mainView = null;
// Remember some things for zooming
PointF start = new PointF();
PointF mid = new PointF();
float oldDist = 1f;
PointF oldDistPoint = new PointF();
public static String TAG = "ZOOM";
static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
int mode = NONE;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mainView = (LinearLayout) findViewById(R.id.linearLayout);
Button buttonZoomOut = (Button) findViewById(R.id.buttonZoomOut);
Button buttonNormal = (Button) findViewById(R.id.buttonNormal);
Button buttonZoomIn = (Button) findViewById(R.id.buttonZoomIn);
buttonZoomOut.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
zoom(0.5f, 0.5f, new PointF(0, 0));
}
});
buttonNormal.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
zoom(1f, 1f, new PointF(0, 0));
}
});
buttonZoomIn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
zoom(2f, 2f, new PointF(0, 0));
}
});
mainView.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
Log.d(TAG, "mode=DRAG");
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
start.set(event.getX(), event.getY());
Log.d(TAG, "mode=DRAG");
mode = DRAG;
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
oldDistPoint = spacingPoint(event);
Log.d(TAG, "oldDist=" + oldDist);
if (oldDist > 10f) {
midPoint(mid, event);
mode = ZOOM;
Log.d(TAG, "mode=ZOOM");
}
System.out.println("current time :" + System.currentTimeMillis());
break;// return !gestureDetector.onTouchEvent(event);
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
Log.d(TAG, "mode=NONE");
mode = NONE;
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
} else if (mode == ZOOM) {
PointF newDist = spacingPoint(event);
float newD = spacing(event);
Log.e(TAG, "newDist=" + newDist);
float[] old = new float[9];
float[] newm = new float[9];
Log.e(TAG, "x=" + old[0] + ":&:" + old[2]);
Log.e(TAG, "y=" + old[4] + ":&:" + old[5]);
float scale = newD / oldDist;
float scalex = newDist.x / oldDistPoint.x;
float scaley = newDist.y / oldDistPoint.y;
zoom(scale, scale, start);
}
break;
}
return true;
}
});
}
/**
* zooming is done from here
*/
public void zoom(Float scaleX, Float scaleY, PointF pivot) {
mainView.setPivotX(pivot.x);
mainView.setPivotY(pivot.y);
mainView.setScaleX(scaleX);
mainView.setScaleY(scaleY);
}
/**
* space between the first two fingers
*/
private float spacing(MotionEvent event) {
// ...
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return FloatMath.sqrt(x * x + y * y);
}
private PointF spacingPoint(MotionEvent event) {
PointF f = new PointF();
f.x = event.getX(0) - event.getX(1);
f.y = event.getY(0) - event.getY(1);
return f;
}
/**
* the mid point of the first two fingers
*/
private void midPoint(PointF point, MotionEvent event) {
// ...
float x = event.getX(0) + event.getX(1);
float y = event.getY(0) + event.getY(1);
point.set(x / 2, y / 2);
}
}
But this zoom is not much smooth :(.
