Zoom imageView

public class Zoom extends View {
    private Drawable image;
    private int zoomControler=200;
    public Zoom(Context context)
    {
    super(context);
    image=context.getResources().getDrawable(R.drawable.gallery_photo_1);
    setFocusable(true);
    }
    @Override
    protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    //here u can control the width and height of the images........ this line is very important
    image.setBounds((getWidth()/2)-zoomControler, (getHeight()/2)-zoomControler, (getWidth()/2)+zoomControler, (getHeight()/2)+zoomControler);
    image.draw(canvas);
    }
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
    if(keyCode==KeyEvent.KEYCODE_DPAD_UP)// zoom in
    zoomControler+=10;
    if(keyCode==KeyEvent.KEYCODE_DPAD_DOWN) // zoom out
    zoomControler-=10;
    if(zoomControler<10)
    zoomControler=10;
    invalidate();
    return true;
    }
    }