Pinch Zoom and 2 finger Rotation the ImageView in Android

Question

I've a problem from last 2 days and unable to tackle it as I'm newbie. Actually I'm working on an Android App that needs pinch-zoom and 2-finger rotation on Android ImageView. I got the multiple tutorials and solutions that work fine for Pinch Zoom and but does not work for 2 finger rotation. I'm sharing the simplest tutorial that's easy to understand and I want to extend it for 2 finger rotation. Here is the code snippet:

    public class MainActivity extends Activity {
    private ImageView mImageView;
    private Matrix mMatrix = new Matrix();
    private float mScale = 1f;
    private ScaleGestureDetector mScaleGestureDetector;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mImageView = (ImageView) findViewById(R.id.imageView);
        mScaleGestureDetector = new ScaleGestureDetector(this, new ScaleListener());
    }

    public boolean onTouchEvent(MotionEvent ev) {
        mScaleGestureDetector.onTouchEvent(ev);
        return true;
    }

    private class ScaleListener extends ScaleGestureDetector.
            SimpleOnScaleGestureListener {
        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            mScale *= detector.getScaleFactor();
            mScale = Math.max(0.1f, Math.min(mScale, 5.0f));
            mMatrix.setScale(mScale, mScale);
            mImageView.setImageMatrix(mMatrix);
            return true;
        }
    }
}

Also I want to use them for GPUImage, I mean despite of Android ImageView I want to use GPUImage. How to transform the GPUImage to ImageView? This is the 2nd thing. First I want to implement the 2 finger rotation (or MultiTouch in some sense). Thanks

Answer 1

Here is the solution that worked good for me. https://stackoverflow.com/a/18276033 Only one line I should add here and that should be

5. add imageView.setRotation(imageView.getRotation() + (-angle)); in OnRotation(RotationGestureDetector rotationDetector) method inside the activity to set the new rotation value to the ImageView

This is for basic help. Remaining of the implementation is just fine