Programmatically rotate drawable or view

Question

<rotate xmlns:android="http://schemas.android.com/apk/res/android"
android:drawable="@drawable/your_drawable"
android:fromDegrees="0"
android:pivotX="50%"
android:pivotY="50%"
android:toDegrees="360" />

I want programmatically rotate the drawable.

How should I do that?

Here is my callback

private class RotateListener implements RotateGestureDetector.OnRotateGestureListener{
    @Override
    public boolean onRotate(MotionEvent event1, MotionEvent event2,
            double deltaAngle) {

        return true;
    }
}

The deltaangle not more than 0.1, I not sure what is the extract value.

Answer 1

here's a nice solution for putting a rotated drawable for an imageView:

Drawable getRotateDrawable(final Bitmap b, final float angle) {
    final BitmapDrawable drawable = new BitmapDrawable(getResources(), b) {
        @Override
        public void draw(final Canvas canvas) {
            canvas.save();
            canvas.rotate(angle, b.getWidth() / 2, b.getHeight() / 2);
            super.draw(canvas);
            canvas.restore();
        }
    };
    return drawable;
}

usage:

Bitmap b=...
float angle=...
final Drawable rotatedDrawable = getRotateDrawable(b,angle);
root.setImageDrawable(rotatedDrawable);

another alternative:

private Drawable getRotateDrawable(final Drawable d, final float angle) {
    final Drawable[] arD = { d };
    return new LayerDrawable(arD) {
        @Override
        public void draw(final Canvas canvas) {
            canvas.save();
            canvas.rotate(angle, d.getBounds().width() / 2, d.getBounds().height() / 2);
            super.draw(canvas);
            canvas.restore();
        }
    };
}

also, if you wish to rotate the bitmap, but afraid of OOM, you can use an NDK solution i've made here

Answer 2

Since you're trying to use Almero's Android Gesture Detectors, I decided to do the same in order to find an appropriate solution:

public class MainActivity extends Activity {

    private RotateGestureDetector mRotateDetector;
    private float mRotationDegrees = 0.f;
    private static final float ROTATION_RATIO = 2;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRotateDetector = new RotateGestureDetector(getApplicationContext(), new RotateListener());
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        mRotateDetector.onTouchEvent(event);
        return super.onTouchEvent(event);
    }

    private class RotateListener extends RotateGestureDetector.SimpleOnRotateGestureListener {
        @Override
        public boolean onRotate(RotateGestureDetector detector) {
            mRotationDegrees -= detector.getRotationDegreesDelta();
            ImageView v = (ImageView) findViewById(R.id.imageView);
            // For NineOldAndroids library only!
            ViewHelper.setRotation(v, mRotationDegrees * ROTATION_RATIO);
            // For HONEYCOMB and later only!
            v.setRotation(mRotationDegrees * ROTATION_RATIO);
            return true;
        }
    }
}

It works fine for me (I'm able to rotate the ImageView with two-finger rotation gesture. NOTE: Don't forget to chose appropriate rotation method call. I commented both of them to draw your attention.

ROTATION_RATIO is just a multiplier to speed-up a rotation response on my fingers movement. You can use any rotation axis (setRotation(), setRotationX() and setRotationY()) methods for a View.

To enable support of this code on Android devices with API Level lower than 11 (pre-Honeycomb devices) you may want to engage NineOldAndroid library.

Answer 3

The following code rotates an ImageView around its center:

ImageView myImageView = (ImageView)findViewById(R.id.my_imageview);

AnimationSet animSet = new AnimationSet(true);
animSet.setInterpolator(new DecelerateInterpolator());
animSet.setFillAfter(true);
animSet.setFillEnabled(true);

final RotateAnimation animRotate = new RotateAnimation(0.0f, -90.0f,
    RotateAnimation.RELATIVE_TO_SELF, 0.5f, 
    RotateAnimation.RELATIVE_TO_SELF, 0.5f);

animRotate.setDuration(1500);
animRotate.setFillAfter(true);
animSet.addAnimation(animRotate);

myImageView.startAnimation(animSet);