Question

I am developing an android app where I have to rotate a circular image around another circular image, but when I am running this the size of my circular image gets automatically changing continuously. So please help me how to solve this. Here is my code

public class JobSearch extends Activity implements OnTouchListener {
    private ImageView dialer;
    private float y=0;
    public boolean onTouch(View v, MotionEvent event) {
        double r=Math.atan2(event.getX()-dialer.getWidth()/2, dialer.getHeight()/2-event.getY());
        int rotation=(int)Math.toDegrees(r);
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                break;
            case MotionEvent.ACTION_MOVE:
                //x=event.getX();
                y=event.getY();
                updateRotation(rotation);
                break;
            case MotionEvent.ACTION_UP:
                break;
        }//switch       
     return true;    
    }//onTouch
    private void updateRotation(double rot){
        float newRot=new Float(rot);
        Bitmap bitmap=BitmapFactory.decodeResource(getResources(),R.drawable.round_button_big);
        Matrix matrix=new Matrix();
        matrix.postRotate(newRot);//,bitmap.getWidth()/2,bitmap.getHeight()/2);
        Bitmap reDrawnBitmap=Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
        dialer.setImageBitmap(reDrawnBitmap);
        if(newRot>=-5 && newRot<=5)
            Toast.makeText(this,"12 O\'Clock",Toast.LENGTH_SHORT).show();
        if(newRot>=85 && newRot<=95)
            Toast.makeText(this,"3 O\'Clock",Toast.LENGTH_SHORT).show();
        if(newRot>=175 || newRot<=-175)
            Toast.makeText(this,"6 O\'Clock",Toast.LENGTH_SHORT).show();
        if(newRot>=-95 && newRot<=-85)
            Toast.makeText(this,"9 O\'Clock",Toast.LENGTH_SHORT).show();
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        dialer = (ImageView) findViewById(R.id.big_button);
        dialer.setOnTouchListener(this);
    }//onCreate
}

Answer 1

Try this code for Rotating Image –

public class bitmaptest extends Activity {
@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    LinearLayout linLayout = new LinearLayout(this);

    // load the origial BitMap (500 x 500 px)
    Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),
           R.drawable.android);

    int width = bitmapOrg.width();
    int height = bitmapOrg.height();
    int newWidth = 200;
    int newHeight = 200;

    // calculate the scale - in this case = 0.4f
    float scaleWidth = ((float) newWidth) / width;
    float scaleHeight = ((float) newHeight) / height;

    // createa matrix for the manipulation
    Matrix matrix = new Matrix();
    // resize the bit map
    matrix.postScale(scaleWidth, scaleHeight);
    // rotate the Bitmap
    matrix.postRotate(45);

    // recreate the new Bitmap
    Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0,
                      width, height, matrix, true);

    // make a Drawable from Bitmap to allow to set the BitMap
    // to the ImageView, ImageButton or what ever
    BitmapDrawable bmd = new BitmapDrawable(resizedBitmap);

    ImageView imageView = new ImageView(this);

    // set the Drawable on the ImageView
    imageView.setImageDrawable(bmd);

    // center the Image
    imageView.setScaleType(ScaleType.CENTER);

    // add ImageView to the Layout
    linLayout.addView(imageView,
            new LinearLayout.LayoutParams(
                  LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT
            )
    );

    // set LinearLayout as ContentView
    setContentView(linLayout);
}
}

And, also see this Tutorial