Animate rotation of an image in Android

Question

• I have a gear image which I want to continuously rotate about a fixed point.

• Earlier I was accomplishing this by including the image in my Android

Answer 1

In your onCreate() do

Matrix matrix = new Matrix();

And in onDraw

float angle = (float) (System.currentTimeMillis() % ROTATE_TIME_MILLIS) 
   / ROTATE_TIME_MILLIS * 360;
matrix.reset();
matrix.postTranslate(-source.getWidth() / 2, -source.getHeight() / 2);
matrix.postRotate(angle);
matrix.postTranslate(centerX, centerY)
canvas.drawBitmap(source, matrix, null);
invalidate(); // Cause a re-draw

ROTATE_TIME_MILLIS is the full circle time, e.g. 2000 is 2 seconds.