try this (this is a little modified version of MyView i already posted as an answer for your previous question):
public class MyView extends View {
private final static String TAG = "Main.MyView";
private static final float CX = 0;
private static final float CY = 0;
private static final float RADIUS = 20;
private static final float BIGRADIUS = 50;
private static final int NORMAL_COLOR = 0xffffffff;
private static final int PRESSED_COLOR = 0xffff0000;
private Paint mPaint;
private Path mSmallCircle;
private Path mCircle;
private Matrix mMatrix;
private float mAngle;
private int mSmallCircleColor;
public MyView(Context context) {
super(context);
mPaint = new Paint();
mSmallCircle = new Path();
mSmallCircle.addCircle(BIGRADIUS + RADIUS + CX, CY, RADIUS, Direction.CW);
mSmallCircleColor = NORMAL_COLOR;
mCircle = new Path();
mCircle.addCircle(0, 0, BIGRADIUS, Direction.CW);
mMatrix = new Matrix();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
if (action == MotionEvent.ACTION_UP) {
mSmallCircleColor = NORMAL_COLOR;
invalidate();
return false;
}
float w2 = getWidth() / 2f;
float h2 = getHeight() / 2f;
float r = 0;
if (action == MotionEvent.ACTION_DOWN) {
float[] pts = {
BIGRADIUS + RADIUS + CX, CY
};
mMatrix.mapPoints(pts);
r = (float) Math.hypot(event.getX() - pts[0], event.getY() - pts[1]);
}
if (r < RADIUS) {
mSmallCircleColor = PRESSED_COLOR;
mAngle = (float) (180 * Math.atan2(event.getY() - h2, event.getX() - w2) / Math.PI);
invalidate();
return true;
}
return false;
}
@Override
protected void onDraw(Canvas canvas) {
float w2 = getWidth() / 2f;
float h2 = getHeight() / 2f;
mMatrix.reset();
mMatrix.postRotate(mAngle);
mMatrix.postTranslate(w2, h2);
canvas.concat(mMatrix);
mPaint.setColor(0x88ffffff);
canvas.drawPath(mCircle, mPaint);
mPaint.setColor(mSmallCircleColor);
canvas.drawPath(mSmallCircle, mPaint);
}
}