On Mar 5, 3:25 am, Bart <bvandep...@gmail.com> wrote:
> Hi, I'd like to display a given String in a circle (so bend the string
> so that the end of the string touches the beginning of the string).
> And Then I'd like to let the user rotate the circle by grabbing and
> dragging it clockwise or counterclockwise.
> Do you guys know what would be the best (simplest, smoothest) way to
> do this? I already saw that using drawOnPath i can draw text in a
> circle. Do you have any tips on how to proceed with dragging and
> rotating the textcircle?

I've done this, and as mentioned, Canvas.translate and canvas.rotate
are the way to go.

If you are just using a hold and drag, you wouldn't have to worry so
much about angular velocity. Code like this would work:

        public boolean onTouchEvent(MotionEvent e) {
        float x = e.getX();
        float y = e.getY();
        switch (e.getAction()) {
        case MotionEvent.ACTION_MOVE:
            //find an approximate angle between them.

                float dx = x-cx;
            float dy = y-cy;
            double a=Math.atan2(dy,dx);

            float dpx= mPreviousX-cx;
            float dpy= mPreviousY-cy;
            double b=Math.atan2(dpy, dpx);

            double diff  = a-b;
            this.bearing -= Math.toDegrees(diff);
        mPreviousX = x;
        mPreviousY = y;
        return true;


You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to android-developers@googlegroups.com
To unsubscribe from this group, send email to
For more options, visit this group at

Reply via email to