Hi , I have the same requirement, I have to rotate an image of a wheel
as the user moves finger on the wheel on screen. Can u pls tell me how
I can use this code thr? What is cx, cy, mPreviousX, mPreviousY?
Thanks
On Mar 6, 2:56 am, Nathan <nathan.d.mel...@gmail.com> wrote:
> On Mar 5, 3:25 am, Bart <bvandep...@gmail.com> wrote:
>
> > Hi, I'd like to display a given String in acircle(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 thecircleby 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 drawtextin 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:
>
> @Override
> 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);
> this.invalidate();
> }
> mPreviousX = x;
> mPreviousY = y;
> return true;
> }
>
> Nathan
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