how to rotate an image in both directions in android

hi i need to rotate an ImageView in my app on touch

and i am using the following code

public android.view.View.OnTouchListener onTableTouched = new android.view.View.OnTouchListener(){
public boolean onTouch(View v, MotionEvent evt) {

WrapMotionEvent event = WrapMotionEvent.wrap(evt);

ImageView view = (ImageView) v;
// Dump touch event to log
dumpEvent(event);
//
switch (event.getAction() & MotionEvent.ACTION_MASK) {

case MotionEvent.ACTION_DOWN:
break;

case MotionEvent.ACTION_POINTER_DOWN:
mode = NONE;      
break;

case MotionEvent.ACTION_UP:
break;

case MotionEvent.ACTION_MOVE:
if(mode == NONE){
updateRotation();
}
break;
}
return true;
}
};


private void updateRotation()
{

 matrix.postRotate(10);

 Bitmap redrawnBitmap = Bitmap.createBit开发者_StackOverflow中文版map(itembmp, 0, 0,itembmp.getWidth(), itembmp.getHeight(), matrix, true);
 itembmp=redrawnBitmap;
 image.setImageBitmap(itembmp);
}

but by using this i can rotate the image in clock-direction only.

But i need to rotate the image in both directions .

How to do that.

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I would make two functions, one called updateRotationClockwise, one called updateRotationCounterClockWise.

In clockwise, it should stay:

 matrix.postRotate(10);

In counterclockwise, it should say:

matrix.postRotate(350);

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I am in process of developing this logic. 1. Difference in angle. one needs to also check other boundary conditions for more accuracy. 2. Instead of handling touch actions. I used in build ScaleGestureDetector class for information. In onScaleBegin assuming I get the event using a setter (called in on touch) in the OnScaleGestureListener. before=gety/getx; In on ScaleEnd after=gety/getx;

thus difference is tan-1(before)-tan-1(after) if +tive anticlockwise -tive clockwise. It is not so accurate I am adding conditions but one can try this out.

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from the class ClockView you can find the method for rotation for your bitmap image

https://github.com/jselbie/xkcdclock