ImageView Drag Limitation In Android

Question

I have an ImageView in a layout and set OnTouchListener on ImageView to drag the ImageView. It\'s working perfectly. My problem is how can I prevent from move ImageView to out o

Answer 1

1. We need to create two Rect objects, one is for our view and another for our image according to the view coordinates.

   float[] values = new float[9];
   matrix.getValues(values);
   float globalX = values[Matrix.MTRANS_X];
   float globalY = values[Matrix.MTRANS_Y];
   float scaleX = values[Matrix.MSCALE_X];
   float scaleY = values[Matrix.MSCALE_Y];
   Rect viewRect = new Rect(0, 0, viewWidth, viewHeight);
   Rect imageRect = new Rect((int) globalX, (int) globalY, Math.round(bitmapWidth * scaleX + globalX),
           Math.round(bitmapHeight * scaleY + globalY));
   

   2. If we want our image be always inside our view, then we check this:

      if (!viewRect.contains(imageRect)) {
          matrix.set(lastSetMatrix); //return to last saved parameters
      }
      

   3. Sometimes we need our image always be bigger than our view to position a part of the image inside the view, then we can check this:

      if (!imageRect.contains(viewRect)) {
         matrix.set(lastSetMatrix);
      }