gistfile1.java

          if (state == MotionState.DRAGGING) {
            bottomCaliperMatrix.set(bottomCaliperSavedMatrix);
            float yoffset = motionEvent.getY() - startPoint.y;
            
            bottomCaliperMatrix.postTranslate(0, yoffset);
            float[] bottomMatrix = new float[9];
            bottomCaliperMatrix.getValues(bottomMatrix);
            float delta = Math.abs(Math.min(bottomMatrix[5] - 79, 0));
            bottomCaliperMatrix.postTranslate(0, delta);
          }