code: private void drawRectHole(Canvas canvas) {
          paint.setStyle(Paint.Style.FILL);
          paint.setColor(backColor);
  
          // Top part
          tmpRectF.set(0f, 0f, canvas.getWidth(), areaRect.top);
          canvas.drawRect(tmpRectF, paint);
  
          // Bottom part
          tmpRectF.set(0f, areaRect.bottom, canvas.getWidth(), canvas.getHeight());
          canvas.drawRect(tmpRectF, paint);
  
          // Left part
          tmpRectF.set(0f, areaRect.top, areaRect.left, areaRect.bottom);
          canvas.drawRect(tmpRectF, paint);
  
          // Right part
          tmpRectF.set(areaRect.right, areaRect.top, canvas.getWidth(), areaRect.bottom);
          canvas.drawRect(tmpRectF, paint);
      }
docs: If cropping area is not rounded we can draw it much faster