private void drawBorders(Canvas canvas) {
    if (mBorderPaint != null) {
      float w = mBorderPaint.getStrokeWidth();
      RectF rect = mCropWindowHandler.getRect();
      rect.inset(w / 2, w / 2);

      if (mCropShape == CropImageView.CropShape.RECTANGLE) {
        // Draw rectangle crop window border.
        canvas.drawRect(rect, mBorderPaint);
      } else {
        // Draw circular crop window border
        canvas.drawOval(rect, mBorderPaint);
      }
    }
  }
Draw borders of the crop area.
core/src/main/java/com/theartofdev/edmodo/cropper/CropOverlayView.java