+static const char *kKeyDrawingRect = "drawing_rect";
+static const char *kKeyX = "x";
+static const char *kKeyY = "y";
+static const char *kKeyWidth = "width";
+static const char *kKeyHeight = "height";
+static const char *kKeyWidthPixel = "width_pixel";
+static const char *kKeyHeightPixel = "height_pixel";
+static const char *kKeyWidthMm = "width_mm";
+static const char *kKeyHeightMm = "height_mm";
+
+