Add borders to BitMap in BitMapEditor

editor/plugins/bit_map_editor_plugin.h

@@ -34,14 +34,25 @@
 #include "editor/plugins/editor_plugin.h"
 #include "scene/resources/bit_map.h"
 
+class AspectRatioContainer;
 class TextureRect;
 
 class BitMapEditor : public VBoxContainer {
 	GDCLASS(BitMapEditor, VBoxContainer);
 
+private:
+	AspectRatioContainer *centering_container = nullptr;
+	Control *outline_overlay = nullptr;
 	TextureRect *texture_rect = nullptr;
 	Label *size_label = nullptr;
 
+	Color cached_outline_color;
+
+	void _draw_outline();
+
+protected:
+	void _notification(int p_what);
+
 public:
 	void setup(const Ref<BitMap> &p_bitmap);