Compress image data that is memorized for undo/redo operations (#890)

* Compress image data that is memorized for undo/redo operations

* Fixed formatting issues

src/Tools/Draw.gd

@@ -209,17 +209,31 @@ func commit_undo() -> void:
 
 	project.undos += 1
 	for image in redo_data:
-		project.undo_redo.add_do_property(image, "data", redo_data[image])
+		var compressed_data = redo_data[image]
+		var buffer_size = compressed_data["data"].size()
+		compressed_data["data"] = compressed_data["data"].compress()
+		project.undo_redo.add_do_method(
+			self, "undo_redo_draw_op", image, compressed_data, buffer_size
+		)
 		image.unlock()
 	for image in _undo_data:
-		project.undo_redo.add_undo_property(image, "data", _undo_data[image])
+		var compressed_data = _undo_data[image]
+		var buffer_size = compressed_data["data"].size()
+		compressed_data["data"] = compressed_data["data"].compress()
+		project.undo_redo.add_undo_method(
+			self, "undo_redo_draw_op", image, compressed_data, buffer_size
+		)
 	project.undo_redo.add_do_method(Global, "undo_or_redo", false, frame, layer)
 	project.undo_redo.add_undo_method(Global, "undo_or_redo", true, frame, layer)
 	project.undo_redo.commit_action()
 
 	_undo_data.clear()
 
 
+func undo_redo_draw_op(image: Object, compressed_image_data: Dictionary, buffer_size: int) -> void:
+	image["data"]["data"] = compressed_image_data["data"].decompress(buffer_size)
+
+
 func draw_tool(position: Vector2) -> void:
 	if Global.mirror_view:
 		# Even brushes are not perfectly centred and are offsetted by 1 px so we add it