From b1f68ff0827fe620cf69270093acbe8c4c3d4db5 Mon Sep 17 00:00:00 2001
From: Nathan Lovato <nathan@gdquest.com>
Date: Thu, 3 Jan 2019 11:27:03 +0900
Subject: [PATCH] RectExtentsGizmo: safely register do and undo commands upon
 releasing the drag action

Gilles explained the UndoRedo object is shared by the entire editor, so another
plugin or function could write to the object in between our do/undo actions,
causing bugs or crashes.
---
 godot/addons/rect_extents_gizmo/plugin.gd | 35 +++++++++++++++++------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/godot/addons/rect_extents_gizmo/plugin.gd b/godot/addons/rect_extents_gizmo/plugin.gd
index af0d4ca..d1b1358 100644
--- a/godot/addons/rect_extents_gizmo/plugin.gd
+++ b/godot/addons/rect_extents_gizmo/plugin.gd
@@ -1,3 +1,8 @@
+"""
+Widget for Godot's 2d viewport. Adds 4 draggable anchors to RectExtents node
+The user can click and drag these anchors to resize a RectExtents node around
+its center.
+"""
 tool
 extends EditorPlugin
 
@@ -8,9 +13,20 @@ enum Anchors {
 	BOTTOM_RIGHT
 }
 
+# Stores the currently edited rect_extents node
+# null if no RectExtents node is selected and active
 var rect_extents : RectExtents
+# List of all anchors drawn over the RectExtents node
+# Each anchor has the form { position: Vector2, rect: Rect2 }
 var anchors : Array
+# Get and stores the anchor the user is dragging from the anchors array above
 var dragged_anchor : Dictionary = {}
+# Stores the RectExtents' state when the user starts dragging an anchor
+# we need this info to safely add undo/redo support when the drag operation ends
+var rect_drag_start : Dictionary = {
+	'size': Vector2(),
+	'offset': Vector2()
+}
 
 const CIRCLE_RADIUS : float = 6.0
 const STROKE_RADIUS : float = 2.0
@@ -96,20 +112,25 @@ func forward_canvas_gui_input(event: InputEvent) -> bool:
 			for anchor in anchors:
 				if not anchor['rect'].has_point(event.position):
 					continue
-				var undo := get_undo_redo()
-				undo.create_action("Move anchor")
-				undo.add_undo_property(rect_extents, "size", rect_extents.size)
-				undo.add_undo_property(rect_extents, "offset", rect_extents.offset)
 				dragged_anchor = anchor
 				print("Drag start: %s" % dragged_anchor)
+				rect_drag_start = {
+					'size': rect_extents.size,
+					'offset': rect_extents.offset,
+				}
 				return true
 		elif dragged_anchor and not event.is_pressed():
-			print("Lifting the cursor: %s" % event.position)
 			drag_to(event.position)
 			dragged_anchor = {}
 			var undo := get_undo_redo()
+			undo.create_action("Move anchor")
+		
 			undo.add_do_property(rect_extents, "size", rect_extents.size)
+			undo.add_undo_property(rect_extents, "size", rect_drag_start['size'])
+		
 			undo.add_do_property(rect_extents, "offset", rect_extents.offset)
+			undo.add_undo_property(rect_extents, "offset", rect_drag_start['offset'])
+		
 			undo.commit_action()
 			return true
 	if not dragged_anchor:
@@ -122,8 +143,6 @@ func forward_canvas_gui_input(event: InputEvent) -> bool:
 	# Cancelling with ui_cancel
 	if event.is_action_pressed("ui_cancel"):
 		dragged_anchor = {}
-		var undo := get_undo_redo()
-		undo.commit_action()
-		undo.undo()
+		
 		return true
 	return false
-- 
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