Undo redo Leak

[qarmin]

Undo Redo needs to be freed to prevent leak

WARNING: cleanup: ObjectDB Instances still exist!
   At: core/object.cpp:2069.
Leaked instance: UndoRedo:2088
Orphan StringName: UndoRedo
StringName: 1 unclaimed string names at exit.

To prevent leak it is enough to add at the Global.gd class in _exit_tree undo_redo.free():

diff --git a/Scripts/Global.gd b/Scripts/Global.gd
index 1d0f7fb..041ac7b 100644
--- a/Scripts/Global.gd
+++ b/Scripts/Global.gd
@@ -457,3 +457,6 @@ func blend_image_with_color(image : Image, color : Color, interpolate_factor : f
                        else: #If color is transparent - if it's the eraser
                                blended_image.set_pixel(xx, yy, Color(0, 0, 0, 0))
        return blended_image
+
+func _exit_tree():
+       undo_redo.free()

[OverloadedOrama]

Hello there. I was expecting objects would be freed automatically on exit_tree(). Or is it just an UndoRedo thing? Also, would there be any difference if I added it in the Main.gd script instead of Global.gd?

[qarmin]

All nodes and objects needs to be freed at the end of life.
Only references(child of Reference node like ImageTexture or BoxShape) are counted and are deleted when no one use it.
Nodes should be deleted with queue_free() and objects with free().
You can check which objects and nodes leaks when you opening godot with verbose flag in terminal godot -v or in monitors inside Godot editor(this only show leaked nodes)

Description of exit_tree function from docs - https://docs.godotengine.org/en/latest/classes/class_node.html#class-node-method-exit-tree

Called when the node is about to leave the SceneTree (e.g. upon freeing, scene changing, or after calling remove_child in a script). If the node has children, its _exit_tree callback will be called last, after all its children have left the tree.

That means, that node is out of scene, but it can be deleted or in any moment node can back to scene

[qarmin]

Also when I paint something then also Image node is leaking

WARNING: cleanup: ObjectDB Instances still exist!
   At: core/object.cpp:2069.
Leaked instance: UndoRedo:2088
Leaked instance: Image:2135 - Resource name:  Path: 
Orphan StringName: UndoRedo
Orphan StringName: Image
StringName: 2 unclaimed string names at exit.

To get more precise info about node, you can set unique name to all node(I will create issue in Godot repository to automate this)
e.g.

var image : Image.new()
image.name = "Image-Tanks.gd"

[OverloadedOrama]

I implemented your fix for the UndoRedo leak in a4b7fe2. I'm not sure how to handle the Image node leaking though. I tried running godot -v in terminal, and run the project, but I didn't get any "Leaked instance" messages. I'm using Godot 3.1.2

[qarmin]

In Pixelorama master branch I can't reproduce leak in Godot 3.1.2 and Godot 3.2 beta 3, so probably the latest commit fixes also this leak.