Area2D receives mouse input events from outside root viewport

[romlok]

Godot version

v4.1.1.stable.official [bd6af8e]

System information

Godot v4.1.1.stable - Debian GNU/Linux trixie/sid trixie - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (nvidia) - Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz (6 Threads)

Issue description

Area2Ds which extend beyond the bounds of the root viewport, eg. when using a canvas_items stretch mode, receive mouse input events even in the black bands letterboxing the game:

simplescreenrecorder-2023-07-29_13.40.59.mp4

Steps to reproduce

1. Set project stretch mode to either canvas_items or viewport
2. Have an Area2D whose CollisionShape extends beyond the bounds of the rendered region
3. Connect the Area2D's mouse_[entered|exited] signal to something
4. Wave the mouse around in the black areas outside the rendered game

Minimal reproduction project

Project used for video demo above:

area2d-oob.zip

This only demos mouse_[entered|exited], but I first encountered this with the Area2D.input_event signal, where it received mouse clicks as well.

[Sauermann]

I can confirm this issue also for the following situations:

• for Control-nodes that are located outside of the stretched root-Viewport
• a SubViewport of size (100,100) is within a SubViewportContainer of size (200,200) and contains a Control/Area2D, that lies right/below of the (100, 100) size.

I had a quick look and these aspects are directly affected by #67791, so I believe, that it would make sense to wait for that PR before diving into this issue.

In the meantime as a workaround for the Area2D.input_event-issue, you could check, if the mouse cursor is within the area of the Viewport.