Modify fullscreen placement logic to take exclusion zone of higher layers into account

[tarek-y-ismail]

Closes #3274

What's new?

• What it says on the tin.

How to test

1. Run mir with layer shell:

miral-app --add-wayland-extensions=zwlr_layer_shell_v1

2. Set waybar to be on the "bottom" layer (`~/.config/waybar/config):

{
    "layer": "bottom", // Waybar at top layer
   ...
}

3. Start an application, a terminal for example
4. Maximize it, it should take up all screen area until it hits waybar.
5. Fullscreen it, it should take up the whole output
6. Change the layer configuration waybar's config to be "top"
7. Repeat step 4. Behavior should be identical
8. Repeat step 5. The application should take up all the screen except for the area used by waybar.

Checklist

• Tests added and pass

[Copilot]

Pull request overview

This PR modifies fullscreen window placement logic to respect exclusion zones from windows in higher depth layers, addressing issue #3274.

Changes:

• Updated fullscreen window placement to consider exclusion zones from higher layers instead of always ignoring them
• Added new method calculate_application_zone_for_depth_layer() to compute application zones based on depth layer hierarchy
• Modified test cases to reflect the new behavior where fullscreen windows respect exclusion zones

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
tests/miral/window_placement_attached.cpp	Updated test names and expectations to verify fullscreen windows now respect exclusion zones from higher layers
src/miral/basic_window_manager.h	Added declaration for calculate_application_zone_for_depth_layer() method and changed apply_exclusive_rect_to_application_zone() to non-static
src/miral/basic_window_manager.cpp	Implemented depth-layer-aware exclusion zone calculation and moved fullscreen surface placement to occur after application zone calculation

[Saviq]

I'm actually not sold on this approach.

It assumes shell components will normally be placed below / bottom, which I don't think will normally be the case?

It's common to be able to push a restored window under a panel, which only works if they're placed above / top?

[github-actions]

TICS Quality Gate

✔️ Passed

mir

Coding Standards: ✔️ Passed

✔️ Condition “No new Coding Standard Violations for level 1, 2, 3 with respect to Previous analysis” passed.

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The following files have been checked for this project

• src/miral/basic_window_manager.cpp
• src/miral/basic_window_manager.h

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[tarek-y-ismail]

It's common to be able to push a restored window under a panel, which only works if they're placed above / top?

I can't entirely follow. Can you provide a more concrete example?