Add a default keyboard shortcut to take a screenshot in a running project

[Calinou]

The default key binding for ui_take_screenshot is F12, but it can be changed in the project settings' input map (make sure to enable Show Built-in Actions). See godotengine/godot-proposals#6789 for detailed rationale.

• This closes Add a default keyboard shortcut to take a screenshot in a running project godot-proposals#6789.

Testing project: test_take_screenshot.zip

Preview

Screenshot of a project with a transparent background while paused, without any tearing despite having V-Sync disabled:

[Calinou]

We should probably use this in other parts of the engine 🙂
See microsoft/vscode#97941.

Note that quoting paths in either single or double quotes will not work, so formatting must be used for "generic" paths. It can be any formatting, not necessarily underline (but I think underline makes the most sense in context – plus, VS Code will display a second underline on hover, so you still get visual feedback on hover). There are other types of paths with spaces supported, but these are intended to be used for programming stack traces.

[Sauermann]

When using embedded windows, the PR will create multiple screenshots, one for each embedded window, that receives the InputEvent, possbibly overwriting each other when they happen within the same second.
Possible solution would be to set the InputEvent as handled after taking the screenshot.

Additional native windows will not be included in the screenshot.
Maybe this PR could be complemented by #75142.

[Calinou]

Possible solution would be to set the InputEvent as handled after taking the screenshot.

Done 🙂

[Sauermann]

Regarding Input-handling, the changes are looking good.

[akien-mga]

I'm conflicted about this for very selfish reasons, as I use F12 for my drop-down terminal yakuake on Linux. I've been using that terminal for years and F12 is its default keybinding. This change would conflict and since it's part of the project input map, it would be impossible for me to disable it in all the tests projects or games I use.

[Zireael07]

oh, another Yakuake user here, yeah F12 would conflict :(((

[Calinou]

I'm conflicted about this for very selfish reasons, as I use F12 for my drop-down terminal yakuake on Linux. I've been using that terminal for years and F12 is its default keybinding. This change would conflict and since it's part of the project input map, it would be impossible for me to disable it in all the tests projects or games I use.

F12 would also conflict with the default Steam screenshot key (resulting in 2 screenshots being taken every time), so maybe it's better to use something like Shift + F12 instead. What do you think?

[akien-mga]

Shift + F12 sounds better to me.

That being said, the more I think about it the more I'm worried about the engine providing a builtin shortcut in all games which may conflict with user systems and favorite tools.

The current builtin input actions are those strictly necessary for expected UI interactions, and are unlikely to conflict with user hotkeys (as they're the same used by other GUI toolkits so they're not suitable for global hotkeys in the first place).

This PR would add something that departs from this and adds an always on hotkey. While the game developer can remove it on a per-project basis, most won't (that's the point of it) and thus most Godot games will support this hotkey, possibly clashing with the player's preference.

So I'm not sure whether we should actually implement this, even if I support the use case.

More opinions would be welcome :)