frontend: Replace add source dropdown with dialog

[Warchamp7]

Description

Replaces the add source context menu with a brand new window.

• Adds new FlowFrame and FlowLayout for automatic wrapping widget frame

  • Supports keyboard navigation of focusable widgets using arrow keys

• Adds ThumbnailManager class

  • Keeps a cache of low resolution thumbnails of all visible sources
  • Periodically updates the oldest preview thumbnail among visible sources only
  • Utilizes ScreenshotObj which performs output over several render ticks
  • Throttled update loop

• Adds new dialog for adding sources

  • Shows static previews of sources when possible
  • Supports selection of multiple existing sources in the list via Ctrl and/or Shift + clicking
  • Supports keyboard navigation of the existing source list
  • Supports drag and drop of individual sources onto the main window without closing the dialog

Sources Dock Menu

New Window

obs64_E0SOtuhy93.mp4

Motivation and Context

The current process for adding a source is rather cumbersome, especially when adding a source that already exists. Ideally users should be re-using Sources whenever it makes sense, so one of the goals of this PR is exposing that better than the old radio button and list selection.

How Has This Been Tested?

Created a number of different sources.

Types of changes

• New feature (non-breaking change which adds functionality)
• Tweak (non-breaking change to improve existing functionality)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[Penwy]

Testing on Ubuntu 24.04,
three suggestions :

• when you add an existing one, have a confirmation button after selecting it, instead of adding it the moment you click.
• a way to show again the "recently added" of all source types once you have selected a given source type (basically to "unselect" a source type).
• bit unsure about this one but the "recently added" sources when no sources have been added manually during the session is based on the most recently added ones during scene collection load, no? If so maybe a way to not add to that list sources created during sc load? idk if that makes sense

one visual bug :

• in all themes except classic, the right bit of the right column of source types gets cut off
  

[Penwy]

Two additional notes after playing more with it :

• the purple color when selecting a source type is unchanged by the theme, so it doesn't fit in some themes, typically in the light theme it makes select source type quite hard to read because of the black text.
  
• the "make source visible" toggle is imo too far away and would benefit from being moved closer to the column where sources are created instead of hanging below the source types.
  

[Warchamp7]

PR has been updated with a new design and UI altogether

[Warchamp7]

This has been updated with a bunch of cleanup and optimizations by @Lain-B. It is ready for proper testing and review now

[PatTheMav]

First very superficial review, the Singleton pattern in the ThumbnailManager is an issue and appears at first glance like a responsibility inversion, will have to analyse this more deeply first.

There a few Qt-isms and C-isms that should use modern C++ style instead.

[Penwy]

After testing latest (Ubuntu 24.04 in case) :

Two theming issues :

• On Yami - Classic, when the source name text field is in focus, it has no border and is indistiguishable from the background.

• On Yami - Light, the Create New button is hardly legible when not hovered.

Two suggestions :

• Double clicking one of the existing sources should add an item of that source, in the same way that double clicking a source type does add a new source of that type.

• I feel the Recently Added tab should be made to stand out more from the list, I would suggest by putting a separator between it and the rest of the list, and/or by giving it an icon to bring it level with the list. Rough mockup attached.

[Warchamp7]

Fixed the above visual issues

Two suggestions :

• Double clicking one of the existing sources should add an item of that source, in the same way that double clicking a source type does add a new source of that type.

I toyed with this idea, but since the items are multi-selectable and can be unselected by clicking, double clicking was a bit confusing.

• I feel the Recently Added tab should be made to stand out more from the list, I would suggest by putting a separator between it and the rest of the list, and/or by giving it an icon to bring it level with the list. Rough mockup attached.

I aimed to distinguish it with the lack of an icon. Adding a separator is also non-trivial due to how simplistic QListWidgets are heh

[Penwy]

Fixed the above visual issues

Can confirm, also did a round of all themes to check for other visual issues, found none.

I aimed to distinguish it with the lack of an icon.

While I agree it is a visual distinction, it does, in my opinion, make it stand out less, as the eye is naturally drawn to the icons as "markers" of the list. Without the presence of such a marker, the "Recently added" does not impart that it is a list item at first sight.

Adding a separator is also non-trivial due to how simplistic QListWidgets are heh

Would it be possible to make it not be the same list but in a separate one(that's what I had in mind in the mockup), or not a list item at all, but still behave like one?

[RytoEX]

Make sure that new code complies with #12567.

[RytoEX]

Nits.