This is to solve a problem in the shotcut package:

Attempting to add text to a movie resulted in this error in the shotcut Application log:
[Warning] [filter 0x2cd39390] QT or GTK modules required for text.
[Warning] [filter 0x36c70710] Unable to create text filter.

This can be traced to
https://github.com/mltframework/mlt/blob/2b650c65cb5e265864cda8c3eff91945d406c56e/src/modules/plus/filter_text.c#L213

which suggests that we either need 'qtext' or pango. I don't know what qtext is, so I've added pango to the mlt dependencies.

mlt's CMakeLists.txt has this:

if(MOD_GDK)
  pkg_check_modules(GdkPixbuf IMPORTED_TARGET gdk-pixbuf-2.0)
  if(TARGET PkgConfig::GdkPixbuf)
    pkg_check_modules(pango IMPORTED_TARGET pango)
    pkg_check_modules(pangoft2 IMPORTED_TARGET pangoft2)
    list(APPEND MLT_SUPPORTED_COMPONENTS gdk)
  else()
    set(MOD_GDK OFF)
  endif()
endif()

The cmake configure log complains about the missing gdk-pixbuf.
So I have added gdk-pixbuf and pango to the dependencies. I've also set MOD_GDK=1 though this is already the default.

I've rebuilt my nixos system and this indeed solves the problem in Shotcut!

Ping shotcut maintainers: @woffs and @peti

I'm new to nixos. In particular I'm not sure if what I did is safe to do on Darwin.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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