Resolve relative UI theme paths

[TurboTheTurtle]

Closes #24489.

Resolves relative custom UI theme paths against the application directory while preserving existing absolute path behavior.

Proof

Validated on Windows using the PR-head CI artifact.

• Configured a relative custom UI theme path: themes/pr24514-relative.qbtheme
• Launched qBittorrent from a different working directory
• Confirmed the relative path resolved against the application directory, not the launch CWD
• Confirmed existing absolute path behavior is preserved

[glassez]

Local validation:

• git diff --check
• cmake -S . -B build/codex-24489 -DCMAKE_BUILD_TYPE=Debug -DGUI=ON -DWEBUI=OFF -DTESTING=OFF -DSTACKTRACE=OFF
• cmake --build build/codex-24489 --target qbt_gui --parallel 4
• cmake --build build/codex-24489 --target qbt_app -j4

@TurboTheTurtle
Could you ask your AI assistant not to add this "garbage" text to the PR description? And put a period at the end of sentences like Closes #24489..

[TurboTheTurtle]

@TurboTheTurtle Could you ask your AI assistant not to add this "garbage" text to the PR description? And put a period at the end of sentences like Closes #24489..

Fair point. I updated my PRs to remove those blocks and made a note to avoid them in the future

[TurboTheTurtle]

Windows proof for latest head a464881033b37bb024d1fd9a1a9bdd9ca7413070.

I tested the PR-head Windows CI artifact on a real Windows 11 machine:

• Host: Windows 11 Home 64-bit, build 10.0.26200
• Artifact run: https://github.com/qbittorrent/qBittorrent/actions/runs/27494256383
• Artifact: qBittorrent-CI_Windows-x64_libtorrent-2.0.12
• Isolated profile: --profile=<temp>\profile
• Launch CWD deliberately different from the app directory: <temp>\launch-cwd
• Configured custom UI theme path: themes/pr24514-relative.qbtheme
• Test file location: <artifact>\qBittorrent\themes\pr24514-relative.qbtheme

The test theme file was intentionally not a valid Qt resource, so successful path resolution should still produce a load warning that names the resolved file. The app was launched from the isolated profile, allowed to initialize, then stopped after the proof line was written.

Observed qBittorrent log line:

(W) 2026-06-14T15:00:32 - Failed to load UI theme from file: "C:\Users\<user>\AppData\Local\Temp\qbt-pr24514-proof-20260614-150031\artifact\qBittorrent\themes\pr24514-relative.qbtheme"

Proof checks from the harness:

{
  "marker": "PR24514-WINDOWS-RELATIVE-THEME-20260614",
  "configuredRelativeTheme": "themes/pr24514-relative.qbtheme",
  "logContainsAppDirThemePath": true,
  "logContainsRawRelativeOnly": false
}

This confirms the Windows GUI artifact resolves a relative custom UI theme path against QCoreApplication::applicationDirPath() / the qBittorrent application directory, not the launch working directory and not the raw relative string. Existing PR CI is also green.

[Chocobo1]

Shouldn't you use the profile folder path instead of app dir path?

[glassez]

@TurboTheTurtle
Why did you mark it as resolved?

[thalieht]

Only one issue that shows up for all relative paths even though the theme is actually applied:

[TurboTheTurtle]

Manual UI validation on macOS:

• Selected a custom UI theme config.json from the isolated test profile and restarted qBittorrent.
• Confirmed the theme loads after restart.
• Reopened Options and confirmed the UI Theme field shows the selected file without a validation warning.

[Chocobo1]

#24514 (comment)

[TurboTheTurtle]

Adjusted this so the stored preference and Options field stay as entered, and relative theme paths are resolved only when the theme manager loads them. The resolution now goes through the existing profile path conversion instead of the application directory.