Windows Wallpaper Changer

A lightweight tray application that randomly cycles through wallpapers in a chosen folder on a configurable timer — a replacement for Windows' built-in Slideshow background, which is known to stop working after sleep, lock, or display changes.

This application is fully vibe-coded, mostly because I was lazy but also because I wanted to test Claude Code a little. :)

Features

• Randomly selects wallpapers from a target folder (.jpg, .jpeg, .png, .bmp)
• Re-scans the folder on every cycle — add or remove images without restarting
• Configurable interval: 5 / 10 / 15 / 30 / 60 minutes
• Lives entirely in the system tray — no window, no taskbar entry, no console
• Left or right click on the tray icon opens the context menu
• Next wallpaper — skip immediately and reset the timer
• Change folder — native Windows folder picker, applies instantly
• Change interval — submenu with the current interval ticked
• Exit — clean shutdown
• Settings persist across restarts via a hidden INI file (%USERPROFILE%\windows_wallpaper_changer_config.ini)
• Single .exe, no installer, no runtime dependencies, ~1–2 MB memory footprint

How it works

On startup the program registers a hidden message-only window (HWND_MESSAGE) — this gives it a message loop without appearing in the taskbar or creating a visible window. It then adds a tray icon via Shell_NotifyIcon and starts a WM_TIMER at the chosen interval.

Each time the timer fires (or "Next wallpaper" is selected), FindFirstFile / FindNextFile enumerate all supported images in the configured folder. A random image — different from the previous one — is passed to SystemParametersInfoW(SPI_SETDESKWALLPAPER, ...), which updates the desktop background. Settings are written to and read from a standard INI file via GetPrivateProfileString / WritePrivateProfileString. The folder picker uses SHBrowseForFolder (COM-based), so COM is initialised on startup with CoInitializeEx.

Building

Requires CMake ≥ 4.1 and a Windows C compiler (MSVC or MinGW-w64).

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --config Release

The resulting Windows_Wallpaper_Changer.exe is fully self-contained and can be placed anywhere. To run it automatically on login, add a shortcut to %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup.

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This project is licensed under the GNU Affero General Public License v3.0. See the LICENSE file for details.