Member Avatar for Sevyt

Is there any way to detect a keypress when your window is not active?

I got a transparant window which is always visible ontop of other applications.
Though the idea is to start timers when the assigned key is pressed.
The problem i got is when the window is on top of the application its visible but not active.
And so it will not detect when a key is pressed that is assigned to the timer.

Can anybody explain me what the best option would be to get this done?

Thanks

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The practical options for a WPF window that must detect keys while not focused are: RegisterHotKey, a low‑level global keyboard hook (WH_KEYBOARD_LL), or Raw Input (RIDEV_INPUTSINK). ’s hint about hooks is on point and ’s follow‑up confirms it’s workable in WPF. Below are WPF‑specific tradeoffs and implementation notes to make the solution robust.

RegisterHotKey: easiest for single hotkeys. Register the combo (modifiers + virtual key) against the window HWND and handle WM_HOTKEY via an HwndSource message hook (or WindowInteropHelper). It works when the window is inactive, is lightweight, and is ideal for “press X to start/stop a timer.” Limitations: registration can fail if another app has the same combo, and it’s awkward for capturing plain single keys or full key-up/key-down sequences.

WH_KEYBOARD_LL (low‑level hook): captures arbitrary key events globally (good for full key streams). WPF cautions: keep the HookProc delegate alive (store it in a static field), keep the callback work minimal (post to Dispatcher for UI work), and always call UnhookWindowsHookEx on shutdown. Also note UIPI/elevation: a non‑elevated hook may not see input from elevated processes. Minimal pattern to hold the delegate:

private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);
private static LowLevelKeyboardProc _proc = HookCallback; // keep alive
private static IntPtr _hookId = IntPtr.Zero;

Raw Input (RIDEV_INPUTSINK): useful when device‑level info or guaranteed WM_INPUT while unfocused is needed. Register the keyboard device and handle WM_INPUT in an HwndSource hook. In WPF get the HWND via WindowInteropHelper or HwndSource, call AddHook, and unregister on close.

Practical tips: prefer RegisterHotKey for simple hotkeys; use WH_KEYBOARD_LL or Raw Input for full key streams. Avoid heavy work in hook callbacks, test with elevated apps, and always clean up hooks/hotkeys on exit.

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Member Avatar for cgeier

Use a keyboard hook. for an article about mouse hooks and keyboard hooks.

Member Avatar for Sevyt

Alright going to look into that again.
Had seen it before, but had trouble getting it to work in wpf.

Member Avatar for Sevyt

Managed to get it working, thanks for the help.

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