PowerToys/doc/devdocs/settingsv2/hotkeycontrol.md

# Custom HotKey Control

The Settings project provides a custom hotkey control which consumes key presses. This control can be used to set the hotkey of any PowerToy.

## HotKey Control in FancyZones
![Image of hotkey control](/doc/images/settingsv2/settingshotkeycontrol.png)

## Hotkey related files

#### [`HotkeySettingsControlHook.cs`](/src/core/Microsoft.PowerToys.Settings.UI.Library/HotkeySettingsControlHook.cs)

- This function initializes and starts the [`keyboardHook`](src/common/interop/KeyboardHook.cpp) for the hotkey control.

```csharp
        public HotkeySettingsControlHook(KeyEvent keyDown, KeyEvent keyUp, IsActive isActive, FilterAccessibleKeyboardEvents filterAccessibleKeyboardEvents)
        {
            _keyDown = keyDown;
            _keyUp = keyUp;
            _isActive = isActive;
            _filterKeyboardEvent = filterAccessibleKeyboardEvents;
            _hook = new KeyboardHook(HotkeySettingsHookCallback, IsActive, FilterKeyboardEvents);
            _hook.Start();
        }
        
```

#### [`HotkeySettingsControl.xaml.cs`](/src/core/Microsoft.PowerToys.Settings.UI/HotkeySettingsControl.xaml.cs)

- The function of this class is to update the state of the keys being pressed within the custom control. This information is stored in `internalSettings`.

- It provides the following callbacks to the `HotKeySettingsControlHook`:

    - `KeyUp`: Resets the key state in `internalSettings` when a key is released.
    - `KeyDown`: Updates the user facing text of the hotkey control as soon as a key is pressed.
    - `isActive`: Sets the current status of the keyboard hook.
    - `FilterAccessibleKeyboardEvents`: This function is used to ignore the `Tab` and `Shift+Tab` key presses to meet the accessibility requirements.

#### [`HotkeySettings.cs`](/src/core/Microsoft.PowerToys.Settings.UI.Library/HotkeySettings.cs)

- Contains the structure of a HotKey where it is represented as a combination of one of the modifier keys (`Alt`, `Shift`, `Win` and `Ctrl`) and a non-modifier key.

#### Note
- The control displays all key presses to the user (except Tab and Shift+Tab which move focus out of the control). However, when the focus is being lost from the control, the `lastValidHotkeySettings` is set as the user facing text.