RegisterRawInput

RegisterRawInput is a function in the Windows API that allows an application to receive raw input from devices such as keyboards, mice, and joysticks. Instead of processing input through standard Windows messages, raw input bypasses these intermediaries and provides the application with direct access to hardware events. This is particularly useful for games and other applications that require precise control over input or need to handle multiple input devices simultaneously.

To use RegisterRawInput, an application first creates a RAWINPUTDEVICE structure that specifies the type of device to register (e.g., keyboard, mouse) and the usage page and ID. This structure is then passed to the RegisterRawInputDevices function along with a flag indicating whether to register or unregister the device. Once registered, the application can receive raw input messages in its message loop. These messages are of type WM_INPUT and contain a pointer to a RAWINPUT structure, which holds information about the device and the input event, such as button presses, movement data, or key codes. Applications must then process these raw input messages to determine the user's intent. This approach offers lower latency and greater flexibility compared to traditional input handling methods.