WM_INPUTLANGCHANGEREQUEST message

Posted to the window with the focus when the user chooses a new input language, either with the hotkey (specified in the Keyboard control panel application) or from the indicator on the system taskbar. An application can accept the change by passing the message to the DefWindowProc function or reject the change (and prevent it from taking place) by returning immediately.

A window receives this message through its WindowProc function.

#define WM_INPUTLANGCHANGEREQUEST       0x0050

wParam

The new input locale. This parameter can be a combination of the following flags.

Expand table

Value	Meaning
INPUTLANGCHANGE_BACKWARD 0x0004	A hot key was used to choose the previous input locale in the installed list of input locales. This flag cannot be used with the INPUTLANGCHANGE_FORWARD flag.
INPUTLANGCHANGE_FORWARD 0x0002	A hot key was used to choose the next input locale in the installed list of input locales. This flag cannot be used with the INPUTLANGCHANGE_BACKWARD flag.
INPUTLANGCHANGE_SYSCHARSET 0x0001	The new input locale's keyboard layout can be used with the system character set.

 

lParam

The input locale identifier. For more information, see Languages, Locales, and Keyboard Layouts.

Type: LRESULT

This message is posted, not sent, to the application, so the return value is ignored. To accept the change, the application should pass the message to DefWindowProc. To reject the change, the application should return zero without calling DefWindowProc.

When the DefWindowProc function receives the WM_INPUTLANGCHANGEREQUEST message, it activates the new input locale and notifies the application of the change by sending the WM_INPUTLANGCHANGE message.

The language indicator is present on the taskbar only if you have installed more than one keyboard layout and if you have enabled the indicator using the Keyboard control panel application.

Reference

DefWindowProc

WM_INPUTLANGCHANGE

Conceptual

Windows