LoadKeyboardLayout

The LoadKeyboardLayout function loads a new input locale identifier (formerly called the keyboard layout) into the system. Several input locale identifiers can be loaded at a time, but only one per process is active at a time. Loading multiple input locale identifiers makes it possible to rapidly switch between them.

- pwszKLID
Points to the buffer that specifies the name of the keyboard layout. This name is a string composed from the hexadecimal value of the primary language identifier (low word) and a device identifier (high word). For example, U.S. English has a language identifier of 0x0409, so the primary U.S. English layout is named “00000409”. Variants of U.S. English layout, such as the Dvorak layout, are named “00010409”, “00020409”, and so on. For a list of the primary language identifiers and secondary language identifiers that make up a language identifier, see the MAKELANGID macro.

- Flags
Specifies how the keyboard layout is to be loaded. This parameter can be one of the following values:
KLF_ACTIVATE
If the given layout is not already loaded, the function loads and activates the layout for the current thread, inserting the layout at the head of the keyboard layouts list in front of the previously active layout. If the layout is already loaded and the KLF_REORDER value is not given, the function simply rotates the keyboard layouts list, making the next layout the active layout.

KLF_NOTELLSHELL
Prevents a ShellProc hook procedure from receiving an HSHELL_LANGUAGE hook code when the new layout is loaded. This value is typically used when an application loads multiple layouts, one after another. Applying this value to all but the last layout delays the shell’s processing until all layouts have been added.

KLF_REORDER
Moves the given layout to the head of the keyboard layouts list, making that layout the active layout for the current thread. This value reorders the keyboard layouts list even if KLF_ACTIVATE is not given.

KLF_REPLACELANG
If the new layout has the same language identifier as a current layout, the new layout replaces the current one as the layout for that language. If this value is not given and the layouts have the same language identifiers, the current layout is not replaced and the function returns NULL.

KLF_SUBSTITUTE_OK
Substitues the given keyboard layout with another layout preferred by the user. The substitution occurs only if the registry key HKEY_CURRENT_USER\Keyboard Layout\Substitutes explicitly defines a substitution layout. For example, if the key includes the value name “00000409” with value “00010409”, loading the U.S. English layout (“00000409”) causes the Dvorak U.S. English layout (“00010409”) to be loaded instead. The system uses KLF_SUBSTITUTE_OK when booting and it is recommended that all applications use this value too.