A custom installer dll should export the Install_Init function. This function will be called before installation begins. This function can be used for custom operations such as checking an application version for application re-installation or determining whether a dependent application is present. For more information, see Optional Setup.dll Files for Installation.
codeINSTALL_INIT Install_Init( HWND hwndParent, BOOL fFirstCall, BOOL fPreviouslyInstalled, LPCTSTR pszInstallDir );
[in] Specifies a handle to the parent window.
[in] Specifies a Boolean value that is set to TRUE to indicate that this is the first time this function is being called.
[in] Specifies a Boolean value that is set to TRUE to indicate that the current application is already installed.
[in] Reference to a null-terminated string that contains the name of the application installation directory that is selected by the user.
This function may be called multiple times, each time with a different string for pszInstallDir. For example, when the current directory does not have enough room, you should call this function for the first time. .
This function is called during installation once the installation process has been completed.