4.7 Functions
Functions are similar to Sections in that they contain zero or more instructions. User functions are not called by the installer directly, instead they are called from Sections using the Call instruction. Callback functions will be called by the installer when a certain event occurs.
Functions must be declared outside of Sections or other Functions.
4.7.1 Function Commands
4.7.1.1 Function
[function_name]
Begins and opens a new function. Function names beginning with "." (e.g. ".Whatever") are generally reserved for callback functions. Function names beginning with "un." are functions that will be generated in the Uninstaller. Hence, normal install Sections and functions cannot call uninstall functions, and the Uninstall Section and uninstall functions cannot call normal functions.
Function func # some commands FunctionEnd Section Call func SectionEnd
4.7.1.2 FunctionEnd
This command closes the current open function.
4.7.2 Callback Functions
You can create callback functions (which have special names), that will be called by the installer at certain points in the install. Below is a list of available callbacks:
4.7.2.1 Install Callbacks
4.7.2.1.1 .onGUIInit
This callback will be called just before the first page is loaded and the installer dialog is shown, allowing you to tweak the user interface.
Example:
!include "WinMessages.nsh"
Function .onGUIInit
# 1028 is the id of the branding text control
GetDlgItem $R0 $HWNDPARENT 1028
CreateFont $R1 "Tahoma" 10 700
SendMessage $R0 ${WM_SETFONT} $R1 0
# set background color to white and text color to red
SetCtlColors $R0 FFFFFF FF0000
FunctionEnd
4.7.2.1.2 .onInit
This callback will be called when the installer is nearly finished initializing. If the '.onInit' function calls Abort, the installer will quit instantly.
Here are two examples of how this might be used:
Function .onInit
MessageBox MB_YESNO "This will install. Continue?" IDYES NoAbort
Abort ; causes installer to quit.
NoAbort:
FunctionEnd
or:
Function .onInit
ReadINIStr $INSTDIR $WINDIR\wincmd.ini Configuration InstallDir
StrCmp $INSTDIR "" 0 NoAbort
MessageBox MB_OK "Windows Commander not found. Unable to get install path."
Abort ; causes installer to quit.
NoAbort:
FunctionEnd
4.7.2.1.3 .onInstFailed
This callback is called when the user hits the 'cancel' button after the install has failed (if it could not extract a file, or the install script used the Abort command).
Example:
Function .onInstFailed
MessageBox MB_OK "Better luck next time."
FunctionEnd
4.7.2.1.4 .onInstSuccess
This callback is called when the install was successful, right before the install window closes (which may be after the user clicks 'Close' if AutoCloseWindow or SetAutoClose is set to false).
Example:
Function .onInstSuccess
MessageBox MB_YESNO "Congrats, it worked. View readme?" IDNO NoReadme
Exec notepad.exe ; view readme or whatever, if you want.
NoReadme:
FunctionEnd
4.7.2.1.5 .onGUIEnd
This callback is called right after the installer window closes. Use it to free any user interface related plug-ins if needed.
4.7.2.1.6 .onMouseOverSection
This callback is called whenever the mouse position over the sections tree has changed. This allows you to set a description for each section for example. The section id on which the mouse is over currently is stored, temporarily, in $0.
Example:
Function .onMouseOverSection
FindWindow $R0 "#32770" "" $HWNDPARENT
GetDlgItem $R0 $R0 1043 ; description item (must be added to the UI)
StrCmp $0 0 "" +2
SendMessage $R0 ${WM_SETTEXT} 0 "STR:first section description"
StrCmp $0 1 "" +2
SendMessage $R0 ${WM_SETTEXT} 0 "STR:second section description"
FunctionEnd
4.7.2.1.7 .onRebootFailed
This callback is called if Reboot fails. WriteUninstaller, plug-ins, File and WriteRegBin should not be used in this callback.
Example:
Function .onRebootFailed MessageBox MB_OK|MB_ICONSTOP "Reboot failed. Please reboot manually." /SD IDOK FunctionEnd
4.7.2.1.8 .onSelChange
Called when the selection changes on the component page. Useful for using with SectionSetFlags and SectionGetFlags.
Selection changes include both section selection and installation type changes. The section id of the changed section is stored in $0. $0 is -1 if the installation type changed. You only get notifications for changes initiated by the user and only one notification per action even if the action also affected child sections and/or parent groups.
4.7.2.1.9 .onUserAbort
This callback is called when the user hits the 'cancel' button, and the install hasn't already failed. If this function calls Abort, the install will not be aborted.
Example:
Function .onUserAbort
MessageBox MB_YESNO "Abort install?" IDYES NoCancelAbort
Abort ; causes installer to not quit.
NoCancelAbort:
FunctionEnd
4.7.2.1.10 .onVerifyInstDir
This callback enables control over whether or not an installation path is valid for your installer. This code will be called every time the user changes the install directory, so it shouldn't do anything crazy with MessageBox or the like. If this function calls Abort, the installation path in $INSTDIR is deemed invalid.
Example:
Function .onVerifyInstDir
IfFileExists $INSTDIR\Winamp.exe PathGood
Abort ; if $INSTDIR is not a winamp directory, don't let us install there
PathGood:
FunctionEnd
4.7.2.2 Uninstall Callbacks
4.7.2.2.1 un.onGUIInit
This callback will be called just before the first page is loaded and the installer dialog is shown, allowing you to tweak the user interface.
Have a look at .onGUIInit for an example.
4.7.2.2.2 un.onInit
This callback will be called when the uninstaller is nearly finished initializing. If the ' un.onInit' function calls Abort, the uninstaller will quit instantly. Note that this function can verify and/or modify $INSTDIR if necessary.
Here are two examples of how this might be used:
Function un.onInit
MessageBox MB_YESNO "This will uninstall. Continue?" IDYES NoAbort
Abort ; causes uninstaller to quit.
NoAbort:
FunctionEnd
or:
Function un.onInit
IfFileExists $INSTDIR\myfile.exe found
Messagebox MB_OK "Uninstall path incorrect"
Abort
found:
FunctionEnd
4.7.2.2.3 un.onUninstFailed
This callback is called when the user hits the 'cancel' button after the uninstall has failed (if it used the Abort command or otherwise failed).
Example:
Function un.onUninstFailed
MessageBox MB_OK "Better luck next time."
FunctionEnd
4.7.2.2.4 un.onUninstSuccess
This callback is called when the uninstall was successful, right before the install window closes (which may be after the user clicks 'Close' if SetAutoClose is set to false)..
Example:
Function un.onUninstSuccess
MessageBox MB_OK "Congrats, it's gone."
FunctionEnd
4.7.2.2.5 un.onGUIEnd
This callback is called right after the uninstaller window closes. Use it to free any user interface related plug-ins if needed.
4.7.2.2.6 un.onRebootFailed
This callback is called if Reboot fails. WriteUninstaller, plug-ins, File and WriteRegBin should not be used in this callback.
Example:
Function un.onRebootFailed MessageBox MB_OK|MB_ICONSTOP "Reboot failed. Please reboot manually." /SD IDOK FunctionEnd
4.7.2.2.7 un.onSelChange
Called when the selection changes on the component page. Useful for using with SectionSetFlags and SectionGetFlags.
Selection changes include both section selection and installation type changes. The section id of the changed section is stored in $0. $0 is -1 if the installation type changed. You only get notifications for changes initiated by the user and only one notification per action even if the action also affected child sections and/or parent groups.
4.7.2.2.8 un.onUserAbort
This callback is called when the user hits the 'cancel' button and the uninstall hasn't already failed. If this function calls Abort, the install will not be aborted.
Example:
Function un.onUserAbort
MessageBox MB_YESNO "Abort uninstall?" IDYES NoCancelAbort
Abort ; causes uninstaller to not quit.
NoCancelAbort:
FunctionEnd