How to use REMOVE or REPAIR feature in NSIS script? - nsis

Question

I have used nsis script for creating installer.When i run my installer second time with same name,REPAIR and REMOVE should be check and do the corresponding operation.I have find out my application already installed or not using following codes,
Function checkinstall
ReadRegStr $R0 HKLM "SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\My app" "UninstallString"
IfFileExists $R0 +1 NotInstalled
call nsDialogpage
NotInstalled:
FunctionEnd
Function nsDialogpage
nsDialogs::Create 1018
Pop $Dialog
${If} $Dialog == error
Abort
${EndIf}
${NSD_CreateRadioButton} 0 5u 100% 10u "Repair"
Pop $hwnd
${NSD_AddStyle} $hwnd ${WS_GROUP}
${NSD_OnClick} $hwnd ???
${NSD_CreateRadioButton} 0 25u 100% 56u "Remove"
Pop $hwnd
${NSD_OnClick} $hwnd ???
nsDialogs::Show
If the user select repair button it should overwrites existing installation path else uninstall existing installed and continue with new one.what am i need do to replace the (???) of the above code
page custom checkinstall
!insertmacro MUI_PAGE_DIRECTORY
My next page is Directory selection.so i need to call this page? How to achieve this?
1.How can i call un installer function if the user selects remove button?
Function un.Init, section /o -un.Main UNSEC000,section -un.post UNSE001
these are the un installer funtions.How can i call these functions? i have tried call method but it did not work.

Answer 1

You need to specify a callback function, like in the nsDialogs documentation, look for the nsDialogsPageLeave function in this example:
!include nsDialogs.nsh
!include LogicLib.nsh
Name nsDialogs
OutFile nsDialogs.exe
XPStyle on
Var Dialog
Var Label
Var Text
Page custom nsDialogsPage nsDialogsPageLeave
Page instfiles
Function nsDialogsPage
nsDialogs::Create 1018
Pop $Dialog
${If} $Dialog == error
Abort
${EndIf}
${NSD_CreateLabel} 0 0 100% 12u "Hello, welcome to nsDialogs!"
Pop $Label
${NSD_CreateText} 0 13u 100% -13u "Type something here..."
Pop $Text
${NSD_OnChange} $Text nsDialogsPageTextChange
nsDialogs::Show
FunctionEnd
Function nsDialogsPageLeave
${NSD_GetText} $Text $0
MessageBox MB_OK "You typed:$\n$\n$0"
FunctionEnd
Function nsDialogsPageTextChange
Pop $1 # $1 == $ Text
${NSD_GetText} $Text $0
${If} $0 == "hello"
MessageBox MB_OK "right back at ya!"
${EndIf}
FunctionEnd
Section
DetailPrint "hello world"
SectionEnd