NSIS - Conditionally Display Components - nsis

Question

I want the installer/uninstaller to check if any of the possible components are installed, and display only relevan components (installer should display only components not already installed and uninstaller should display only already-installed components)
I'm using MUI.
The component section of my .nsi looks something like this:
; Section descriptions
!insertmacro MUI_FUNCTION_DESCRIPTION_BEGIN
!insertmacro MUI_DESCRIPTION_TEXT ${Component1} "Component1 Description"
!insertmacro MUI_DESCRIPTION_TEXT ${Component2} "Component2 Description."
!insertmacro MUI_DESCRIPTION_TEXT ${Component3} "Component3 Description."
!insertmacro MUI_FUNCTION_DESCRIPTION_END
I've tried a couple of different ways:
First, I tried using this macro for checking if a registry exists:
!insertmacro IfKeyExists HKEY_LOCAL_MACHINE SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall "Component1"
Pop $R0
${If} $R0 == 0 #Not installed yet. Display.
!insertmacro MUI_DESCRIPTION_TEXT ${Component1} "Component1"
${EndIf}
This didn't work.
Then I tried using the Registry Plug-In:
${registry::KeyExists} "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\Component1" $R0
${If} $R0 == 0 #Not installed yet. Display.
!insertmacro MUI_DESCRIPTION_TEXT ${Component1} "Component1"
${EndIf}
This didn't work either.
So then I thought maybe there was some other more basic problem, and I tried this:
StrCpy $0 "0"
${If} $0 == "1"
!insertmacro MUI_DESCRIPTION_TEXT ${Component1} "Component1 Description."
${EndIf}
But even then I still saw "Component1" as a possible component during installation!
What am I doing wrong and how can I go about achieving my goal?
Thanks in advance!

Answer 1

To select a section (= a component) at runtime you can use SectionGetFlag / SectionSetFlag and some bit manipulation :
SectionGetFlags ${test_section_id} $0
IntOp $0 $0 | ${SF_SELECTED}
SectionSetFlags ${test_section_id} $0
To deselect it, just toogle its selected bit, with
SectionGetFlags ${test_section_id} $0
IntOp $0 $0 ^ ${SF_SELECTED}
SectionSetFlags ${test_section_id} $0
These are simpler if you include the Sections.nsh header and use the SelectSection and UnselectSection macros.
If you want to hide a section, you just need to set its text to "" (empty string)
SectionSetText ${test_section_id} ""

Answer 2

You are modifying the wrong text. MUI_DESCRIPTION_TEXT is the long description that is typically displayed when hovering the mouse over a component. But the visibility of a section depends on its name to be empty or not empty.
Therefore you have to use this instead to hide your component1:
SectionSetText ${Component1} ""