October 15th, 2018
As you may know, Inno Setup is one of the best Windows-based solutions to make professional installers for your software.
Since I’m going to release a new version of Converseen and it requires Ghostscript as external resource to manage PDF files, I needed to find an escamotage to notify the user, through the setup program, that the Ghostscript package have to be installed in order to let Converseen working properly.
Inno Setup allows the user to code some routines using the Delphi (pascal) programming language so I’ve written a little code that checks if Ghostscript is installed in the system (reading the registry key HKEY_CURRENT_USER\SOFTWARE\GPL Ghostscript) and, in negative case, it queries the user that the external package have to be installed through a yes/no message box; if the user presses the yes button, the setup program will open the Ghostscript download page.
Here is the code snippet to do this work. Obviusly you can adapt it on your needs.
[Code] function gsInstalled(): Boolean; begin if RegKeyExists(HKEY_CURRENT_USER, 'SOFTWARE\GPL Ghostscript') then begin Result := true; end else begin Result := false; end end; procedure installGs(); var ErrCode: integer; begin if (msgbox('In order to enable Converseen to manage PDF files you have to download and install Ghostscript. Do you want to download it now?', mbConfirmation, MB_YESNO) = IDYES) then begin ShellExec('open', 'http://www.ghostscript.com/download/gsdnld.html', '', '', SW_SHOW, ewNoWait, ErrCode); end end; procedure CurPageChanged(CurPageID: Integer); var gsIsInstalled : boolean; begin if CurPageID = wpFinished then begin gsIsInstalled := gsInstalled(); if gsIsInstalled = false then installGs(); end end;