How can I prevent showing the splash screen when I need it in Inno Setup? - installation

Question

How can I prevent showing the splash screen when I need it?
Should I add some ISSI-code to do that?
Here is my code:
#define ISSI_Splash "C:\InnoSetupProject\Images\client.bmp"
#define ISSI_Splash_T 3
#define ISSI_Splash_X 500
#define ISSI_Splash_Y 220
[Code]
function ISSI_InitializeSetup : Boolean;
begin
Result := True;
if not RegValueExists(HKLM, 'SOFTWARE\MyApp\Client', 'LocaleID') then
if MsgBox('Client does not exist', mbCriticalError, MB_OK) = IDOK then
begin
Result := False;
{ How can I prevent showing the splash screen here? }
Exit;
end
end;
#define ISSI_InitializeSetup
#define ISSI_IncludePath "C:\ISSI"
#include ISSI_IncludePath+"\_issi.isi"

Answer 1

Instead of legacy ISSI_InitializeSetup function, use Inno Setup 6 event attributes:
[Code]
<event('InitializeSetup')>
function MyInitializeSetup: Boolean;
begin
Result := True;
if not RegValueExists(HKLM, 'SOFTWARE\MyApp\Client', 'LocaleID') then
if MsgBox('Client does not exist', mbCriticalError, MB_OK) = IDOK then
begin
Result := False;
end;
end;
and remove this:
#define ISSI_InitializeSetup
The MyInitializeSetup will be called before the ISSI InitializeSetup. And if it returns False, the ISSI won't ever be called, so no splash screen will show.
Check the documentation for Event Attributes:
The implementations will be called in order of their definition except that any main implementation (=the implementation without an event attribute) will be called last.
If the event function has a return value then lazy evaluation is performed:
InitializeSetup, BackButtonClick, NextButtonClick, InitializeUninstall:
All implementations must return True for the event function to be treated as returning True and an implementation returning False stops the calls to the other implementations.