Inno Setup - Display MessageBox to run additional file - inno-setup

Question

I am new to Inno Setup and having difficulty find this answer...
I have included a DirectX9 setup file in the installer, but I want to display a MessageBox to the user to ask "Do you want to install DirectX9?" that is done before the regular installation of my game... if he says yes, then I want to run this additional file that I included, but otherwise just proceed to install the game.

Answer 1

The following code will run just before the installation begins. It asks for confirmation from the user and then runs "InstallDirectX.exe" (which must be available to the installer).
[Code]
function PrepareToInstall(var NeedsRestart: Boolean): String;
var
ResultCode: integer;
begin
if (msgbox('Do you want to install DirectX ?', mbConfirmation, MB_YESNO) = IDYES) then
begin
if Exec(ExpandConstant('InstallDirectX.exe'), '', '', SW_SHOW, ewWaitUntilTerminated, ResultCode) then
begin
// handle success if necessary; ResultCode contains the exit code
MsgBox('Everything is proceeding according to plan', mbInformation, MB_OK);
end
else
begin
// handle failure if necessary; ResultCode contains the error code
MsgBox('Something went horribly wrong', mbError, MB_OK);
end;
end;
end;

Answer 2

If you want to display message box when installation finished, you can use this code:
[Code]
procedure CurStepChanged(CurStep: TSetupStep);
var
ResultCode: Integer;
begin
if CurStep = ssPostInstall then
begin
if (msgbox('Do you want to install DirectX ?', mbConfirmation, MB_YESNO) = IDYES) then
begin
if Exec(ExpandConstant('{src}\dxwebsetup.exe'), '', '', SW_SHOW, ewWaitUntilTerminated, ResultCode) then
begin
MsgBox('Installing DirectX completed', mbInformation, MB_OK);
end
else
begin
MsgBox('Installing Error', mbError, MB_OK);
end;
end;
end;
end;