In Inno Setup create page where the user may select files from a folder that is packaged in the setup file

Question

In Inno Setup I want to create a page that has a list of checkboxes that correspond to the files in a folder I have listed in the [Files] section.

How can I read the files in this folder and then copy only those files, that the user selected? Right now, I don't even get the list, because the folder {tmp}\list doesn't exist.

[Files]
Source: "list\*"; DestDir:"{tmp}"; Flags: recursesubdirs

[Code]

var
  karten : TNewCheckListBox;
  FileListBox : TNewListBox;
  KartenFormular: TWizardPage;

procedure KartenEinlesen(const Directory: string; Files: TStrings);
var
  FindRec: TFindRec;
begin
  Files.Clear;
  if FindFirst(ExpandConstant(Directory + '*'), FindRec) then
  try
    repeat
      if FindRec.Attributes and FILE_ATTRIBUTE_DIRECTORY = 1 then
        Files.Add(FindRec.Name);
    until
      not FindNext(FindRec);
  finally
    FindClose(FindRec);
  end;  
end;

procedure InitializeWizard;
var 
  AfterID: Integer;
begin
  AfterID := wpSelectTasks;
  KartenFormular := 
    CreateCustomPage(
      AfterID, 'Kartendaten', 'Ort für den Ordner Kartendaten auswählen');
  FileListBox := TNewListBox.Create(WizardForm);
  FileListBox.Parent := KartenFormular.Surface;
  FileListBox.Align := alClient;
  AfterID := KartenFormular.ID;
    
  KartenEinlesen('{tmp}\maptiles\*',FileListBox.Items)
end;

Answer 1

The InitializeWizard happens at the very beginning, long before the files are extracted. Moreover it would be inefficient to extract (all) files to {tmp} and then copy them somewhere else after users selects the files to install. And you would have to code the actual installation process.

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The right solution is to generate the list box contents on compile (not install) time, using Inno Setup preprocessor.

The following question shows something similar. It creates a Inno Setup component for each file. It might even be better than a custom page.
Dynamically add an Inno Setup component for all files in a folder and its subfolders

But if you want the custom page, the solution won't be too different. You just would generate FileListBox.Items.Add call for each file, instead of [Components] section entry. The code is somewhat complicated as it works recursively (what you do not seem to need). For flat solution, it can be simplified.

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Also note that there's CreateInputOptionPage, what makes it easier to create a custom page with check list box.