This article shows you how to extract the associated icon of any file. Including files that use shell icon handlers such as ICO and Corel Draw files.

Just a few days ago, I published an article on creating an shell icon handler allowing you to manually create icons for every file of a specific file type.

This article shows you how to get such icons without much work. Using the function SHGetFileInfo from the ShellAPI unit it is a rather simple task.

This article will simply provide you with the steps you have to take in order to get the icon.

Starting with creating a new application drop a PaintBox, a Button and a OpenDialog on the form. Fill the Button OnClick with the following procedure:

procedure TForm1.Button1Click(Sender: TObject);
begin
  if OpenDialog1.Execute then
    DrawFile(OpenDialog1.FileName);
end;

Next you need the DrawFile method. The lines are commented.

procedure TForm1.DrawFile(Name: String);
var
  FileInfo: TSHFileInfo;
  ImageListHandle: THandle;
  aIcon: TIcon;
begin
  // clear the memory
  FillChar(FileInfo, SizeOf(FileInfo), #0);
  // get a handle to the ImageList for the file selected
  ImageListHandle := SHGetFileInfo(
    PChar(Name), 0, FileInfo, SizeOf(FileInfo),
    // we want an icon in LARGE
    SHGFI_ICON or SHGFI_LARGEICON
  );
  try
    // create a icon class
    aIcon := TIcon.Create;
    try
      // assign the handle of the icon returned
      aIcon.Handle := FileInfo.hIcon;
      // lets paint it transparent
      aIcon.Transparent := True;
      with PaintBox1 do begin
         // resize the paint box to icon size
         Width := aIcon.Width;
         Height := aIcon.Height;
         // tell our app to first resize the paint box before we draw the icon
         Application.ProcessMessages;
         // clear the paintbox
         Canvas.Rectangle(-1, -1, Succ(Width), Succ(Height));
         // copy the icon
         Canvas.Draw(0, 0, aIcon);
      end;
    finally
      // free our icon class
      FreeAndNil(aIcon);
    end;
  finally
    // !!! FREE THE ICON PROVIDED BY THE SHELL
    DestroyIcon(FileInfo.hIcon);
    // free the image list handle
    ImageList_Destroy(ImageListHandle);
  end;
end;


I hope this will help you.

Daniel Wischnewski.