function ThumbFilename(AFilename: string): string;
begin
  Result := TPath.Combine(ExtractFilePath(AFilename), '_thumbs');
  Result := TPath.Combine(Result, ExtractFilename(AFilename));
  // Result := ChangeFileExt(Result, '.bmp');
end;

procedure TFormMain.IEMView1ImageLoaded(Sender: TObject; idx: Integer);
var
  IEIO: TImageEnIO;
  sThumbFilename: string;
begin
  // sl.Add('OnImageLoaded ' + IEMView1.ImageFileName[idx]);
  sThumbFilename := ThumbFilename(IEMView1.ImageFileName[idx]);
  if not System.SysUtils.FileExists(sThumbFilename) then
  begin
    IEIO := TImageEnIO.CreateFromBitmap(IEMView1.GetTIEBitmap(idx));
    try
      IEIO.Params.JPEG_Quality := 90;
      ForceDirectories(ExtractFilePath(sThumbFilename));
      IEIO.SaveToFile(sThumbFilename);
    finally
      IEIO.Free;
    end;
  end;
end;

procedure TFormMain.IEMView1ImageOut(Sender: TObject; idx: Integer; OutBitmap: TIEBitmap);
begin
  // sl.Add('OnImageOut ' + IEMView1.ImageFileName[idx]);
  OutBitmap.IECanvas.Font.Size := 24;
  OutBitmap.IECanvas.DrawText(ExtractFilename(IEMView1.ImageFileName[idx]),
    Rect(0, 0, OutBitmap.Width, OutBitmap.Height));
end;

procedure TFormMain.FormCreate(Sender: TObject);
begin
  with IEMView1 do
  begin
    Align := alClient;
    Parent := self;
    Background := clWindow;
    FlatScrollBars := True;
    TextMargin := 4;
    GridWidth := -1;
    SelectionWidth := 1;
    SelectionColor := $CEA27D;
    Style := iemsFlat;
    AutoAdjustStyle := False;

    ThumbWidth := 150;
    ThumbHeight := 150;
    StoreType := ietFastThumb;
    ThumbnailsBorderWidth := 0;
    // ThumbnailsBorderWidth := 1;
    ThumbnailsBackground := clWindow;
    ThumbnailsBackgroundSelected := $FCEADA;
    // ThumbnailResampleFilter := rfFastLinear;
    ThumbnailResampleFilter := rfBiCubic;
    ThumbnailDisplayFilter := rfFastLinear;
    ThumbnailsBorderCurved := False;
    HorizBorder := 2;
    VertBorder := 2;

    EnableMultiSelect := True;
    MultiSelectionOptions := [iemoRegion, iemoOptimizeForDragging, iemoSelectOnRightClick];

    DefaultTopText := iedtNone;
    DefaultInfoText := iedtNone;
    DefaultBottomText := iedtFilename;
    BottomTextFont.Color := clGray;
    BottomTextFont.Name := 'Segoe UI';
    BottomTextFont.Size := 7;
    SelectedFontColor := clNone;

    MouseWheelParams.Action := iemwVScroll;
    MouseWheelParamsAlt.Action := iemwZoom;

    EnableAdjustOrientation := True;
    EnableImageCaching := True;

    //
    OnImageOut := IEMView1ImageOut;
    OnImageLoaded := IEMView1ImageLoaded;
    OnImageFilename := IEMView1ImageFilename;

    ImageCacheSize := 512;
    LookAhead := 80;
  end;
end;

procedure TMyForm.ImageEnMViewOnGetLoadFilename(Sender: TObject; Index: integer; var Filename: string);
var
  cacheFilename: string;
begin
  // Use our own cache as a source for thumbnails
  cacheFilename := LookupCacheTable( Filename );
  if cacheFilename = '' then
  begin
    cacheFilename := GenerateCacheFile( Filename );
    AddToCacheTable( Filename, cacheFilename );
  end;

  Filename := cacheFilename;
end;