VirtualStringTree mit PNG Grafik

[stOrM]

Hi,
hab mal schnell was ausprobiert sollte eigentlich funzen:

Delphi-Quellcode:

uses
  pngimage;

function LoadPng(Width, Height: integer): TBitmap;
var
  Png : TPngImage;
begin
  Result := TBitmap.Create;
  Png := TPngImage.Create;
  try
    Png.LoadFromFile('Your Png Image');
    Result.PixelFormat := pf32bit;
    Result.SetSize(Width, Height);
    Result.Assign(Png);
  except
    Result.Free;
    raise;
  end;
   FreeAndNil(Png);
end;

procedure TForm1.FormShow(Sender: TObject);
var
  BlendRec: TBlendFunction;
  TestBitmap: TBitmap;
begin

  BlendRec.BlendOp := AC_SRC_OVER;
  BlendRec.BlendFlags := 0;  
  BlendRec.SourceConstantAlpha := 255;  
  BlendRec.AlphaFormat := AC_SRC_ALPHA;  

  TestBitmap := LoadPng(Img1.Width, Img1.Height);

  try
    Img1.Picture.Bitmap.Assign(TestBitmap);

    Windows.AlphaBlend(Img2.Canvas.Handle, 0, 0, TestBitmap.Width,
      TestBitmap.Height, TestBitmap.Canvas.Handle, 0, 0,
      TestBitmap.Width, TestBitmap.Height, BlendRec);

  finally
    TestBitmap.Free;
  end;
end;

procedure TForm1.vstPaintBackground(Sender: TBaseVirtualTree;
  TargetCanvas: TCanvas; R: TRect; var Handled: boolean);
var
  BlendRec: TBlendFunction;
begin
  Handled := True; 

  BlendRec.BlendOp := AC_SRC_OVER;
  BlendRec.BlendFlags := 0;  
  BlendRec.SourceConstantAlpha := 255;  
  BlendRec.AlphaFormat := AC_SRC_ALPHA;  

  Windows.AlphaBlend(TargetCanvas.Handle,
    Sender.ClientWidth - img2.Width, Sender.ClientHeight - img2.Height, Img2.Width,
    Img2.Height, Img2.Canvas.Handle, 0, 0,
    Img2.Width, Img2.Height, BlendRec);
end;

Benötige Komponenten Vst = VirtualStringTree
Img1 = TImage
Img2 = TImage

Ggf. sollte man noch prüfen ob die "Alphablend Function" verfügbar ist.

In TreeOptions des Vst bei PaintOptions noch toShowBackground = True einstellen.

Gruß
s!