為什么載入jpeg無法stretchblt?

Question

首先加2個TImage,Img1載入jpeg,把結果blt到Img2上。但是源用canvas.handle或者picture.bitmap.handle都無法stretchblt,如下： Stretchblt(Img2.Canvas.Handle,0,0,Img2.Width,Img2.height,Img1.canvas.handle,0,0,img1.width,img1.height,srccopy); Stretchblt(Img2.Canvas.Handle,0,0,Img2.Width,Img2.height,Img1.picture.bitmap.handle,0,0,img1.width,img1.height,srccopy);但是載入bmp,卻可以使用第1條語句。有沒有載入jpeg,也可以把結果blt到Img2的解決辦法？謝謝

Answer 1

var
  tmp: TBitmap;
begin
  if Img1.Picture.Graphic is TBitmap then
    Stretchblt(Img2.Canvas.Handle,0,0,Img2.Width,Img2.height,Img1.canvas.handle,0,0,img1.width,img1.height,srccopy)
  else
  begin
    tmp := TBitmap.Create;
    tmp.Assign(Img1.Picture.Graphic);
    Stretchblt(Img2.Canvas.Handle,0,0,Img2.Width,Img2.height,tmp.Canvas.Handle,0,0,img1.width,img1.height,srccopy);
    tmp.Free;
  end;