改变图像大小并显示

uses   jpeg;

var
  Bmp,Bmp2:TBitmap;
  Jpg:TJPEGImage;

begin
  if OpenPictureDialog1.Execute then
    begin
      Bmp:=TBitmap.Create;
      Jpg:=TJPEGImage.Create;
      if ExtractFileExt(OpenPictureDialog1.FileName)='.bmp' then
        Bmp.LoadFromFile(OpenPictureDialog1.FileName);
      if ExtractFileExt(OpenPictureDialog1.FileName)='.jpg' then
        begin
          Jpg.LoadFromFile(OpenPictureDialog1.FileName);
          Bmp.Assign(Jpg);
        end;
      //改变位图大小

      Bmp2:=TBitmap.Create;
      Bmp2.Assign(Bmp);     //色彩深度一致
      Bmp2.Width:=105;
      Bmp2.Height:=135;
      Bmp2.Canvas.StretchDraw(Bmp2.Canvas.ClipRect,Bmp);  //缩放适应
      Jpg.Assign(Bmp2);
      Image1.Picture.Assign(Jpg);
      Bmp.Free;
      Bmp2.Free;
      Jpg.Free;
    end;
end;