delphi JPG/JPEG 图片缩放函数

function ChangeJpegSize(FileName,FileName2: string; W, H: Integer): Boolean;

var

jpg: TJPEGImage;

bmp: TBitmap;

begin

Result := False;

jpg := TJPEGImage.Create;

try

    jpg.LoadFromFile(FileName);

    bmp := TBitmap.Create;

    bmp.Width := W;

    bmp.Height := H;

    bmp.Canvas.StretchDraw(Rect(0, 0, bmp.Width, bmp.Height), jpg);

    jpg.Assign(bmp);

    try

      jpg.SaveToFile(FileName2);

      Result := True;

    finally

      bmp.Free;

    end;

finally

    jpg.Free;

end;

end;