用GraphicEx将Bmp转PNG,转出后还是BMP格式.不知如何写?请帮忙

Question

png := TPNGGraphic.Create;
      try
        Image1.Picture.LoadFromFile(sBmpName);
        if Image1.Picture.Graphic is TBitmap then
           png.Assign(Image1.Picture.Graphic)
        else
        begin
          png.PixelFormat := pf16bit;
          png.Width := Image1.Picture.Width;
          png.Height := Image1.Picture.Height;
          png.Canvas.Draw(0, 0, Image1.Picture.Graphic);
        end;
        png.SaveToFile(sSaveName);
      finally
        png.Free;
      end;

Answer 1

用GDI+
function TmainForm.SaveFileToPng(SaveBmp:TBitMap32;FileName :String):Boolean;
var
 B:TBitmap32;
 encoderClsid: TGUID;
 TempGBitmap :TGPbitmap;
 i,j :integer;
 color: Cardinal;
 stat: TStatus;
begin
  result :=false;
  B :=TBitMap32.Create;
  B.DrawMode := dmBlend;
  B.Assign(SaveBmp);
  TempGBitMap :=TGPbitMap.Create(B.width, B.height, PixelFormat32bppARGB);
  for i :=0 to B.Width -1 do
   for j :=0 to B.Height -1 do
    begin
       Color:=B.Pixel[i,j];
       TempGBitMap.SetPixel(i,j,Color);
     end;
  GetEncoderClsid('image/png', encoderClsid);
  stat := TempGBitMap.Save(FileName, encoderClsid, nil);
  if Stat=Ok then
    result :=true;
end;

Answer 2

请参见下面帖中我的回复:http://community.csdn.net/Expert/topic/5172/5172039.xml?temp=.6034052