uses 
pngimage
---------------------
var
rgn:HRGN;
PNG: TPNGObject;
---------------------
begin
  try
  PNG:=TPNGObject.Create;
  PNG.LoadFromFile('./大.png');
  Image1.Picture.Assign(Png);
  finally
  Png.Free;
  end;                     //读取png文件,关联Image1
 Image1.AutoSize:=False;
  Image1.Stretch:=True;
  Image1.Top:=0;
  Image1.Left:=0;
  Image1.Height:=Image1.Parent.Height;
  Image1.Width:=Image1.Parent.Width;  //Image1平铺
end;执行后 读取png没有问题,但是png图出现在Form的左上角,平铺那一段代码为什么无效