LoadFromStream(Stream : TStream; ABackColor : TBDColor): Boolean;
var
FileHeader : TBitmapFileHeader;
InfoHeader : TBitmapInfoHeader;
begin
//读取文件头
Stream.Read(FileHeader,SizeOf(TBitmapFileHeader));
Stream.Read(InfoHeader,SizeOf(TBitmapInfoHeader));
with FileHeader,InfoHeader do
begin
//确定位图格式
if (bfType<>$4D42) or (biSize<>SizeOf(TBitmapInfoHeader)) or
(biBitCount<>BD_BITCOUNT) or (biCompression<>BI_RGB) then
begin
self.Error:='错误的数据格式!';
result:=false;
exit;
end;