问一个关于TImage和Stream的简单问题!(200分)

现在通过stream传送图像,格式可能是bmp,ico,gif或其他,用流发送给接收端,
接收端收到这个stream之后,不保存临时文件,如何让image把stream中的图像显示出来.
(好像image没有loadfromstream方法呀).

image.picture.bitmap.loadfromstream呢？

gif的怎么显示？

BMP，ICO可以直接Load，但是其它格式就行了，要转换一下
以GIF为例
gif:TGifImage;
bmp:TBitmap;
begin
try
gif:=TgifImage.Create;
bmp:=TBitmap.create;
gif.loadFromStream(stream);
bmp.assign(gif);
Image.Picture.assign(bmp);
finally
bmp.free;
gif.free;
end
end;

关键问题是我得到stream后怎么知道是bmp还是gif,还是ico呢??

看文件头

得到stream后分别按bmp,gif,ico处理一下，哪个成功了就做个标记;显示出来

根据文件头可以知道是什么图片。建立对应的图类。

看文件头愿书的前几个字节,好像是4-8个字节中可以大体上确认是什么文件(仅这几种图像文件)

class function TGGraphicUtils.GetImageStreamType(AImageStream: TStream;
ASpeedGet: Boolean): TGImageStreamType;
const
cSBMPCodeStr = '424D';
cSICOCodeStr = '000001';
cSJPGCodeStr = 'FFD8FFE000104A464946';
cSGIFCodeStr = '474946';
cSWMFCodeStr = 'D7CDC69A';
cSTIFCodeStr = '49492A0008';
var
vCode: array [0..9] of Char;
vCodeStr: string;
I, vOldPos: Integer;
begin
if ASpeedGet then
begin
vOldPos := AImageStream.Position;
AImageStream.Position := 0;
AImageStream.ReadBuffer(vCode, 1);
vCodeStr := IntToHex(Byte(vCode[0]), 2);
if vCodeStr = '42' then Result := istBMP
else if vCodeStr = '00' then Result := istICO
else if vCodeStr = 'FF' then Result := istJPG
else if vCodeStr = '47' then Result := istGIF
else if vCodeStr = 'D7' then Result := istWMF
else if vCodeStr = '49' then Result := istTIF
else Result := istCustom;
AImageStream.Position := vOldPos;
end
else begin
vOldPos := AImageStream.Position;
AImageStream.Position := 0;
AImageStream.ReadBuffer(vCode, 10);
for I := 0 to 9 do
vCodeStr := vCodeStr + IntToHex(Byte(vCode), 2);
if Pos(cSBMPCodeStr, vCodeStr) = 1 then Result := istBMP
else if Pos(cSICOCodeStr, vCodeStr) = 1 then Result := istICO
else if Pos(cSJPGCodeStr, vCodeStr) = 1 then Result := istJPG
else if Pos(cSGIFCodeStr, vCodeStr) = 1 then Result := istGIF
else if Pos(cSWMFCodeStr, vCodeStr) = 1 then Result := istWMF
else if Pos(cSTIFCodeStr, vCodeStr) = 1 then Result := istTIF
else Result := istCustom;
AImageStream.Position := vOldPos;
end;
end;

http://www.moon-soft.com/program/FORMAT/