远程控制篇：抓取远程屏幕图像

{抓屏幕图像，保存为内存流--BMP流,压缩BMP流,JPG流，以及使用流}
{在网络中传送BMP流和JPG流的速度没测试过}
{BMP流的压缩是无损压缩}
{
全局变量
memoryStream:TMemoryStream;
memoryStream:=TMemoryStream.create;
}

var
image:Timage;
jpgstream:TJPEGImage;
ss:tcanvas;

begin
ss:=tcanvas.Create;
ss.Handle:=getdc(0);
image:=timage.Create(self);
image.width:=Screen.width;
image.Height:=screen.Height ;
image.picture.bitmap.PixelFormat:= pf16bit;
bitblt(image.canvas.handle,0,0,image.width,image.height,ss.handle,0,0,srccopy);

{大大的原始BMP流
image.picture.bitmap.SaveToStream(memoryStream);
}

{无损压缩BMP流  uses Zlib.pas
{先定义变量count,DestStream,SourceStream}
image.picture.bitmap.SaveToStream(memoryStream);
Count:=memoryStream.Size;
DestStream:=TMemoryStream.Create;
{压缩方式:clnone,clfastest,cldefault,clmax}
SourceStream:=TCompressionStream.Create(cldefault, DestStream);
try
memoryStream.SaveToStream(SourceStream);
SourceStream.Free;
memoryStream.Clear;
memoryStream.WriteBuffer(Count, SizeOf(Count));
memoryStream.CopyFrom(DestStream, 0);
finally
DestStream.Free;
end;
}

{JPG流  uses jpeg
jpgstream:= TJPEGImage.Create;
jpgstream.Assign(image.picture.bitmap);
jpgstream.CompressionQuality:=50; {压缩质量}
jpgstream.Compress;
jpgstream.SaveToStream(memoryStream);{保存为JPG流}
jpgstream.free;
}

ReleaseDC(0,ss.Handle);
image.free;

{发送内存流...}

-----------------------------------------------------
{接收内存流...}

{使用BMP流
image.Picture.Bitmap.LoadFromStream(bmpStream);}

{还原压缩的BMP流  uses:Zlib.pas
先定义变量count,buffer,DestStream,SourceStream
memoryStream是压缩的BMP流
memoryStream.ReadBuffer(Count, SizeOf(Count));
GetMem(Buffer, Count);
DestStream:=TMemoryStream.Create;
SourceStream:=TDecompressionStream.Create(memoryStream);
Try
SourceStream.ReadBuffer(Buffer^, Count);
  DestStream.WriteBuffer(Buffer^, Count);
  DestStream.Position:=0;
  image.Picture.Bitmap.LoadFromStream(DestStream);
finally
FreeMem(Buffer);
DestStream.Free;
end;
}

使用JPG流 image.Picture.Assign(jpgstream);