ZLib解压流和压缩流

时间：2011/9/3 15:38:22 点击：

　　核心提示：procedure UnCompressStream(var MyStream: TMemoryStream);var SourceStream: TDecompressionStream; Buff...

procedure UnCompressStream(var MyStream: TMemoryStream);
var
SourceStream: TDecompressionStream;
Buffer: PChar;
Count: Integer;
begin
MyStream.Position := 0;
//还原被压缩图像
//从被压缩的图像流中读出原始图像的尺寸
MyStream.ReadBuffer(Count, SizeOf(Count));
//根据图像尺寸大小为将要读入的原始图像流分配内存块
GetMem(Buffer, Count);
SourceStream := TDecompressionStream.Create(MyStream);
try
    //将被压缩的图像流解压缩，然后存入 Buffer内存块中
    SourceStream.ReadBuffer(Buffer^, Count);
    //将原始图像流保存至 DestStream流中
    MyStream.Clear;
    MyStream.WriteBuffer(Buffer^, Count);
    //复位流指针
    MyStream.Position := 0;
finally
    FreeMem(Buffer);
end;
end; procedure CompressStream(var MyStream: TMemoryStream);
var
SourceStream: TCompressionStream;
DestStream: TMemoryStream;
Count: Integer;
begin
//压缩图像
//获得图像流的原始尺寸
Count := MyStream.Size;
DestStream := TMemoryStream.Create;
SourceStream := TCompressionStream.Create(clDefault, DestStream);
try
    //SourceStream中保存着原始的图像流
    MyStream.SaveToStream(SourceStream);
    //将原始图像流进行压缩， DestStream中保存着压缩后的图像流
    SourceStream.Free;
    MYStream.Clear;
    //写入原始图像的尺寸
    MyStream.WriteBuffer(Count, SizeOf(Count));
    //写入经过压缩的图像流
    MyStream.CopyFrom(DestStream, 0);
    //复位流指针
    MyStream.Position := 0;
finally
    DestStream.Free;
end;
end;