流的压缩和解压

(*// 标题:流的压缩和解压 说明:适用文件压缩、图象压缩等;调用ZLib单元的方法实现 设计:Zswang 支持:[email protected] 日期:2004-03-24 //*)

(*//============================================================================ 设计思路: 创建TCompressionStream、TDecompressionStream实例进行压缩和解压 ============================================================================//*)

uses ZLib;

const cBufferSize = $4096;

function StreamCompression(mInputStream: TStream; mOutputStream: TStream): Integer; var I: Integer; vBuffer: array[0..cBufferSize]of Char; begin Result := -1; if not (Assigned(mInputStream) and Assigned(mOutputStream)) then Exit; with TCompressionStream.Create(clMax, mOutputStream) do try for I := 1 to mInputStream.Size div cBufferSize do begin mInputStream.Read(vBuffer, cBufferSize); Write(vBuffer, cBufferSize); end; I := mInputStream.Size mod cBufferSize; if I > 0 then begin mInputStream.Read(vBuffer, I); Write(vBuffer, I); end; finally Free; end; end; { StreamCompression }

function StreamDecompression(mInputStream: TStream; mOutputStream: TStream): Integer; var vBuffer: array[0..cBufferSize]of Char; I: Integer; begin Result := -1; if not (Assigned(mInputStream) and Assigned(mOutputStream)) then Exit; with TDecompressionStream.Create(mInputStream) do try repeat I := Read(vBuffer, cBufferSize); mOutputStream.Write(vBuffer, I); until I = 0; Result := mOutputStream.Size; finally Free; end; end; { StreamDecompression }

//Example procedure TForm1.Button1Click(Sender: TObject); var vInputStream: TFileStream; vOutputStream: TFileStream; begin vInputStream := TFileStream.Create('c:\temp\temp.exe', fmOpenRead); vOutputStream := TFileStream.Create('c:\temp\temp.exe.z', fmCreate); try StreamCompression(vInputStream, vOutputStream); finally vInputStream.Free; vOutputStream.Free; end; end;

procedure TForm1.Button2Click(Sender: TObject); var vInputStream: TFileStream; vOutputStream: TFileStream; begin vInputStream := TFileStream.Create('c:\temp\temp.exe.z', fmOpenRead); vOutputStream := TFileStream.Create('c:\temp\temp~.exe', fmCreate); try StreamDecompression(vInputStream, vOutputStream); finally vInputStream.Free; vOutputStream.Free; end; end;

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