Delphi 使用 ZLib 压缩和解压 GZip

uses System.ZLib;

const
  ZLIB_GZIP_WINDOWBITS    = 31;
  ZLIB_DEFLATE_WINDOWBITS = 15;

type
  TZLibCompressionLevel = TZCompressionLevel;

  /// <summary>
  /// 使用 ZLib 压缩流
  /// </summary>
  /// <param name="Source">要压缩的数据流</param>
  /// <param name="Dest">压缩后的数据流</param>
  /// <param name="Level">压缩级别</param>
  /// <param name="GZipFormat">是否使用 GZip 压缩算法</param>
procedure ZLibCompressStream(Source, Dest: TStream;
  const Level: TZLibCompressionLevel = zcFastest;
  const GZipFormat: Boolean = True); overload;

/// <summary>
/// 使用 ZLib 解压缩流
/// </summary>
/// <param name="Source">要解压的数据流</param>
/// <param name="Dest">解压后的数据流</param>
/// <param name="GZipFormat">是否使用 GZip 压缩算法</param>
procedure ZLibDecompressStream(Source, Dest: TStream;
  const GZipFormat: Boolean = True); overload;
  
procedure ZLibCompressStream(Source, Dest: TStream; const Level: TZLibCompressionLevel; 
    const GZipFormat: Boolean);
var
  WindowBits: Integer;
  Zip: TZCompressionStream;
begin
  if GZipFormat then
    WindowBits := ZLIB_GZIP_WINDOWBITS
  else
    WindowBits := ZLIB_DEFLATE_WINDOWBITS;

  Zip := TZCompressionStream.Create(Dest, Level, WindowBits);
  try
    Zip.CopyFrom(Source, 0);
  finally
    FreeAndNil(Zip);
  end;
end;

procedure ZLibDecompressStream(Source, Dest: TStream; const GZipFormat: Boolean);
var
  WindowBits: Integer;
  UnZip: TDecompressionStream;
begin
  if GZipFormat then
    WindowBits := ZLIB_GZIP_WINDOWBITS
  else
    WindowBits := ZLIB_DEFLATE_WINDOWBITS;

  UnZip := TDecompressionStream.Create(Source, WindowBits);
  try
    Dest.CopyFrom(UnZip, 0);
  finally
    FreeAndNil(UnZip);
  end;
end;