unit1.pas

DELPHI的压缩控件,非常实用的第三方控件

// *******************************************************
// There are no restrictions placed on the use of the code
// contained in this project.  These project files include
// Project1.dpr, unit1.dfm, and unit1.pas.
// *******************************************************

// This project is a visual demonstration of how to compress data
// to a memory stream.

Unit unit1;

Interface

Uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ExtCtrls, StdCtrls, ComCtrls, ztvStreams;

Type
	TForm1 = Class(TForm)
   	Memo1: TMemo;
    	Memo2: TMemo;
    	Label1: TLabel;
    	Label2: TLabel;
    	Button1: TButton;
    	Button2: TButton;
    	Procedure Button1Click(Sender: TObject);
    	Procedure Button2Click(Sender: TObject);
	 	Procedure CompressToMemory(StrmToCompress: TStream32);
  	Private
    	{ Private declarations }
  	Public
    	{ Public declarations }
  	End;



Var
  Form1: TForm1;

Implementation

{$R *.DFM}

Uses
	ztvBase, ztvInflate, ztvDeflate;

//-------------------------------------------------------------

// for retrieving data from a memo control
Procedure StrToBuf( Buf: Pointer; Str: String );
Begin
   Move( Str[1], Buf^, Length( Str ) );
End;
//-------------------------------------------------------------

// for placing into a memo control
Function BufToStr( Buf: Pointer; Size: Integer ): String;
Begin
   SetLength( Result, Size );
   Move( Buf^, Result[1], Size );
End;
//-------------------------------------------------------------

// flush stream data to the forms memo controls
Procedure StreamToMemo(Strm: TStream32; Memo: TMemo);
Var
	Buf: Pointer;
Begin
   // place the compressed memory stream in memo2.text
   GetMem(Buf, Strm.Size);
   Try
      Strm.Read( Buf^, Strm.Size );
   Finally
      Memo.Text := BufToStr( Buf, Strm.Size );
      FreeMem(Buf);
   End;
End;
//-------------------------------------------------------------

Procedure TForm1.CompressToMemory(StrmToCompress: TStream32);
Var
	MemStrm: TMemoryStream32;
Begin

   // memory stream to hold compressed data
   MemStrm := TMemoryStream32.Create();
   Try
      // ztvCompress_StreamToStream in ztvDeflate.pas
      // It returns the crc value of the compressed stream (MemStrm)
      ztvCompress_StreamToStream( StrmToCompress, MemStrm );

      // placed the compressed data into memo and release stream
   	StreamToMemo(MemStrm, Memo2);
   Finally
      MemStrm.Free();
   End;
End;
//-------------------------------------------------------------

Procedure TForm1.Button1Click(Sender: TObject);
Var
	CompressStream: TStream32;
Begin
   CompressStream := TMemoryStream32.Create();
   Try
      // place uncompressed data into the stream for compression
   	CompressStream.Write(Memo1.Text[1], Length(Memo1.Text));
   	CompressToMemory(CompressStream);
   Finally
   	CompressStream.Free();
   End;

   // clear the uncompressed data memo control
   Memo1.Text := '';
End;
//-------------------------------------------------------------

Procedure TForm1.Button2Click(Sender: TObject);
Var
   buf: Pointer;
   BufSize: Integer;
   CompressedStrm,
   	DecompressedStrm: TStream32;
Begin
	CompressedStrm := TMemoryStream32.Create();
   Try
   	BufSize := Length( Memo2.Text );

      // place the compress data from memo into stream from decompresssion
		GetMem( Buf, BufSize + 1 );
   	Try
      	StrToBuf( Buf, Memo2.Text );
         CompressedStrm.Write(Buf^, BufSize);
      Finally
         CompressedStrm.Position := 0;
      	Freemem(Buf, BufSize + 1);
      End;


      DecompressedStrm := TMemoryStream32.Create();
      Try
         // ztvDecompress_StreamToStream in ztvInflate.pas
         // StreamToStream returns crc value of decompressed stream
         ztvDecompress_StreamToStream( CompressedStrm, DecompressedStrm, CompressedStrm.Size );
      Finally
         StreamToMemo(DecompressedStrm, Memo1);
      	DecompressedStrm.Free();

         // clear the compressed data memo control
         Memo2.Text := '';
      End;

   Finally
   	CompressedStrm.Free();
   End;
End;
//-------------------------------------------------------------

End.