使用Zlib解壓縮不完整，該怎麼解決? |
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答題得分者是：yowlc
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Reiji
初階會員   發表：30 回覆：57 積分：32 註冊：2008-06-26 發送簡訊給我 |
小弟試著網路上找來的範例寫了一段壓縮和解壓縮的程式
使用光碟中的Zlib 壓縮過程看似沒有問題 但解壓縮就問題很大了 例如壓縮一個bmp檔，解壓縮後根本打不開 壓縮一個jpg檔，解壓縮後圖片打開有45%是灰色的(被吃掉了  )壓縮文件後解壓縮會打不開... 仔細查看解壓縮後檔案，大小和壓縮後檔案一樣大?! 例如我壓縮1.bmp(1MB)，壓縮後1.pk(1KB)，解壓縮另存為1-2.bmp(
use zlib; procedure TForm1.PackStream(const Src: TStream; Dst: TStream);
var CompStream: TCompressionStream;
begin
Assert(Src<>Nil);
Assert(Dst<>Nil); CompStream := TCompressionStream.Create(clDefault,Dst); try
Src.Seek(0,soFromBeginning);
CompStream.CopyFrom(Src,0);
finally
CompStream.Free;
end; end; procedure TForm1.test;
var SrcStream,PackedStream,UnpackedStream:TMemoryStream;
begin
SrcStream:=TMemoryStream.Create;
Try
SrcStream.LoadFromFile('c:\1.bmp');
PackedStream:=TMemoryStream.Create;
try
PackStream(SrcStream,PackedStream);
PackedStream.Seek(0,soFromBeginning);
PackedStream.saveToFile('c:\1.pk'); UnpackedStream:=TMemoryStream.Create;
try
UnpackStream(PackedStream,UnpackedStream);
UnpackedStream.Seek(0,soFromBeginning);
UnpackedStream.SaveToFile('c:\1-2.bmp');
finally
UnpackedStream.Free;
end; finally
PackedStream.Free;
end;
finally
SrcStream.Free;
end; end; procedure TForm1.UnpackStream(const Src: TStream; Dst: TStream);
var DecompStream: TDecompressionStream;
NewSize:integer;
begin
Assert(Src<>Nil);
Assert(Dst<>Nil);
DecompStream := TDecompressionStream.Create(Src);
try
//NewSize:=Src.Seek(0,soFromEnd);
NewSize:=Src.Size;
Src.Seek(0,soFromBeginning);
NewSize:=Dst.CopyFrom(DecompStream,NewSize);
Dst.Size:=NewSize;
finally
DecompStream.Free;
end;
end; procedure TForm1.Button1Click(Sender: TObject);
begin
test;
end;[/code]
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永遠都是新手 |
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yowlc
一般會員  發表：1 回覆：5 積分：6 註冊：2005-04-24 發送簡訊給我 |
試試看可不可以 [code delphi] .... .... uses ZLib, Classes, StrUtils, SysUtils; ..... ..... {================================================================= 功能: 壓縮串流類資料 參數: InStream: 要壓縮的串流資料; OutStream: 壓縮後的串流資料 CompressLevel: 壓縮程度 1: 沒壓縮 2: 快速壓縮 3: 一般壓縮 4: 最大壓縮 返回: 成功: True; 失敗: False 備注: 版本: =================================================================} Function CompressStream(InStream, OutStream: TStream; CompressLevel: Byte = 3) : Boolean; var cps : TCompressionStream; clv : TCompressionLevel; begin Result := False; case CompressLevel of 1 : clv := clNone; 2 : clv := clFastest; 3 : clv := clDefault; 4 : clv := clMax; else clv := clDefault; end; InStream.Position := 0; try cps := TCompressionStream.Create(clv, OutStream); try cps.CopyFrom(InStream, 0); OutStream.Position := 0; Result := True; finally cps.Free; end; except end; end; {================================================================= 功能: 解壓縮串流類資料 參數: InStream: 要解壓縮的串流資料; OutStream: 解壓縮後的串流資料 返回: 成功: True; 失敗: False 備注: 版本: =================================================================} Function DeCompressStream(InStream, OutStream: TStream) : Boolean; var cps : TDeCompressionStream; Buf : Array[1..2048] of Byte; iByteRead : Integer; begin Result := False; InStream.Position := 0; try cps := TDeCompressionStream.Create(InStream); try Repeat iByteRead := cps.Read(Buf, Sizeof(Buf)); if iByteRead > 0 then OutStream.Write(Buf, iByteRead); Until (iByteRead = 0); OutStream.Position := 0; Result := True; finally cps.Free; end; except end; end; procedure TForm1.Button01Click(Sender: TObject); var InStream, OutStream : TMemoryStream; begin // 檔案壓縮 InStream := TMemoryStream.Create; OutStream := TMemoryStream.Create; try InStream.LoadFromFile('C:\org.bmp'); CompressStream(InStream, OutStream); OutStream.SaveToFile('c:\org-pak.pak'); InStream.Clear; OutStream.Clear; InStream.LoadFromFile('C:\org-pak.pak'); DeCompressStream(InStream, OutStream); OutStream.SaveToFile('c:\org-upak.bmp'); finally OutStream.Free; InStream.Free; end; end; [/code] |
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