请问如何用zlib解压保存在数据库中的流 ( 积分: 50 )

piaoping · 2007-10-11

procedure TForm1.Button1Click(Sender: TObject); var   i:Integer;   Strm:TmemoryStream;   JPG:TJPEGImage; begin   if OpenPictureDialog1.Execute then   begin     //保存图片到数据     for i:=0 to OpenPictureDialog1.Files.Count-1 do     begin       application.ProcessMessages;       try         ADOQuery1.Close;         ADOQuery1.Sql.Clear;         ADOQuery1.Sql.Add('select * from tPCStylePicData');         ADOQuery1.Open;         ADOQuery1.Append;         JPG:=TJPEGImage.Create;         JPG.CompressionQuality := 30;//压缩率         Strm:=TmemoryStream.Create ;         JPG.LoadFromFile(OpenPictureDialog1.Files.Strings);         JPG.SaveToStream(Strm);         Strm.Position:=0;         CompressBitmap(Strm,clmax); // 调用压缩函数进行压缩         TBlobField(ADOQuery1.FieldByName('Pic')).LoadFromStream(strm);         ADOQuery1.Post;       finally         JPG.Free;         Strm.Free;       end;     end;   end ; end; procedure TForm1.CompressBitmap(var CompressedStream: TMemoryStream;const CompressionLevel: TCompressionLevel); var SourceStream: TCompressionStream;     DestStream: TMemoryStream;     Count: Integer; Begin   //获得图像流的原始尺寸   Count := CompressedStream.Size;   DestStream := TMemoryStream.Create;   SourceStream:=TCompressionStream.Create(CompressionLevel, DestStream);   Try     //SourceStream中保存着原始的图像流     CompressedStream.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;     CompressedStream.Clear;     //写入原始图像的尺寸     CompressedStream.WriteBuffer(Count, SizeOf(Count));     //写入经过压缩的图像流     CompressedStream.CopyFrom(DestStream, 0);   finally     DestStream.Free;   end; end; 我用上面的代码把jpg图片用流压缩后存进了数据库,下面的代码是显示图片, 但只能显示未压缩的流，希望兄弟帮忙改一下，可以把压缩过的流从数据库中读出来， 然后解压，然后再显示 procedure TForm1.DBGrid1CellClick(Column: TColumn); var   Stream :TMemorystream;   JPG:TJPEGImage; begin   Stream:= TMemorystream.Create;   try     TBlobField(ADOQuery1.FieldByName('Pic')).SaveToStream(Stream);     Stream.Position:=0;     JPG:=TJPEGImage.Create;     JPG.LoadFromStream(Stream);     Image1.Picture.Assign(JPG);   finally    JPG.Free;     Stream.Free;   end; end;

ANiDelphi · 2007-10-12

procedure DecompressStream(Source, Target: TStream); var   Stream: TDecompressionStream;   nRead: Integer;   Buffer: array [0..1023] of Char; begin   Stream := TDecompressionStream.Create(Source);   try     repeat       nRead := Stream.Read(Buffer, 1024);       Target.Write(Buffer, nRead);     until nRead = 0;   finally     Stream.Free;   end; end; procedure TForm1.DBGrid1CellClick(Column: TColumn); var   Stream, Target:TMemorystream;   JPG:TJPEGImage; begin   Stream:= TMemorystream.Create;   try     TBlobField(ADOQuery1.FieldByName('Pic')).SaveToStream(Stream);     Stream.Position:=0;     Target := TMemoryStream.Create;     try       DecompressStream(Stream, Target);       JPG:=TJPEGImage.Create;       JPG.LoadFromStream(Target);       Image1.Picture.Assign(JPG);     finally       Target.Free;     end;   finally    JPG.Free;     Stream.Free;   end; end;

piaoping · 2007-10-12

非常感谢ANiDelphi,不知您调试过没有,在DBGrid1CellClick事件中总提示 project project.exe raised exception class ECompressionError with message 'Error'. process stopped. Use step or Run to contionue. 然后就停在 JPG:=TJPEGImage.Create;这一行

firstrose · 2007-10-13

until nRead <1024;

qjh0142008 · 2007-10-13

学习

SP229 · 2007-10-14

//才没几天用过的，好象JPG,TIF,BMP经过压缩的大小都差不了多少 procedure TFrmKXT.SpeedButton1Click(Sender: TObject); var   ext: string; begin   GifFile.Clear;   if not picopen.Execute then exit;   ext:=ExtractFileExt(picopen.FileName);   image1.Picture.LoadFromFile(picopen.FileName);   PicFBN(Image1);   if ext<>'.gif' then   begin     GifFile:=pictogif(image1.Picture);   end else     GifFile.LoadFromFile(picopen.FileName); end; procedure TFrmKXT.SpeedButton2Click(Sender: TObject); var   MS: TMemoryStream; begin   if (edit1.Text='') or (memo1.Text='') then exit;   MS:=TMemoryStream.Create;   GifFile.SaveToStream(MS);   ZipPicStream(MS,clMax);   WITH TABLE1 DO   begin      if locate('名称',trim(edit1.Text),[loPartialKey]) then     begin       showmessage('该编号已存在！！！');       exit;     end;     append;     fieldbyname('名称').AsString:=trim(edit1.Text);     fieldbyname('说明').asstring:=memo1.Text;     TBlobField(Table1.fieldbyname('图片')).LoadFromStream(MS);     post;     messagebox(getactivewindow(),'图像保存完毕！','保存',mb_ok);   end;   MS.Free; end; procedure TFrmKXT.DBGrid1CellClick(Column: TColumn); var   Stream:TMemoryStream;   b: Tbitmap; begin   b:=tbitmap.Create;   if isbegin then   begin     Stream:=TMemoryStream.Create;     if Table1.FieldByName('图片').IsNull then exit;     TBlobField(Table1.FieldByName('图片')).SaveToStream(Stream);     Stream.Position:=0;     UnPic(Stream,b);     image1.Picture.Bitmap:=b;     PicFBN(image1);     Stream.Free;      b.Free;     memo1.Text:=table1.FieldValues['说明'];     edit1.Text:=table1.FieldValues['名称'];   end; end;

piaoping · 2007-10-16

to:SP229兄,把你写的函数UnPic(Stream,b);PicFBN(image1);ZipPicStream(MS,clMax);发出来

piaoping · 2007-11-16

多人接受答案了。

请问如何用zlib解压保存在数据库中的流 ( 积分: 50 )

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