Jepg Error #41是什么原因？

Question

为了显示SQL Server数据库中的jpg图片到image中，写了如下代码：
保存image1里面的图片
var
  MyJPEG:TJPEGImage;
  MS:TMemoryStream;
begin
  MyJPEG:=TJPEGIMage.Create;
  MS:=TMemoryStream.Create;
  try
    MyJPEG.Assign(Image1.picture.bitmap);
    MyJPEG.SaveToStream(MS);
    MS.position:=0;
    Adotable1.Append;
    Adotable1.FieldByName('编号').AsVariant := 2;
    TBlobField(Adotable1.FieldByName('照片')).savetostream(MS);
    AdoTable1.Post;
  finally
    MyJPEg.free;
    MS.free;
  end;
  Showmessage('保存完毕！');显示数据库中的图片，此时返回Jepg Error #41,不知是什么原因错误了，请指点！
var
  MyJPEG:TJPEGImage;
  MS:TMemoryStream;
begin
  MyJPEG:=TJPEGIMage.Create;
  MS:=TMemoryStream.Create;
  try
    TBlobField(ADOQuery1.FieldByName('照片')).savetostream(MS);
    MS.position:=0;
    MyJPEG.LoadFromStream(MS);
    Image1.picture.Bitmap.assign(MyJPEG);
  finally
    MyJPEg.free;
    MS.free;
  end;
end;

Answer 1

保存图片应该用LoadFromStream，而不是SaveToStream，
TBlobField(Adotable1.FieldByName('照片')).LoadFromStream(MS);你原来的语句并没有把图片写进数据库，读取时是空的，就报错了。

Answer 2

我觉得是这句错了：
MyJPEG.Assign(Image1.picture.Graphic);
你的语句取的是Bitmap，没有数据的。
当然，你后面的语句也错了。应当是：
Image.Picture.Graphic.LoadFromStrea（好像是这么写的）

Answer 3

谢谢，我现在已经把保存image1里面的jpg图片 这段代码改成
var
  MyJPEG:TJPEGImage;
  MS:TMemoryStream;
begin
  MyJPEG:=TJPEGIMage.Create;
  MS:=TMemoryStream.Create;
  try
    MyJPEG.Assign(Image1.picture.bitmap);
    MyJPEG.SaveToStream(MS);
    MS.position:=0;
    Adotable1.Append;
    Adotable1.FieldByName('编号').AsVariant := 2;
    TBlobField(Adotable1.FieldByName('照片')).LoadFromStream(MS);
    AdoTable1.Post;
  finally
    MyJPEg.free;
    MS.free;
  end;
  Showmessage('保存完毕！');
end;但是读取的时候还是发生 Jepg Error #41 错误。
如果按 jufeng_zhu 的方法把
MyJPEG.Assign(Image1.picture.bitmap);改为MyJPEG.Assign(Image1.picture.Graphic);
将无法保存该图片到SQL Server数据库，出错信息为"Bitmap image is not valid"
请问是什么原因啊？

Answer 4

保存前
    MyJPEG.Assign(image1.picture.Bitmap);
    MyJPEG.CompressionQuality:=100;
    MyJPEG.Compress;
试试

Answer 5

jpgstream:= TJPEGImage.Create;
    jpgstream.Assign(image1.picture.Bitmap);
    jpgstream.CompressionQuality:=100;
    jpgstream.Compress;
       Stream:=TMemoryStream.Create;
       jpgstream.SaveToStream(Stream);
       Stream.Position:=0;
       ADODataSet2.append;
       TBlobField(ADODataSet2.FieldByName(b3)).LoadFromStream(Stream);
       ADODataSet2.Post;我的保存jpg的全部代码！

Answer 6

qwertyasd , 我加了
 MyJPEG.CompressionQuality:=100;
 MyJPEG.Compress;
还是报错啊，图片不能在image1里面显示出来
你能把你的显示jpg的代码给我看看吗？

Answer 7

procedure Tscanfrm.keyChange(Sender: TObject);
var
   jpgstream:TJPEGImage;
    Stream: TMemoryStream;
begin
   try
          Stream:=TMemoryStream.Create;
          TBlobField(ADODataSet2.FieldByName(b3)).SaveToStream(Stream);
          Stream.Position:=0;
          jpgstream:= TJPEGImage.Create;
          jpgstream.LoadFromStream(Stream);
          image2.Picture.Assign(jpgstream);
        finally
            Stream.Free;
            jpgstream.Free;       
        end;
end;
调jpg得全部代码！
给分吧！

Answer 8

应该是 MyJPEG.Assign(Image1.picture.Graphic);

Answer 9

保存图片为jpg到数据库！
procedure Tscanfrm.Button14Click(Sender: TObject);
var
   jpgstream:TJPEGImage;
   Stream: TMemoryStream;
   idh:pchar;
begin
    if MessageDlg('保存此图片,请确认!',mtWarning,[mbYes, mbNo],0)=mrno then exit;
    StatusBar1.Panels[0].Text:='正在保存文件';
    StatusBar1.Refresh;
    jpgstream:= TJPEGImage.Create;
    jpgstream.Assign(image1.picture.Bitmap);
    jpgstream.CompressionQuality:=100;
    jpgstream.Compress;
    with ADODataSet2 do
       begin
        if  key.Text='0' then append else edit ;
        FieldValues[b1]:=ly.Text;
        FieldValues[b2]:=ly.Tag;
      end;
    try       Stream:=TMemoryStream.Create;
       jpgstream.SaveToStream(Stream);
       Stream.Position:=0;
       TBlobField(ADODataSet2.FieldByName(b3)).LoadFromStream(Stream);
       ADODataSet2.Post;
    finally
       jpgstream.Free;
       StatusBar1.Panels[0].Text:='宽度：'+inttostr(image1.Picture.Width)+'  高度:'+inttostr(image1.Picture.height);
    end;
    if key.text='0' then
        begin
        ADODataSet2.Last;
        pages.Caption:=inttostr(strtoint(pages.Caption)+1);
        page.caption:=pages.Caption
        end;
    key.text:=idh;
end;从数据库读出jpg文件，并存为bmp.
procedure Tscanfrm.keyChange(Sender: TObject);
var
   jpgstream:TJPEGImage;
    Stream: TMemoryStream;
begin
    if key.Text<>'0' then
      begin
        try
          Stream:=TMemoryStream.Create;
          TBlobField(ADODataSet2.FieldByName(b3)).SaveToStream(Stream);
          Stream.Position:=0;
          jpgstream:= TJPEGImage.Create;
          jpgstream.LoadFromStream(Stream);
          image2.Picture.Assign(jpgstream);
          image1.Picture.Bitmap.Width:=image2.picture.Width;
          image1.Picture.Bitmap.Height:=image2.picture.Height;
          image1.Left:=0;
          image1.Top:=0;          
          image1.Picture.Bitmap.Canvas.Draw(0,0,image2.Picture.Graphic);
          image1.Width:=image2.Picture.Width;
          image1.Height:=image2.Picture.Height;
          page.Caption:=inttostr(adodataset2.RecNo  );
          pages.Caption:=inttostr(adodataset2.RecordCount);
        finally
            Stream.Free;
            jpgstream.Free;
            image2.Picture:=nil;
        end;
        cmddel.Enabled:=true;
        Button14.Enabled:=true;
      end
    else
      begin
        cmddel.Enabled:=false;
        Button14.Enabled:=false;
        image1.Picture:=nil;
        image2.Picture:=nil;
        page.Caption:='0';
        pages.Caption:='0';
        StatusBar1.Panels[0].Text:='';      end;
end;
以上是我的全部代码，运行n遍了,绝对没问题，如果在出错说明是你哪写得不对，多试试
我这也是经过多次试验才得出来的！
另外在user加上jpeg

Answer 10

我用的是类似的代码也出同样的错误?我是delphi 7+sqlsever 2k ,xp