Re: Unziping a stream from a binary field - test.zip (0/1)

On Fri, 27 Jan 2006 20:03:31 -0200, "Bernardo de Castilho"
wrote:

Hrm..ok so the end result is..this can't be uncompressed in memory.
The test.zip file was meant to prove it could work, not be used. My
goal was to not have temp files when pulling the file out of the
database. Basically what you've done is what I was already doing with
the demo app included with C1 ZIP - create a .zip file and open it
with C1zipfile.

Bummer. Still better than in Cold Fusion where I was having to
actually point the link to a physical file - at least now I can
immediately delete the temp file. Thanks for your time and effort.
Nick

Click here to view the original newsgroup article (read only).

Hi Nick.

The problem here is that the code is opening a reader directly on the zip
file data. The zip file contains a header, directory info, and a number of
compressed streams. The reader needs to be opened on one of the compressed
streams within the zip file, not on the zip file itself.

I wrote a new version of the code that should help:

private void Form1_Load(object sender, System.EventArgs e)
{

// create output stream
// (not needed in actual app, use Response.OutputStream there)
Stream Response_OutputStream = new MemoryStream();

// this will create the zip file from data in the db
//System.IO.FileStream FileS = new FileStream(
// "E:/ProjAspNet/Trak/temp/test.zip", FileMode.OpenOrCreate );
//int iSize = ( (byte[])rdrImage[ "mData" ] ).Length;
//FileS.Write( (byte[])rdrImage[ "mData" ], 0, iSize );
//FileS.Close();

// open the zip file created above
// (E:/ProjAspNet/Trak/temp/test.zip in actual app)
C1.C1Zip.C1ZipFile zip = new C1.C1Zip.C1ZipFile();
zip.Open(@"c:\temp\test\test.zip");

// decompress the data and write it into the output stream
byte[] buff = new byte[4000];
using (Stream reader = zip.Entries[0].OpenReader())
{
for (;;)
{
int count = reader.Read(buff, 0, buff.Length);
if (count == 0) break;
Response_OutputStream.Write(buff, 0, count);
}
}

// check that the output stream contains a valid image
Response_OutputStream.Position = 0;
this.BackgroundImage = Image.FromStream(Response_OutputStream);
}

I tested this with the zip file you sent, it showed the image without any
problems. Hope it helps (and makes sense).



"Nick Hustak" wrote in message
news:j8ukt1l3og3e5d654e31j8pbtb5a1oct9p@4ax.com...
> On Fri, 27 Jan 2006 12:00:45 -0200, "Bernardo de Castilho"
> wrote:
>
>>Hi Nick.
>>
>>I suspect the problem might be related to the compression encoding.
>>Streams
>>compressed into zip files use a slightly different header than plain
>>stand-alone streams. You may want to try this:
>>
>> //C1ZStreamReader sr = new C1ZStreamReader( Compressed );
>> C1ZStreamReader sr = new C1ZStreamReader( Compressed, true );
>>
>>This tells the component to open the stream as a zip-compressed stream
>>(the
>>true stands for 'zip format').
>>
>>If that doesn't work, let me know and I'll suggest something else (will
>>have
>>to ask you how the data was compressed exactly and for a copy of the
>>actual
>>compressed stream).
>>
>
>
> Hi,
> Now I'm getting this 'Error inflating: invalid stored block lengths'.
> This was stored with VCLZip, a zip library for Delphi. I've never had
> any problem reading the zips once they've been extracted to a file
> from the database wtih WinRAR or PKZip (as well as the included demo
> program for C1 Zip) I'm going to attach the zip.
>
> And here's my current display code
>
>
> string cSelect = "select mData, mThumbNail from
> tBinaryData where ibinarydataID =
> '8EFB2E3B-D327-4C06-AFB8-FE4218BD6604'";
> SqlCommand SqlCom = new SqlCommand( cSelect, ConnectToDB()
> );
> // SqlCom.Parameters.AddWithValue( "@iBinaryDataID",
> iBinaryDataID );
> SqlDataReader rdrImage = SqlCom.ExecuteReader();
>
> rdrImage.Read();
>
> Response.ContentType = "image/pjpeg"; // (string)rdrImage[
> "ContentType" ];
>
> System.IO.FileStream FileS = new FileStream(
> "E:/ProjAspNet/Trak/temp/test.zip", FileMode.OpenOrCreate );
>
> int iSize = ( (byte[])rdrImage[ "mData" ] ).Length;
>
> FileS.Write( (byte[])rdrImage[ "mData" ], 0, iSize );
> FileS.Close();
>
> Compressed.Write( (byte[])rdrImage[ "mData" ], 0, iSize );
> Compressed.Position = 0;
> C1ZStreamReader sr = new C1ZStreamReader( Compressed, true
> );
>
> Buffer = new byte[ iSize * 2 ];
> int iFullSize = sr.Read( Buffer, 0, iSize * 2 );
> // Error happens at the above line
>
> Response.OutputStream.Write( Buffer, 0, Buffer.Length );
>
> //Response.OutputStream.Write( (byte[])rdrImage[ "mData"
> ], 0, iSize );
>
> Response.End();
>
> rdrImage.Close();
>
> This is a copy/paste out of Query Analyzer - no idea if it will help
> but I figured I'd include it
>
> 0x504B0304140002000800787923344B28EBE1E8C001001FEB01000D0000006D61726B696E6731382E6A70679CBC7B5C13D7BE37BC929080111075544040C08233B62031A380A01DA40172C35C6CEBCEA116C18D19CED64AF18A4777102FED34224A14182E8EC94C80DDC33EED6E6CB52DBB78895677539349CA69A9755BDAA2

Click here to view the original newsgroup article (read only).

> Bummer. Still better than in Cold Fusion where I was having to
> actually point the link to a physical file - at least now I can
> immediately delete the temp file. Thanks for your time and effort.

The ability to read a zip stream is in the to-do list. Thanks for commenting
on this, I will increase bump up the priority on this item.

Click here to view the original newsgroup article (read only).