Re: Best way to extract an image from a stream at a position other than 0? - C# Discussion Boards

Alan N1-Mar-09 8:02

1-Mar-09 8:02

Hey,
I've just looked up your questions on Google and there's quite a few hits for you to read. If you want me to write a synopsis for you then get back to me!

Results 1 - 10 of about 1,840,000 for virtual node algorithm. (0.36 seconds)

Results 1 - 10 of about 543,000 for graph embedded ring. (0.30 seconds)

Alan.

Re: virtual node algorithm

sunnyk861-Mar-09 8:36

sunnyk86

1-Mar-09 8:36

I would appreciate that.. Smile | :)

delegate

sheemap1-Mar-09 5:54

sheemap

1-Mar-09 5:54

can u suggets me some website only for delegates where we can find all the details by example

rizvan sivally

Re: delegate

Calin Tatar1-Mar-09 6:01

Calin Tatar

1-Mar-09 6:01

http://msdn.microsoft.com/en-us/library/ms173171(VS.80).aspx[^]

http://msdn.microsoft.com/en-us/library/ms173172(VS.80).aspx[^]

http://msdn.microsoft.com/en-us/library/ms173176(VS.80).aspx[^]

Best way to extract an image from a stream at a position other than 0? [modified]

harold aptroot1-Mar-09 5:32

harold aptroot

1-Mar-09 5:32

The problem is, Image.FromStream likes to reset the position to 0 (somewhere in its scary native methods) and that's exactly what I do not want, since the image in question is simply not located there. Currently I work around this by copying a big part of the stream starting at the point where the image starts to a MemoryStream, but it's taking quite a while and it seems like it shouldn't be needed. This means I have to scan for a pattern that "looks like the header of the next image" which may not always work (what if the data itself contains sometime that looks like a header but isn't?).
I'm sure there is a better way to do this.
I've tried creating a stream that does not support seeking, but Image.FromStream hates that and copies the stream over to a MemoryStream itself so it's effectively equivalent to the "manual" way. Silently ignoring seeks and assignments to Position didn't exactly work so I guess it somehow needs them - would it be ok accept seeks and positions as long as they don't move the position to before a certain value? That sounds a lot like a hack to me - I hope there is a better way.

Last modified: 11mins after originally posted --

Re: Best way to extract an image from a stream at a position other than 0?

Alan N1-Mar-09 8:22

Alan N

1-Mar-09 8:22

Hi,

This idea look interesting and appears to be exactly what you want. It a wrapper around a stream that applies an offset to the requested position. http://www.pixvillage.com/blogs/devblog/archive/2005/03/08/151.aspx[^]

Alan.

Re: Best way to extract an image from a stream at a position other than 0?

harold aptroot1-Mar-09 9:29

harold aptroot

1-Mar-09 9:29

That looks very promising, thanks Smile | :)

A bit of a hack IMO but well

Re: Best way to extract an image from a stream at a position other than 0?

Anthony Mushrow1-Mar-09 8:24

Anthony Mushrow

1-Mar-09 8:24

Where are you trying to read from? I've done something like this before, but I had a file set up like this:

[File]
 [DataType]
 [Length of data]
   [stuff]
 [DataType]
 [Length of data]
   [stuff]
 [end of file]
[/File]

So I knew how much data I needed to read out of the file, I then like you did, read the data to a memory stream and then used Image.FromStream. If you have any control over the creation of the files you're reading in, then you may want to get it changed so it's similar to what I used, or better yet has some kind of index at the top that tells you where everything is.

My current favourite word is: Delicious!

-SK Genius

Game Programming articles start -here[^]-

Re: Best way to extract an image from a stream at a position other than 0?

harold aptroot1-Mar-09 9:29

harold aptroot

1-Mar-09 9:29

Unfortunately it's just like [data][data][data][data] and they're mostly PNG images, and it can not be changed Frown | :(

Re: Best way to extract an image from a stream at a position other than 0?

Anthony Mushrow1-Mar-09 9:42

Anthony Mushrow

1-Mar-09 9:42

That's a shame, at least Alan's reply can help you out with extracting the image.

As for finding the actual images themselves, the image files should store the length of their contents in their header. So as long as you get the first image right, it should lead on to the next and so on. Removing the need to try and figure it out.

PNG files for example are pretty much an eight bit signature, then the length of the data, a 4-byte code, [the image itself], then a CRC at the very end. See here[^]

Jpegs are similar giving the length of the data inside as well as other information jpeg header[^]

It might be a bit of work to manage each type of image format you're going to come across but it will be worth it in the end right? Right? Unsure | :~

My current favourite word is: Delicious!

-SK Genius

Game Programming articles start -here[^]-

Re: Best way to extract an image from a stream at a position other than 0?

harold aptroot1-Mar-09 10:04

harold aptroot

1-Mar-09 10:04

Well I can do that and still fall back to brute force searching for the next image if it fails Smile | :)

reduce blocking queue of Tcp socket c#

abdul jalil1-Mar-09 3:37

abdul jalil

1-Mar-09 3:37

i have want to entertanin one client when second client want to connect then it will not connect i have set the tcplistner.listen(1) also, but when i connect to this i will place the second client to blocking queue.
i dont want to stop the listening socket. but i want to reduce the blocking queue.

i have tested tcplistner.listen(1) and tcpListener.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.MaxConnections, 1);

when i set SocketOptionName.MaxConnections then i get the following exception
{"An unknown, invalid, or unsupported option or level was specified in a getsockopt or setsockopt call"}

connect to sql server 2000 on another computer

H.R1-Mar-09 2:51

H.R

1-Mar-09 2:51

I want to connect to a sqlserver instance on another computer in the workgroup network.
----------------------------------
my application: VS.NET 2008-C#
my DB: SQL Server 2000 Personal Edition
my OS: Win XP Profesional sp3
----------------------------------
I have done these steps:

1. in target sql server instance: Enterprise Manager -> server -> right click -> Properties -> Connections tab -> tick:
-allow other sql servers to connect remotely to this sql server using RPC
-enforce distributed transactions

2. in target sql server instance: Enterprise Manager -> server -> right click -> Properties -> General tab -> Network Configuration... button ->
enabling TCP/IP

3. in target sql server instance: Enterprise Manager -> server -> right click -> Properties -> Security tab -> Authentication ->
SQL Server and Windows

4. I created a New Login in target sql server instance:
Name=admin , Password=1001 , SQL Server Authentication , Database=Exam

5. my SqlConnection in application:
"Server=192.168.0.205\\MYSQLSRV; Initial Catalog=Exam; Integrated Security=False; Persist Security Info=False; User ID=admin;Password=1001";

6. I removed anti virus softwares and turned off Windows Firewall.

7. I tested both of my computers to ping to another

But I have an error yet:
an error was occured while establishing a connection to the server. when connecting to sql server 2005, this failure may be caused by the fact under the default settings sql server dose not allow remote connections.
(provider:sql network interfaces, error:26-error locating server/instance specified)
----------------------------------
can any one help me ?

H.R

Re: connect to sql server 2000 on another computer

Douglas Troy1-Mar-09 6:56

Douglas Troy

1-Mar-09 6:56

H.R wrote:
may be caused by the fact under the default settings sql server dose not allow remote connections

Hopefully, this will help with your problem:

How to configure SQL Server 2005 to allow remote connections[^]

how can i increament an integer variable by one when the application has two threads running?

shanjaf1-Mar-09 1:40

shanjaf

1-Mar-09 1:40

Hi guys,
i am implementing a RTP application. i have created an RTP class. there are two bytes Header fields, one is Sequence Number(size of 2 bytes) and 2nd is TimeStamp(size of 4 bytes). i want to increment sequence number by 1 and Time Stamp by 160 when i send the packet to the network.
This increment will be done when the bufferfull event is called. i am incrementing with the mentioned values but when i monitor it, it increases randomly. is this the thread problem?
any solution for this problem. i am writing my event handler here of buffer full event.

void m_pWaveIn_BufferFull(byte[] buffer)<br />
        {<br />
            <br />
            byte[] sentData = G711.Encode_aLaw(buffer, 0, buffer.Length);<br />
<br />
            sentData = rtpPacket.getRTP_Packet(sentData);<br />
<br />
            byte[] seqNo = BitConverter.GetBytes(seq);<br />
            byte[] TimeStamp = BitConverter.GetBytes(timStm);<br />
<br />
            Buffer.BlockCopy(seqNo, 0, sentData, 2, 2);<br />
            Buffer.BlockCopy(TimeStamp, 0, sentData, 4, 4);<br />
<br />
            m_pUdpServer.Send(sentData, sentData.Length, m_pTargetEP);<br />
<br />
            seq++;<br />
            <br />
            timStm += 160;<br />
        }<br />
<br />

Thanks to All.

Re: how can i increament an integer variable by one when the application has two threads running?

Calin Tatar1-Mar-09 1:59

Calin Tatar

1-Mar-09 1:59

try Interlocked.Increment()

Calin Tatar

Re: how can i increament an integer variable by one when the application has two threads running?

waqarmushtaq845-Mar-09 2:41

waqarmushtaq84

5-Mar-09 2:41

if there are two threads running then you should declare the seq as a volatile int.
When ever a thread is to modify the value it should be locked.

lock(seq);
seq++;
unlock(seq);

btw what sort of RTP application is this?? Smile | :)

Open Form Incide another Form

CristianConrads1-Mar-09 0:58

CristianConrads

1-Mar-09 0:58

Hi I create a main Form with a splitContainer
In the Left panel I put a Tree View
In the Right panel I like to open diferent forms according to de selected information in the treeview.
Example
Tre view - Item - Customer xxx
When double click on on this customer a new CustomerFor with customer details open in Right panel
If anoter customer yyy is selected a second CustomerForm open in the same panel
A sort of tabContol cold be use to swich between Customer xxx and Customer yyy
I try with MDE but I dont know hot to restrict the opening of the Child forms to the right panel of the splitContainer or anoder object capable of containing Forms.
any clue?

Re: Open Form Incide another Form

Henry Minute1-Mar-09 1:19

Henry Minute

1-Mar-09 1:19

I do not know of a way to constrain a form within another form. I don't think that it is possible in C#, perhaps someone with more knowledge will respond and let you know.

However, what you can do is build a 'customer' control. Add a new User Control to your project and design it like you would a form. Add this control to the right panel. Then, when the TreeView is clicked, just fill whatever controls you have put on your 'customer' control with the data for that customer.

You can then have a separate form just containing the new control, for occasions when it is more appropriate to display it as a form.

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”

Re: Open Form Incide another Form

Trooks1-Mar-09 3:08

Trooks

1-Mar-09 3:08

Henry is definitely on the right track. Think of forms as layouts. Which in turn have panels. You then create a user control for the "subform" and load it into the right panel of the main form. This works extremely well and now you can decouple your views and reuse them in different layouts and containers.

I hope that this helps you.

Re: Open Form Incide another Form

CristianConrads1-Mar-09 3:22

CristianConrads

1-Mar-09 3:22

I think is a good idea
But very complex to maintain
We are all use of this kind of interface
The IDE work exactly as I want:
Multiple pages, im my case Forms
The tree view is the solution explorer.
How could be this so dificult to replicate. Frown | :(

Cristian

Re: Open Form Incide another Form

Henry Minute1-Mar-09 7:16

Henry Minute

1-Mar-09 7:16

If you are absolutely determined to do 'Form Docking', it can be done. But not in pure c#. A great deal of P/Invoke is required, to get this functionality.

Take a look at this[^] for examples.

Re: Open Form Incide another Form

Henry Minute1-Mar-09 7:30

Henry Minute

1-Mar-09 7:30

I take back some of my last post.
I have just read Eddy Vluggens response.
This definitely CAN be done in pure c#. Smile | :)

Very slight modification to his code

private void btnForm_Click(object sender, EventArgs e)
{
    Form newForm = new Form();
    newForm.TopLevel = false;
    newForm.Parent = this;
    newForm.Visible = true;
    newForm.Location = new Point(10, 10);
    newForm.Size = new Size(this.ClientSize.Width - 20, this.ClientSize.Height - this.panel1.Height - 20);
    newForm.BackColor = Color.Bisque;
    newForm.FormBorderStyle = FormBorderStyle.None;
    this.Controls.Add(newForm);
        }

getting rid of the border, to save you having to look it up if you weren't aware of it already.

Re: Open Form Incide another Form

Peter_Weber1-Mar-09 2:37

Peter_Weber

1-Mar-09 2:37

Hey Christian,

I am having exactly the same problem.
I use a SplitContainer and and have placed a TreeView control inside. In the right side of the split container, one of five different Forms shall be loaded, depending on what's selected in the TreeView. Up to now, I unfortunately have not found a solution, but I'm new to C#, so this does not mean anything Wink | ;-)

"SubForms" even work in LabVIEW, so I would be very amazed, if C# would be unable to do the same...

Peter

Re: Open Form Incide another Form

CristianConrads1-Mar-09 3:00

CristianConrads

1-Mar-09 3:00

I have seen this in 3P Component, I think it was .Net Bar
But this is out of my budget, So I'm trying to develop a solution with the component that come with C#.
If I find something I let you know.

Cristian

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.