C# Discussion Boards - CodeProject

Andreas Philipson4-Dec-03 5:18

4-Dec-03 5:18

Thanks for the help! I'll try it when I get home.

And regarding my use of this code - I'm trying to create a Password Manager which allows Drag&Drop to any edit control.

Andreas Philipson

Re: Using ::SendMessage in C#

Andreas Philipson4-Dec-03 5:23

Andreas Philipson

4-Dec-03 5:23

After changing the solution to

[DllImport("user32.dll", CharSet=CharSet.Ansi)]
static extern int SendMessage(IntPtr hWnd, int msg, int wParam, [Out]StringBuilder lParam);

It works perfectly! Thanks again!

Andreas Philipson

Journal Hook

lajiyo3-Dec-03 22:18

lajiyo

3-Dec-03 22:18

Thank you Heath Stewart:
I saw all of the source-code.But they are local-hooks
I really want to know journal-hooks .
thamk you.

sdfasd

Hide Commandbars in word doc shown in axWebBrowser...

Martin Jonsson3-Dec-03 20:02

Martin Jonsson

3-Dec-03 20:02

I have a problem with axWebBrowser/Word, then opening a document in axWebBrowser.

I want to open the document without commandbars and ruler, but word get the settings from a template file (Normal.dot) witch has the settings from the last used word document stored.

I do not want to delete the users registry settings or template file OMG | :OMG:

might not be so popular, even if it's recreated the next time word ends.

Please, how can i by code (C#) turn the commandbars and rulers off in both office 2000 and XP.....

any help is appriciated: martin.jonsson@ifsab.se

Martin Jonsson

Re: Hide Commandbars in word doc shown in axWebBrowser...

Heath Stewart4-Dec-03 4:53

Heath Stewart

4-Dec-03 4:53

Both the WebBrowser control (and MSHTML that it hosts) and Word implement the IOleCommandTarget. This interface (or rather, its implementation) allows for command execution using simple strings (when used in automation) or command IDs. The WebBrowser control also has a custom set of command IDs, as well as MSHTML.

One of the standard command IDs, OLECMDID_HIDETOOLBARS, should be supported by Word. I'm not sure if IOleCommandTarget implementations MUST support the standards, but rest assured Office most likely does because the standard OLEDMCID enumerations were first defined by Office 95 (good indication that Office supports them still).

Now, because the WebBrowser control is an ActiveX container, getting its IOleCommandTarget interface (in .NET, querying for an interface is as simple as casting your object to said interface) and sending that command may just be enough. You'll either have to create an interop assumly with IOleCommandTarget and the various enumerations it uses, or create it yourself.

You can also send the command IDs (perhaps identified by their numbers, like OLECMDID_HIDETOOLBARS is defined as 24) through IWebBrowser2.ExecWB (IWebBrowser2 is the class interface for the WebBrowser control). I don't know if this will automatically be sent to the automation server (in this case, Word.Application) but - depending on how everything is sited - it's pretty likely and definitely worth a try. If not, you'll have to request the child object from the WebBrowser's site to get the Word doc in order to get the Word.Application, and cast to IOleCommandTarget to execute the command on it.

-----BEGIN GEEK CODE BLOCK-----
Version: 3.21
GCS/G/MU d- s: a- C++++ UL@ P++(+++) L+(--) E--- W+++ N++ o+ K? w++++ O- M(+) V? PS-- PE Y++ PGP++ t++@ 5 X+++ R+@ tv+ b(-)>b++ DI++++ D+ G e++>+++ h---* r+++ y+++
-----END GEEK CODE BLOCK-----

C# Threads

Anonymous3-Dec-03 19:35

Anonymous

3-Dec-03 19:35

Hi I am karthik, I need to create application, which creates thread dynamically and I need to pass unique Data/message to the thread (dynamically created thread).

How to pass Data/message from the application to the thread? It varies from thread to thread.

Re: C# Threads

Anonymous4-Dec-03 2:16

Anonymous

4-Dec-03 2:16

You cannot pass parematers to a method on a new thread. The method signature must be as follows:

void DoStuff(){
}

Instead of passing parameters use static variables. Note: Access to a static variable from multiple threads must be synchronized ..

Re: C# Threads

Heath Stewart4-Dec-03 4:40

Heath Stewart

4-Dec-03 4:40

A better way than using Thread as the above Anonymous person said, is to use worker threads in a thread pool, which can take a state object (which could be a single object, and array, collection, list, whatever). See ThreadPool.QueueUserWorkItem. There are many other useful methods that are helpful when synchronizing threads in the ThreadPool class you should check out. The ThreadPool, btw, is to make sure your application doesn't spawn threads uncontrollably. Many times, this is very important unless you're dealing with real-time apps (and most you write in your life won't be) otherwise you could monopolize the system's resources.

Copy files across networked servers

stateyama3-Dec-03 14:11

stateyama

3-Dec-03 14:11

Hi,
I'm a beginner Windows programmer. I need to write a program that will copy files across networked servers, which may need to authenticate the user as he/she access the remote server. The user may type "\\remoteserver\d$\afile". If the user has accounts on both servers, it will just copy. If the currently logged in user does not have the same account on the remote server, the program is supposed to get the user id and password and pass it along to the remote server, just like the Windows Explorer.
I went round and round and trying with WNet APIs, System.Security.Permissions, System.Security.Principal. I did not get anywhere.
Any help will be greatly appreciated.
Thanks!!

Re: Copy files across networked servers

Heath Stewart4-Dec-03 4:37

Heath Stewart

4-Dec-03 4:37

Actually - in a domain setup - the user account doesn't exist on different computers (except, perhaps, different DCs that either cache or backup accounts). That's only a low-grade workgroup trick or for local users.

To accomplish what you want, you have to program the prompt yourself and deal with impersonation (which may cause problems on the local end if the impersonated user doesn't have access to the source resource). The fact is that .NET is a basic framework and doesn't include all functionality in Windows.

First, attempt a File.Copy. If you get an UnauthorizedAccessException, show a modal dialog to get the username and password (of course, mask the password using the TextBox.PasswordChar property). Then you're going to want to impersonate the requested user account. See the SDK documentation for WindowsIdentity.Impersonate for details and very good example source (P/Invoking native functions is required in .NET 1.x at least). Finally, perform the File.Copy again, and undo and close the impersonation handles (this is covered in the sample source I mentioned).

Re: Copy files across networked servers

stateyama4-Dec-03 6:57

stateyama

4-Dec-03 6:57

Heath, Thank you so much for your help. I will give it a try.
~Sherry

TextBox Arrays

spindar3-Dec-03 13:33

spindar

3-Dec-03 13:33

Im am trying to write an application that involves alot of TextBoxes that the user can input to. Is there a way to create an array of TextBoxes so I can just loop through them all?

Thanks

Matt

Re: TextBox Arrays

Colin Angus Mackay3-Dec-03 15:03

Colin Angus Mackay

3-Dec-03 15:03

Yes. The easiest (if not the most type-safe) way is to create an ArrayList and Add(aTextBox) for each TextBox that is created.

Then when you need to loop over them you can do

foreach(object obj in myArrayOfTextBoxes)
{
    TextBox tb = (TextBox)obj;
    // Do whatever is needed to the TextBox tb
}

I'd recommend creating a type-safe collection to hold your text boxes in though.

--Colin Mackay--

"In the confrontation between the stream and the rock, the stream always wins - not through strength but perseverance." (H. Jackson Brown)

Re: TextBox Arrays

Nick Seng3-Dec-03 15:40

Nick Seng

3-Dec-03 15:40

TextBox[] txt = new TextBox[10];
txt[0] = txtForm1;
txt[1] = txtForm2;
....

Sorry, no short way that I know of.

"if you vote me down, I shall become more powerful than you can possibly imagine" - Michael P. Butler.

Support Bone

Re: TextBox Arrays

Heath Stewart4-Dec-03 4:28

Heath Stewart

4-Dec-03 4:28

TextBox[] txt = new TextBox[] {txtForm1, txtForm2};

Waiting for threads finish question

clayne3-Dec-03 12:48

clayne

3-Dec-03 12:48

Let me start by saying I am very new to multithreading.

I have a web app where I want to execute two searches in parallel, when the both finish, move on and process the returned data. I did what I thought would accomplish this but my search times did not change. What am I missing?

Also, if it matters, both search functions are adding nodes to the same xml document in memory. Each function has duplicate checking before it enters the data. Could I be getting caught by resource locking to keep from really multithreading? thoughts?

Here is a piece of what I have so far. Thanks in advance.

<br />
Thread seaThread = new Thread(new ThreadStart(GetSeaAttachments)); <br />
Thread ilThread = new Thread(new ThreadStart(GetIlAttachements)); <br />
<br />
seaThread.Start(); <br />
ilThread.Start(); <br />
<br />
seaThread.Join();<br />
ilThread.Join();<br />
<br />
if (seaThread.IsAlive)<br />
{<br />
   seaThread.Abort();<br />
}<br />
if (ilThread.IsAlive)<br />
{<br />
   ilThread.Abort();<br />
}<br />

Re: Waiting for threads finish question

Heath Stewart4-Dec-03 4:26

Heath Stewart

4-Dec-03 4:26

The reason you're not noticing any differences in time - and why you don't currently have to worry about resource locking - is in the following code you wrote:

seaThread.Join();
ilThread.Join();

The method Thread.Join blocks the current thread (your page's thread of execution) till the thread is done. So in your code, the page thread waits till the seaThread is finished, then executes the ilThread and waits till it finishes. This also means that your checks to see if the thread is still alive are pointless. The thread is alive until it either completes or is aborted. Since you're joining thread, the thread will be allowed to complete unless the thread itself (or another thread with a reference to said thread) aborts itself.

As far as resource locking is concerned, resources are synchronized unless otherwise stated. Some resources (like various collects and lists) have a SyncRoot (as it's commonly called), which returns a static object that's been initialized. With this, you can (and must in this case) perform locking yourself. In C#, you have the handy lock keyword. You don't have to use the SyncRoot for classes that have it, though - this is simply for disparate threads in different blocks of code (so you don't have to worry about passing your own object to synchronized against).

To use your own sync objects, one typically locks against typeof(MyType) for static methods and properties that need to be synchronized, and locks against this for instance methods and properties. See the lock keyword documentation for more information and examples.

So, to add resource locking to your XmlDocument (which doesn't have the SyncRoot property I was talking about), your threads need to lock against something (like either this, which refers to the page, or to the instance of your XmlDocument (make sure you've instantiated it first, though, since locking against null throws an exception). For example, lets say that both threads want to write something to the document. In either thread, do something like this:

XmlElement elem = this.myXmlDocument.CreateElement("exmaple");
lock(this.myXmlDocument)
{
  this.myXmlDocument.DocumentRoot.ChildNodes.Add(elem);
}

Notice how I created the element before locking? Knowing when to lock your resources is important. Locking them too early could result in O(n) execution times, instead of O(n/m) (where m is the number of threads) like you desire. And you typically don't need to worry about locking while reading a resource, unless you face a potential reader/writer problem. In that case, see the ReaderWriterLock in the System.Threading namespace.

Finally, to suggest a solution to your problem, see the documentation for the ThreadPool class. Besides the benefits gained from a thread pool (like you don't have too many threads spawning uncontrollably), you have many other gains from methods like ThreadPool.RegisterWaitForSingleObject, which lets you use a WaitHandle you want to create (such as an AutoResetEvent handle or a Mutex) which gives you signaling (helpful when synchronizing threads) capabilities, plus it allows you to pass state information to the thread that will be spawned (where the Thread class forces you to use fields to store data, which isn't thread safe without going to a lot of work to synchronize).

Basically, you'd be wise to read the SDK documentation for the System.Threading namespace. It may be daunting at first, but - when yielded properly - can be very powerful.

Re: Waiting for threads finish question

clayne4-Dec-03 8:37

clayne

4-Dec-03 8:37

Thanks for all the information But I am still a little confused. The seaThread.join line stops the current thread from processing till the seaThread finishes. That is what I want and since I have already started the ilThread, shouldn't it continue to run. the ilThread.join will hold the main thread in case it takes longer. I do want the main processing to stop till both threads finish.

I have looked into the threadpool a bit but find it just as confusing. I don't think my task really that complicated. How will thread pooling help me there?

For simplicity sake, I tried this with just a console program and it is working as I would expect. It is below.

<br />
using System;<br />
using System.Threading;<br />
<br />
namespace test_multithreading<br />
{<br />
	/// <summary><br />
	/// Summary description for Class1.<br />
	/// </summary><br />
	class Class1<br />
	{<br />
		public static void PrintCurDateTime()<br />
		{ <br />
			Console.WriteLine( " Secondary Thread Started" );<br />
			for (int i = 1; i <= 10; i++)<br />
			{<br />
				Console.WriteLine(" Second Thread working");<br />
				Thread.Sleep(1985);<br />
			}<br />
			Console.WriteLine( " Second Thread time: " + DateTime.Now.ToLongTimeString() );<br />
			Console.WriteLine( " Second Thread Finished" );<br />
		} <br />
		public static void PrintFutureDateTime()<br />
		{ <br />
			Console.WriteLine( "  Third Thread Started" );<br />
			for (int i = 1; i <= 100; i++)<br />
			{<br />
				Console.WriteLine("  Third Thread working");<br />
				Thread.Sleep(93);<br />
			}<br />
			Console.WriteLine( "  Third Thread time: " + DateTime.Now.ToLongTimeString() );<br />
			Console.WriteLine( "  Third Thread Finished" );<br />
		} <br />
		public static int Main(String[] args)<br />
		{<br />
			Console.WriteLine("Main Thread \n");<br />
<br />
			try<br />
			{<br />
				Thread futThread = new Thread(new ThreadStart( PrintFutureDateTime ));<br />
				futThread.Priority = ThreadPriority.Highest;<br />
				futThread.Start();<br />
<br />
				Thread secThread = new Thread(new ThreadStart( PrintCurDateTime ));<br />
				secThread.Priority = ThreadPriority.Highest;<br />
				secThread.Start();<br />
<br />
				Console.WriteLine("Waiting for theads to join");<br />
				secThread.Join();<br />
				futThread.Join();<br />
				Console.WriteLine("Joined");<br />
		<br />
				Console.WriteLine( "Main Thread time: " + DateTime.Now.ToLongTimeString() );<br />
				<br />
			}<br />
			catch (Exception e) <br />
			{<br />
				Console.WriteLine( e.ToString());<br />
			}<br />
			return 0;<br />
		} <br />
	}<br />
}<br />

How to play audio files ?

pahluwalia3-Dec-03 5:31

pahluwalia

3-Dec-03 5:31

Hi,

I want to know how can I play audio files like mp3 files with basic functionality of play/pause/stop/forward/rewind.

Thanks.
Paul

Re: How to play audio files ?

Heath Stewart3-Dec-03 6:29

Heath Stewart

3-Dec-03 6:29

You could try searching first. Use that little textbox torward the top of this page labeled "Search:", or click "Search Comments" to search this forum because that topic has been covered to death. There are plenty of examples on CodeProject, and many more if you google the 'net.

RichTextBox contents in a DB

phimix3-Dec-03 5:19

phimix

3-Dec-03 5:19

Hi
We have created a small application with a RichTextBox on. In the RichTextBox we can write text and add pictures by copy-pasting them. Later on we can press a button and save the contents into a table on a SQL Server 2000*.

This works fine, the problem is that the size of the added pictures is huge. Adding just a screenshot of the app. to the textbox adds another 3 MB to the size of the DB.

Does any of you have an idea on how to decrease the size of the pictures?

Currently saving/loading data works with the use of filestreams. When we press the save button, the contents of the textbox is written to a file - and then the file is saved in the DB as a BLOB.

Thanks in advance, Mads

*) Of course, we can also load the contents back into the app.

Re: RichTextBox contents in a DB

Heath Stewart3-Dec-03 6:27

Heath Stewart

3-Dec-03 6:27

The image is what it is. If the image is 3MB, it's going to be that large. About your only options are to compress the image (either using image compression or stream compression (like ZIP)) and storing that blob in SQL Server. Unless the size of the database (which is typically on a server that can handle it) is really an issue, the above options will hamper performance. Disk size (and memory, for that matter) is cheap - CPU cycles are not.

Re: RichTextBox contents in a DB

Joel Lucsy3-Dec-03 8:43

Joel Lucsy

3-Dec-03 8:43

We had the same issue. Any OLE object attached to the RTF is stored as text and bloats the size of RTF. We implemented compression before sending the data to the server. This reduces the time to transfer data, but does add a some amount of time on the client (which may be negligitable).

--
Joel Lucsy

Re: Creating a new database...

Heath Stewart3-Dec-03 5:15

Heath Stewart

3-Dec-03 5:15

Neither ADO or ADO.NET has this capability. You can, instead, use an interop assembly with the Jet DDL to create the MDB and then access it using the ADO.NET classes. See the following article for more information: http://www.tek-tips.com/gfaqs.cfm/pid/796/fid/3888[^].

Creating a new database...

Amirjalaly3-Dec-03 5:09

Amirjalaly

3-Dec-03 5:09

Does anyone know about creating a new database by coding with ADO.NET?
for example access(*.mdb)
in this example code must create mdb file and all tables and file needed for database .and i want create new tables in database and update database.

Regards'
Amir Jalaly

The life is two days ,
one day is paid to love someone ,
another day is paid to hate him ,

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