Re: Events - C# Discussion Boards

17-Jun-04 2:14

DWebBrowserEvents2::DocumentComplete fires only after all lower-level frames have been loaded (in the case of a frameset). So using a state variable is still the way to go, but you'll actually want to store the URL being requested initially and compare that with the URL passed through the event arguments. If they are the same, your frameset is loaded.

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Threads

bouli17-Jun-04 1:03

17-Jun-04 1:03

Hi gurus,

it's me again.

My question is simple.

How can I create a thread in C#?

I would like to call DirectPlay functions in a thread.

The thread would manage all connections: Hosting/Connecting/enumerating/disconnecting sessions etc.

Because when I use the Peer's methods like Host, Connect etc. the interface do not answer anymore. The application look frozen.

I could do this in MFC but C# is different...

Thanks for the help.

best regards.

There is no spoon.

Re: Threads

Corinna John17-Jun-04 1:32

17-Jun-04 1:32

bouli wrote:
How can I create a thread in C#?

A thread in C# needs a delegate for a void method without any parameters:

<br />
Thread thread = new Thread(new ThreadStart(doSomething));<br />
thread.Start();<br />

In this example doSomething runs in the new thread. If the thread needs parameters, you have to use instance variables.

Log URL's visited

Stuggo17-Jun-04 1:00

Stuggo

17-Jun-04 1:00

Hi,

I'd like to monitor the sites a user visits, so i'd like to log all the url's visited by a particular user!

Would it be possible to copy the url as soon as the user hits enter after typing in the url or am i going to have to copy the url from the browser cache or history!

Can some please help me out with the source code to do this Big Grin | :-D

, no matter what way you choose to do it!

Thanx 4 the help ..!

Re: Log URL's visited

Heath Stewart17-Jun-04 1:39

17-Jun-04 1:39

This is best done by using a Browser Helper Object (BHO). An old article on MSDN describing BHOs uses just the example you're looking for, except that instead of logging the URL it displays the content of the page when the document is done download. Read Browser Helper Objects: The Browser the Way You Want It[^]. If you need further help on this, please visit the VC++ forum here on CodeProject.

You can write a BHO using C#, but you need to declare a lot of interop'd interfaces and perform a lot of marshaling. Sorry to say, based on how you phrased your question you may have more problems with this. Besides, when you're hooking a majority of the events on DWebBrowserEvents2, you need to be quick. Managed code can be faster than native code, but when a lot of marshaling is involved, you'll find that performance is quite a bit slower.

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Events

bouli17-Jun-04 1:00

17-Jun-04 1:00

Hi gurus,

How can I create my own event and fire it in C#?

example code:

this following is taken from DirectX SDK DirectPlay tutorii
this event is fired by the Peer.FindHosts method

 <br />
        public void FindHostResponseHandler(object sender, FindHostResponseEventArgs args)<br />
        {<br />
            HostInfo Node = new HostInfo();<br />
            Node.GuidInstance  = args.Message.ApplicationDescription.GuidInstance;<br />
            Node.HostAddress   = (Address) args.Message.AddressSender.Clone();<br />
            Node.SessionName   = args.Message.ApplicationDescription.SessionName;<br />
<br />
            if (!FoundSessions.Contains(Node))<br />
            {<br />
                FoundSessions.Add(Node);<br />
                // how to fire an event here to tell the main form to fill the listbox with the new added node as parameter?????<br />
            }<br />
        }<br />

Thanks for the help.

best regards.

There is no spoon.

Heath Stewart17-Jun-04 1:34

17-Jun-04 1:34

The correct way is to define a delegate that extends EventHandler, or use an existing one (depending on whether or not a particular delegate declares a param with an EventArgs-derivative that suits your needs).

Raising Events[^] in the .NET Framework SDK explains the recommended way of firing events, which includes declaring a delegate and EventArgs derivative (like I said, if necessary), declaring the event on your class, and making a protected virtual member named OnEventName that actually fires the event (so that derivative classes can either override it to handle events without a delegate (faster, with more control) or raise the event themselves).

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Corinna John17-Jun-04 1:47

17-Jun-04 1:47

You've been faster again! This is the second time today that I write an answer to a new question, and when it is posted your answer is already there.

BTW: It's not necessary to derive from EventArgs. FxCop wants me to do so, but where is the real benefit?

Heath Stewart17-Jun-04 1:50

17-Jun-04 1:50

It's just common for events. You're right, though, it's not necessary. Commonality, though, fosters better programming for those (few these days, it seems) that recognize the pattern.

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bouli17-Jun-04 1:56

17-Jun-04 1:56

ok, I've got it... thanks Smile | :)

I start to understand the way it works.

it's even more simple than MFC... :P

There is no spoon.

bouli17-Jun-04 1:48

17-Jun-04 1:48

Hi Heath,

I was looking that way... Delegates. it seems they look like callbacks.
I can declare my delegate, but I don't understand yet how to use it in my class.

I have done the following:

<br />
class PeerPlayer<br />
{<br />
  ...<br />
  public delegate void HostFound(HostInfo node);<br />
<br />
  public void FindHostResponseHandler(object sender, FindHostResponseEventArgs args)<br />
  {<br />
   HostInfo			node=new HostInfo();<br />
			<br />
  node.GuidInstance=args.Message.ApplicationDescription.GuidInstance;<br />
			node.HostAddress=(Address) args.Message.AddressSender.Clone();<br />
			node.SessionName=args.Message.ApplicationDescription.SessionName;<br />
<br />
			if (!m_sessions.Contains(node))<br />
			{<br />
				m_sessions.Add(node);<br />
                               // i need to call the delegate here<br />
			}<br />
		}<br />
  ...<br />
}:((<br />

There is no spoon.

Heath Stewart17-Jun-04 1:52

17-Jun-04 1:52

Did you read the article I linked? It's really quite clear.

A delegate is a managed function pointer. By declaring an event on your class, you in effect declare a MulticastDelegate that maintains a list of delegates. When you invoke your event delegate, any handlers are called in any given order.

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bouli17-Jun-04 2:08

17-Jun-04 2:08

ok, I can fire my event now Smile | :)

but I don't understand how I can use it outside of the class...

PeerPlayer pp=new PeerPlayer();

pp.HostFound+=new??? // new what???

I have implemented a HostFound handler in the form class.

There is no spoon.

Heath Stewart17-Jun-04 2:15

17-Jun-04 2:15

bouli wrote:
// new what???

Use whatever delegate declared by the event. So if you declared public event EventHandler HostFound, then use new EventHandler(myhandler).

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bouli17-Jun-04 2:34

17-Jun-04 2:34

ok, I've got it Smile | :)

the delegate was inside the PeerPlayer class.
I have done the following now:

pp.HostFound+=new HostFoundHandler(OnHostFound);

and it works Smile | :)

I'm now working on how to write the calls of the DirectPlay connections in a thread.

I would like to execute the following code in a thread:

<br />
		public bool Enumerate(String hostName)<br />
		{<br />
			m_sessions.RemoveRange(0, m_sessions.Count);<br />
<br />
			Address			hostAddress=new Address();<br />
			<br />
			hostAddress.ServiceProvider=Address.ServiceProviderTcpIp;<br />
            <br />
			if (hostName.Length > 0)<br />
				hostAddress.AddComponent(Address.KeyHostname, hostName);<br />
            <br />
			hostAddress.AddComponent(Address.KeyPort, m_port);<br />
<br />
			ApplicationDescription		appDesc=new ApplicationDescription();<br />
			<br />
			appDesc.GuidApplication=m_appGuid;<br />
<br />
			try<br />
			{<br />
				m_peer.FindHosts(appDesc, hostAddress, m_localAddress, null, 0, 0, 0, FindHostsFlags.Sync);<br />
			}<br />
			catch(Exception ex)<br />
			{<br />
				Debug.WriteLine(ex.Message);<br />
				return false;<br />
			}<br />
<br />
			return true;<br />
		}<br />

There is no spoon.

Corinna John17-Jun-04 1:39

17-Jun-04 1:39

If the event needs parameters, you can define your own delegate:

<br />
public delegate void MyEventHandler (object sender, HostInfo details);<br />
public event MyEventHandler MyEvent;<br />

To fire your event, just call it as if it was a method:

<br />
if(MyEvent != null){<br />
  MyEvent(this, Node);<br />
}<br />

bouli17-Jun-04 1:45

17-Jun-04 1:45

Do you always need to declare an event with a delegate?

as I come from MFC, if I understand well, it seems that delegates are to C# what callbacks are to C/C++...

There is no spoon.

Corinna John17-Jun-04 1:52

17-Jun-04 1:52

1) There are a couple pre-defined delegates (EventHandler, CancelEventHandler, and so on). If you need other parameters, you have to define a delegate.

2) Exactly. There are no "official" callback in C#, they have been replaced by delegates. Cry | :((

bouli17-Jun-04 1:56

17-Jun-04 1:56

ok, I understood how it works... thanks Smile | :)

it's more simple than MFC... Big Grin | :-D

There is no spoon.

bouli17-Jun-04 2:01

check programatically if IIS is installed

17-Jun-04 2:01

oh, yes, one more thing,

how the caller of the event can use the fired event???

I have done this:

class PeerPlayer
{
public delegate void HostFoundHandler(HostInfo node);
public event HostFoundHandler HostFound;
...
}

...
PeerPlayer=pp=new PeerPlayer();
...

pp.HostFound+=????

There is no spoon.

michalJ17-Jun-04 0:13

michalJ

17-Jun-04 0:13

I'm writing instalation program that creates web application. Before this could happen, IIS must be installed on the machine. If it is not, I would like to show warning message and gracefully end the installation process.
How can I check programatically if IIS is installed ?

Thank You
Michał

Re: check programatically if IIS is installed

Heath Stewart17-Jun-04 1:27