how to select a node?

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Hi, I am working on a project and I am using the treeview tool to organize some functions on one side and a richtextbox on the other providing some descriptions of each one.

So far I know how to create a node using the properties menu but I am having some trouble doing events on them. For example I want it so that when someone double clicks on a node it will fire an if command that when a node is selected it will display a text on the richtextbox providing the description for that particular node.

I'm using Visual C# and my application is a window form

Thanks,

Posted 14-Dec-11 13:27pm

MR. AngelMendez

Updated 14-Dec-11 16:21pm

v3

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Sergey Alexandrovich Kryukov 14-Dec-11 20:50pm

Which TreeView? There are more than one class with this name. Fully-qualified name, please. Tag you UI library: WPF, Silverlight, Form, what?

Now, how about just reading MSDN help page? Everything is crystal-clear...
--SA

MR. AngelMendez 14-Dec-11 21:20pm

sorry about that, my application is a windows form, now about the TreeView I don't know how to explain it because all I see is one but here is the tooltip definition.

Displays a hierarchical collection of labeled items to the user that optionally contains an image.

Sergey Alexandrovich Kryukov 14-Dec-11 22:08pm

That's better. Just add the tag "WinForms" ("Improve question"). The solution of Robin is not really correct. Don't worry, give me some time...
--SA

MR. AngelMendez 14-Dec-11 22:18pm

ok thanks, well Robins solution works because instead of textbox1.text = e.Node.text I changed it to textbox1.text = e.Node.tooltip

which all i do is change the tooltip to my description but if you have a better way then I would appreciate it.

Sergey Alexandrovich Kryukov 14-Dec-11 22:44pm

No, no, don't do it! "Working" does not mean right.
I've demonstrated all the techniques you need. This code is clean.
And you need different events for a command and showing description.
--SA

Robin Rizvi 14-Dec-11 23:01pm

Sometimes elegant and simple solutions work. If you can do it simpler then it should be done that way to increase code understandability and semantics.

Sergey Alexandrovich Kryukov 14-Dec-11 23:31pm

You are right. I added fixes to my code.

Your code have some problems. It is shorter only because you don't show some code. First of all, it does not solve the problem. Read the OP's description of behavior. Two different handlers are needed -- for a command and for description, and the description should be on selection, nothing else. Also, you violate Microsoft naming conventions.

This is a common mistake: people think that the names like treeView1_NodeMouseClick are acceptable only because they were generated by Microsoft code. They are not. Nobody says generated names should be preserver. Just the opposite: they should be renamed -- using refactorization engine -- to semantic names. Again, read the naming conventions -- they are very reasonable.

Also, named event handlers are damn obsolete. Main thing is: you don't show where the event handler is added to the invocation list of the event instance. One class of errors people report is lost (removed) auto-generated handler; people are confused by the name of the method suggesting it is used as a handler.

--SA

Robin Rizvi 15-Dec-11 0:50am

I respect your comments. but you are really confused in your writing and thought I guess, you made me wonder why you are arguing on something which is correct, your solution is correct (maybe I haven't read it though), mine would not be better than yours (according to you) but not wrong perhaps. Tell me if you are not a expert abt something then how would you expect someone to explain you that, in a naive way for sure, so whats wrong about that to do something easily and bluntly to get the job done. I am not a theory or a prototype person like you, I like being practical, I just want things to get done smartly, easily and efficiently.

I don't know if I have offended you in any way sorry for that If I have. You are for sure way better than me. I can see that in your code and your ratings.
PEace

Sergey Alexandrovich Kryukov 15-Dec-11 14:22pm

The term "wrong" is very fuzzy. I only see the problems I listed above. It's not more wrong than thaot, or, if you prefer, it is perfectly right except those problems. :-)
Thank you, Robin.
--SA

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-12-14T16:38:00

Solution 2

You are asking about selection of the node, but by description of the behavior it looks like you need to handle selection of the node itself.

First of all, put some relevant data in each node to use while processing event.

C#

internal struct TreeNodeData {
    internal TreeNodeData(string name, string description) { fName = name; fDescription = description; }
    internal string Name { return fName; }
    internal string Description { return fDescription; }
    string fName, fDescription;
}

Add the items of this type to your tree view, add more relevant data (command, as you say). I would suggest you add a delegate instance which will run execute the command.

You should assign an instance of this structure to the property Tag of each node you want to process.

Now, I don't think you need a click to show description. The description should be shown on selection. Set it up like this:

C#

myTreeView.AfterSelect += (sender, eventArgs) => {
    if (eventArgs.Node.Tag == null) return;
    TreeNodeData nodeData = (TreeNodeData)eventArgs.Node.Tag; //this is selected node because "After Select"
    ProcessTreeViewNodeSelection(nodeData); //all clear, not more type casts
}

myTreeView.NodeMouseDoubleClick += (sender, eventArgs) => {
    TreeViewNode selectedNode = eventArgs.Node;
    if (selectedNode.Tag == null) return;
    TreeNodeData nodeData = (TreeNodeData)selectedNode.Tag;
    RunTreeViewCommand(nodeData);
}

void ProcessTreeViewNodeSelection(TreeNodeData nodeData) {
    textBoxNodeDescription.Text = nodeData.Description; //assuming your text box was added earlier
    //...
}

void RunTreeViewCommand(TreeNodeData nodeData) {
    // you did not ask about this part, so this is on you
    // I would suggest you store some delegate instance in each node,
    // and to implement a command you add some handler to the invocation list of each delegate instance
    // and just invoke the delegate instance right here
}

Both event handlers shown above should be added (+=) before the form is shown. I usually call the code adding handlers in the constructors after InitializeComponent.

Is it clear now?

Good luck,

—SA

Posted 14-Dec-11 16:38pm

Sergey Alexandrovich Kryukov

Updated 14-Dec-11 17:21pm

v5

Comments

MR. AngelMendez 14-Dec-11 23:19pm

ive been trying your code and I cant seem to figure out how to implement it. I am somewhat as a beginner/ almost intermediate :) so It's a lot to take in. Is there an easier way or can you try to explain it based at my skill level? I know im asking for a lot because based on how much programming is involved here but I would deeply appreciate some extra help.

To make things more clear I will explain what my project is. My project is to make a GUI form of the command prompt. How was I going to achieve this? well I learned from recent research that visual C# is able to call events from the command-line itself. So the real problem is just organizing all of its functions. So I decided to go with the treeview tool because there are so many sub-commands within a command in the command line. Like I said earlier I wanted a treeview with the name of all the functions and a textbox with the description when someone selects a command. then I would add a button which would call the command-line command.

well thats what I am aiming for, so I hope this info can help you help me better.

Sergey Alexandrovich Kryukov 15-Dec-11 5:39am

You don't have to implement anything in the part related to the scope of your question. You can add this code literally and just change the names of controls myTreeView, textBoxNodeDescription which I assume you should have. I did not put much detail on event instances for commands. But you did not put enough information on your commands, so I left it to you.

If you feel delegates are difficult, add any data which would help you to implement the commands. Add it to TreeNodeData. You have a ready to use skeleton. Now, leave commands in this skeleton form, first make sure Description works, to feel the techniques.

Now, I cannot understand your ultimate goals. You should explain them in the very beginning, but clearly. What is "a GUI form of the command line"? "C# is able to call events from the command line itself" -- who told you that? Command line is just a source of string information passed on start nothing else, has nothing to do with events -- at all.

TreeView with the names of the functions won't help you to call the functions -- you need to have functions themselves, and the only reference to a function is the delegate instance. You need to create them, then you can store them in data such as TreeNodeData, with some human-readable names.

The question is: where will you have the methods to call as commands? They should be ultimately predefined in your call? How this is related to command line? I don't think it can be. By the way, for a command-line parser you can use my work published in my article, you will find the link in my CodeProject profile.

Please understand that I cannot afford writing the whole application for you. Also, the solution cannot be simpler unless I make a big mistake, but I don't think so. Just the opposite, I suggested you compact code skeleton which helps to avoid meticulous error-prone work.
--SA

MR. AngelMendez 15-Dec-11 13:20pm

I got it to work thanks for all the help, now to explain myself. my project is to make a GUI form of command prompt which means graphic user interface. Pretty much I'm making a graphical menu for all the commands so you can just click on them to execute. Now for your question of "C# is able to call events from the command line itself" -- who told you that?" well here is a sample code which will shutdown the computer using a command-line command.

System.Diagnostics.Process.Start("Shutdown", "/s");

hope this clarifies your questions.

Sergey Alexandrovich Kryukov 15-Dec-11 14:19pm

I see. The thing is: what you call event is not an event in the sense of event-oriented programming. Event in .NET is something expressed by a keyword "event".

Also, what you do via UI won't do anything about command line, as I understand. This is something like a menu command behavior driven by data. It could be a very good idea if you use a good approach.

Read about them on a fundamental level starting from delegates. Actually, the standard documentation is very obscure, so, on top of that, please read corresponding section in my article "Dynamic Method Dispatcher", see http://www.codeproject.com/KB/dotnet/DynamicMethodDispatcher.aspx
It explains the nature of them which looks mysterious.

By the way, this article can give you a good idea about your graphical commands and menu -- the technique I develop is a very general yet easy-to-use approach to dispatching of method calls by keys of any nature. For example, the keys could be menu or list items, any set of unique object. I even demonstrated the use of System.Type keys, etc. Do you see the picture? You can dynamically associate delegate instances with the keys like UI elements and lot more. So, read the articles, ask me questions if you have to.

Good luck, call again.
--SA

Robin Rizvi · Accepted Answer · 2011-12-14T15:40:00

1.Add a treeview and a textbox.

Sample Code from the Form1.Designer.cs:

private System.Windows.Forms.TreeView treeView1;
private System.Windows.Forms.TextBox textBox1;

2.Add a event handler to the treeview. The event is called nodemouseclick. See the events list and you will find it.

Sample code about eventhandler from Form1.Designer.cs:

this.treeView1.NodeMouseClick += new System.Windows.Forms.TreeNodeMouseClickEventHandler(this.treeView1_NodeMouseClick);

3.Now the code to put in Form1.cs:

C#

private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
{
    textBox1.Text = e.Node.Text;
}