Re: Class or Struct - C# Discussion Boards

OMalleyW12-Jul-04 9:02

12-Jul-04 9:02

Ok,
I am going to write a Wizard for a new project that I am doing at work. Depending on where you are in the Wizard the screen will have different controls. My problem is that if I re-use the same form I will have to change the size and mess around with the posision of controls..

My question is when creating a Wizard is it better to use more then one form or re-use the same Form and just re-size it as needed..

Thanks
Will

Re: need an opinion..

Nick Parker12-Jul-04 9:11

Nick Parker

12-Jul-04 9:11

I would suggest you read a few of the articles on CP regarding writing your own wizard. James T. Johnson has written one: TSWizard - a wizard framework for .NET[^] and there is another one, however I can't find the link at this moment.

- Nick Parker
My Blog | My Articles

Re: need an opinion..

OMalleyW12-Jul-04 9:35

OMalleyW

12-Jul-04 9:35

thank you very much for the quick reply. The link that you provided is great and I will be sure to take some notes from that. As always I try to do a little research before I do anything. I guess I will try to use the same form and just adjust it as I need to, not sure how that will look yet..

thanks again
Will

Re: need an opinion..

Heath Stewart12-Jul-04 9:41

Heath Stewart

12-Jul-04 9:41

I would also study how current property sheets / wizards work in the Platform SDK. Both the Shell APIs and MFC contain implementations (MFC is most often a wrapper around the common APIs) of the property sheets and pages and offer good idea to implementing your own. For example, by simply setting a single variable your property sheet is not a wizard. Perhaps this isn't important to you, but what should be is the implementation.

Through interface support, the property sheet (hosts the tab control and buttons, or simply controls the paging of wizard pages) can determine whether a page should allow the user to go back or forward, or cancel, etc. In a property sheet, this wizard-like behavior often corresponds to the Apply button being enabled (i.e., data has changed to either Apply is enabled (for property sheets) or the Next button is enabled (data has been provided).

Even if you completely ignore the property sheet implementation, the power is still in the interface. Your wizard could accept an list or collection of Control, UserControl, or whatever basic class that implements a particular interface (for example, IWizardPage), or simply an abstract class (for example, WizardPage). The pages determine what buttons are enabled and how pages are cycled (depending on their own internal state). You don't really need to worry about resizing the dialog: always maintain a particular order of buttons. If a button is needed, squeeze the buttons down (like if no Next button is needed, a Back button may shift over to where the Next button is, and a Done button should replace a Next button on the final step. The recommended and consistent order of buttons is Back, Next/Finish, Cancel. Sometimes a Help button may be shoved way over to the left corner or be found in the far right after (in a LTR reading order) the Cancel button.

A good wizard control would also make it easy for pages to communicate by implementing a property bucket (a place where pages can store information used by other pages).

Again, many of these concepts are supported by the Shell API for property pages (the very ones you see in the file Properties dialog, etc.).

For a starting point, look-up IPropertyPage in the Platform SDK in the MSDN Library[^].

Microsoft MVP, Visual C#
My Articles

Re: need an opinion..

OMalleyW12-Jul-04 10:55

OMalleyW

12-Jul-04 10:55

Awsome.. thank you for the reply.

This wizard is being created to giude users throught the complex process of creating a Bill OF Material or Assembly.

I have a Windows Form all ready setup to allow for the basic functionality
Enter the Top Level Number
if Not Exists
Create New Part
else
Get the Parts Record Number
Add Components to the Bill Of Material by using a TreeView and Context Menu
Bill Of Material -- Component Status
Bill Of Material -- Component Effectivity

.... ect ..

I am just thinking that I would like the process to be more (hand held) then it is now. That is why I have choosen to create a Wizard type of interface. This way I can give a very easy to use Navigation system to get through the process..

well thank you again
Will

playing a wav file :- directx/c#

Anonymous12-Jul-04 8:57

Anonymous

12-Jul-04 8:57

anyone know the easiest way to play a wav file with direct x maybe a link to a tutorial or summet?

Class or Struct

Gomac12-Jul-04 7:34

Gomac

12-Jul-04 7:34

Hi,

I need to hold a string, int and a boolean in a class or struct. However I want to override the ToString() method and use it in a listbox. As Listbox Items are objects if I use a struct a lot of boxing and unboxing will be involved.

As I only have 3 vairables and accessor methods plus ToString I swing towards a struct, but would a class be better to avoid all the boxing and unboxing operations?

Thanks.

Re: Class or Struct

Heath Stewart12-Jul-04 9:31

Heath Stewart

12-Jul-04 9:31

How many properties you have and whether or not you override ToString should not be a deciding factory for using a struct or a class.

Here are some of the factors:

Will it be short-lived? (y: struct, n: class)
Must the item be instantiated quickly (y: struct (alloc'd on the stack), n: class (alloc'd on the heap))
Will a lot of boxing/unboxing be required? (y: class, n: struct - which you obviously already know)
Are small in size (.NET Framework recommends 16 bytes) (y: struct, n: class)

This is by no means a comprehensive list, but it does contain the things you should consider. Both classes and struct can define fields, properties, and methods, and both can implement interfaces. Classes can extend another class and define events. Both can also contain nested types.

If you feel you'll incur a big performance penalty from boxing and unboxing, then use a class. But if your structs are seldomly accessed as struct (i.e., you read in a bunch of structs once and don't deal with them again in your ListView or whatever), then I wouldn't worry about it.

If you want to take advantage of the fact that structs can be destroyed and memory on the stack can be reused ASAP, I would use the disposable pattern and implement IDisposable on a class. While instantiate does take only slightly longer (negligible in most cases), it probably won't affect you any.

So, here are some of the things you have to ask yourself. You know the scenario so you're really the only one that can answer them. More information is needed in order for anyone that doesn't already understand your project to draw any decent conclusion.

Microsoft MVP, Visual C#
My Articles

Scroll a Treeview in Code?

selden0312-Jul-04 6:29

selden03

12-Jul-04 6:29

I have a treeview which I'm loading with various types of nodes, some with long text strings. If the last node to be loaded has a long string, the treeview scrolls horizontally to the right, so you can't see any of the nodes.

Is there any way to scroll the treeview back to the left in code, or can you think of any other way around this situation?

Thanks,
---Selden McCabe

Re: Scroll a Treeview in Code?

Jay Shankar12-Jul-04 20:54

Jay Shankar

12-Jul-04 20:54

You need to P/Invoke SetScrollInfo(user32.dll) to set the scrollbar positon.
In case you need further assistance, please revert back.

Regards,
Jay.

Constructing a setup project with variable paths not working???

LongRange.Shooter12-Jul-04 5:13

LongRange.Shooter

12-Jul-04 5:13

I have a VSS setup project that will copy files into a remote web server location.

In the View/UI I added a textbox dialog for the 3 key folders that can be created. The first is the path to the server. default is C:\Inetpub\wwwroot\yourwebsitedir and what I typed in was D:\Junk. The variable name (Property Name) was WEBSITEDIR.

In my View..FileSystem my ApplicationFolder is set to the property of [WEBSITEDIR] so it should pick up whatever is typed into the box.

When I type in D:\Junk and then do the setup, all files get sent to the C:\... directory instead of the overridden name (D:\Junk). I am stumped and cannot figure out why it is not setting the property to the new EditValue.

Can not catch KeyDown message from RETURN key

Roman Muntyanu12-Jul-04 3:49

Roman Muntyanu

12-Jul-04 3:49

Hi all,

I got a problem with Return key in my C++/C# application.
On CView dilalog I put my C# control. This C# control has couple
other controls nested. I have problem with RichTextBox control which
is at the bottom of my control hierarchy. It does not process
VK_RETURN key down. So I can not create new line. All other keys work
in RichTextBox. Of course I made it Multiline. I used Spy++ tool to
figure out what is going on. I managed to see that RichTextBox window
receives ON_KEYDOWN message with VK_RETURN. But there is no WM_CHAR message which normally should follow WM_KEYDOWN. As a result no new line is created in RichTextBox.

Tried to catch WM_KEYDOWN in WndProc and OnKeyDown. But they are hit for all keys except of RETURN

I would greatly appreciate any hints.

Thanks in advance,
Roman

Roman

Re: Can not catch KeyDown message from RETURN key

Peter Vertes12-Jul-04 4:22

Peter Vertes

12-Jul-04 4:22

I over came this problem by using the ASCII value for the return key (13). Here's how it works in code:

<br />
private void YouCallBackMethod(object sender, System.Windows.Forms.KeyPressEventArgs e)<br />
{<br />
    // was the return key pressed ?<br />
    if (e.KeyChar == (char)13)<br />
    {<br />
        // yes the return key was pressed<br />
    }<br />
    else<br />
    {<br />
        // no the return key was not pressed<br />
    }<br />
}<br />

Hope this helped...

Re: Can not catch KeyDown message from RETURN key

Nick Parker12-Jul-04 4:56

Nick Parker

12-Jul-04 4:56

Peter Vertes wrote:
if (e.KeyChar == (char)13)

You could also do the following:

if(e.KeyChar == Keys.Return)

- Nick Parker
My Blog | My Articles

Re: Can not catch KeyDown message from RETURN key

Roman Muntyanu12-Jul-04 6:28

Roman Muntyanu

12-Jul-04 6:28

Thanks guys for the reply.
But my problem is a little deeper.
I can't hit WndProc or OnKeyPressed method at all when I press Return.
For other keys I can hit methods. Of course everething works fine if I put .Net control on c# Windows.Form. But if I reside .Net control on C++ CView form something goes wrong. System messaging works differently in these two cases. In Spy++ I can see that C# RichTextbox got message WM_KEYDOWN for VK_RETURN and then WM_KEYUP.
Normally WM_CHAR should follow WM_KEYDOWN which I can see when work in C# environment. Looks like ::TranslateMessage(msg) failed.

Roman

Re: Can not catch KeyDown message from RETURN key

Mike Dimmick12-Jul-04 12:51

Mike Dimmick

12-Jul-04 12:51

Is it a CFormView? CFormView calls IsDialogMessage, which assumes that you're trying to press the default button on the form, or raises WM_COMMAND for IDOK if there is no default.

IsDialogMessage first probes the control with focus to see if it wants to handle this character. It does this by sending the control the WM_GETDLGCODE message. IIRC, the control has to return a code including the flag DLGC_WANTALLKEYS or DLGC_WANTMESSAGE in order to swallow the RETURN keypress. You'll need to experiment a little.

In your C# code, you'll probably have to override WndProc. The reason it works on a C# form is that the C# form manager doesn't use the pre-existing Windows dialog manager code - it's a new implementation.

Stability. What an interesting concept. -- Chris Maunder

Re: Can not catch KeyDown message from RETURN key

Roman Muntyanu12-Jul-04 14:31

Roman Muntyanu

12-Jul-04 14:31

Thanks Mike for attention to the problem.

Actually I managed to catch pressing Enter key in WindowProc overriden method in CFormView with WM_COMMAND message for IDOK. Then I simplify my testing project and put C# control on CDialog. Same thing. On C# side I cannot catch Enter in overriden WndProc. No messages at all when pressing Enter. Probably message could not reach C# control on its way. So I need to do all necessary message calls on C++ side in WindowPoc. I tried to call TranslateMessage(msg) with hwnd of my RichTextBox to get WM_CHAR in textbox. This call was not successful and returned 0. When I did the same call against CEdit control it worked and message was translated. Now the question for me is : which kind of message should I send to RichTextBox ? Maybe it is IsDialogMessage(RichTextBox_HWND, WM_KEYDOWN_MSG) if I understood your comment correctly. I hope RichTextBox will swallow Return keypress. But I need to know hwnd of RichTextBox. For testing app it was not difficult. But in real app will not be so easy to get it on surface. Any idea how to avoid knowing RichTextBox hwnd ?
Thanks a lot

Roman

Re: Can not catch KeyDown message from RETURN key

Roman Muntyanu14-Jul-04 1:55

Roman Muntyanu

14-Jul-04 1:55

Finally solution was found
I had to override WndProc in the derived class of RichEditBox,
catch pressing Enter key and do my job.

protected override void WndProc(ref Message m)
{
int WM_GETDLGCODE = 0x0087;
int VK_RETURN = 0x0D;
if (m.Msg == WM_GETDLGCODE)
{
if (m.WParam.ToInt32() == VK_RETURN)
{
base.SelectedText = "\n";
return ;
}
}
base.WndProc (ref m);
}

block an IP

chuchichäschtli12-Jul-04 2:28

chuchichäschtli

12-Jul-04 2:28

aloa

okay buddies =D my idea is to develop an ip-blocker. the user defines a set of ips that are blocked from the system.

my question is now: is this in c# actually possible or do i have to switch to c++?

regards

Re: block an IP

Heath Stewart12-Jul-04 3:04

Heath Stewart

12-Jul-04 3:04

As discussed before, .NET is too high level for such a task at this time. There is a lot of native APIs and interfaces to both implement and consume. You should download and read the networking sections of the Microsoft Platform SDK[^]. There's a lot to understand. A firewall is a very low-level application and requires that you understand how the Microsoft networking protocols work together and with the network interface cards (NICs).

Microsoft MVP, Visual C#
My Articles

request socket

shahrokh nabavi12-Jul-04 1:31

shahrokh nabavi

12-Jul-04 1:31

please introduce me a way to notify user that a process
request a socket in c#

koosha

Re: request socket

Heath Stewart12-Jul-04 4:07

Heath Stewart

12-Jul-04 4:07

.NET is too high-level for this sort of operation. This requires very low-level APIs and implementations with the Microsoft networking protocols, which also requires extremely efficient code with a small footprint - another reason not to use .NET.

There are already several commercial (typically free for home use) applications that do this already.

This has been discussed in the forums before. If you want to see how that thread progressed (to the same conclusion), please click "Search comments" directly above the message board.

Microsoft MVP, Visual C#
My Articles

request socket

shahrokh nabavi12-Jul-04 1:29

shahrokh nabavi

12-Jul-04 1:29

is there any messsage to notify user that a process
request a socket in c# or by win apis

koosha

A serious bug of list view in compact framework

ting66812-Jul-04 0:18

ting668

12-Jul-04 0:18

Hi~

Lei wrote
"I have 2 forms, form1 contains a ListView. What I want to do is, when
clicking an item in the ListView, hide form1 and show form2. Code for
ListView's SelectedIndexChanged: { form2.Show(); this.Hide(); }. When I
click the item, form2 shows with form1's title and menu. I noticed that when mouse down, the SelectedIndexChanged event was triggered and bring form2 to front. But when mouse up, system redrawed the selected item and bring title and menu back to form1's. I tried to handle MouseDown and MouseUp event of ListView but they were never triggered. Now I used a tricky way to solve the problem: start a thread and use Control.Invoke to switch forms. It is not good, I think there must be a better solution. Thanks."

I am facing the same problem. Someone solve it with setting timer. However, is there any other way to solve it?
Thanks~

Re: A serious bug of list view in compact framework

Mike Dimmick12-Jul-04 12:43

Mike Dimmick

12-Jul-04 12:43

Don't use the SelectedIndexChanged event. It won't tell you if the user clicks on the currently selected item, either. Also, if the user is trying to use the direction pad or scroll wheel, the event will fire as they're scrolling between items; you probably want it to fire only when they press the Action button.

What you should do is set the Activation property to ItemActivation.OneClick, and handle the ItemActivate event. This also gives you keyboard/keypad interaction for free.

Don't you just love the complete, comprehensive nature of the documentation? In response to your post, I tried this out on both .NET CF 1.0 SP3 and on 2.0 Beta 1. At least 2.0 Beta 1 gives you a compiler warning. I've raised the issue on the Compact Framework newsgroup, and I hope that will encourage clearer documentation.

Stability. What an interesting concept. -- Chris Maunder

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