Re: PropertyGrid - C# Discussion Boards

19-Dec-07 4:27

Is there a way I can limit the number of characters inside the PropertyGrid items. I want to allow only 5 characters. Please help

TJoe19-Dec-07 5:30

19-Dec-07 5:30

The only thing you can do is to validate the data *after* the user has already entered it. There is a third-party control, which does allow you to restrict what the user can enter. Check it out here[^].

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

netJP12L19-Dec-07 5:37

19-Dec-07 5:37

Is there a possiblity to attach a textbox within the PropertyGrid control griditem
so this way i can set the textbox.MaximumLength =5 or something.

TJoe19-Dec-07 6:05

19-Dec-07 6:05

Unfortuantely, no. The data entry portion of the PropertyGrid is not accessible and there are no hooks for "when data is being entered". So you cannot restrict what is entered while it's being entered or swap out the entry control for you own control (even if it's just a TextBox).

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

netJP12L19-Dec-07 6:58

19-Dec-07 6:58

this is exactly what i want. Although the codes are very complex can't seems to figure out much

http://www.codeproject.com/KB/edit/PropertyGridDataFormattin.aspx[^]

TJoe20-Dec-07 3:00

20-Dec-07 3:00

Maybe I should have been more clear in my answer. There is no correct way to do this. The article you posted uses internal control names to find the proper control inside the PropertyGrid. The name "System.Windows.Forms.PropertyGridInternal.PropertyGridView+GridViewEdit" is internal to the PropertyGrid and could be changed by Microsoft. So this means your application may just stop working at some point.

Using Reflection (or in this case internal control names), you can gain access to any field/property/method/event in a .Net class. This includes all private and internal members. It is highly recommended that you don't do this, because again the creator of the class can change the inner workings at anytime (thus breaking your application).

That aside, the article's code is pretty straight forward. An attribute is created so that the developer can mark each appropriate property with a "format". Then the custom PropertyGrid looks for that format and restricts the input.

I *think* that you would need to:

1. Create an attribute that takes a maximum length and apply this attribute to your properties.
2. In CustomPropertyGrid, you can remove the m_TextBox_TextChanged method, because you won't need to use that to enforce the max length.
3. In CustomPropertyGrid, replace the parts of code where the m_TextBox_TextChanged method is assigned to and removed from the TextChanged event so that you set and reset the MaxLength property, respectivly.

Give it a shot, if you have problems then email me and I can help you work through it.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

netJP12L20-Dec-07 5:26

20-Dec-07 5:26

Thanks Tom, I appreicated the time you took out to answer me. Can you enlightened more as you said that "the creator of the class can change the inner workings at anytime (thus breaking your application).". What about if lets say i run my application on .Net version 2.0 and even microsoft change the PropertyGrid control properties in .Net vesrsion 3.0 or so, will that effect ? Excuse me, as you have propbably have figured it out that I am a newbie and willing to explorer and learn more with people like you. Atleast, you have given me some thought to look after Reflection and what is that all about.

Thanks

TJoe20-Dec-07 5:59

Problems with PAINT program

20-Dec-07 5:59

Let's take an example. Assume that I'm a company providing a class/control that you purchased (e.g. Microsoft), and I have the following class that I provide you (the developer):

public class SomeClass {
    private Int32 hiddenInt = 0;
    
    public Int32 SomeProperty {
        get {
            return this.hiddenInt;
        }
    }    
}

Now, I would compile this class and only provide you with the assembly. So in your code, you would only be able to see SomeProperty, because it's public. You cannot see hiddenInt, because it's private.

Also, let's assume you want to change hiddenInt (probably because changing it would result in some effect you desire, such as limiting the number of characters that can be entered into a text box). You can use Reflection to change this value, like so:

//...
using System.Reflection;
 
//...
SomeClass c = new SomeClass();
Type t = typeof(SomeClass);
FieldInfo fi = t.GetField("hiddenInt",
    BindingFlags.NonPublic | BindingFlags.Instance);
fi.SetValue(c, 1);
  
// c.SomeProperty will now return 1, NOT 0

So you build your application and everything works great. But now I update my class (with bug fixes or optimizations) and I change it to:

public class SomeClass {
    public Int32 SomeProperty {
        get {
            return 0;
        }
    }    
}

As you can see, I removed the field and simply hard-coded the 0 in the property. Since hiddenInt was not visible to consumers of my class, I am free to change or remove it. Now if you start to use my new class, then you application will be broken. Because I no longer have the hiddenInt field.

This is a simple example, where you could simply detect that the field is no longer there and ignore the "error". But in the case of the PropertyGrid, you are enforcing user input. So your users would see a change in functionality or usability, if you were to ignore the error.

Now, in the case of the article you linked to. The code uses the "internal" name of the grid's control. This name can be changed at any time by MS.

Basically, if you start using things that are not publically visible (either public or protected in C# speak), then you can run into problems.

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

help quick

nta_388619-Dec-07 4:26

nta_3886

19-Dec-07 4:26

who did made a program that is like Pain(simple,it only draw line,rectangular...) in Windown.if you made,you can share for me.I am making it,but it is dificult

leo

Re: help quick

m@u19-Dec-07 4:45

m@u

19-Dec-07 4:45

nta_3886 wrote:
help quick

help please? and even that would be a horrible subject

nta_3886 wrote:
a program that is like Pain

you know, this post IS a pain

use google

Re: help quick

Paul Conrad24-Dec-07 19:43

Paul Conrad

24-Dec-07 19:43

m@u wrote:
you know, this post IS a pain

"Real programmers just throw a bunch of 1s and 0s at the computer to see what sticks" - Pete O'Hanlon

Luc Pattyn19-Dec-07 5:21

Luc Pattyn

19-Dec-07 5:21

Hi, there are several articles about paint programs here on CodeProject. Did you care to
look at any of them?

And if you have a specific problem, ask a clear and specific question, you will get
answers as good as your questions are.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Sorry for any delays in replying, I currently don't always get e-mail notifications.

Session

anupamwb19-Dec-07 3:38

anupamwb

19-Dec-07 3:38

1.
for Sign in
-------------
Session["original"]=user_id.Text;
FormsAuthentication.RedirectFromLoginPage(user_id.Text,false);

for sign Out
------------
FormsAuthentication.SignOut();

The problem is after sign out from user acount
if I use Internet Explorer Back Option ,
I am able to enter my previous logged in page.
How can i stop it. i.e. after logout from my account, if i use Internet Explorer Back Option ,then a message will come that your session is over. How can i do this.

Re: Session

DotNetXenon19-Dec-07 9:57

DotNetXenon

19-Dec-07 9:57

It happens because browser loads the page from the local cache.

Try this.
On Page_Load of each page.

Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetExpires(DateTime.Now.ToUniversalTime());

On the Sign Out button click,
Session.Abandon();
FormsAuthentication.SignOut();
Response.Redirect(FormsAuthentication.LoginUrl);

------------------------------------------------------------
"The only true wisdom is in knowing you know nothing." --Socrates

Re: Session

anupamwb20-Dec-07 3:02

anupamwb

20-Dec-07 3:02

thank u very much

Generics - How to implement Compare Methods

gunner_uk200019-Dec-07 2:27

gunner_uk2000

19-Dec-07 2:27

I have a List of Tasks that I want to Search, so Have created this method on my task:

public static int CompareID(Task x, Task y) Which returns 1 if X is bigger, 0 if equal and -1 if y is bigger as it says on the MSDN site documentation. My question is how to get the List's Find method to use this alogrithmn?

My current code is

<br />
List<task> tasks = new List<task>();<br />
<br />
//InstertCode to fill the task<br />
<br />
<br />
Task Top = tasks.Find(Task.CompareID);<br />
<br />
</task></task>

Anyone know how to get the find method to use my comparison method?

Re: Generics - How to implement Compare Methods

OsoreWatashi19-Dec-07 2:52

OsoreWatashi

19-Dec-07 2:52

If you want to only have a list of possible items, then you should use a List.
Instead, if you want to have each item in a list to have some sort of reference number, a key, you should use a Dictionary.

The dictionary is located at System.Collections.Generic;

To make a Dictionary and use the basic functionality, see the following example:

<br />
public void myMethod()<br />
{<br />
    Dictionary<int, string=""> dict = new Dictionary<int, string="">();<br />
    dict.Add(1, "item1");<br />
    dict.Add(2, "item2");<br />
    <br />
    dict.ContainsKey(1); //Returns true<br />
    dict.ContainsKey(5); //Returns false<br />
    dict.ContainsValue("item1"); //Returns true<br />
    dict.ContainsValue("item5"); //Returns false<br />
    <br />
    string value = dict[1]; //Returns "item1"<br />
    string value = dict[2]; //Returns "item2"<br />
}<br />
</int,></int,>

Here it will add 2 values with each an own key. "item1" with the key 1, "item2" with the key 2. So if you for instance want to find the value that belongs to the key 1 (in your example Task.CompareID), you do string value = dict.[Taks.ComprareID].

Note here that you can use everything for the key and value, not only int and string. You are able to use objects. For objects it goes exact the same as with the int and string to find them: they have to be an exact match.

Re: Generics - How to implement Compare Methods

LongRange.Shooter19-Dec-07 11:18

LongRange.Shooter

19-Dec-07 11:18

Your current code isn't using generics. If it was, then it would be more like

    List<task> tasks = new List<task>();
</task></task>

For the compare code, look into how the List takes a custom IComparable object at creation time. I think it is just on the constructor. So you would create a class for your compare logic that implementes IComparable. Then pass that into the constructor for you list. Example:

     public class TaskComparer: IComparable
     {
         public int Compare(Task x, Task y){}
     }

     ...

     List<task> tasks = new List<task>( TaskComparer );
</task></task>

If that doesn't work, then you need to create your own type of List that inherets from the base List<> class, override the Find and implement your own code.

Capturing messeges from other program

OsoreWatashi19-Dec-07 2:14

OsoreWatashi

19-Dec-07 2:14

I am working with Visual Studio 2008, .NET Framework 3.5 and C#.

I have my own Console Application that needs some functionality. Currently it is able to change the Windowtitles, read it's location on the screen, read it's width and height, send mouse-events and send key-events. This can be done to any open window, as long as I have the handle for it (which normally never is the problem).

The only thing I am missing is how to capture the messages that are send to this handle. With Spy++ I am able to see all the messages send to a window, I want the same functionality in my Console Application.

A simple example of such message will be: WM_MOUSEMOVE fwKeys:0000 xPos:10 yPos10

To make everything clear what I exactly want:
My Console Application has to read all messages send to a handle that is not created by the Console Application, for instance a window like Internet Explorer or Notepad. Those messages have to be captured.

So far I have tried both GetMessage and PeekMessage. The code I used for that is as follows

<br />
//Get the messages send to the window<br />
[DllImport("User32.dll", CharSet = CharSet.Auto)]<br />
private static extern bool PeekMessage(out MSG msg, IntPtr hWnd, uint messageFilterMin, uint messageFilterMax, uint flags);<br />
<br />
//Get the messages send to the window<br />
[DllImport("User32.dll", CharSet = CharSet.Auto)]<br />
private static extern bool GetMessage(out MSG msg, IntPtr hWnd, uint messageFilterMin, uint messageFilterMax);<br />
<br />
[StructLayout(LayoutKind.Sequential)]<br />
public struct MSG<br />
{<br />
    public IntPtr hWnd;<br />
    public uint Message;<br />
    public uint WParam;<br />
    public uint LParam;<br />
    public uint Time;<br />
    public System.Drawing.Point Point;<br />
}<br />
<br />
static void Main(string[] args)<br />
{<br />
    System.Threading.Thread.Sleep(2000);<br />
    <br />
    MSG msg;<br />
    while (PeekMessage(out msg, new IntPtr(0x000A053A), 0, 0, 0))<br />
    {<br />
        //Bla<br />
        System.Threading.Thread.Sleep(2000);<br />
    }<br />
    <br />
    while (GetMessage(out msg, new IntPtr(0x000A053A), 0, 0, 0))<br />
    {<br />
        //Bla<br />
        System.Threading.Thread.Sleep(2000);<br />
    }<br />
}<br />

For me, this always results a false value for both the PeekMessage and GetMessage methods and thus no value in msg. Does anybody know how to solve my problem?

Thank you very much in advance!

Re: Capturing messeges from other program

TJoe20-Dec-07 3:11