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I have two listviews in my app. The user may make multiple selections in one of them, but may not have selections in both at the same time. To enforce this requirement I'm responding to the SelectedIndexChanged event and having it clear the selections in the other LV. The problem is that the clear() method operates incrementally and immediately fires the event in the listview it's working on, which results in both listviews clearing each others selections. I tried using the lock statement, but the second event handler is able to gain the lock even though the first hasn't completed. Since all the examples I've seen are for controlling across threads I'm assuming the problem is that the second event handler is being ran in the same thread as the first.
What happens is the following:
State: LV1 - 2 items selected, LV2 0 items selected
Click on an item in LV2
State: LV1 - 2 items selected, LV2 1 items selected
LV2 handler called. LV1.Clear method called.
LV1.Clear cancels the 1st selection in LV1
State: LV1 - 1 items selected, LV2 1 items selected
LV1 handler called. It calls LV2.Clear called.
LV2.Clear cancels the selection in LV2
State: LV1 - 1 items selected, LV2 0 items selected
second LV2 handler called. Terminates because LV2 has no items selected.
LV1.Clear() called by the first LV2 handler regains control. Remaining LV1 selection is now cleared.
State: LV1 - 0 items selected, LV2 0 items selected
The result I want is: State: LV1 - 0 items selected, LV2 1 items selected
I could use a bool flag as a psuedo-lock to control the updates but am hoping there's a more graceful way to do it.
LV2 has a handler identical to this.
private void LV1SelectedIndexChanged(object sender, System.EventArgs e)<br />
{<br />
lock(this)<br />
{<br />
if (this.LV1.SelectedItems.Count >0)<br />
{<br />
this.LV2.SelectedItems.Clear();<br />
}<br />
}<br />
}
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Sometimes the simple solution is the best. Try removing the event before clearing the listbox and adding it again afterward. Not elegant, but works.
only two letters away from being an asset
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Hello
If you don't want to use bool psuedo locks, you could unregister the other event handler and reregistring it again after making the changes.
EventHandler MyLV2Handler = new EventHandler(LV2SelectedIndexChanged)
private void LV1SelectedIndexChanged(object sender, System.EventArgs e)
{
if (this.LV1.SelectedItems.Count >0)
{
LV2.SelectedIndexChanged -= MyLV2Handler;
this.LV2.SelectedItems.Clear();
LV2.SelectedIndexChanged += MyLV2Handler;
}
}
Regards ![Rose | [Rose]](https://www.codeproject.com/script/Forums/Images/rose.gif)
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this could work, except that I'd need to move the event handler installation from the designer to user edited code so that it would be available to remove/readd.
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Hi!
I think you have a misconception of lock() here...
lock(obj) is used to prevent two or more different threads from entering the same critical section.
Both listviews are handled by the same thread - the UI thread and the listviews are just regular win32 common controls underneath which are sending their windows messages to the thread's message queue.
It's because of these queued messages that your listviews receive their SelectedIndexChanged events...
Removing and re-adding the eventhandlers, as the others have suggested, seems a bit clumsy to me.
As you wrote, a boolean pseudo-lock seems to be the easier solution.
Regards,
mav
--
Black holes are the places where god divided by 0...
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Hello!
I'm trying to use the PStoreC.dll (Windows Protected Storage -- Internet Explorer, Outlook, etc. are storing their passwords in this).
I added a reference to PStoreC.dll. After using the PSTORECLib namespace, there are several classes available now. When I try to construct an instance of the main class (CPStoreClass), I get the following COM error:
Retrieving the COM class factory for component with CLSID {5A6F1EC3-2DB1-11D0-8C39-00C04FD9126B} failed due to the following error: 80040154.
Do you have any idea how to fix this? I already tried to use regsvr32 to register the PStoreC.dll file, but this unfortunetely doesn't help anything, the same COM exception is thrown... 
Best regards
Dominik
_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do?? 
(doesn't work on NT)
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Hi Dominik,
Try to register the dll using regsvr32.exe
if you still get the same issue then
that means that you are trying to register a non COM server DLL.
All COM server DLL's should have the DLLRegisterServer entry point.
Regards,
Bhupesh.
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i finsh makeing my Winapp
now i want to make setup file
my qyestion
* how can include the .Net FrameWork in my setup ...
and instual it if the computer dont have it . ???
Palestine
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Hello
Right Click on your Setup projects name in solution Exploere => Properties => Settings => Prerequisites => Check .Net FrameWork => From the radio buttons below check "Download from same location as my application"
Regards
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Is there any method for creating a new .net solution from any other .net solution and we can add all the referenced DLL's projects and all kind of stuff in such a manner that when u visit that new solution u should be able to directly build the software.
In short my need is that there are different componets available and i have to create a new solution using this different components(projects).
Plz answer as fast as possible.
Is ADD-Ins Capable of solving my problem.
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Hello
Your question is not clear. What are you trying to do:
1- Make a program that makes C# projects at runtime?
2- Make a project from an existing one to inherit its references?
3- Choose between several projects and merge the chosen ones into one big project?
4- More than one of the above?
Please post more details.
Regards
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yes 1 and 3 is the options that i want to perform. That is a program should be able to make new c# projects at the run time and also several small projects can be added into it at run time.
Sorry that my question was not clear and u were not able to recognize it.
Regard
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Hello
Well, yes VS add-ins can do it. Here is an Article[^] about it.
Yet, first you should understand the structure of VS project files. If you do, you can write an odinary exe program to mix up or segregate different projects based on theri files.
Regards
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Hi
I need to use MD5 technics for encripting & decripting the password.
So if any body knows about that, plz give me an idea to use the MD5 technics.
Just give me some example that to know the process.
Thanking u
Regards,
Naren.
please help me
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MD5 in itself can't be 'decrypted'.
MD5 is a hash. It is commonly used to store passwords in the following manner:
Step 1) The user signs up and enters his/her password, where it is MD5ed and stored locally.
Step 2) The user logs on with a password, which is MD5ed and compared with the local hash.
I'm sure you can find an article on MD5 on google or here on codeproject. 
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MD5 hashing is one way, so you can't 'decrypt' it as such. You'd usually use it to store passwords in a file or database so they're not readable by anyone with access to the database. When someone comes to log-in, you hash the password again and compare the hashed passwords to see if they're entered the correct one.
.NET has a built in function for this:
string hashedPassword = FormsAuthentication.HashPasswordForStoringInConfigFile("Password to Hash", "MD5");
http://msdn2.microsoft.com/en-us/library/system.web.security.formsauthentication.hashpasswordforstoringinconfigfile.aspx[^]
Regards,
Rob Philpott.
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My App keeps on throwing a System.OutOfMemoryException on the e.Graphics.DrawCurve(...) line. Any Ideas? 
private void Charges_Paint(object sender, PaintEventArgs e)
{
if (activeParticles < 1)
return;
Pen myPen = new Pen(Color.FromArgb(128, 0, 0, 0), 2.0f);
for(int i = 0; i < activeParticles; i++)
{
if (myParticles[i].Charge)
myPen.Color = Color.FromArgb(128, 255, 0, 0);
else
myPen.Color = Color.FromArgb(128, 0, 0, 255);
e.Graphics.DrawCurve(myPen, myParticles[i].GetCurve());
}
}
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Hello,
I think you have to dispose the pen. Otherwise the GC doesn't clean it.
mypen.Dispose();
Hope that helps,
All the best
Martin
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Hey Martin,
Thanks for your input. I had indeed forgotten to Dispose of the pen, but there is still the same error on the same line.
private void Charges_Paint(object sender, PaintEventArgs e)
{
if (activeParticles < 1)
return;
Pen myPen = new Pen(Color.FromArgb(128, 0, 0, 0), 2.0f);
for(int i = 0; i < activeParticles; i++)
{
if (myParticles[i].Charge)
myPen.Color = Color.FromArgb(128, 255, 0, 0);
else
myPen.Color = Color.FromArgb(128, 0, 0, 255);
e.Graphics.DrawCurve(myPen, myParticles[i].GetCurve());
}
myPen.Dispose();
}
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SharpenedC wrote: myParticles[i].GetCurve()
without knowing what that call does, its impossible to tell you why your app is running out of memory. Likely candidate is an infinate loop within that method call (have you incrememnted all loop control variables - thats a common cause). Of course the other possibility is that you have a huge number of elements in your myParticles array (activeParticles), and it is genuinely running out of available memory to draw all the curves.
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Indeed. Although I might add, the exact error message is "An unhandled exception of type 'System.OutOfMemoryException' occurred in System.Drawing.dll"
public PointF[] GetCurve()
{
PointF[] myPoints = new PointF[4];
myPoints[0] = location.ToPoint();
for(int i = 1; i < 4; i++)
{
myPoints[i] = History[i - 1].ToPoint();
}
return myPoints;
}
EDIT: And the exception is thrown as soon as activeParticles exceeds 1.
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SharpenedC wrote: An unhandled exception of type 'System.OutOfMemoryException' occurred in System.Drawing.dll
Yes, I assumed so, this message often is thrown when an infinite loop is entered into.
Have you tried stepping through the code to see what is happening?
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Hello,
Maybe you have a recursive Call here.
Try to prefent it with a boolean flag:
private void Charges_Paint(.....)
{
if(allreadyinuse==false)
{
allreadyinuse= true;
//Start Youre code
//End Youre code
allreadyinuse= false;
}
}
All the best,
Martin
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I implemented your idea, but now nothing happens :<
private void Charges_Paint(object sender, PaintEventArgs e)
{
if (!isPainting)
{
isPainting = true;
if (activeParticles < 1)
return;
Pen myPen = new Pen(Color.FromArgb(128, 0, 0, 0), 2.0f);
for (int i = 0; i < activeParticles; i++)
{
if (myParticles[i].Charge)
myPen.Color = Color.FromArgb(128, 255, 0, 0);
else
myPen.Color = Color.FromArgb(128, 0, 0, 255);
e.Graphics.DrawCurve(myPen, myParticles[i].GetCurve());
}
myPen.Dispose();
isPainting = false;
}
}
-- modified at 9:37 Thursday 31st August, 2006
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Hello,
Sorry but I don't get your 'if' statement here.
if(!isPainting)
{
isPainting = true
//I think, here should be youre code
}
else
{
}
isPainting = false;
All the best,
MArtin
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