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Hi folks,
Background:
I am creating a control using VS2005 .NET Framework that reports on the progress of some background processes. There is no concept of data entry or selection here; the only user action is to scroll the list if required. The current implementation of this uses a ListBox-derived control with drawing code implemented in the DrawItem event handler. That code works (more or less) fine when the data that backs each item in the list is static. I have two items that change dynamically: a progress bar and a text field that must be able to change fairly quickly over time. The current implementation includes custom drawing code for the whole - there are no child controls.
My problem is that although I can change the value of the data field easily enough, all I can think of doing to make the ListBox aware of the change is to call Invalidate() for the whole control, and the paint events don't keep up, and the resulting effect is very jerky - tending in fact towards only updating once the progress reaches 100%
The reason for a global Invalidate is that I am not aware of anything in ListBox that enables me to discover where an individual item is on screen, so I can't paint it explicitly or do a bounded invalidate. I am wondering if ListView offers that ability, but can't see it if that's so.
So, to put the question straight: With an owner drawn list box/view, how to I tell the control that a (sub)item must be repainted now - preferably this instant - because the data backing it has changed?
Regards
Ruth
Ruth Ivimey-Cook
VS2005 / C# & VB
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The ListBox has a public GetItemRectangle[^] function which will tell you the bounds. You could put this one into the Invalidate call.
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I eventually solved the problem using the List View SubItem Bounds property, which returns the bounds of the specific SubItem.
I check that the bounds are contained by the parent's ClientRectangle, to avoid invalidate calls for items that are invisible, then pass the Bounds into the Invalidate call as Robert suggested. This is still slightly flickery, but not too bad.
Thanks.
Ruth Ivimey-Cook
VS2005 / C# & VB
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Does anyone know of a way to retrieve information from a Microsoft Wireless Optical Mouse? The Intellipoint software contains a signal strength and batery level monitor, I would really like to be able to query that information from within an application I am building.
Does anyone know of an API or DLL I can use to get at the information?
Thanks in advance!
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Thanks, I'll give it a try.
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Hi,
Has anybody try SDI Video Capture & PlayBack using Matrox X.mio Card in .Net Framework ? If yes, plz help me for Capture & Playback of SDI Video.
Thanks,
Aniket
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Hi,
when I load an image using this
Bitmap bitmap = (Bitmap)Image.FromFile(pic.Path),
it is not possible to delete the file afterwards, unless you exit the program. I tried to call .Dispose() on the object, but it seems like a bug in the FromFile method.
I found out a workaround
Bitmap origbmp = new Bitmap(pic.Path);<br />
Bitmap bitmap = new Bitmap(origbmp);<br />
origbmp.Dispose(); .
I keep working with the copy of the original bitmap as it's not locked anymore.
But, loading an image using Bitmap's constructor, it's impossible to load animated GIFs as it seems that Bitmap doesn't support them.
Now, how can I use animated GIFs and other image formats AND be able to delete the file afterwards?
Thx 
Stefan
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Please don't cross post.
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Hi guys,
I have a problem. I am trying to extract data from one column in a bound datagrid and place it in a listbox on another form. I keep getting the datarow view statement in the listbox instead of the actual item
What should i do??
thnx for ur help
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jaded_angel wrote: What should i do??
Show the code.
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When I add ‘Microsoft Excel 11.0 Object Library’ reference to my form(VS2005), Excel namespace remains invisible??
Importing same dll to VS2003 works fine (Excel namespace is visible).
Is anyone having same problem?
thanks
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Hi,
Am trying to implement a encryption-decryption system beween, Windows and Linux. and am planning to implement it in .NET.
Plese guide me and suggest some references.
Thanks.
Manivannan
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Hi all!. Im using Agilent Vee and .NET Framework 2.0. Agilent Vee its a visual language and I can use all libs of .NET Framework 2.0.
I want to create some forms who capture some instrument status, I create a form, show, etc ... ok all perfect. But if I move the window, the aplication stop the adquisition. And restart adquisition when I dont move the window.
Anyone can help me????
Thanks and regards.
P.D. Sorry for my english...
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You are probably better of capturing your information on a worker thread. Notice you can't update the GUI from this worker thread, so you would have to get the data to the GUI thread somehow.
Some of the options are:
1) Share the data, do a lock when it is updated/read
2) Clone the data and send the data to the GUI though BeginInvoke
I can't say which one (or something completely different) is best, it comes down to the data and - not least - your personal taste.
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Hi. This is the problem. Agilent Vee crash with .NET Threading... 
The other question is, only GUI stop or all program stop??? If only stop the gui, no problem, the most important its a second work...
Thank your for your ideas  .
Best Regards.
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If you can't get Vee to work with Threading (and you've confirmed it's not an issue in your code **), you could try a background process that does the acquisition and send the data to the GUI foreground process using a Windows Named Pipe.
HTH,
Ruth
** Most threading problems arise from invalidly sharing data - either implicitly or explicitly. Keep data sharing to an absolute minimum and ensure you're "lock"ing the rest.
Ruth Ivimey-Cook
VS2005 / C# & VB
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I have to Impersonate my windowsApplication (C#) to the Credential (which will be send by user).. Give below is my same function (Which wont work) what i need.
public class clsImpersonate{
public void Impersonate(ICredential UserCredential){
WindowsIdentity newId = (WindowsIdentity)UserCredential;
WindowsImpersonationContext impersonatedUser = newId.Impersonate();
MessageBox.Show(WindowsIdentity.GetCurrent().Name);
}
}
I will call the function like below..
public static void mail(){
clsImpersonate objImp = new clsImpersonate();
ICredentials NWC = System.Net.CredentialCache.DefaultCredentials;
objImp.Impersonate(NWC);
}
But above code is wrong because we can not typecast from Icredential to WinndowsIdentity.
Is there any other way to do the same.
Thanks
Saravanakumar.K
India
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How will the runtime allocate memory for a string if the same variable is allotted different values in a block of code.
For example:
{
string str = “value1”
.
.
.
.
str = “value2”
}
In the above case, when str=”value” is done, memory is allotted to str and “value1” is stored. Again, when “value2” is allotted to the same variable, is a new memory block allotted or will the value “value2” replace the value “value1” in the current memory block?
Please Help.
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Strings in .NET are immutable. That means that a string value is never ever changed.
If you assign a new string value to a variable, the new string value is stored at a different location and the variable is changed to reference that location.
Another example:
str = "asdf";
str = str.ToUpper();
The ToUpper method will create a new string and return the reference to it. The original string is never changed, the variable is just changed to reference the new string.
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hm Very interesting!
and what about integers and doubles. Are they treated the same way?
One more question....what would be the advantage behind allocating separate space to strings everytime you update them and changing the reference.
Thanx in advance
Regards
mubashir
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_mubashir wrote: and what about integers and doubles. Are they treated the same way?
No. They are value types, not reference types.
_mubashir wrote: One more question....what would be the advantage behind allocating separate space to strings everytime you update them and changing the reference.
The advantage is that whenever you use a string you only send the reference instead of copying the entire string. If you would copy the contents of the string every time you assign a string or use it in a method call, there would be a whole lot of copying.
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 Hi all,
I am very new to .net programming and doing alot of reading but am getting a bit list with some of the terminologies. Could somebody explain the building blocks of .net programming eg: objects, classes, methods etc etc.
All responses will be gratefully accepted.
csp
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 Hi
There are somany thing in that case...
tell me which one you are looking....
Chinna Srihari
Tech Lead, Capgemini
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Hi Chinna,
Thankyou very much for answering my post. I am just starting to teach myself .NET programming. I have taught myself basic programming, but wish to channel all my studies in to .NET. I am at the very beginning and was hoping that somebody would be able to give me an application diagram or something similar which would show me the concepts of object oriented programming eg: how classes, objects, methods, functions, enumerations, interfaces etc etc all fit in together.
Hopefully this is making sense. As I mentioned I am right at the beginning of my studies but this is something that I really want to devote alot of time to, and I will keep on reading but am hoping somebody can give a clear picture of how an application all fits together.
Much appreciated.
Craig.
csp
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