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Ok.
Good luck!
Henry Minute
Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”
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Greeting,
I want to monitor the data that I received continuously.I use Datagridview control to monitor data(a data received as a structure of some fields and i show them as some columns )
It seems the Datagridview is slow and when number of records is growing this control will be very slow.
Which control is better?
I should monitor data in some columns , and every columns should has title.
Thanks
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A datagridview has a lot of intelligence for sorting and the likes. Lots of data makes every control slow. Fill a textbox with 10Mb and you'll see what I mean 
If it's for personal viewing then you might consider using a TextBox with a fixedsize-font.
I are troll
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In my current c# application I need a combobox that can have in it atleast 500 entries. But when I tried to do I, it says it can store at the max! only 100 entries in it.
Is there any way I can set the combo's max drop down items?!
Regards,
na_ab
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then just put 500 items in, its not a problem.
The MaxDropDownItems value is the number of item to be displayed during drop down at any one time. Which is limited to 100
May i also just suggest that a combo box with so many items is not very user friendly IMO
If only MySelf.Visible was more than just a getter...
A person can produce over 5 times there own body weight in excrement each year... please re-read your questions before posting
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this is can change simply.
first you must change the property DropDownHeight (Default value 106 you can change to 100) and then reset it again(to 106).
then you can change the value in maxDropDownItems = 10 or your value.
it's work great.......!!!!!!!!
thanks
gihan
gihan_chandima@yahoo.com
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Hi.
Why do i get this error when opening a file as bitmap : "Parameter is not valid"
I'm trying to open a .tif file, with calling a funtcion.
The code:
Bitmap tif = new Bitmap(fileName, false);
I googled a bit and tried with casting the bitmap like this:
"bitmap tif = (bitmap)bitmap.fromfile(filename);"
but i got another error saying - "out of memory".
i also read something with using stream, but didnt quite get it on how to work...
Can someone please help?
PS: the tif file has 4 EMPTY pages. And everything stopped only with this file. Many tifs before went through well.
Thanks in advance.
Regards,
Matjaž
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Since you are setting the second param (useIcm, i think) to false, omit it altogether.
Bitmap tif = new Bitmap(filename);
If you still get the error, then it is likely that the tif file has been created in an unorthodox (to MS, at least) way.
As far as using streams is concerned try something like:
Bitmap tif = null;
using (FileStream fs = new FileStream(filename, FileMode.Open))
{
tif = new Bitmap(fs);
}
Henry Minute
Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”
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Anybody help me
In my application, we used to the tableLayoutPanel , the 24 rows and 7 coloums
But show only 10 rows , after that all are in scroll bar. Now what i am want means, if scroll the mouse ,tableLayoutPanel didn't scroll. can i set any property or write the code to the mousewheel callback event.
Thanks.
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Does the TableLayoutPanel have Focus?
IIRC it will only scroll when focussed.
Henry Minute
Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”
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Hi,
I am developing an smartdevice application to convert text to speech using Visual Studio 2008 with .NET Compact Framework 3.5 and C#..
I learnt that SpeechLib is the namespace used for this conversion..
While using this namespace the error i received is
Error: The type or namespace name 'SpeechLib' could not be found (are you missing a using directive or an assembly reference?)
What should i do inorder to rectify this error??
Thanks in advance..
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YOu need to make a reference to the Library.
Excellence is doing ordinary things extraordinarily well.
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Hi,
Thanks for ur fast reply..
I tried adding reference to the library by right clicking on the smartdeviceproject>add reference.. from that i chose browse tab, selected C:>program files>reference assemblies>microsoft>framework>v 3.0 >System.speech.dll
Is the way i proceeded is correct..If not Can u tell me how to make the reference to the library..
Thanks once again..
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We have done one project(software).we are giving our software to our clients.Now we are deploying our software in client server system.But they are asking permission for 10 systems only.We want to resit for 10 systems only.
Eg:We are deploying software in our client server system.They are having 50 systems.But they have use our software for 10 systems at a time.If any 11th person will want to enter he should get one message like room is full.If any one from 10 system
is Logout then other person can enter.
How to do this application.
New Q: You u not getting me.At a time our client's should use our software in 10 system.while use the 10 system no other(11 person) should not login .If any person from 10 systems is logout,then only 11person can login from person who was logout.
thank's in adv
M.lavan
modified on Friday, February 20, 2009 3:28 AM
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hi lavankumar
There are Different ways of doing this, but in your case i assume your App has some login system in it, So you have to create 10 logins and dont allow a user to login with the same credentials in two different machines. Then you will always have 10 users opr les logged into your system
Simple nee 
Vuyiswa Maseko,
Few companies that installed computers to reduce the employment of clerks have realized their expectations.... They now need more and more expensive clerks even though they call them "Developers" or "Programmers."
C#/VB.NET/ASP.NET/SQL7/2000/2005/2008
http://www.vuyiswamaseko.tiyaneProperties.co.za
vuyiswa@its.co.za
www.ITS.co.za
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Does your application use a central database? If so simply have a login table, add 1 when a user logs in and subtract1 when they log out. Check the count before allowing a login. Personally I would actually keep a record of login/out with user name and times.
Bob
Ashfield Consultants Ltd
Proud to be a 2009 Code Project MVP
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The logic for keeping track of who is logged in, preventing multiple simultaneous logins by the same user (if desired), and denying login for an 11th user is straightforward. But presumably you would like to avoid hard-coding this yet add some sort of protection so users cannot too easily get around the restrictions.
My suggestion is to use a license file in flat or XML format and sign it digitally. Digital signatures work similarly to public-key encryption (and indeed one normally uses the same keys for signing and encryption purposes). Basically, there is a key pair consisting of a private key used for decryption and signing, and a public key which is used for encryption and verifying signatures. This is handy, because it means you can embed the public key in your application to verify that the license file has indeed been signed by the corresponding private key, which you don't have to distribute.
I can make you - for a reasonable fee - a license class that takes care of the details of signing a license. Then you simply create your key pair (using sn.exe, provided with Visual Studio), and focus on the business logic rather than the tech details. The class will represent the license as a collection of name-value pairs, keep the file in plain text so it can be read by a human, but detect it if the file is modified so the information no longer matches the signature.
Just message me if you are interested.
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dojohansen wrote: My suggestion is to use a license file in flat or XML format and sign it digitally
I may be missing something, but if the licence file is distributed with the application how will it prevent more than x concurrent users, which is what the OP was getting at?
The only way I know of to prevent more than a given number (say 10) of concurrent users is to have a central 'register' of currently logged in users. By including the user name etc if required you can display a list of current users (so the 11th person could see if anyone could log out). The actual number of allowed users can be stored as an encrypted value, so the chances of it being changed to another value are slim.
As an extra check, you can validate the user is still logged in before allowing functionality.
Bob
Ashfield Consultants Ltd
Proud to be a 2009 Code Project MVP
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You are indeed missing something: The point.
As I wrote, counting the number of users and taking action in the application according to what license has been bought is fairly straightforward. The challenge in making an application enforce license options is not this code, but how to make licensing flexible without making it easy to circumvent restrictions (hard-coding limitations simply means you must build the application for each combination of options you offer, and requires a complete deployment operation to change the license options, e.g. by upselling).
You suggest storing this information (number of allowed users, i.e. the license data) as an encrypted number. Doing so would make it harder to cheat, but is not secure because you now need to store the encryption key securely. The advantage of using signatures is that they are verified using the PUBLIC key, so everything - the signature and the key and the license data - can be kept in human-readable clear text form without compromising the integrity of the system.
How would you suggest storing the decryption key for your proposed implementation?
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dojohansen wrote: You are indeed missing something: The point.
I think I am somewhere. Can you explain a bit more what you mean? I am, genuinely, puzzled by how, having a licence file which is distributed with your application, can limit the number of concurrent users. Or have I misunderstood what you meant?
dojohansen wrote: How would you suggest storing the decryption key for your proposed implementation?
The application would have the key to decrypt the number, obviously. And yes, I know this could be reverse engineered, but if you use obfusication etc its relatively safe from most casual users. Its all down to how valuable your application is.
Bob
Ashfield Consultants Ltd
Proud to be a 2009 Code Project MVP
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Dear Bob,
Ashfield wrote: Can you explain a bit more what you mean? I am, genuinely, puzzled by how, having a licence file which is distributed with your application, can limit the number of concurrent users. Or have I misunderstood what you meant?
You may feel that your intellect is of such an unrivalled caliber that no further contributions from other people could possibly add anything to what you have to say. I may feel differently.
Right from the start, I made it clear that I consider there is one part of implementing license solutions that is tricky, and that is to ensure the integrity of the license information. I then provided an elegant solution to this problem. I don't know if it was exactly what the OP had in mind, but it surely is related to implementing a licensing system and as such potentially useful.
I'll let the OP choose whether or not he wishes to use my input, and if I didn't address his issue precisely then relatively little damage was done. His issue wasn't very clearly defined, at least not to me, and to be honest I have some serious doubts as to how useful your own contribution is to the OP. Perhaps you shouldn't throw stones when in a glass house.
Ashfield wrote: I know this could be reverse engineered, but if you use obfusication etc its relatively safe from most casual users
I am curious to know what makes you elevate this to a better solution than using digital signatures - apart from the fact that it was you who suggested it - since you seem to understand that it would not be secure, and it offers absolutely no advantages to compensate for this drawback when compared to using signatures. I will suggest a possible explanation: your ego does not allow you to ever face up to the fact that you aren't necessarily the most brilliant person in the universe - but this is of course just speculation on my part.
Ashfield wrote: Its all down to how valuable your application is.
Actually, it isn't - rather, it's down to how important it is to make sure the application can enforce license options. An application may well be very valuable without extensive protection - for proof, consider the two most valuable pieces of software ever written (for the owner anyway), Windows and Office, until very recently. Also, even if strong protection is not necessary, a more complicated solution that is less secure does not suddenly become preferrable to a simpler one that is more secure and allows you to keep everything in clear text.
I happen to have spent some time thinking about this for the simple reason that I was charged to invent such a thing a few years ago - and that solution has been for years, and is currently, in use by Europe's second-largest ISV, even if only for select products.
modified on Friday, February 20, 2009 9:37 AM
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Please accept my apologies if you feel I am trying in some way to denigrate your replies, I'm not. I am probably was not very clear in what I meant, I have just not grasped what you mean. I assume (and this is probably where I am wrong) that each installation (i.e. on each PC) there is a copy of the app and a digitally signed licence file. I'm with you to there. Now the bit where I am lost, and you seem to have taken offence at - does this somehow limit the number of users, or is that not part of what you are talking about? I know you said originally about limiting the number of users to be easy (or words to that effect), is the bit about licences more of an insight into a way of securing your app?
Bob
Ashfield Consultants Ltd
Proud to be a 2009 Code Project MVP
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Ashfield wrote: Please accept my apologies
Accepted. If I misinterpreted you, I apologize for retorting!
Ashfield wrote: I assume that each installation (i.e. on each PC) there is a copy of the app and a digitally signed licence file.
Relatively little is known about the mysterious "systems" - whether it is clients or servers or complete client-server installations that is meant - so I for one don't know how to help with that. If you notice my other post I'm trying to make the point there that the key is to figure out how the systems can communicate, and we have no way of knowing based on what's provided so far by the OP.
So you're absolutely right, if maybe needlessly sarcastic, that putting a license file, signed or not, onto the computers will not automatically restrict the number of users logged on. So that is indeed not part of what I am talking about.
In our own case, we restrict the number of users that can be simultaneously logged on to any given database, and the code required is very simple since obviously all the apps (web apps in a farm, typically) can share information in the database. I guess I couldn't quite believe that the poster would be asking about how the systems can communicate without saying more about it, so I assumed the real problem was a more general "how can we make such a thing as a license system?" and rolled out from there.
Peace & Love... 
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dojohansen wrote: I apologize for retorting!
Also accepted
dojohansen wrote: So you're absolutely right, if maybe needlessly sarcastic,
The sarcasm was unintentional, but on re-reading my post I see why you interpreted it as such. I should make myself clearer!
dojohansen wrote: I guess I couldn't quite believe that the poster would be asking about how the systems can communicate without saying more about it
I could - I've probably read more posts than you 
Anyway, on a serious note, I think it would make a good article if you have the time to go into it in a bit more depth as you obviously have some significant experience in this area.
Bob
Ashfield Consultants Ltd
Proud to be a 2009 Code Project MVP
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Well obviously it is not possible unless the systems have some means of communication. So based on no more information than "they have 10 systems" it's not really possible to give useful advice.
Among the numerous potential solutions, the processes could communicate via:
- remoting
- sockets
- web services
- accessing a common database
- sattelite link
- gsm modem
- fm radio
and many many others. But there is no magic dust that you can sprinkle on just *any* type of system and have it suddenly communicate with other systems that resemble itself. At least not that I know of.
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