|
I forgot to mention one popular way to cause a random freeze: invalid cross-thread GUI operations (either in .NET 1.x, or by setting Control.CheckForIllegalCrossThreadCalls false); when in doubt, read this article[^].
|
|
|
|
|
I have a form with a lot of textboxes, etc... that are set to read-only or disabled. I have a "edit" button that allows the user to edit values on the form. I would like to add a "cancel" button that returns all of the controls back to their default state. I would like to know if there is a simple function that can be called similar to the initial load of the form. If not, I suppose I have to write a lot of code to change all of the controls back, one by one.
|
|
|
|
|
Two easy ways would be:
1. create a new Form
2. remove all top-level controls (this.Controls.Clear) and call InitComponent() again.
Both are more costly than is necessary.
Approach #3: You could enumerate all controls and reset them; in general this takes a recursive approach as TextBoxes could sit in Panels in SplitContainers, etc.
All these approaches have one thing in common: they are Form-agnostic, they don't really care exactly what Controls are present.
Approach #4 (More advanced): if your app is data-driven, chances are your Form represents one data object which has a class and probably also a DataRow, corresponding to a row in some DB table. If so, you are already using data binding, and could bind with a new (i.e. empty) object to clear everything.
FWIW a final remark: if your Form holds that many Controls that you see clearing them as a problem, then your users will probably not like it either for how it looks and how uneasy it is to use.
|
|
|
|
|
I have noticed that why anti virus, and other programs can gain administrator access when the app started when computer starts?
And why not .net created application? If I set to request administrator level in exe manifest, it will prompt user for permission, and it is very annoying since this application is automatically started at computer startup. How do I gain administrator permission (or at least the user login permission) without asking for password?
Why native exe can do it and why not .net exe?
Should we all move to C++ instead of supporting C#?
Any idea? or complains?
|
|
|
|
|
|
It is my understanding that apps like anti-virus programs appear to have admin access from their client tools because they talk to a windows service which is running with elevated privileges. The service is installed when you install the app (which you do get a UAC prompt for) after that point the client tools use IPC to communicate with the privileged service.
There may be (and most probably are) exceptions to this rule, I have not done much work in this area. So if your app really needs admin privileges (it probably shouldn’t) a workaround would be to install a windows service which performs the admin functions and communicate with that.
|
|
|
|
|
i see, my app is this one Writing a Folder Synchronization application[^]
which i think it should have admin privileges, since it is running in background doing synchronization works, which may include synchronizing folder in C or even program files
and recently i am having another project, which the application need to configure write its configuration files in its program files folder, but it does not have permission to do so, isn't this weird? for example, what if the application is extendable, where it can download new version or its plugin and put it in it's executable directory, shouldn't it have administrator privileges? Why microsoft need to limit the privileges of executable?
|
|
|
|
|
John Kenedy S.Kom wrote: Why microsoft need to limit the privileges of executable?
Any executable runs AS the user that launched it. There are no special restrictions on .EXE's of different types.
The "security" model you're assuming is not correct. When you install, say, an anti-virus engine, it installs a service that is actually doing all the work. It usually runs under the Local System account, which has pretty much admin priv's to the entire machine. Any UI program that you use to interact with this anti-virus app always runs as YOU. This app talks to the service and tells the service what it needs to do. The service runs as the local system, giving you the ILLUSION that what you ran has admin priv's.
John Kenedy S.Kom wrote: for example, what if the application is extendable, where it can download new version or its plugin and put it in it's executable directory
Writing to the Program Files fold is off-limits to normal users, but not admins. But, an .EXE can be installed to other locations that the user CAN write to. All it takes is for the updater to copy down the new .EXE to the correct location, but always the one you think it does. It's also possible that when the app was installed, the security for the apps folder under the Program Files folder was opened up to allow users to write to it.
Installers are written to run under administrator accounts, meaning they have free reign to configure the system, security, accounts, ... anything it needs to get the app installed and the rights it needs to do whatever it needs to.
|
|
|
|
|
I see, thanks Dave for the answer... Then I might consider to improve my app into a service instead and also learn about IPC, since these two are really new to me. Thanks!
Btw, what is the different between Local System account and the admin account? If a user is not an admin and installing the service, can the service then have the admin privileges, such as those own by anti virus?
|
|
|
|
|
John Kenedy S.Kom wrote: If a user is not an admin and installing the service,
If a user is not an admin, they're not installing the service. Also, even if they could, they cannot grant anything more rights than they themselves have. The only accounts that can grant admin permissions, are administrators.
The Local System is the account the, well, system uses. Even Windows has to provide credentials to Windows Security.
|
|
|
|
|
The synchronization app is exactly the kind of app that should be implemented as a windows service even without the UAC prompting issues.
UAC has imposed some architecture changes, configuration files should be place in “Application Settings” directories or isolated storage which are accessible without elevation. Similarly plug-ins can be placed and loaded from those 2 locations. A self updating app could be achieved be installing a basic exe to program files and then loading the bulk of the app code into app settings so it can be replaced if needed or UAC elevation for this feature is completely understandable and the standard practice (Firefox, OpenOffice, etc) all prompt for elevation when updating.
|
|
|
|
|
I have t1,t2,t3, 3 threads, and 1 AutoResetEvent(ar),
Is ar able to synchronize the three threads?
|
|
|
|
|
what do you mean by "synchronize three threads"? could be many things, such as: have the starting thread wait for all of them to finish; have all of them to wait for a common event; etc.
Whatever it is, the answer is: yes. The way to get it done will be different however.
|
|
|
|
|
jason_mf wrote: Is ar able to synchronize the three threads?
Yes ar able to synchronize the three threads.
|
|
|
|
|
i think synchronizing itself has a lot of meaning... like is all 3 threads running together? or is it waiting for autoresetevent set method, and which thread is waiting for which thread? at foldersync i recently create, i use 3 autoresetevent to control 3 threads.... L 
|
|
|
|
|
Hi,
When i type any value in a cell of a DataGridView a new row is added automatically in the DataGridView, but if i select any value from a combobox, in some case a new row is generated, but not in some cases.
I need to generate a blank row when i click on any cell of the last row.
Thankyou
YPKI
|
|
|
|
|
What you are running across is the limitation and inconsistency of editing in a list control (DGV). Most developers will not supply inline editing unless it is for a trivial set of data (1 cell only).
What I suggest you do is pop a dialog when the user double clicks (for edit) or clicks an add button. In the dialog you have complete control of the data. When the user has completed editing and closes the form then reload the list control and select the edited item.
Never underestimate the power of human stupidity
RAH
|
|
|
|
|
hi! everyone!!
I am using Windows application. I want to get single,single value from listview(contains two column) when I click a row.
my 1st column name is 'code'and value is '123' and second column name 'desc' value 'good'
If i click its return value but gives this type of value:
listview1:{123}
code sample:
private void listView1_Click(object sender, EventArgs e)
{
ListViewItem value1 = (ListViewItem)listView1.Items[0];
string val =Convert.ToString(value1);
}
please guide me,
thanx and regards
|
|
|
|
|
ListViewItem item = listView1.Items[0]
string val = item.Text;
string desc = item.SubItems[0].Text
|
|
|
|
|
thanx sir!
but i get only code value not desc value. in desc value also contain the code value.
I ask one more question.
actually when i click one row its work properly. but when i click secong row it returns also previous value instead of current selected row.
please guide me what can i do when i select different rows the selected rows returns value
thans and best regards
|
|
|
|
|
Phil pointed you to another ListView property: SubItems, which is indexable.
Did you read up on it? did you perform a little experiment?
BTW: when you know a column isn't text (say a number), and you want its value, then don't use Convert or ToString(), just cast!
|
|
|
|
|
hey you can use given code to get value based on row on which you click.
string txt = listView1.Items[listView1.FocusedItem.Index].SubItems[0].Text;
if you need value of both second column you have to change value of SubItems to column index as
string txt1 = listView1.Items[listView1.FocusedItem.Index].SubItems[0].Text;
string txt2 = listView1.Items[listView1.FocusedItem.Index].SubItems[1].Text;
you can also use loop with SubItems for getting value..
|
|
|
|
|
thank you very much!
you have solved my problem.
|
|
|
|
|
Hi,,
I have a Code in VB. Pls Convert this to c# using DeveloperFusion Website.
textbox1.Text = trim(listview.SelectedItems(0).SubItems(1).Text)
regards,
Saran..t
|
|
|
|
|
saransaki08 wrote: I have a Code in VB. Pls Convert this to c# using DeveloperFusion Website.
I am not getting it properly I think your question is not clear. will you elaborate it for better understand for me or others. 
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
