C# Discussion Boards - CodeProject

printing

cmarmr11-Mar-04 4:01

cmarmr

11-Mar-04 4:01

i know this sounds simple but can someone please tell me how i can draw boxes and circles to the printer

thanks
chad

Re: printing

Not Active11-Mar-04 4:30

Not Active

11-Mar-04 4:30

Check out the PrintDocument and Graphics classes. Printing is essentially no different from drawing on a windows form, the medium is just different.

Lock a file?

Anonymous11-Mar-04 3:29

Anonymous

11-Mar-04 3:29

How can you lock a file in .NET? I have a windows application that reads xml files. If two users are trying to read the same file, I want to lock the file so the second user can't read or change the file.

I'm looking for the most bare bones lock and unlock functionality.

Thanks
Wink | ;)

Re: Lock a file?

Heath Stewart11-Mar-04 5:25

Heath Stewart

11-Mar-04 5:25

The System.IO.FileStream can do this. Read the .NET Framework SDK for more information:

FileStream stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.None);
XmlTextReader reader = new XmlTextReader(stream);
try
{
  // Read from "reader" or something.
}
finally
{
  reader.Close();
  stream.Close();
}

This is a very simplistic example. Read about the FileStream constructor for more information.

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Re: Lock a file?

Manster11-Mar-04 5:46

Manster

11-Mar-04 5:46

I just figured this out:

		private bool LockFile( string sFilePathToLock )<br />
		{<br />
			bool bFileLocked = false;<br />
<br />
			if( File.Exists( sFilePathToLock ) && ( File.GetAttributes( sFilePathToLock ) != FileAttributes.ReadOnly ) )<br />
			{<br />
				File.SetAttributes( sFilePathToLock, FileAttributes.ReadOnly );<br />
				// Use the FileAttributes.Archive to mark a file for deletion.<br />
<br />
				bFileLocked = true;<br />
			}<br />
<br />
			return bFileLocked;<br />
		}<br />
<br />
		private bool UnLockFile( string sFilePathToUnLock )<br />
		{<br />
			bool bFileUnLocked = false;<br />
<br />
			if( File.Exists( sFilePathToUnLock ) && ( File.GetAttributes( sFilePathToUnLock ) == FileAttributes.ReadOnly ) )<br />
			{<br />
				File.SetAttributes( sFilePathToUnLock, FileAttributes.Normal );<br />
<br />
				bFileUnLocked = true;<br />
<br />
			}<br />
<br />
			return bFileUnLocked;<br />
		}

Hope this helps.

Wink | ;)

Re: Lock a file?

astanley12-Mar-04 2:06

astanley

12-Mar-04 2:06

Although I'm a C# newbie, I can see Manster's solution will not work. See my (AS) comments below:

if( File.Exists( sFilePathToLock ) && ( File.GetAttributes( sFilePathToLock ) != FileAttributes.ReadOnly ) )<br />
{<br />
// AS Another thread/process could lock the file here, before this thread gets a chance<br />
// to lock it. Therefore the SetAttributes call will fail (throw an exception?).<br />
File.SetAttributes( sFilePathToLock, FileAttributes.ReadOnly );<br />
// Use the FileAttributes.Archive to mark a file for deletion.<br />
<br />
bFileLocked = true;<br />
}<br />
<br />
return bFileLocked;<br />
}

The original reply (to use FileStream) seems more like it, but you still need to trap the error when it fails to open the file because it is already locked.

Re: Lock a file?

Heath Stewart12-Mar-04 3:11

Heath Stewart

12-Mar-04 3:11

This is not a correct solution. This only makes the file read-only to programs that check it. See my post for the correct solution, a solution that has been used for as long as filesystems have been around. This is the way it's supposed to be done and truly locks it while it's open from reading or writing by other processes.

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LicenseManager, LicenseProvider

claude12345678911-Mar-04 3:11

claude123456789

11-Mar-04 3:11

Hi,
I want to protect my component so i followed the sample from Microsoft but i get always the LicenseException. I have to say that i don't know how to implement the part in the host application. That a part of the code of my component :
[LicenseProviderAttribute(typeof(LicFileLicenseProvider))]

public class Info: Component
{
private License license = null;
public Info()
{
license = LicenseManager.Validate(typeof(Info), this);
}
Thanks in advance

Re: LicenseManager, LicenseProvider

Heath Stewart11-Mar-04 4:47

Heath Stewart

11-Mar-04 4:47

Read the documentation for LicFileLicenseProvider.GetLicense. The default LicFileLicenseProvider imlpementation looks for a file named myClass.lic, where myClass is the full name of the class. So, if you have a namespace like MyNamespace.MyClass, you must have a file in the same directory as your assembly that contains the component called MyNamespace.MyClass.lic. Inside that file you must include "MyNamespace.MyClass is a licensed component.".

Note, this LicenseProvider is meant only as an example. This is by no means secure and you should derive your own LicenseProvider to provide a more secure means of licensing your control.

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How to use SetForegroundWindow in C#...??

Member 94012510-Mar-04 23:55

Member 940125

10-Mar-04 23:55

I want my program to open a postscript file and send Ctrl+C to ghostview,
this is part of my code:

Process.Start("gsview32.exe", openFileDialog.FileName);
SendKeys.Send("^c");

but I found ^c was sent to my own program not to ghostview, Confused | :confused:

someone told me I should use SetForegroundWindow to activate ghostview,
(like AppActivate in VB)
but I don't know how to give the parameter to SetForegroundWindow,
Can anyone give an simple example to activate my ghostview...?? Cry | :((

Thanks a lot !! Wink | ;)

Re: How to use SetForegroundWindow in C#...??

Syed Abdul Khader11-Mar-04 2:05

Syed Abdul Khader

11-Mar-04 2:05

You need window handle to use SetForeGroundWindow method.
You can the window handle using the FindWindow method.

HWND FindWindow(LPCTSTR lpClassName, LPCTSTR lpWindowName);

you can give null to the lpClassName and give the Windows title to the
lpWindowName to find the Window handle.

BOOL SetForegroundWindow(HWND hWnd);

Re: How to use SetForegroundWindow in C#...??

Heath Stewart11-Mar-04 4:42

Heath Stewart

11-Mar-04 4:42

A much simpler way is to use the Process object that is returned from Process.Start and to use the Process.MainWindowHandle to the call for SetForegroundWindow:

Process p = Process.Start("gsview32.exe, openFileDialog.FileName);
if (p != null)
  SetForegroundWindow(p.MainWindowHandle);

Where SetForegroundWindow is defined as:

[DllImport("user32.dll")]
private static extern bool SetForegroundWindow(IntPtr hWnd);

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Re: How to use SetForegroundWindow in C#...??

Member 94012511-Mar-04 15:58

Member 940125

11-Mar-04 15:58

Thanks for sssyed_in and Heath,
Finally I use Heath's method to solve my problem... Laugh | :laugh:

But then I have one new problem to ask:
How to set my own program back to ForegroundWindow...?? Unsure | :~

Thank you very much!!

Re: How to use SetForegroundWindow in C#...??

Heath Stewart12-Mar-04 2:58

Heath Stewart

12-Mar-04 2:58

Pass either your main Form's Handle property (inherited from Control) into SetForegroundWindow, or use Process.GetCurrentProcess().MainWindowHandle. The former is much quicker and recommended if possible.

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How to serialize static variables of a class ?

Eric Marchesin10-Mar-04 21:54

Eric Marchesin

10-Mar-04 21:54

Here's the issue :
I want to serialize some objects whose class contains a static attribute and I need to find this value again when I deserialize my objects.

For example :

[Serialize]<br />
public class MyObject<br />
{<br />
    static int _NbInstances;<br />
    string _Name;<br />
    <br />
    ...<br />
}

How to make _NbInstances persistant ? Where should this value be saved ?

- Éric -

Re: How to serialize static variables of a class ?

Daniel Turini11-Mar-04 2:55

Daniel Turini

11-Mar-04 2:55

This is a conceptual no-no.
Static attributes should not be serialized with instances, because static attributes are not instance attributes. You can include these values by creating your custom serializer, but if you include these values in serialization, this will lead to inconsistent values, because every time you deserialize an instance, the static values will change.
A better design would be creating two methods, e.g. saveStatics() and readStatic() on each class that needs it.
BTW, a static "string _Name" smells bad design...

Perl combines all the worst aspects of C and Lisp: a billion different sublanguages in one monolithic executable. It combines the power of C with the readability of PostScript. -- Jamie Zawinski

Re: How to serialize static variables of a class ?

Eric Marchesin11-Mar-04 4:44

Eric Marchesin

11-Mar-04 4:44

Hello Daniel,

I know what you mean and I don't want to serialize the static value WITH each instance, but I was thinking of a kind of "meta-serialization" for class (just as static constructors exist).

In fact I'd like to know which design is the best for that. But it has to be done manually.

Note that I've writen these three lines of code quickly just as an illustration because the complexity of a better code is useless for the question.

Thank you,

- Éric -

Re: How to serialize static variables of a class ?

Daniel Turini11-Mar-04 6:14

Daniel Turini

11-Mar-04 6:14

Well, in that case, I think that one interesting possibility would be: group your static properties into a Singleton class. Then, serialize this Singleton. This way, you can only mark the singleton [Serializable].
If you think about it, you may be missing a class on your design that is simply a singleton...

Perl combines all the worst aspects of C and Lisp: a billion different sublanguages in one monolithic executable. It combines the power of C with the readability of PostScript. -- Jamie Zawinski

How to set defaultprinter

yu-yu10-Mar-04 21:01

yu-yu

10-Mar-04 21:01

Hello,

Now I try to change default printer using C#.
After my investigation, I found it use WMI.
I used to WMI (Win32_Printer), but I couldn't.
The following is the source.
Please advice me.

best regards,
yu-yu

ManagementPath path = new ManagementPath();
ManagementBaseObject inParams = null;
ManagementBaseObject outParams = null;
string[] stemp = PrinterID.Split("\\".ToCharArray(), 8);
path.Server = stemp[2];
path.NamespacePath = @"root\CIMV2";
string relPath = string.Format("Win32_Printer.DeviceID='{0}'",PrinterID);
path.RelativePath = relPath;
try
{
ManagementObject mo = new ManagementObject(path);
outParams = mo.InvokeMethod("SetDefaultPrinter", inParams, null);
Console.WriteLine("Printer {0} is default now ", PrinterID);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}

Re: How to set defaultprinter

Heath Stewart11-Mar-04 4:04

Heath Stewart

11-Mar-04 4:04

What didn't work about it? Give us a clue. Was an exception thrown and written out to the console in your catch block? Was the printer found? Make sure you're doing checks to see if an object is null, too. What if your printer object wasn't found. Since your try-catch block doesn't encompas everything, a NullReferenceException would've gone uncaught.

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Re: How to set defaultprinter

yu-yu11-Mar-04 15:57

yu-yu

11-Mar-04 15:57

Hello,

>What didn't work about it? Give us a clue.

Yes, thank you.

when InvokeMethod() called, exception occuered.

>Was an exception thrown and written out to the console in your catch block?

Exception name is ManagementException: MethodNotImplemented System.Management.ManagementBaseObject

>Was the printer found?

Yes. I set 2 printers.
There are 2 printers in my network, and my pc too.
So I used them as network printer.

My environment is
Win2000Pro
.NET Framework1.1
VSNet2003

>Make sure you're doing checks to see if an object is null, too. What if your printer >object wasn't found. Since your try-catch block doesn't encompas everything, a >NullReferenceException would've gone uncaught.

I remade a source.

Hope your help.

regards,
yu-yu

------------------------------------------------------------------------------
ManagementPath path = new ManagementPath();
ManagementBaseObject inParams = null;
ManagementBaseObject outParams = null;
path.Server = "."; <- local PC setting
path.NamespacePath = @"root\CIMV2";
string relPath = string.Format("Win32_Printer.DeviceID='{0}'",PrinterID);
path.RelativePath = relPath;
try
{
ManagementObject mo = new ManagementObject(path);
outParams = mo.InvokeMethod("SetDefaultPrinter", inParams, null);
Console.WriteLine("Printer {0} is default now ", PrinterID);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}

Re: How to set defaultprinter

Heath Stewart12-Mar-04 2:56

Heath Stewart

12-Mar-04 2:56

Instead of setting inParams to just null, try setting it to a valid instance like so:

ManagementBaseObject inParams = mo.GetMethodParameters("SetDefaultPrinter");

It won't contain any parameters, but it will be a valid instance with additional data. The following worked for me:

using System;
using System.Management;

public class SDP
{
  static void Main(string[] args)
  {
    if (args.Length != 1)
    {
      Console.Error.WriteLine("Invalid printer name.");
      Environment.Exit(1);
    }

    ManagementObject mo = new ManagementObject(
      string.Format("Win32_Printer='{0}'", args[0]));
    ManagementBaseObject inParams = 
      mo.GetMethodParameters("SetDefaultPrinter");
    ManagementBaseObject outParams =
      mo.InvokeMethod("SetDefaultPrinter", inParams, null);
    if ((uint)outParams["ReturnValue"] == 0)
      Console.WriteLine("Success!");
  }
}

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Re: How to set defaultprinter

yu-yu12-Mar-04 5:10

yu-yu

12-Mar-04 5:10

Mr. Stewart

Thanks,
May I ask a question.
Please tell me your Environment.
I checked SetDefaultPrinter(). so I found it need to XP higher.
Now the environment I think is Win2000 higher.
If this method can't use, how do you set default printer ?

regards,

yu-yu

Re: How to set defaultprinter

Heath Stewart12-Mar-04 5:15

Heath Stewart

12-Mar-04 5:15

I'm on WinXP, but the WMI providers are pretty much universal (there's some that aren't supported in Win9X, but 2000 and above supports about the same functionality). You should go to MSDN[^] and download the WMI SDK to use the management application to see what's available. There's also a Server Explorer extension for management classes and events you can download for both VS.NET 2002 and 2003. Just search for "Server Explorer Management" on MSDN and you should find the links.

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Re: How to set defaultprinter

yu-yu14-Mar-04 16:43

yu-yu

14-Mar-04 16:43

Thanks,

I try to do.

regards,
yu-yu

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