C# Discussion Boards - CodeProject

Re: To know which file was opened by an application.

2-Feb-06 11:11

FileSytemWatcher is watching for changes. When you open a file, the OS puts a virtual lock on the file but does actually modify the file. But when a file is saved, the FSW will trigger the modify event.

- Malhar

yjoo93172-Feb-06 11:26

yjoo9317

2-Feb-06 11:26

Thanks for reply...
Yes,I know we can detect any changes if made to a file.

In case of pdf file,
The file will unlikely change.
What I want is that,
if I know msword or acrobat(these are examples) is running,
then I want to know which file was opened by the application.

Thanks..

Re: To know which file was opened by an application.

Dave Kreskowiak2-Feb-06 15:40

Dave Kreskowiak

2-Feb-06 15:40

There is no easy little API call to make. This will require a black belt in Windows internals. Not all expose an API to tell you what files that app has open, and most apps don't expose any kind of API at all.

You'd have to enumerate the handles of the process you're interested in, be it Word or Acrobat Reader. The problem is this technique is not documented anywhere, source code for it is very sparse, and it's all written in C++. You can find an example buried in the source for a Task Manager Extension, found right here[^] on CodeProject.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

Validation of WinForm Data

Wayne Phipps2-Feb-06 9:51

Wayne Phipps

2-Feb-06 9:51

Hi There,

I want to be able to validate data entered by a user onto a form.

Different fields will have different validation requirements.

As an example, a text box may only allow numeric, alpha or alpha numeric entry and/or may have limitations on length or value.

I thought about inheriting a control from one of the standard forms controls and adding the validation code required but was thinking that this would make the application heavier than necessary because certain fields only require certain validation.

I wanted a way to add validation only where required so thought of creating a validator object which could have various validationRule objects added as required.

The validator could respond to events like textChanged on a text box and where it would then check the rules that had been applied.

I thought that the validationRule object would be either abstract or impliment specific interface.

I like the GOF 'Chain of Responsibility' pattern as a way of getting the rule objects to respond to a message from the validator however, I don't know how to ensure that all the rule objects have received/responded to the message.

Does this concept make sense? Is this the best way to go about validating user input? Is this pattern appropriate in this example?

Your thoughts/ideas/comments appreciated.

Regards

Wayne Phipps
____________

Time is the greatest teacher... unfortunately, it kills all of its students
View my Blog

Pixel size of frame and control changed

xjsun2-Feb-06 9:35

xjsun

2-Feb-06 9:35

Hello,

I am having a very strange problem with my .NET/C# application and I need help here. Thank you very much.

The problem is that when I run my GUI program on one laptop (xp/sp2), the size of the frame and controls are somehome changed/stretched. I tried to adjust all sorts of windows settings but no help. I then brought the source code to the machine and run the .NET VS (1.1), what I found is that the size (pixels) of the frame and controls are changed automatically. I don't understand why it happens...Could anyone know about this issue?

Regards,
John

Re: Pixel size of frame and control changed

malharone2-Feb-06 11:15

Re: Pixel size of frame and control changed

2-Feb-06 11:15

Are you running an OS verion with Asian culture and/or using wide-screen monitor? (I had similar issue .. but couldnot find any relevant articles for the cause). I changed my entire UI to utilize docking (previously it used anchoring) and then UI problems disappeared.

- Malhar

xjsun7-Feb-06 8:09

xjsun

7-Feb-06 8:09

Thanks for the help. But I've found the cause of the problem and the solution (workaound) as well.

The cuase of the issue is by changing the DPI setting (under Display -> Settings -> Advanced). When the DPI is set to 120 instead of default 96, some of the controls will get this problem, ie. the picture box. To fix it, there is a workaround to add the following code after the InitializeComponent() in formMain().

SizeF sf = Form.GetAutoScaleSize (this.Font);
this.AutoScaleBaseSize = sf.ToSize ();

John

Re: Pixel size of frame and control changed

malharone7-Feb-06 8:11

7-Feb-06 8:11

Thanks .. I wonder if this is the cause of the problems I was having. Thanks for your input.

- Malhar

thread safe calls

Manu_812-Feb-06 8:37

Manu_81

2-Feb-06 8:37

Hi,
I posted this message earlier and some one posted a link to an article. It helped, but still I am confused how to do it in my scenario.
I have a HomeForm (main form which has main()). In one of its meathod I have

<br />
PrimeInfoThread pTh = new PrimeInfoThread(this.pictureBox1,this.panel4,this.button1,this.button3,this.SLabel);<br />
Thread t = new Thread(new ThreadStart(pTh.ThreadProc));<br />
t.Start();

PrimeInfoThread is another class as follows

public class PrimeInfoThread<br />
	{<br />
		private System.Windows.Forms.PictureBox hPic ;<br />
		private System.Windows.Forms.Panel hPan ;<br />
		private System.Windows.Forms.Button but1 ;<br />
		private System.Windows.Forms.Button but2 ;<br />
		private System.Windows.Forms.Label slab ;<br />
<br />
		// The constructor <br />
		public PrimeInfoThread(System.Windows.Forms.PictureBox hP,<br />
								System.Windows.Forms.Panel hpanel,<br />
								System.Windows.Forms.Button b1,<br />
								System.Windows.Forms.Button b2,<br />
								System.Windows.Forms.Label Sl) <br />
		{<br />
			hPic = hP;<br />
			hPan = hpanel;<br />
			but1 = b1;<br />
			but2 = b2;<br />
			slab = Sl;<br />
		}<br />
<br />
		public void ThreadProc() <br />
		{<br />
			EnumGetEDID InitEnumObj = new EnumGetEDID();<br />
			InitEnumObj.AppInitEnum(slab);	<br />
			hPic.Hide();<br />
			hPan.Hide();<br />
			but1.Show();<br />
			but2.Show();<br />
			<br />
		}<br />
<br />
	}

In threadProc I call another class EnumGetEDID and call AppInitEnum(slab) where I pass the label. Inside AppInitEnum() I do 'slab.Text' to set the text values.
Now how do I make this Thread safe. Can anyone show it in my code.
Thanks a lot.

kasik2-Feb-06 9:35

2-Feb-06 9:35

It seems to me that you're making this more complicated than it needs to be with the use of an entirely seperate class (PrimeInfoThread) to run your other thread. Why don't you just have a method in your HomeForm class called ThreadProc() and then reference the UI components (labels, buttons, etc...) without passing them to another object. You can use the ParameterizedThreadStart delegate to pass the label 'slab' - although it might make more sense to just pass the string value of its Text property if thats the only reason you need it... If you do that, then the following code should make it thread safe...

This goes in the routine that starts the thread:

Thread t = new Thread(new ParameterizedThreadStart(ThreadProc));
t.Start(this.SLabel);

Then this in HomeForm:

private void ThreadProc(object data)
{
	EnumGetEDID InitEnumObj = new EnumGetEDID();
	InitEnumObj.AppInitEnum((Label)data); 
	UpdateUI();
}

private delegate void UpdateUIDelegate();
private void UpdateUI()
{
	if (this.InvokeRequired)
	{
		this.BeginInvoke(new UpdateUIDelegate(UpdateUI));
		return;
	}
	pictureBox1.Hide();
	panel4.Hide();
	button1.Show();
	button3.Show();
}

Hope this helps Smile | :)

Oh... forgot to say that this uses .Net Framework v2, since the ParameterizedThreadStart delegate isn't available in v1.1 D'Oh! | :doh:

Cheers,
Will H

-- modified at 15:41 Thursday 2nd February, 2006

eligazit2-Feb-06 10:50

eligazit

2-Feb-06 10:50

If you use the 2.0, try to use the BackgroundWorker, it gives the abilty to update without the cross-thread exception.

kasik2-Feb-06 11:01

2-Feb-06 11:01

Thanks. I've only recently started using 2.0 in the last few days. I'll definitely look into that one.

Cheers,
Will H

kasik2-Feb-06 11:19

2-Feb-06 11:19

I just gave the BackgroundWorker class a whirl, and I don't think it does allow you to update the UI from a seperate thread. Maybe I miss-read your meaning, but I took the C# code from the example in the MSDN library (here[^]), then I added the line this.Text = percentComplete + "%"; just after worker.ReportProgress(percentComplete); in the ComputeFibonacci method (the one that's running on the seperate thread), and this caused a System.InvalidOperationException - a cross thread exception Confused | :confused:

Cheers,
Will H

Dave Kreskowiak2-Feb-06 15:29

Dave Kreskowiak

2-Feb-06 15:29

You can only update UI controls on the thread that created them. Property updates and method calls on those controls must be marshalled back onto the UI thread. Lookup Control.Invoke for more information.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

kasik3-Feb-06 2:26

3-Feb-06 2:26

I know that. In this[^] thread I tried to explain that, but was told by eligazit that the BackgroundWorker class could let you get around this.

Cheers,
Will H

Dave Kreskowiak3-Feb-06 3:07

Dave Kreskowiak

3-Feb-06 3:07

It doesn't "get around it". It just fire an event on the correct thread. It insulates you from the details of getting code that modifies a UI control to run on the correct thread.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

eligazit2-Feb-06 20:42

eligazit

2-Feb-06 20:42

To update GUI with the BackgroundWorker, you need to do the following steps:
1. When creating the wroker:
public void InitWorker()
{
worker = new BackgroundWorker();
worker.WorkerReportsProgress = true;
worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
worker.DoWork += new DoWorkEventHandler(worker_DoWork);
}
Note that I've creating new event handler to update GUI, when ever I want to set something on the GUI, I should call the ReportProgress(...) method of the worker:

void worker_DoWork(object sender, DoWorkEventArgs e)
{

// Some long operation
// .....
Thread.Sleep(2000);
// Update GUI
worker.ReportProgress(30);
// Some long operation
// .....
Thread.Sleep(2000);
// Update GUI
worker.ReportProgress(60);
// Some long operation
// .....
Thread.Sleep(2000);
// Update GUI
worker.ReportProgress(90);

}

And, on the ReportProgress handler, I can update the GUI as I want, this is beacuse the worker handles moving the OS the the right thread so it is not my problem...

void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
Label label;
label.Text = e.ProgressPercentage + "%";
}

Note that on the ReportProgress you can send an object that will be set on the ProgressChangedEventArgs (State), in this property you can set all the values you want to update on the GUI (other than the precentage).

kasik3-Feb-06 2:32

transferring vb.net solution to c#.net

3-Feb-06 2:32

Ah... i see. Thanks Smile | :)

Cheers,
Will H

kourvoisier2-Feb-06 8:34

kourvoisier

2-Feb-06 8:34

I have a complete API all in vb.net.

I need to view all code and run all code in visual studio express edition c#

How do i do this?

please tell me this is possible (it has got to be)

Re: transferring vb.net solution to c#.net

malharone2-Feb-06 11:19

Re: transferring vb.net solution to c#.net

2-Feb-06 11:19

You can use Lutz Roeder's .NET Reflector (FYI: very nice tool) to anlyze the IL code.
http://www.aisto.com/roeder/dotnet/[^]

kourvoisier2-Feb-06 11:20

kourvoisier

2-Feb-06 11:20

your link is an error

Re: transferring vb.net solution to c#.net

malharone2-Feb-06 11:41