How to show warning message when an already opened file ismodified in external editor

[anupam roy]

Hi All,

I have one text editor application which can open XML files for editing.

Now when a file is aleady opened, i have opened the same file in an external editor(notepad or wordpad) and saved it.

In this scenario, how to throw a warning message to the XML editor, notifying that file has been chaged in an external editor and how to accept or reject that change?

I am using C# .NET

Thanks,
-Anupam

[hemantpatil]

hi
by using following code help you to solve problem

string    stringFileName ;
DateTime  openingtime;
        private void trim_Load(object sender, System.EventArgs e)
        {
            if(openFileDialog1.ShowDialog() == DialogResult.OK)
            {
              openingtime =Convert.ToDateTime( DateTime.Now.ToString());
                stringFileName = openFileDialog1.FileName ;
 
 
            }
        }
 
        private void button2_Click(object sender, System.EventArgs e)
        {
            FileInfo objFileSize = new         FileInfo(stringFileName);
            DateTime     dtCreateDate = objFileSize.CreationTime; 
            //GetLastWriteTime(stringFileName);
            DateTime dtModifyDate = objFileSize.LastWriteTime; 
            if(openingtime < dtModifyDate)
            {
                MessageBox.Show("file aready  modified");
            }
        }

[anupam roy]

hi
by using following code help you to solve problem

string    stringFileName ;
DateTime  openingtime;
        private void trim_Load(object sender, System.EventArgs e)
        {
            if(openFileDialog1.ShowDialog() == DialogResult.OK)
            {
              openingtime =Convert.ToDateTime( DateTime.Now.ToString());
                stringFileName = openFileDialog1.FileName ;
 
 
            }
        }
 
        private void button2_Click(object sender, System.EventArgs e)
        {
            FileInfo objFileSize = new         FileInfo(stringFileName);
            DateTime     dtCreateDate = objFileSize.CreationTime; 
            //GetLastWriteTime(stringFileName);
            DateTime dtModifyDate = objFileSize.LastWriteTime; 
            if(openingtime < dtModifyDate)
            {
                MessageBox.Show("file aready  modified");
            }
        }

Hi hemant,

Thanks a lot for your reply...but i have some doubts which i want to clarify.

If i am not wrong you have created two event handler classes
"button2_Click" and "trim_Load" and implemented your logic inside it.

But i m confused how to register the event handler and how shall i pass the name of the file in a correct way.

i have one class in which i have called the ShowEditor() function which will open the editor.

I have the editorfile name inside the class and its full path as of now.So after ShowEditor() is called i want to invoke the Watcher and start looking for any change in the file in some external editor(process)

Now i want to implement your code.

Could you provide me the way how i can acheive this?

Thanks and Regards,
-Anupam

[Plater]

I think there is a FileSystemWatcher that can be used for this?

System.IO.FileSystemWatcher sw = new System.IO.FileSystemWatcher("c:\", "filename.txt");
sw.Changed += new System.IO.FileSystemEventHandler(sw_Changed);
 

void sw_Changed(object sender, System.IO.FileSystemEventArgs e)
{//file has been changed
}
 

[anupam roy]

I think there is a FileSystemWatcher that can be used for this?

System.IO.FileSystemWatcher sw = new System.IO.FileSystemWatcher("c:\", "filename.txt");
sw.Changed += new System.IO.FileSystemEventHandler(sw_Changed);
 

void sw_Changed(object sender, System.IO.FileSystemEventArgs e)
{//file has been changed
}
 

Hi plater,

Thanks for the reply!!
I have already implemented FileSystemWatcher class.

My code is somewhat like this..

MyWatcherClass(editorFile.FullPath.ToString());... .editorfile is the file to be watched

public static void MyWatcherClass(string File)
{

FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path="C:\\abc\\xyz\\........";


/* Watch for changes for the specific file*/


watcher.Filter = "*.xml"; or even i can specify the file..


/* Watch for changes */
watcher.NotifyFilter = NotifyFilters.LastWrite;


// Add event handlers.
watcher.Changed += new FileSystemEventHandler(OnChanged);

//watcher.WaitForChanged;

watcher.EnableRaisingEvents = true;


}

private static void OnChanged(object source, FileSystemEventArgs e)
{
Type type=e.GetType();

WatcherChangeTypes type1=e.ChangeType;
// Specify what is done when a file is changed, created, or deleted.
MessageBox.Show("File: " + e.FullPath + " " + e.ChangeType);


}


but the problem is as soon as the watcher.EnableRaisingEvents = true is set t starts watching the file and throws the warning irrespective from where the file is accesssed.

But my requirement is iff and if only the file is modified from some external process(like notepad,wordpad) the warning message should generate.

But in this scenario, this is not the case,.
Even when the file is modified from my customised editor( the xml editor which is invoking or opening the file) its thrwing the warning message!!

Since we are not able to filter the process from where the file is accessed!! this is not helping me...

Hope i could make my point clear!!

Thanks,
-ANupam

[Plater]

Don't have your editor edit the file itself, but an in-memory copy of it.
Then it won't tip off the watcher

[anupam roy]

Don't have your editor edit the file itself, but an in-memory copy of it.
Then it won't tip off the watcher

Hi Plater!

Could you please kindly elaborate your comment.

I am not very sure how you wanted me to implement.

Can you please give some reference?


How to do the editing in an in-memory copy?

Thanks and Regards,
-ANupam!!

[Plater]

The contents of the file to a string, or a byte[] or something.
And than manipulate that. The watcher won't be tipped off until you go to "save" the data back to the file

[anupam roy]

The contents of the file to a string, or a byte[] or something.
And than manipulate that. The watcher won't be tipped off until you go to "save" the data back to the file

I could certainly understand ur point but i have a doubt like i have to atlast save the contents back to the file while closing the file from my customised editor itself....

So in this scenario, watcher will again throw the warning...

How to get rid off this scenario is my doubt!

Thanks a lot for your inputs!!

Regards,
-ANupam

[Plater]

Well when you actually WANT to do the saving, change a boolean value that the watcher handler function can look and decided if it need to "alert" you to the change?

[anupam roy]

Well when you actually WANT to do the saving, change a boolean value that the watcher handler function can look and decided if it need to "alert" you to the change?

Hi Plater,

I have declared a public static bool variable, which will decide whether the event handler function to show the warning message or not.

just before saving the file i am setting that variable to false so that it warning message is not thrown,but after the saving is done i am again setting this value to true.

Immeadiately after this the event handler function is throwing the warning message since file has been changed.

Is there any way i can stop the watcher?

By setting the value
FileSystemWatcher.EnableRaisingEvents =false will stop the watcher or the thread will keep running?

My intention is to stop the watcher when i am finally writing the file contents back and once it is done i should start the Watcher.

How to control this behaviour?

Regards,
-Anupam

[Plater]

setting enableraising events to false will just "pause" it i think.
You want the event to fire when you save it, you just want to ignore the event.

Or did it fire twice?