File modification alert from windows api

Hello!

I want my matlab program to receive a notification from or through the windows api whenever a file is externally modified (a picture) so that it can immediately load the new file. I am basically trying to avoid using a timer function as that one only looks for changes once a time interval and when i make the interval too small it produces problems.

Thanks!

[Oleg Komarov]

Too small how small?

[Image Analyst]

What problems do you get? What's wrong with a timer? What file parameters are you checking? The date/time via fileinfo()?

Answer 1

[Jiro Doke]

You may be able to use the .NET interface, using the FileSystemWatcher class.

Here's a simple example in MATLAB (assuming you have an image called "mypicture.jpg" in the current folder:

% Watch this folder
w = System.IO.FileSystemWatcher(pwd);

% Watch a particular image file
w.Filter = 'mypicture.jpg';

% Notify when the file changes
w.NotifyFilter = System.IO.NotifyFilters.LastWrite;

% Create a listener for change
addlistener(w, 'Changed', @changedFcn);

% Start watching.
w.EnableRaisingEvents = true;

You also need to create a function like this:

function changedFcn(obj, eData)

   fprintf('Changed: %s\n', char(eData.FullPath));

end

Try modifying the image.