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Facts about MATLAB:

  1. MATLAB UI is Java Swing.
  2. MATLAB has excellent interoperability with Java, it is possible to initialize Java objects and call their methods directly from MATLAB code, it is even possible to pass in MATLAB defined listeners to Java!

My problem:

MATLAB does not offer background threads, so to make MATLAB UI responsive we have to call function drawnow which flushes Swing EDT queue, see also here and here. This is a known fact, so far so good.

But now I have a customer whose code which performs the computation is a MATLAB p-file (encrypted) so I have no access to the code to put drawnow there.

Unsuccessful attempt:

I tried spinning up a timer to do the job of calling drawnow but it does not seem to work - timer itself needs a precedent drawnow to fire its callbacks.

EDIT: At the end I implemented GUI with .NET/WPF running on another thread, so it remains always responsive and looks much better then original MATLAB.

Community
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Mikhail Poda
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2 Answers2

7

I don't know whether this can be done properly. I've never found a way of getting the effect of drawnow in the middle of a mex file, and I would guess this situation is similar. But here is an incredibly messy hack anyway :D. If you have a p-file, you can run:

profile on;
pfile();
profile viewer;

and get an idea of what functions pfile() is calling. If the code is calling any built-in functions (e.g. disp) or any function whose source-code you have access to, you can create your own version of that file further up the path, which will be called by the p-file, e.g.

function disp(X)
  if (toc > 5)
    drawnow;
    tic;
  end
  builtin('disp', X);

This will call drawnow at most once every 5 seconds, though it won't be much use unless disp were called regularly. If you can't find a builtin to override, you could use any other function and just insert the drawnow part at the top, like:

function primes(N)
  if (toc > 5)
    drawnow;
    tic;
  end
  The rest of the original primes.m here.
Richante
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  • Very clever! What about visibility/precedence when I override (a) built-in function like `disp` (b) user defined function like `primes`, which is possibly p-coded itself? – Mikhail Poda Apr 07 '12 at 18:24
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    It's quite messy. I thought that there was always a way to specifically refer to a function (even if it was override), but I can't find it now. As I understand it, `path` defines exactly which functions are visible. Any other overriden functions don't seem to be accessible, except for built-in functions, where `builtin(...)` lets you access them. I don't think p-coded-ness affects visibility/precedence: if there is a function with the same name further up the path then it will have precedence. – Richante Apr 07 '12 at 20:02
2

Just an idea. You could build a jar file from the p-file using Matlab builder for java. From within Java you could do the calculation now in a separate thread.

bdecaf
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