Dynamically add functions to qt program

[magland]

what are the examples of the plugin functions? I need to teach the students how to create their own plugins too so I need to document it. I sort of need to create my own API for it.

Here is an example of the ChainLink "rand" plugin function which returns a random multi-dimensional array of numbers.

//[function] rand
//input: integer [N1], integer [N2], integer [N3], integer [N4], integer [N5], integer [N6]
//output: mda ret
//description: define a multidimensional array of random numbers
bool rand(mda &ret, integer N1=-1, integer N2=-1, integer N3=-1, integer N4=-1, integer N5=-1,integer N6=-1);

//[function] rand
//input: integer [N1], integer [N2], integer [N3], integer [N4], integer [N5], integer [N6]
//output: mda ret
//description: define a multidimensional array of random numbers
bool rand(mda &ret, integer N1=-1, integer N2=-1, integer N3=-1, integer N4=-1, integer N5=-1,integer N6=-1);

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... and the implementation ...

bool rand(mda &ret, integer N1, integer N2, integer N3, integer N4, integer N5,integer N6) {
	ret.allocate(MDA_TYPE_REAL,N1,N2,N3,N4,N5,N6);
	int32 j;
	for (j=0; j<ret.size(); j++)
		ret.set((real)rand()/RAND_MAX,j);
	return true;
}

bool rand(mda &ret, integer N1, integer N2, integer N3, integer N4, integer N5,integer N6) {
	ret.allocate(MDA_TYPE_REAL,N1,N2,N3,N4,N5,N6);
	int32 j;
	for (j=0; j<ret.size(); j++)
		ret.set((real)rand()/RAND_MAX,j);
	return true;
}

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This is the kind of thing that the students would need to write to create custom functions. Here mda is a fundamental datatype in chaninlink (multi-dimensional array).

From the console it would just be

> X=rand(100,100);
> viewmda(X);

I really would like to get everything going with the QGraphicsView Framework, even the application of the image processing function. But if there's no other way to use the functions, the second step, "> Y = my_processing_function(X)" is alright

The QGraphicsView framework would certainly be possible even from within chainlink.

JM

[sincnarf]

So my natural question would be "why?".

C++ is already the standard P.L. for image processing in this university. Maybe because as compared to other programming languages that are taught here (Java, C, Matlab, etc ) C++ is the fastest on image sequences and the instructors already made their own libraries using C++. So as much as possible they would want to integrate their libraries to other future C++ programs created by us students.

But you can provide a template that uses Qt and students can fill that template using pure C++ (or whatever they like in fact, including QtScriptEngine)

Hmmm, how can I find examples of such templates that can be filled?

[wysota]

C++ is already the standard P.L. for image processing in this university. Maybe because as compared to other programming languages that are taught here (Java, C, Matlab, etc ) C++ is the fastest on image sequences and the instructors already made their own libraries using C++. So as much as possible they would want to integrate their libraries to other future C++ programs created by us students.

So why do you want to taint your pure C++ libraries with Qt code? If people were always thinking like that we'd be still writing our programs in binary code or assembly.

You won't be able to use Qt plugins in other non-Qt based applications in a straightforward way anyway. And if you'll want to incorporate Qt into them, you'll be able to incorporate the script engine as well. So the question still stands.

And the link you requested: http://doc.trolltech.com/latest/plug...t-applications

[sincnarf]

So why do you want to taint your pure C++ libraries with Qt code? If people were always thinking like that we'd be still writing our programs in binary code or assembly.

I really am not sure, I'm not the one who selected the use of Qt anyway. Maybe because Qt is a fast way to build GUI (compared to others?), and Qt has a large base of users nowadays. So we want to be with the Qt community. Something like that.

[wysota]

I really am not sure, I'm not the one who selected the use of Qt anyway.

The only thing I'm saying is that maybe you should discuss (discuss, not ask) it with the person who introduced the C++ requirement. Maybe it's not important at all and you'll save yourself time and effort trying to implement automatic recompilation and reloading of C++ plugins into your application and you'll help the students using the application. I guess you could even use ChainLink as your base application and implement your image manipulating functionality there not having to write a single line of C++ code.

[sincnarf]

The only thing I'm saying is that maybe you should discuss (discuss, not ask) it with the person who introduced the C++ requirement. Maybe it's not important at all and you'll save yourself time and effort trying to implement automatic recompilation and reloading of C++ plugins into your application and you'll help the students using the application. I guess you could even use ChainLink as your base application and implement your image manipulating functionality there not having to write a single line of C++ code.

Well, just asked him a while ago. He's my adviser for my S.P. (Special Problem) - sort of like a thesis. He requires that I make the template for the students in pure C++ or mix of C++/Qt. End of story guru wysota..

Anyway I saw the Plug and Paint example in the Qt examples. The Filter Interface is the perfect example of what I want to implement... Although I don't know where pnp_extrafilters.dll came from. How can I make a template based on pnp_extrafilters? I want to create a modified pnp_extrafilters.dll that can select what widget it will apply its functions on. Will this be hard and does creating my own dll satisfy the requirement that i only use pure C++ or mix of C++/Qt? If not, then I have to make an extra effort in teaching other students how to create their own dlls that are not pure c++ / mix of c++/qt

[wysota]

Look at the link I gave you in #23.

BTW. I suggest you implement a QtScript-enabled plugin anyway, just to have an option Especially that it's only a few lines of code...

[sincnarf]

Okay .. . error here

g++ -enable-stdcall-fixup -Wl,-enable-auto-import -Wl,-enable-runtime-pseudo-reloc -mthreads -Wl -Wl,-subsystem,windows -o "debug\SP.exe" object_script.SP.Debug -L"c:\Qt\4.3.1\lib" -L"c:\Qt\4.3.1\lib" -lmingw32 -lqtmaind -LC:/Qt/4.3.1/IADFUQ/SP/plugins -lpnp_extrafiltersd -lQtGuid4 -lQtCored4
./tmp\obj\debug_shared\main.o: In function `ZN5QListI7QStringE13node_destructEPNS1_4NodeES3_' :C:/Qt/4.3.1/IADFUQ/SP/../../include/QtCore/../../src/corelib/thread/qatomic.h.text$_ZN36Staticpnp_extrafiltersPluginInstanceC1E v[Staticpnp_extrafiltersPluginInstance::Staticpnp_ex trafiltersPluginInstance()]+0x9): undefined reference to `qt_plugin_instance_pnp_extrafilters()'
collect2: ld returned 1 exit status
mingw32-make[1]: *** [debug\SP.exe] Error 1
mingw32-make[1]: Leaving directory `C:/Qt/4.3.1/IADFUQ/SP'
mingw32-make: *** [debug-all] Error 2

[wysota]

Ok, but what is it?

[sincnarf]

Ok, but what is it?

error solved. still have the dilemma on the template that's supposed to be filled by my students (with pure c++ code)

[sincnarf]

Ok, but what is it?

error solved. still have the dilemma on the template that's supposed to be filled by my students (with pure c++ code)

Thanks for all the suggestions especially on chainlink i'm trying to study this still

[sincnarf]

Look at the link I gave you in #23.

BTW. I suggest you implement a QtScript-enabled plugin anyway, just to have an option Especially that it's only a few lines of code...

I think I really may have to use QtScript after all if I want to pursue Linux support for this system. Now studying QtScript. Thanks again for all comments and suggestions.