I am developing an math-oriented GUI application in Qt/C++ and would like to embed a Python scripting, including NumPy and Matplotlib. Using Python C API, I finally managed to run a script, retrieve the values from the Python variables, including NumPy arrays etc. But I failed at drawing Matplotlib charts into my Qt/C++ application.
It is better to say, I have managed to save the chart's RGBA buffer to a variable using Python script, then get the value of the variable as a PyObject of buffer type, get the buffer and transform it to QImage then to QPixmap and finally put it into QLabel and display it.
But I am still missing its interactive behaviour, resizing etc. though it seems that it can be done by forwarding Qt mouse events to figure.canvas.button_press_event but it is then getting overly complicated... So I concluded I do not understand the principles of Python embedding well enough. I am missing something obvious.
I found some samples of embedding matplotlib charts into PyQt or PySide (i.e. written in Python) applications where I have seen something like QMainWindow.setCentralWidget(canvas) or layout.addWidget(canvas). Here canvas is FigureCanvasQTAgg object ( http://matplotlib.org/api/backend_qt4agg_api.html ).
This suggests that canvas inherits from QWidget. But when I try mimic this in C++ code using Python's C API, I end with just a PyObject *canvas, not knowing how to trasform it to a QWidget. This is my snippet without the important step:
//draw a figure in Python script called from C++ app
PyRun_SimpleString("import matplotlib\n"
"matplotlib.use('Qt4agg')\n" //use Qt4 backend
"import pylab\n"
"pylab.plot(randn(10))\n" //plot something
"fig = pylab.gcf()\n" //take current figure
"canvas = fig.canvas" //canvas is of FigureCanvasQTAgg type
//get canvas as PyObject
PyObject* m = PyImport_AddModule("__main__");
PyObject* canvas = PyObject_GetAttrString(m, "canvas");
//from what I know, canvas is a PyObject wrapped around an object derived from QWidget
//...
//... here I do not know how to convert canvas (i.e. PyObject) into canvasWidget (i.e. QWidget)???
//...
//show chart as a widget
MyWindow.setCentralWidget(canvasWidget)
As I wrote, I must be missing something obvious. I googled everywhere but without success. Any help would be very appreciated.
