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POEmbedding a matplotlib chart into Qt/C++ application
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copied!<p>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.</p> <p>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.</p> <p>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.</p> <p>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 ( <a href="http://matplotlib.org/api/backend_qt4agg_api.html">http://matplotlib.org/api/backend_qt4agg_api.html</a> ).</p> <p>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:</p> <pre><code>//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) </code></pre> <p>As I wrote, I must be missing something obvious. I googled everywhere but without success. Any help would be very appreciated.</p>

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