/*! \page page_qtgui QT Graphical User Interface

\section Introduction

This is the gr-qtgui package. It contains various QT-based graphical
user interface blocks that add graphical sinks to a GNU Radio
flowgraph. The Python namespaces is in gnuradio.qtgui, which would be normally
imported as:

\code
    from gnuradio import qtgui
\endcode

See the Doxygen documentation for details about the blocks available
in this package. The relevant blocks are listed in the \ref
qtgui_blk group.

A quick listing of the details can be found in Python after importing
by using:

\code
    help(qtgui)
\endcode


\section Dependencies

The QT GUI blocks require the following dependencies.

\li QtCore (version >= 4.4)
\li QtGui (version >= 4.4)
\li QtOpenGL (version >= 4.4)
\li PyQt4 for Qt4 (version >= 4.4)
\li Qwt (version >= 5.2)
\li PyQwt5 for Qt4 (version >= 5.2)

\section Usage

To use the qtgui interface, a bit of boiler-plate lines must be
included. First, the sink is defined, then it must be exposed from C++
into Python using the "sip.wrapinstance" command, and finally, the
"show" method is run on the new Python object. This sets up the QT
environment to show the widget, but the qApplication must also be
launched.

In the "main" function of the code, the qApp is retrieved. Then, after
the GNU Radio top block is started (remember that start() is a
non-blocking call to launch the main thread of the flowgraph), the
qapp's "exec_()" function is called. This function is a blocking call
while the GUI is alive.

\code
from PyQt4 import Qt
from gnuradio.qtgui import qtgui
import sys, sip

class grclass(gr.top_block):
    ....

    self.snk = qtgui.sink_c(1024,           #fftsize
    	       		    samp_rate,      #bw
			    "QT GUI Plot")  #name

    self.snk_win = sip.wrapinstance(self.snk.pyqwidget(), Qt.QWidget)
    self.snk_win.show()

def main():
    qapp = Qt.QApplication(sys.argv)
    tb = grclass()
    tb.start()
    qapp.exec_()
    tb.stop()


\endcode

*/