Hi Activecat,
typical GUI problem; background is that X applications are inherently hard
to multithread, which basically requires graphical toolkits to run in a
main loop. This conflicts with every block being run in its own thread.
The easiest solution nowadays should be that you generate a QT flow graph
in GRC, use PyQT to generate your GUI, register a message handler and
integrate matplotlib (there are examples out there, just don't have one at
my fingertips right now), and use the message passing interface to get data
out of your flow graph into your GUI.
Greetings,
Marcus
On Fri, May 2, 2014 at 2:17 PM, Activecat <active...@gmail.com> wrote:
> Gurus,
>
> I try to transfer an image file via a pair of USRPs.
> At the receiver side, the data is fed into a custom block, where it plots
> the image in realtime using matplotlib's pyplot.imshow().
> Unfortunately, in the work() function, the pyplot.draw() causes below
> runtime error.
>
> handler caught exception: main thread is not in main loop
> Traceback (most recent call last):
> File "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/gateway.py",
> line 55, in eval
> try: self._callback()
> File "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/gateway.py",
> line 160, in __gr_block_handle
> ) for i in self.__out_indexes],
> File "/usr/local/lib/python2.7/dist-packages/activecat/image_sink1.py",
> line 72, in work
> self.axes1.figure.canvas.draw() #pyplot.draw()
> File
> "/usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py", line
> 349, in draw
> tkagg.blit(self._tkphoto, self.renderer._renderer, colormode=2)
> File "/usr/lib/pymodules/python2.7/matplotlib/backends/tkagg.py", line
> 13, in blit
> tk.call("PyAggImagePhoto", photoimage, id(aggimage), colormode,
> id(bbox_array))
> RuntimeError: main thread is not in main loop
> thread[thread-per-block[1]: <block image_sink1 (2)>]: caught unrecognized
> exception
>
>
> The custom block (perform plotting) is written in Python, as below:
>
> #!/usr/bin/env python
> # -*- coding: utf-8 -*-
>
> import numpy
> from gnuradio import gr
> from matplotlib import image, pyplot
>
> class image_sink1(gr.sync_block):
>
> def __init__(self):
> gr.sync_block.__init__( self, name="image_sink1",
> in_sig=[ numpy.complex64 ],
> out_sig=None)
>
> pyplot.figure()
> pyplot.ion()
> pyplot.show()
>
> self.axes1 = pyplot.gca()
> #self.win = self.axes1.figure.canvas.manager.window
> #self.win.after(100,animate)
>
> self.completed = False
> self.img2 = numpy.zeros( (150,150,4), numpy.uint8 )
>
> self.coordinate = self.coordinate_stream()
>
>
> def coordinate_stream(self):
> for y in range(150):
> for x in range( 0, 150, 2 ):
> yield y,x
>
> def work(self, input_items, output_items):
> in0 = input_items[0]
>
> if self.completed:
> return -1
>
> for sample1 in in0:
> try:
> y,x = next( self.coordinate )
>
> if sample1.real > 0:
> self.img2[y,x] = numpy.array([255,255,255,255])
> else:
> self.img2[y,x] = numpy.array([0,0,0,255])
>
> if sample1.imag > 0:
> self.img2[y,x+1] = numpy.array([255,255,255,255])
> else:
> self.img2[y,x+1] = numpy.array([0,0,0,255])
>
> except StopIteration:
> print "Receiver side completed!"
> self.complete = True
>
> self.axes1.imshow( self.img2 )
>
> self.axes1.figure.canvas.draw() # or, pyplot.draw(), both gives
> error !!!
>
> return in0.size
>
>
> Please advise,
> thanks in advance.
>
>
>
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>
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