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  1. 7th July 2020, 17:51 #1
    SaibotMagd
    SaibotMagd is offline Beginner
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    Default QApplication Process seems to hang

    Hello,

    I'm a somewhat programming and python nooby and I have to implement a pipeline in my institut. A researcher create a dataviewer in the tutorial file using PyQt5 but even the test-function push the process into a hanging state (kernel is forced to restart after the window is terminated). i.e. it creates a pop-up window with the correct name and resolution but the window itself is black without any widgets and it halts immediately.

    I know it's a somewhat impossible mission to find the solution but maybe someone got a climse of a idea what I could try next.

    Qt Code: 
    1. class DataViewer(pg.QtGui.QWidget):
    2.   def __init__(self, source, axis = None, scale = None, title = None, invertY = False, minMax = None, screen = None, parent = None, *args):        
    3.  
    4.     ### Print pointer to QApplication Instance (we now know that at this time a QApp is initalized)
    5.     print(pg.QtGui.QApplication.instance())    
    6.     print(pg.QtGui.QApplication.allWidgets())
    7.  
    8.     ### Images soures
    9.     self.initializeSources(source, axis = axis, scale = scale)
    10.     #print('init')
    11.     ### Gui Construction
    12.     pg.QtGui.QWidget.__init__(self, parent, *args);
    13.     #print('gui')    
    14.  
    15.     if title is None:
    16.       if isinstance(source, str):
    17.         title = source;
    18.       elif isinstance(source, io.src.Source):
    19.         title = source.location;
    20.       if title is None:
    21.         title = 'DataViewer';                             
    22.     self.setWindowTitle(title);
    23.     self.resize(1600,1200)      
    24.     #print('title')
    25.  
    26.  
    27.     self.layout = pg.QtGui.QGridLayout(self);
    28.     self.layout.setContentsMargins(0,0,0,0)     
    29.     #print('layout')
    30.  
    31.     # image pane
    32.     self.view = pg.ViewBox();
    33.     self.view.setAspectLocked(True);
    34.     self.view.invertY(invertY)    
    35.  
    36.     self.graphicsView = pg.GraphicsView()
    37.     self.graphicsView.setObjectName("GraphicsView")
    38.     self.graphicsView.setCentralItem(self.view)
    39.  
    40.     splitter = pg.QtGui.QSplitter();
    41.     splitter.setOrientation(pg.QtCore.Qt.Horizontal)
    42.     splitter.setSizes([self.width() - 10, 10]);
    43.     self.layout.addWidget(splitter);
    44.  
    45.     image_splitter = pg.QtGui.QSplitter();
    46.     image_splitter.setOrientation(pg.QtCore.Qt.Vertical)
    47.     image_splitter.setSizePolicy(pg.QtGui.QSizePolicy.Expanding, pg.QtGui.QSizePolicy.Expanding)
    48.     splitter.addWidget(image_splitter);
    49.     #print('image')
    50.  
    51.     #  Image plots
    52.     image_options = dict(clipToView = True, autoDownsample = True, autoLevels = False, useOpenGL = None);
    53.     self.image_items = [pg.ImageItem(s[self.source_slice[:s.ndim]], **image_options) for s in self.sources];
    54.     for i in self.image_items:
    55.       i.setRect(pg.QtCore.QRect(0, 0, self.source_range_x, self.source_range_y))
    56.       i.setCompositionMode(pg.QtGui.QPainter.CompositionMode_Plus);
    57.       self.view.addItem(i);
    58.     self.view.setXRange(0, self.source_range_x);
    59.     self.view.setYRange(0, self.source_range_y);
    60.     #print('plots')
    61.  
    62.     # Slice Selector
    63.     self.slicePlot = pg.PlotWidget()
    64.     sizePolicy = pg.QtGui.QSizePolicy(pg.QtGui.QSizePolicy.Preferred, pg.QtGui.QSizePolicy.Preferred)
    65.     sizePolicy.setHorizontalStretch(0)
    66.     sizePolicy.setVerticalStretch(0)
    67.     sizePolicy.setHeightForWidth(self.slicePlot.sizePolicy().hasHeightForWidth())
    68.     self.slicePlot.setSizePolicy(sizePolicy)
    69.     self.slicePlot.setMinimumSize(pg.QtCore.QSize(0, 40))
    70.     self.slicePlot.setObjectName("roiPlot");    
    71.     #self.sliceCurve = self.slicePlot.plot()
    72.  
    73.     self.sliceLine = pg.InfiniteLine(0, movable=True)
    74.     self.sliceLine.setPen((255, 255, 255, 200))
    75.     self.sliceLine.setZValue(1)
    76.     self.slicePlot.addItem(self.sliceLine)
    77.     self.slicePlot.hideAxis('left')
    78.  
    79.     self.updateSlicer();
    80.  
    81.     self.sliceLine.sigPositionChanged.connect(self.updateSlice)
    82.     #print('slice')
    83.  
    84.     # Axis Tools
    85.     axis_tools_layout = pg.QtGui.QGridLayout()
    86.     self.axis_buttons = [];
    87.     axesnames = ['x', 'y', 'z'];
    88.     for d in range(3):
    89.       button = pg.QtGui.QRadioButton(axesnames[d]);
    90.       button.setMaximumWidth(50);
    91.       axis_tools_layout.addWidget(button,0,d);
    92.       button.clicked.connect(ft.partial(self.setSliceAxis, d));
    93.       self.axis_buttons.append(button);
    94.     self.axis_buttons[self.source_axis].setChecked(True);
    95.     axis_tools_widget = pg.QtGui.QWidget();
    96.     axis_tools_widget.setLayout(axis_tools_layout);
    97.     #print('axis')
    98.  
    99.     # coordinate label
    100.     self.source_pointer = [0,0,0];
    101.     self.source_label = pg.QtGui.QLabel("");
    102.     axis_tools_layout.addWidget(self.source_label,0,3);
    103.  
    104.     self.graphicsView.scene().sigMouseMoved.connect(self.updateLabelFromMouseMove);
    105.     #print('coords')
    106.  
    107.     #compose the image viewer
    108.     image_splitter.addWidget(self.graphicsView);
    109.     image_splitter.addWidget(self.slicePlot)
    110.     image_splitter.addWidget(axis_tools_widget); 
    111.     image_splitter.setSizes([self.height()-35-20, 35, 20])
    112.     #print('viewer')
    113.  
    114.     # lut widgets
    115.     if self.nsources == 1:
    116.       cols = ['flame'];
    117.     elif self.nsources == 2:
    118.       cols = ['purple', 'green'];
    119.     else:
    120.       cols = np.array(['white', 'green','red', 'blue', 'purple'] * self.nsources)[:self.nsources];
    121.  
    122.     self.luts = [LUT(image = i, color = c) for i,c in zip(self.image_items, cols)];
    123.  
    124.     lut_layout = pg.QtGui.QGridLayout();
    125.  
    126.     lut_layout.setContentsMargins(0,0,0,0);
    127.     for d,l in enumerate(self.luts):
    128.       lut_layout.addWidget(l,0,d);  
    129.     lut_widget = pg.QtGui.QWidget();    
    130.     lut_widget.setLayout(lut_layout);
    131.     lut_widget.setContentsMargins(0,0,0,0);
    132.     lut_widget.setSizePolicy(pg.QtGui.QSizePolicy.Preferred, pg.QtGui.QSizePolicy.Expanding)
    133.     splitter.addWidget(lut_widget);
    134.  
    135.     splitter.setStretchFactor(0, 1);
    136.     splitter.setStretchFactor(1, 0);
    137.  
    138.     # update scale
    139.     for l in self.luts:
    140.       l.range_buttons[1][2].click();
    141.     if minMax is not None:
    142.       self.setMinMax(minMax);
    143.  
    144.     self.show();
    145.     print(pg.QtGui.QApplication.instance())
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    What I found out till now:
    • the "allWidget()" function print out all widgets collected by the QApp. and this works finde
    • the code runs till the end (I got a instance pointer at the beginning and in the end; there're the same)
    • I tried several PyQt examples to test for openGL or non openGL Outputs and they all worked fine
    • there's no out-of-memory or CPU overload
    • I tried to cut the code per widget to find the issue, but whatever line of code I commented out no window pops-up anymore
    • I found this great article: https://doc.qt.io/archives/qq/qq27-r...tml#conclusion Could it be something like that?


    Like I said I'm not a programmer and I didn't write the code myself (the author don't answer right now). Its overwhelming but I have to find a solution. Any ideas what I could try next? Anything would be helpful.
    Last edited by SaibotMagd; 7th July 2020 at 17:57.
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