Chaco和PyQt发出信号失败

Question

我试图与Chaco和pyqt一起绘制实验室硬件的实时数据采集任务。我以前使用matplotlib，但它证明太慢了（我甚至尝试过动画）。当我在pyqt窗口中嵌入一个matplotlib图时，下面的代码工作的很好，但是当使用chaco时，当我从线程内部发出更新信号时没有任何反应。如果您不使用线程进行模拟采集，此代码将起作用。我曾尝试使用qthreads也无济于事（包括这样的事情：Threading and Signals problem in PyQt）。有没有人使用pyqt + chaco +线程来帮助我找到错误的地方，或者发生了什么？

import sys 
import threading, time 
import numpy as np 

from enthought.etsconfig.etsconfig import ETSConfig 
ETSConfig.toolkit = "qt4" 

from enthought.enable.api import Window 
from enthought.chaco.api import ArrayPlotData, Plot 

from PyQt4 import QtGui, QtCore 


class Signals(QtCore.QObject): 
    done_collecting = QtCore.pyqtSignal(np.ndarray, np.ndarray) 

class PlotWindow(QtGui.QMainWindow): 
    def __init__(self): 
     QtGui.QMainWindow.__init__(self) 

     x = np.linspace(0,2*np.pi,200) 
     y = np.sin(x) 
     plotdata = ArrayPlotData(x=x, y=y) 
     plot = Plot(plotdata, padding=50, border_visible=True) 
     plot.plot(('x', 'y')) 

     window = Window(self,-1, component=plot) 
     self.setCentralWidget(window.control) 
     self.resize(500,500) 

     self.pd = plotdata 

    def update_display(self, x, y): 
     print 'updating' 
     self.pd.set_data('x', x) 
     self.pd.set_data('y', y) 


def run_collection(signal): 
    # this is where I would start and stop my hardware, 
    # but I will just call the read function myself here 
    for i in range(1,10): 
     every_n_collected(i, signal) 
     time.sleep(0.5) 

def every_n_collected(frequency, signal): 
    # dummy data to take place of device read 
    x = np.linspace(0,2*np.pi,200) 
    y = np.sin(x*frequency) 
    print 'emitting' 
    signal.emit(x, y) 
    QtGui.QApplication.processEvents() 

def main(): 
    plt = PlotWindow() 
    plt.show() 
    QtGui.QApplication.processEvents() 

    signals = Signals() 
    signals.done_collecting.connect(plt.update_display) 

    t = threading.Thread(target=run_collection, args=(signals.done_collecting,)) 
    t.start() 
    t.join() 
    QtGui.QApplication.processEvents()  

    # it works without threads though... 
    # run_collection(signals.done_collecting) 

if __name__ == "__main__": 
    app = QtGui.QApplication(sys.argv) 
    main() 

Answer 1

您在主线程（即UI线程）上加入的呼叫阻止该线程并阻止事件由UI处理。如果您在主函数中启动app/GUI事件循环并等待应用程序在不调用t.join（）的情况下关闭，它应该可以正常工作。

这是使用常规Traits/TraitsUI/Chaco应用程序的方法。

import time 
import threading 

import numpy as np 

from traits.etsconfig.etsconfig import ETSConfig 
ETSConfig.toolkit = "qt4" 

from enable.api import ComponentEditor 
from chaco.api import ArrayPlotData, Plot 

from traits.api import Event, HasTraits, Instance 
from traitsui.api import View, Item 

class PlotWindow(HasTraits): 

    dataset = Instance(ArrayPlotData) 
    plot = Instance(Plot) 

    def _dataset_default(self): 
     x = np.linspace(0,2*np.pi,200) 
     y = np.sin(x) 
     plotdata = ArrayPlotData(x=x, y=y) 
     return plotdata 

    def _plot_default(self): 
     plot = Plot(self.dataset, padding=50, border_visible=True) 
     plot.plot(('x', 'y')) 
     return plot 

    def update_display(self, x, y): 
     print 'updating', threading.current_thread() 
     self.dataset.set_data('x', x) 
     self.dataset.set_data('y', y) 

    traits_view = View(
     Item('plot', editor=ComponentEditor(size=(400, 400)), show_label=False) 
    ) 

def run_collection(datamodel): 
    # this is where I would start and stop my hardware, 
    # but I will just call the read function myself here 
    for i in range(1,10): 
     x = np.linspace(0,2*np.pi,200) 
     y = np.sin(x*i) 
     datamodel.update_display(x, y) 
     time.sleep(0.5) 

def main(): 
    plot = PlotWindow() 

    t = threading.Thread(target=run_collection, args=(plot,)) 
    t.start() 

    # Starts the UI and the GUI mainloop 
    plot.configure_traits() 

    # don't call t.join() as it blocks the current thread... 

if __name__ == "__main__": 
    main()