Wie gehe ich mit einem Matplotlib-Pick-Artist-Ereignis in einem dynamisch erstellten QMdiAreaSubWindow um?(Beispiel gegeben – teilweise funktionsfähig!)

Question

Ich versuche, eine Qt4-Anwendung mit Python und Matplotlib zu erstellen, aber ich bin in einem Verhalten stecken geblieben, das mir nicht ganz klar ist.

Diese Anwendung verfügt über eine QMdiArea, die die dynamisch erstellten Diagramme in einzelnen Unterfenstern speichert.Alles scheint gut zu funktionieren, außer den Artist Picking Events, die zuvor beim Plotten der Daten definiert wurden.Anscheinend wird die „pick_event“ mpl_connection gelöscht, wenn eine QMdiAreaSubWindow-Instanz innerhalb der MainWindow-Klasse erstellt wird.

Kurioserweise, wenn derselbe Codeabschnitt außerhalb der MainWinddow-Anwendung ausgeführt wird.

Ich habe eine vereinfachte Version meines Codes geschrieben, um das Verhalten zu reproduzieren, und vielleicht könnte mir jemand einen Hinweis darauf geben, was ich falsch mache.

Prost!

#!/usr/bin/python
import sys
from PyQt4.QtGui import QWidget, QPushButton, QMainWindow, QMdiArea, QVBoxLayout, QApplication
from PyQt4.QtCore import Qt

from pylab import *
from matplotlib.backends.backend_qt4agg import (
    FigureCanvasQTAgg as FigureCanvas,
    NavigationToolbar2QTAgg as NavigationToolbar)
from matplotlib.backend_bases import key_press_handler


class MyMainWindow(QMainWindow):
    """ Defines a simple MainWindow with a QPushButton that plots a Random Wave Fucntion
    which must be shown in a Window within a QMdiArea Widget.
    """

    def __init__(self, parent=None):
        """
        """

        super(MyMainWindow,self).__init__(parent)
        self.setWidgets()

    def setWidgets(self, ):
        """ Createsthe QPushButton and QMdiArea Widgets, organising them in 
        QVBoxLayout as a central Widget of the MainWindow
        """

        vBox = QVBoxLayout()
        mainFrame = QWidget()

        self._plotGraphButton = QPushButton("Plot Graph")
        self._plotGraphButton.clicked.connect(self.plotRandom)

        self._mdiArea = QMdiArea()
        vBox.addWidget(self._plotGraphButton)
        vBox.addWidget(self._mdiArea)

        mainFrame.setLayout(vBox)
        self.setCentralWidget(mainFrame)


    # This is the function called when the Plot Graph Button is pressed
    #and where the Picking event does not work.
    # When the button is pressed a new window with the plot is shown, but
    #it is not possible to drag the rectangle patch with the mouse.
    def plotRandom(self, ):
        """ Generates and Plots a random wave function (+noise) embedding into a 
        QMdiAreaSubWindow.
        """
        print "Plotting!!"
        x = linspace(0,10,1000)
        w = rand(1)*10
        y = 100*rand(1)*sin(2*pi*w*x)+rand(1000)

        p = PlotGraph(x,y)
        child = self._mdiArea.addSubWindow(p.plotQtCanvas())
        child.show()



class PlotGraph(object):
    """
    """

    def __init__(self, x,y):
        """ This class plots the data and encapsulates the figure instance in a FigureCanvasQt4Agg,
        which can be used to create a QMdiArea SubWindow.
         A rectangle patch is added to the plot and linked to the methods that
        can drag it horizontally in the graph.

        Arguments:
        - `x`: Data
        - `y`: Data
        """
        self._x = x
        self._dx = x[1]-x[0]
        self._y = y


    def _createPlotWidget(self, ):
        """ Creates a figure and a NavigationBar organising them vertically into a QWidget,
        which can be used by a QMdiArea.addSubWindow method.
        """
        self._mainFrame = QWidget()

        self._fig = figure(facecolor="white")
        self._canvas = FigureCanvas(self._fig)
        self._canvas.setParent(self._mainFrame)
        self._canvas.setFocusPolicy(Qt.StrongFocus)

        # Standard NavigationBar and button press management
        self._mplToolbar = NavigationToolbar(self._canvas, self._mainFrame)
        self._canvas.mpl_connect('key_press_event', self.on_key_press)

        # Layouting
        vbox = QVBoxLayout()
        vbox.addWidget(self._canvas)  # the matplotlib canvas
        vbox.addWidget(self._mplToolbar)
        self._mainFrame.setLayout(vbox)

    def plotQtCanvas(self, ):
        """ Plots data using matplotlib, adds a draggable Rectangle and connects the dragging
        methods to the mouse events
        """
        self._createPlotWidget()
        ax = self._fig.add_subplot(111)
        ax.plot(self._x,self._y)
        ax.set_xlim(self._x[0],self._x[-1])
        ax.set_ylim(-max(self._y)*1.1,max(self._y)*1.1)

        xlim = ax.get_xlim()
        ylim = ax.get_ylim()

        wd = (xlim[1]-xlim[0])*0.1
        ht = (ylim[1]-ylim[0])

        rect = Rectangle((xlim[0],ylim[0]),wd,ht,alpha=0.3,color="g",picker=True)
        ax.add_patch(rect)


        # Connecting Events to Rectangle dragging methods
        self._canvas.mpl_connect("pick_event",self.on_pick)
        self._canvas.mpl_connect("button_release_event",self.on_release)

        return self._mainFrame

    def on_pick(self,event):
        """ Manages the Artist Picking event. This method register which 
        Artist was picked and connects the rectOnMove method to the mouse
        motion_notify_event SIGNAL.

        Arguments:
        - `event`:
        """
        if isinstance(event.artist, Rectangle):

            rectWd = event.artist.get_width()
            if event.mouseevent.button == 1:
                self._dragged = event.artist
                self._id = self._canvas.mpl_connect("motion_notify_event",self.rectOnMove)


    def rectOnMove(self, event):
        """ After being picked, updates the new position of the Artist.

        Arguments:
        - `event`:
        """
        rectWd = self._dragged.get_width()
        if event.xdata:
            i = event.xdata
            n2 = rectWd/2.0
            if i>=n2 and i<(self._x[-1]-n2):
                self._dragged.set_x(i-n2)
                self._canvas.draw()

    def on_release(self,event):
        """ When the mouse button is released, simply disconnect the
        SIGNAL motion_notify_event and the rectOnMove method.

        Arguments:
        - `event`:
        """
        self._canvas.mpl_disconnect(self._id)


    def on_key_press(self, event):
        # implement the default mpl key press events described at
        # http://matplotlib.org/users/navigation_toolbar.html#navigation-keyboard-shortcuts
        key_press_handler(event, self._canvas, self._mplToolbar)



if __name__ == '__main__':
    qApp = QApplication(sys.argv)
    MainWindow = MyMainWindow()

    # By calling the piece of code bellow everything works fine and the
    # the rectangle patch can be dragged, as expected.

    # This piece of code "theoretically" does the same thing as the 
    # method plotRandom() defined in the class MyMainWindow.
    print "Plotting!!"
    x = linspace(0,10,1000)
    w = rand(1)*10
    y = 100*rand(1)*sin(2*pi*w*x)
    ####################################################################

    p = PlotGraph(x,y)
    child = MainWindow._mdiArea.addSubWindow(p.plotQtCanvas())
    child.show()

    MainWindow.show()
    sys.exit(qApp.exec_())

Answer 1

Das funktioniert nicht:

p = PlotGraph(x,y)
child = MainWindow._mdiArea.addSubWindow(p.plotQtCanvas())
child.show()
p = PlotGraph(x,y)
child = MainWindow._mdiArea.addSubWindow(p.plotQtCanvas())
child.show()

Das funktioniert:

p = PlotGraph(x,y)
child = MainWindow._mdiArea.addSubWindow(p.plotQtCanvas())
child.show()
p2 = PlotGraph(x,y)
child2 = MainWindow._mdiArea.addSubWindow(p2.plotQtCanvas())
child2.show()

Bearbeiten:Lösung:

Mach das in setwidgets

self.plotList = []

und das hier plotRandom

self.plotList.append(p)

Und das löst ein weiteres Problem, auf das ich gestoßen bin:

Fügen Sie dies in die ein on_release Funktion

Nicht jeder Mausklick löst ein Picker-Ereignis aus. Sie können die Verbindung also nicht trennen, wenn es nicht ausgelöst wurde.

try:
    self._canvas.mpl_disconnect(self._id)
except AttributeError:
    pass