CODEWITHSUNDEEP
pythonmatplotlibpyqt4
ntmt
ntmt

Reputation: 173

pyqt4 scrollArea Event and matplotlib wheelEvent

Regarding to this question and the answer here, is there a way to pass the wheel scroll event to the scrollbar when the mouse is located over the plots? I've tried using an event filter in the Main Widget, but it doesn't registered that the wheel is scrolled in the Main, only in the canvas/plots. I don't need the plots to know that it is being scrolled, only the GUI. Any help would be greatly appreciated, thank you.

Upvotes: 1

Views: 1301

Answers (1)

ImportanceOfBeingErnest
ImportanceOfBeingErnest

Reputation: 339430

One solution to scroll the FigureCanvas inside a QScrollArea in PyQt is to use matplotlib's "scroll_event" (see Event handling tutorial) and connect it to a function which scrolls the scrollBar of the QScrollArea.

The example (from my answer to this question) can be extended to connect to a function scrolling via

self.canvas.mpl_connect("scroll_event", self.scrolling)

inside this function the scrollbar value is updated.

import matplotlib.pyplot as plt
from PyQt4 import QtGui
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar

class ScrollableWindow(QtGui.QMainWindow):
    def __init__(self, fig):
        self.qapp = QtGui.QApplication([])

        QtGui.QMainWindow.__init__(self)
        self.widget = QtGui.QWidget()
        self.setCentralWidget(self.widget)
        self.widget.setLayout(QtGui.QVBoxLayout())
        self.widget.layout().setContentsMargins(0,0,0,0)
        self.widget.layout().setSpacing(0)

        self.fig = fig
        self.canvas = FigureCanvas(self.fig)
        self.canvas.draw()
        self.scroll = QtGui.QScrollArea(self.widget)
        self.scroll.setWidget(self.canvas)

        self.nav = NavigationToolbar(self.canvas, self.widget)
        self.widget.layout().addWidget(self.nav)
        self.widget.layout().addWidget(self.scroll)

        self.canvas.mpl_connect("scroll_event", self.scrolling)

        self.show()
        exit(self.qapp.exec_())

    def scrolling(self, event):
        val = self.scroll.verticalScrollBar().value()
        if event.button =="down":
            self.scroll.verticalScrollBar().setValue(val+100)
        else:
            self.scroll.verticalScrollBar().setValue(val-100)


# create a figure and some subplots
fig, axes = plt.subplots(ncols=4, nrows=5, figsize=(16,16))
for ax in axes.flatten():
    ax.plot([2,3,5,1])

# pass the figure to the custom window
a = ScrollableWindow(fig)

Upvotes: 1

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