Question

目前已修复此问题！

我正在尝试使用带有嵌入式matplotlib画布的PyQt4制作GUI。当我将光标滚动到画布上时，我希望能够基于另外的按键控制行为（在这种情况下为控制）。但是，链接到'scroll_event'的mouseEvent的键属性始终为None。我测试了我的代码正确注册了'button_press_event'生成的mouseEvent的密钥。在下面的示例中，on_press方法正确打印了同时按下的键。而on_scoll始终打印无。

如何访问鼠标滚动事件期间按下的键？

提前致谢！

import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *

import matplotlib
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar
from matplotlib.figure import Figure


class GraphicTool(QMainWindow):
    def __init__(self, parent=None):
        QMainWindow.__init__(self, parent)
        self.create_menu()


    def on_press(self, event):
        print event.key

    def on_scroll(self, event):
        print event.key
        if event.key == 'ctrl':
            # do something
            pass
        else:
            # do something else
            pass

    def create_main_frame(self):
        self.main_frame = QWidget()

        # Create the mpl Figure and FigCanvas objects.
        # 10x8 inches, 100 dots-per-inch
        self.dpi = 100
        self.fig = Figure((10.0, 8.0), dpi=self.dpi)
        self.canvas = FigureCanvas(self.fig)
        self.canvas.setParent(self.main_frame)
        self.canvas.setFocusPolicy(Qt.ClickFocus)
        self.canvas.setFocus()

        self.axes = self.fig.add_subplot(111)
        self.canvas.mpl_connect('scroll_event', self.on_scroll)
        self.canvas.mpl_connect('button_press_event', self.on_press)

        # Create the navigation toolbar, tied to the canvas
        self.mpl_toolbar = NavigationToolbar(self.canvas,
                                             self.main_frame)

        vbox = QVBoxLayout()
        vbox.addWidget(self.canvas)
        vbox.addWidget(self.mpl_toolbar)

        self.main_frame.setLayout(vbox)
        self.setCentralWidget(self.main_frame)


def main():
    app = QApplication(sys.argv)
    viewer = GraphicTool()
    viewer.show()
    viewer.raise_()
    app.exec_()

if __name__ == "__main__":
    main()

上面的简短示例实际上按预期工作。但是，当我将它合并到一个更大的项目中时，它就失败了。我将继续调试以查看是否有任何其他事件干扰滚动事件。

Answer 1

我检查了你的代码。这是按预期工作的。

def on_scroll(self, event):
    print event.xdata
    print event.ydata
    print event.key
    if event.key == 'ctrl':
        # do something
        pass
    else:
        # do something else
        pass

这是代码的输出。我刚刚在你的代码中添加了xdata和ydata。

0.480977867785
0.57896567718
control
0.480977867785
0.57896567718
shift
0.480977867785
0.57896567718
shift

matplotlib和Qt：鼠标滚动事件键始终为None

1 个答案: