python - 在pyqt中拖动 Canvas 时将 Canvas 绑定(bind)到窗口

Question

我有一个应用程序，它将 matplotlib 图形设置为 FigurCanvas，然后将 FigurCanvas 添加到我的 AppWindow，我已将其设置为可拖动图形。但是，当我拖动图形时，它所包含的窗口会保持在原来的位置，因此图形会被拖离窗口。有没有办法将两者绑定(bind)在一起，以便当图形移动时窗口保持不变？这是代码。

from PyQt4 import QtCore
from PyQt4 import QtGui
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas


class GraphCanvas(FigureCanvas):
    def __init__(self):

        # The window
        self.fig = Figure(figsize=(5, 5), dpi=100)
        self.ax1 = self.fig.add_subplot(111)
        self.ax1.plot([1,2,3], [1,2,3], linewidth=2, color="#c6463d", label="line1")
        FigureCanvas.__init__(self, self.fig)

        # drag properties
        self.draggable = True
        self.dragging_threshold = 5
        self.__mousePressPos = None
        self.__mouseMovePos = None

    def mousePressEvent(self, event):
        if self.draggable and event.button() == QtCore.Qt.LeftButton:
            self.__mousePressPos = event.globalPos()                # global
            self.__mouseMovePos = event.globalPos() - self.pos()    # local
        super(GraphCanvas, self).mousePressEvent(event)

    def mouseMoveEvent(self, event):
        if self.draggable and event.buttons() & QtCore.Qt.LeftButton:
            globalPos = event.globalPos()
            moved = globalPos - self.__mousePressPos
            if moved.manhattanLength() > self.dragging_threshold:
                # move when user drag window more than dragging_threshould
                diff = globalPos - self.__mouseMovePos
                self.move(diff)
                self.__mouseMovePos = globalPos - self.pos()
        super(GraphCanvas, self).mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        if self.__mousePressPos is not None:
            if event.button() == QtCore.Qt.LeftButton:
                moved = event.globalPos() - self.__mousePressPos
                if moved.manhattanLength() > self.dragging_threshold:
                    # do not call click event or so on
                    event.ignore()
                self.__mousePressPos = None
        super(GraphCanvas, self).mouseReleaseEvent(event)

''' End Class '''


class AppWindow(QtGui.QWidget):
    def __init__(self, parent=None):
        super(AppWindow, self).__init__(parent)
        self.setWindowFlags(QtCore.Qt.FramelessWindowHint)

        layout = QtGui.QVBoxLayout(self)
        cpu_canvas = GraphCanvas()
        layout.addWidget(cpu_canvas)

''' End Class'''

if __name__ == '__main__':
    import sys
    app = QtGui.QApplication(sys.argv)
    main = AppWindow()
    main.show()
    sys.exit(app.exec_())

Answer 1

如果你想拖动AppWindow，你应该在这个类中注册拖动，而不是在图形 Canvas 中。然后，您可以在图形 Canvas 内将拖动事件路由到 AppWindow。

以下内容应该适合您，我没有更改太多代码，只是重新排列它，将父参数添加到 GraphCanvas并让拖动函数调用其父函数。

from PyQt4 import QtCore
from PyQt4 import QtGui
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas


class GraphCanvas(FigureCanvas):
    def __init__(self, parent = None):
        self.parent = parent
        # The window
        self.fig = Figure(figsize=(5, 5), dpi=100)
        self.ax1 = self.fig.add_subplot(111)
        self.ax1.plot([1,2,3], [1,2,3], linewidth=2, color="#c6463d", label="line1")
        FigureCanvas.__init__(self, self.fig)


    def mousePressEvent(self, event):
        self.parent.mousePressEvent(event)

    def mouseMoveEvent(self,event):
        self.parent.mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        self.parent.mouseReleaseEvent(event)


''' End Class '''


class AppWindow(QtGui.QWidget):
    def __init__(self, parent=None):
        super(AppWindow, self).__init__(parent)
        self.setWindowFlags(QtCore.Qt.FramelessWindowHint)

        layout = QtGui.QVBoxLayout(self)
        cpu_canvas = GraphCanvas(self)
        layout.addWidget(cpu_canvas)

        self.draggable = True
        self.dragging_threshold = 5
        self.__mousePressPos = None
        self.__mouseMovePos = None

    def mousePressEvent(self, event):
        if self.draggable and event.button() == QtCore.Qt.LeftButton:
            self.__mousePressPos = event.globalPos()                # global
            self.__mouseMovePos = event.globalPos() - self.pos()    # local
        super(AppWindow, self).mousePressEvent(event)

    def mouseMoveEvent(self, event):
        if self.draggable and event.buttons() & QtCore.Qt.LeftButton:
            globalPos = event.globalPos()
            moved = globalPos - self.__mousePressPos
            if moved.manhattanLength() > self.dragging_threshold:
                # move when user drag window more than dragging_threshould
                diff = globalPos - self.__mouseMovePos
                self.move(diff)
                self.__mouseMovePos = globalPos - self.pos()
        super(AppWindow, self).mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        if self.__mousePressPos is not None:
            if event.button() == QtCore.Qt.LeftButton:
                moved = event.globalPos() - self.__mousePressPos
                if moved.manhattanLength() > self.dragging_threshold:
                    # do not call click event or so on
                    event.ignore()
                self.__mousePressPos = None
        super(AppWindow, self).mouseReleaseEvent(event)

''' End Class'''

if __name__ == '__main__':
    import sys
    app = QtGui.QApplication(sys.argv)
    main = AppWindow()
    main.show()
    sys.exit(app.exec_())