Question

我有一些似乎可以单独工作的代码，但是一旦将它们组合在一起，我会得到一个错误，提示.progressbar li:nth-child(2n) { top: -50px; } .progressbar li:nth-child(2n):after { top: 57px; } .progressbar li:nth-child(2n):before { top: 50px; }。我的目标是用鼠标左键在这些点周围绘制一个框（稍后将选择该框周围的这些点。尚未弄清该部分），我的滚轮进行放大和缩小以及我的中心按钮进行平移周围的景色。感谢您的帮助。

代码

RecursionError: maximum recursion depth exceeded while calling a Python object

Answer 1

您的问题有助于指定self.mousePressEvent(event)和QGraphicsView.mousePressEvent(self,event)的区别

1。 self.mousePressEvent(event) 这意味着该事件将自己递归。

2。 QGraphicsView.mousePressEvent(event) 这意味着它将在另一个通用QGraphicsView.mousePressEvent

上执行

以1。

请记住，在上一个问题中，您在LeftButton中制作了一个MidButton的手工对象。如果制作并扔进self.mousePressEvent(handmade_event)，因为handmade_event是实际上解释为LeftButton，因此它在if event.button() == Qt.LeftButton代码的正上方执行。因此，发生了永恒递归。请尝试在LeftButton事件下写return。错误将停止，而不是完全不操作。

以2。

这是一个更通用的方法，它非常流行并且不会破坏递归。因为它不是Viewer mousePressEvent。默认情况下，mousePressEvent安装在所有小部件对象中。但是执行是相当可附加的。一言以蔽之，您将事件扔到另一个事件处理程序中。在1的场合，您将事件扔到同一事件处理程序中。因此，发生递归。

我的目标是用鼠标左键在这些点周围绘制一个框（稍后将选择框周围的这些点。

我于13:19更新如果发生其他问题，请问我。

结果

所有事件都一样执行。只有对象和事件类型可能是区别的标记。如果我们重写它并在其之前编写命令，我们可以预先调节其执行。无需处理，您只需将mousePressEvent放在最后一个位置。（如果其他都一样）。

请尝试一下此代码，它不会出现错误。提示：QGraphicsView.mousePressEvent(self,event)和super(Viewer, self).mousePressEvent(event)是同一件事，您可以删除其中任何一个。

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
import sys
from math import sqrt

class Point(QGraphicsItem):
    def __init__(self, x, y):
        super(Point, self).__init__()
        self.setFlag(QGraphicsItem.ItemIsSelectable, True)
        self.rectF = QRectF(0, 0, 30, 30)
        self.x=x
        self.y=y
        self._brush = QBrush(Qt.black)

    def setBrush(self, brush):
        self._brush = brush
        self.update()

    def boundingRect(self):
        return self.rectF

    def paint(self, painter=None, style=None, widget=None):
        painter.fillRect(self.rectF, self._brush)

    def hoverMoveEvent(self, event):
        point = event.pos().toPoint()
        print(point)
        QGraphicsItem.hoverMoveEvent(self, event)


class Viewer(QGraphicsView):
    photoClicked = pyqtSignal(QPoint)
    rectChanged = pyqtSignal(QRect)

    def __init__(self, parent):
        super(Viewer, self).__init__(parent)
        self.rubberBand = QRubberBand(QRubberBand.Rectangle, self)
        self.setMouseTracking(True)
        self.origin = QPoint()
        self.changeRubberBand = False

        self._zoom = 0
        self._empty = True
        self._scene = QGraphicsScene(self)

        self.setTransformationAnchor(QGraphicsView.AnchorUnderMouse)
        self.setResizeAnchor(QGraphicsView.AnchorUnderMouse)
        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setFrameShape(QFrame.NoFrame)
        self.area = float()
        self.setPoints()

    def setItems(self):
            self.data = {'x': [-2414943.8686, -2417160.6592, -2417160.6592, -2417856.1783, -2417054.7618, -2416009.9966, -2416012.5232, -2418160.8952, -2418160.8952, -2416012.5232, -2417094.7694, -2417094.7694], 'y': [10454269.7008,
     10454147.2672, 10454147.2672, 10453285.2456, 10452556.8132, 10453240.2808, 10455255.8752, 10455183.1912, 10455183.1912, 10455255.8752, 10456212.5959, 10456212.5959]}
            maxX = max(self.data['x'])
            minX = min(self.data['x'])
            maxY = max(self.data['y'])
            minY = min(self.data['y'])
            distance = sqrt((maxX-minX)**2+(maxY-minY)**2)

            self.area = QRectF(minX, minY, distance, distance)
            for i,x in enumerate(self.data['x']):
                x = self.data['x'][i]
                y = self.data['y'][i]
                p = Point(x,y)
                p.setPos(x,y)
                self._scene.addItem(p)
            self.setScene(self._scene)



    def fitInView(self, scale=True):
        rect = QRectF(self.area)
        if not rect.isNull():
            self.setSceneRect(rect)

            unity = self.transform().mapRect(QRectF(0, 0, 1, 1))
            self.scale(1 / unity.width(), 1 / unity.height())
            viewrect = self.viewport().rect()
            scenerect = self.transform().mapRect(rect)
            factor = min(viewrect.width() / scenerect.width(),
                             viewrect.height() / scenerect.height())
            self.scale(factor, factor)
            self._zoom = 0

    def setPoints(self):
        self._zoom = 0
        self.setItems()
        self.setDragMode(True)
        self.fitInView()

    def wheelEvent(self, event):
            if event.angleDelta().y() > 0:
                factor = 1.25
                self._zoom += 1
            else:
                factor = 0.8
                self._zoom -= 1
            if self._zoom > 0:
                self.scale(factor, factor)
            elif self._zoom == 0:
                self.fitInView()
            else:
                self._zoom = 0


    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:

            self.origin = event.pos()
            self.rubberBand.setGeometry(QRect(self.origin, QSize()))
            self.rectChanged.emit(self.rubberBand.geometry())
            self.rubberBand.show()
            self.changeRubberBand = True
            return
            #QGraphicsView.mousePressEvent(self,event)
        elif event.button() == Qt.MidButton:
            self.viewport().setCursor(Qt.ClosedHandCursor)
            self.original_event = event
            handmade_event = QMouseEvent(QEvent.MouseButtonPress,QPointF(event.pos()),Qt.LeftButton,event.buttons(),Qt.KeyboardModifiers())
            QGraphicsView.mousePressEvent(self,handmade_event)

        super(Viewer, self).mousePressEvent(event)

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:

            self.changeRubberBand = False
            QGraphicsView.mouseReleaseEvent(self,event)
        elif event.button() == Qt.MidButton:
            self.viewport().setCursor(Qt.OpenHandCursor)
            handmade_event = QMouseEvent(QEvent.MouseButtonRelease,QPointF(event.pos()),Qt.LeftButton,event.buttons(),Qt.KeyboardModifiers())
            QGraphicsView.mouseReleaseEvent(self,handmade_event)
        super(Viewer, self).mouseReleaseEvent(event)


    def mouseMoveEvent(self, event):
        if self.changeRubberBand:
            self.rubberBand.setGeometry(QRect(self.origin, event.pos()).normalized())
            self.rectChanged.emit(self.rubberBand.geometry())
            QGraphicsView.mouseMoveEvent(self,event)
        super(Viewer, self).mouseMoveEvent(event)

class Window(QWidget):
    def __init__(self):
        super(Window, self).__init__()
        self.viewer = Viewer(self)
        self.btnLoad = QToolButton(self)
        self.btnLoad.setText('Load Points')
        self.btnLoad.clicked.connect(self.loadPoints)

        VBlayout = QVBoxLayout(self)
        VBlayout.addWidget(self.viewer)
        HBlayout = QHBoxLayout()
        HBlayout.setAlignment(Qt.AlignLeft)
        HBlayout.addWidget(self.btnLoad)

        VBlayout.addLayout(HBlayout)

    def loadPoints(self):
        self.viewer.setPoints()




if __name__ == '__main__':
    import sys
    app = QApplication(sys.argv)
    window = Window()
    window.setGeometry(500, 300, 800, 600)
    window.show()
    sys.exit(app.exec_())

鼠标左键，用于橡皮筋，中间用于平移PYQT

1 个答案: