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BrainSwitch
Asked:2020-02-27 19:02:02 +0000 UTC2020-02-27 19:02:02 +0000 UTC

PyQt5 中的自定义 QGraphicsRectItem 事件

  • 772

我创建了自己的 QGraphicsRectItem，但问题是它的鼠标悬停事件方法不起作用。

编码：

import sys

from PyQt5.QtCore import Qt, QRectF
from PyQt5.QtWidgets import \
    QGraphicsScene, QGraphicsRectItem, QGraphicsView, QMainWindow, QApplication


class CustomRectItem(QGraphicsRectItem):

    def mousePressEvent(self, event):
        print('mousePressEvent')

    def mouseReleaseEvent(self, event):
        print('mouseReleaseEvent')

    def hoverMoveEvent(self, event):
        print('hoverMoveEvent')

    def hoverLeaveEvent(self, event):
        print('hoverLeaveEvent')

    def hoverEnterEvent(self, event):
        print('hoverEnterEvent')


class CustomScene(QGraphicsScene):
    def __init__(self, parent=None):
        super(CustomScene, self).__init__(QRectF(-500, -500, 500, 200), parent)
        rect = CustomRectItem()
        rect.setRect(50, 50, 50, 50)
        rect.setBrush(Qt.green)
        self.addItem(rect)


class Window(QMainWindow):
    def __init__(self, parent=None):
        super(Window, self).__init__(parent)
        self.scene = CustomScene(self)
        view = QGraphicsView(self.scene, self)
        view.setSceneRect(0, 0, 500, 200)
        view.setGeometry(0, 0, 600, 300)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    mainWindow = Window()
    mainWindow.setWindowTitle('App')
    mainWindow.setGeometry(50, 50, 800, 500)
    mainWindow.show()

    sys.exit(app.exec_())
python

2 个回答

  1. Best Answer

    在元素上调用setAcceptHoverEvents方法，然后将处理悬停事件：

    class CustomRectItem(QGraphicsRectItem):
    def __init__(self):
        super().__init__()

        self.setAcceptHoverEvents(True)

    def mousePressEvent(self, event):
        print('mousePressEvent')

    def mouseReleaseEvent(self, event):
        print('mouseReleaseEvent')

    def hoverMoveEvent(self, event):
        print('hoverMoveEvent')

    def hoverLeaveEvent(self, event):
        print('hoverLeaveEvent')

    def hoverEnterEvent(self, event):
        print('hoverEnterEvent')
    • 3

  2. 只需在@gil9red 的正确答案中添加一个更实用的示例：

    import sys
from PyQt5.QtCore import Qt, QRectF, QPointF
from PyQt5.QtGui  import QBrush, QPainterPath, QPainter, QColor, QPen, QPixmap
from PyQt5.QtWidgets import (QGraphicsRectItem, QApplication, QGraphicsView, 
                             QGraphicsScene, QGraphicsItem)


class GraphicsRectItem(QGraphicsRectItem):

    handleTopLeft      = 1
    handleTopMiddle    = 2
    handleTopRight     = 3
    handleMiddleLeft   = 4
    handleMiddleRight  = 5
    handleBottomLeft   = 6
    handleBottomMiddle = 7
    handleBottomRight  = 8

    handleSize  = +8.0
    handleSpace = -4.0

    handleCursors = {
        handleTopLeft:      Qt.SizeFDiagCursor,
        handleTopMiddle:    Qt.SizeVerCursor,
        handleTopRight:     Qt.SizeBDiagCursor,
        handleMiddleLeft:   Qt.SizeHorCursor,
        handleMiddleRight:  Qt.SizeHorCursor,
        handleBottomLeft:   Qt.SizeBDiagCursor,
        handleBottomMiddle: Qt.SizeVerCursor,
        handleBottomRight:  Qt.SizeFDiagCursor,
    }

    def __init__(self, *args):
        """ Инициализируйте форму. """

        super().__init__(*args)
        self.handles = {}
        self.handleSelected = None
        self.mousePressPos  = None
        self.mousePressRect = None

        # Если установлено значение true, этот элемент будет принимать 
        # события при наведении курсора.
        self.setAcceptHoverEvents(True)                                # <---

        self.setFlag(QGraphicsItem.ItemIsMovable, True)
        self.setFlag(QGraphicsItem.ItemIsSelectable, True)
        self.setFlag(QGraphicsItem.ItemSendsGeometryChanges, True)
        self.setFlag(QGraphicsItem.ItemIsFocusable, True)
        self.updateHandlesPos()

    def handleAt(self, point):
        """ Возвращает маркер изменения размера ниже заданной точки. """
        for k, v, in self.handles.items():
            if v.contains(point):
                return k
        return None

    def hoverMoveEvent(self, moveEvent):
        """ Выполняется, когда мышь перемещается по фигуре (NOT PRESSED). """
        if self.isSelected():
            handle = self.handleAt(moveEvent.pos())
            cursor = Qt.ArrowCursor if handle is None else self.handleCursors[handle]
            self.setCursor(cursor)
        super().hoverMoveEvent(moveEvent)

    def hoverLeaveEvent(self, moveEvent):
        """ Выполняется, когда мышь покидает фигуру (NOT PRESSED). """
        self.setCursor(Qt.ArrowCursor)
        super().hoverLeaveEvent(moveEvent)

    def mousePressEvent(self, mouseEvent):
        """ Выполняется при нажатии мыши на элемент. """
        self.handleSelected = self.handleAt(mouseEvent.pos())
        if self.handleSelected:
            self.mousePressPos  = mouseEvent.pos()
            self.mousePressRect = self.boundingRect()
        super().mousePressEvent(mouseEvent)

    def mouseMoveEvent(self, mouseEvent):
        """ Выполняется, когда мышь перемещается над элементом при нажатии. """
        if self.handleSelected is not None:
            self.interactiveResize(mouseEvent.pos())
        else:
            super().mouseMoveEvent(mouseEvent)

    def mouseReleaseEvent(self, mouseEvent):
        """ Выполняется, когда мышь освобождается от элемента. """
        super().mouseReleaseEvent(mouseEvent)
        self.handleSelected = None
        self.mousePressPos  = None
        self.mousePressRect = None
        self.update()

    def boundingRect(self):
        """ Возвращает ограничивающий прямоугольник фигуры 
            (включая маркеры изменения размера). """
        o = self.handleSize + self.handleSpace
        return self.rect().adjusted(-o, -o, o, o)

    def updateHandlesPos(self):
        """ Обновите текущие маркеры изменения размера 
            в соответствии с размером и положением фигуры. """
        s = self.handleSize
        b = self.boundingRect()
        self.handles[self.handleTopLeft]      = QRectF(b.left(), b.top(), s, s)
        self.handles[self.handleTopMiddle]    = QRectF(b.center().x() - s / 2, b.top(), s, s)
        self.handles[self.handleTopRight]     = QRectF(b.right() - s, b.top(), s, s)
        self.handles[self.handleMiddleLeft]   = QRectF(b.left(), b.center().y() - s / 2, s, s)
        self.handles[self.handleMiddleRight]  = QRectF(b.right() - s, b.center().y() - s / 2, s, s)
        self.handles[self.handleBottomLeft]   = QRectF(b.left(), b.bottom() - s, s, s)
        self.handles[self.handleBottomMiddle] = QRectF(b.center().x() - s / 2, b.bottom() - s, s, s)
        self.handles[self.handleBottomRight]  = QRectF(b.right() - s, b.bottom() - s, s, s)

    def interactiveResize(self, mousePos):
        """ Выполните форму интерактивного изменения размера. """
        offset       = self.handleSize + self.handleSpace
        boundingRect = self.boundingRect()
        rect         = self.rect()
        diff         = QPointF(0, 0)

        self.prepareGeometryChange()

        if self.handleSelected == self.handleTopLeft:

            fromX = self.mousePressRect.left()
            fromY = self.mousePressRect.top()
            toX   = fromX + mousePos.x() - self.mousePressPos.x()
            toY   = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setX(toX - fromX)
            diff.setY(toY - fromY)
            boundingRect.setLeft(toX)
            boundingRect.setTop(toY)
            rect.setLeft(boundingRect.left() + offset)
            rect.setTop(boundingRect.top() + offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleTopMiddle:

            fromY = self.mousePressRect.top()
            toY = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setY(toY - fromY)
            boundingRect.setTop(toY)
            rect.setTop(boundingRect.top() + offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleTopRight:

            fromX = self.mousePressRect.right()
            fromY = self.mousePressRect.top()
            toX   = fromX + mousePos.x() - self.mousePressPos.x()
            toY   = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setX(toX - fromX)
            diff.setY(toY - fromY)
            boundingRect.setRight(toX)
            boundingRect.setTop(toY)
            rect.setRight(boundingRect.right() - offset)
            rect.setTop(boundingRect.top() + offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleMiddleLeft:

            fromX = self.mousePressRect.left()
            toX   = fromX + mousePos.x() - self.mousePressPos.x()
            diff.setX(toX - fromX)
            boundingRect.setLeft(toX)
            rect.setLeft(boundingRect.left() + offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleMiddleRight:
            print("MR")
            fromX = self.mousePressRect.right()
            toX   = fromX + mousePos.x() - self.mousePressPos.x()
            diff.setX(toX - fromX)
            boundingRect.setRight(toX)
            rect.setRight(boundingRect.right() - offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleBottomLeft:

            fromX = self.mousePressRect.left()
            fromY = self.mousePressRect.bottom()
            toX   = fromX + mousePos.x() - self.mousePressPos.x()
            toY   = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setX(toX - fromX)
            diff.setY(toY - fromY)
            boundingRect.setLeft(toX)
            boundingRect.setBottom(toY)
            rect.setLeft(boundingRect.left() + offset)
            rect.setBottom(boundingRect.bottom() - offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleBottomMiddle:

            fromY = self.mousePressRect.bottom()
            toY   = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setY(toY - fromY)
            boundingRect.setBottom(toY)
            rect.setBottom(boundingRect.bottom() - offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleBottomRight:

            fromX = self.mousePressRect.right()
            fromY = self.mousePressRect.bottom()
            toX   = fromX + mousePos.x() - self.mousePressPos.x()
            toY   = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setX(toX - fromX)
            diff.setY(toY - fromY)
            boundingRect.setRight(toX)
            boundingRect.setBottom(toY)
            rect.setRight(boundingRect.right() - offset)
            rect.setBottom(boundingRect.bottom() - offset)
            self.setRect(rect)

        self.updateHandlesPos()

    def shape(self):
        """ Возвращает форму этого элемента в виде QPainterPath в локальных координатах. """
        path = QPainterPath()
        path.addRect(self.rect())
        if self.isSelected():
            for shape in self.handles.values():
                path.addEllipse(shape)
        return path

    def paint(self, painter, option, widget=None):
        """ Нарисуйте узел в графическом представлении. """
        painter.setBrush(QBrush(QColor(255, 0, 0, 100)))
        painter.setPen(QPen(QColor(0, 0, 0), 1.0, Qt.SolidLine))
        painter.drawRect(self.rect())

        painter.setRenderHint(QPainter.Antialiasing)
        painter.setBrush(QBrush(QColor(255, 0, 0, 255)))
        painter.setPen(QPen(QColor(0, 0, 0, 255), 1.0, Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
        for handle, rect in self.handles.items():
            if self.handleSelected is None or handle == self.handleSelected:
                painter.drawEllipse(rect)


if __name__ == '__main__':
    app = QApplication(sys.argv)

    grview = QGraphicsView()
    scene  = QGraphicsScene()
    scene.setSceneRect(0, 0, 680, 459)
    scene.addPixmap(QPixmap('D:/_Qt/img/qt-logo.png'))
    grview.setScene(scene)

    item = GraphicsRectItem(0, 0, 300, 150)
    scene.addItem(item)

    grview.fitInView(scene.sceneRect(), Qt.KeepAspectRatio)
    grview.show()
    sys.exit(app.exec_())

    在此处输入图像描述

    • 1

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