pyqt5如何在label中实现可用鼠标改变大小，可旋转的矩形，代码实现

可以使用QGraphicsView、QGraphicsScene和QGraphicsItem来实现可用鼠标改变大小、可旋转的矩形。以下是代码示例：

import sys
from PyQt5.QtWidgets import QApplication, QGraphicsView, QGraphicsScene, QGraphicsRectItem
from PyQt5.QtGui import QBrush, QPen, QColor
from PyQt5.QtCore import Qt

class GraphicsRectItem(QGraphicsRectItem):
    def __init__(self, *args, **kwargs):
        super(GraphicsRectItem, self).__init__(*args, **kwargs)
        self.setFlag(QGraphicsItem.ItemIsMovable, True)
        self.setFlag(QGraphicsItem.ItemIsSelectable, True)
        self.setFlag(QGraphicsItem.ItemIsFocusable, True)
        self.setFlag(QGraphicsItem.ItemSendsGeometryChanges, True)
        self.setAcceptHoverEvents(True)
        self.setCursor(Qt.SizeFDiagCursor)
        self.setBrush(QBrush(QColor(255, 255, 255, 127)))
        self.setPen(QPen(Qt.black, 1, Qt.SolidLine))
        self.setZValue(1)

    def hoverMoveEvent(self, event):
        if self.isSelected():
            self.setCursor(Qt.SizeFDiagCursor)

    def itemChange(self, change, value):
        if change == QGraphicsItem.ItemPositionChange:
            self.scene().update()
        elif change == QGraphicsItem.ItemSelectedChange:
            self.setCursor(Qt.SizeFDiagCursor if value else Qt.ArrowCursor)
        return super(GraphicsRectItem, self).itemChange(change, value)

    def paint(self, painter, option, widget):
        painter.setRenderHint(QPainter.Antialiasing)
        painter.setPen(self.pen())
        painter.setBrush(self.brush())
        painter.drawRect(self.rect())

    def boundingRect(self):
        return self.rect().adjusted(-4, -4, 4, 4)

    def shape(self):
        return QGraphicsRectItem.shape(self)

class GraphicsView(QGraphicsView):
    def __init__(self, *args, **kwargs):
        super(GraphicsView, self).__init__(*args, **kwargs)

    def wheelEvent(self, event):
        if event.orientation() == Qt.Vertical:
            factor = 1.1 if event.angleDelta().y() > 0 else 0.9
            self.scale(factor, factor)

    def keyPressEvent(self, event):
        if event.key() == Qt.Key_Delete:
            for item in self.scene().selectedItems():
                self.scene().removeItem(item)
        else:
            super(GraphicsView, self).keyPressEvent(event)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    view = GraphicsView()
    scene = QGraphicsScene(view)
    view.setScene(scene)
    rect = GraphicsRectItem(0, 0, 100, 100)
    scene.addItem(rect)
    view.show()
    sys.exit(app.exec_())

在这个示例中，我们创建了一个名为GraphicsRectItem的类，该类继承自QGraphicsRectItem，并重写了一些方法来实现可用鼠标改变大小、旋转的矩形。然后，我们创建一个名为GraphicsView的类，该类继承自QGraphicsView，并重写了一些方法来实现鼠标滚轮缩放、按键删除等功能。最后，我们在主函数中创建视图、场景和矩形对象，并将矩形添加到场景中。