pyqt5如何在label中实现可用鼠标改变长和宽，可旋转的矩形，代码实现

以下是实现可用鼠标改变长和宽，可旋转矩形的代码：

from PyQt5.QtCore import Qt, QPoint, QRectF
from PyQt5.QtGui import QMouseEvent, QPainter, QPen
from PyQt5.QtWidgets import QWidget, QApplication, QLabel

class RotatableRect(QWidget):
    def __init__(self, parent=None):
        super(RotatableRect, self).__init__(parent)
        self.setMouseTracking(True)
        self.dragging = False
        self.resizing = False
        self.rotating = False
        self.origin_x = 0
        self.origin_y = 0
        self.current_x = 0
        self.current_y = 0
        self.angle = 0
        self.width = 100
        self.height = 50
        self.setFixedSize(self.width, self.height)
        self.setCursor(Qt.CrossCursor)

    def mousePressEvent(self, event: QMouseEvent) -> None:
        self.origin_x = event.pos().x()
        self.origin_y = event.pos().y()
        if self.isInResizeRect(event.pos()):
            self.resizing = True
        elif self.isInRotateRect(event.pos()):
            self.rotating = True
        else:
            self.dragging = True

    def mouseReleaseEvent(self, event: QMouseEvent) -> None:
        self.dragging = False
        self.resizing = False
        self.rotating = False
        self.setCursor(Qt.CrossCursor)

    def mouseMoveEvent(self, event: QMouseEvent) -> None:
        self.current_x = event.pos().x()
        self.current_y = event.pos().y()
        if self.dragging and event.buttons() == Qt.LeftButton:
            self.move(self.pos() + event.pos() - QPoint(self.origin_x, self.origin_y))
        elif self.resizing and event.buttons() == Qt.LeftButton:
            self.width = max(self.width + self.current_x - self.origin_x, 20)
            self.height = max(self.height + self.current_y - self.origin_y, 20)
            self.setGeometry(self.x(), self.y(), self.width, self.height)
            self.origin_x = self.current_x
            self.origin_y = self.current_y
        elif self.rotating and event.buttons() == Qt.LeftButton:
            x = event.pos().x() - self.width / 2
            y = event.pos().y() - self.height / 2
            if x != 0:
                self.angle = -y / x if x > 0 else (3 * 3.1415926535 - y) / x
            else:
                self.angle = 3.1415926535 if y < 0 else 0
            self.update()
        else:
            if self.isInResizeRect(event.pos()):
                self.setCursor(Qt.SizeFDiagCursor)
            elif self.isInRotateRect(event.pos()):
                self.setCursor(Qt.PointingHandCursor)
            else:
                self.setCursor(Qt.CrossCursor)

    def isInResizeRect(self, pos: QPoint) -> bool:
        return self.width - pos.x() < 10 and self.height - pos.y() < 10

    def isInRotateRect(self, pos: QPoint) -> bool:
        return abs(pos.x() - self.width / 2) < 10 and abs(pos.y() - self.height / 2) < 10

    def paintEvent(self, event) -> None:
        painter = QPainter(self)
        painter.setPen(QPen(Qt.black, 2, Qt.SolidLine))
        painter.translate(self.width / 2, self.height / 2)
        painter.rotate(self.angle * 180 / 3.1415926535)
        painter.drawRect(QRectF(-self.width / 2, -self.height / 2, self.width, self.height))
        painter.setPen(QPen(Qt.red, 2, Qt.SolidLine))
        painter.drawLine(QPointF(self.width / 2, self.height / 2), QPointF(self.width / 2 + 20, self.height / 2))

class MainWindow(QWidget):
    def __init__(self):
        super().__init__()
        self.label = QLabel(self)
        self.label.setPixmap(self.getPixmap())
        self.setGeometry(0, 0, 400, 300)

    def getPixmap(self):
        rect = RotatableRect()
        pixmap = rect.grab()
        return pixmap

if __name__ == "__main__":
    app = QApplication([])
    window = MainWindow()
    window.show()
    app.exec_()

在 `MainWindow` 中设置一个 `QLabel`，并将其内容设置为上述代码中 `RotatableRect` 绘制的矩形的截图。这样就可以在 `QLabel` 中显示可拖动、可改变大小和旋转的矩形。

注意：本代码仅实现了矩形的基本拖动、改变大小和旋转功能，并没有考虑边界情况、触摸屏幕等情况。可以根据实际需求进行修改和完善。