pyqt5 graphicsView 加载显示图片，在图片上鼠标框选红色矩形并返回矩形在图片上的坐标

可以通过以下代码实现pyqt5 graphicsView加载显示图片，并在图片上鼠标框选红色矩形并返回矩形在图片上的坐标。

from PyQt5.QtCore import Qt, QRectF
from PyQt5.QtGui import QPixmap, QColor, QPen
from PyQt5.QtWidgets import QGraphicsScene, QGraphicsView, QGraphicsRectItem, QApplication, QMainWindow

class GraphicsView(QGraphicsView):
    def __init__(self, parent=None):
        super(GraphicsView, self).__init__(parent)
        self.scene = QGraphicsScene(self)
        self.setScene(self.scene)
        self.setDragMode(QGraphicsView.ScrollHandDrag)
        self.setRenderHint(QPainter.Antialiasing)

    def setImage(self, image):
        self.image = QPixmap(image)
        self.scene.clear()
        self.scene.setSceneRect(QRectF(self.image.rect()))
        self.scene.addPixmap(self.image)

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.origin = event.pos()
            self.rubberBand = QGraphicsRectItem()
            self.rubberBand.setPen(QPen(QColor(Qt.red), 2, Qt.SolidLine))
            self.scene.addItem(self.rubberBand)
            self.rubberBand.setPos(self.mapToScene(self.origin))

    def mouseMoveEvent(self, event):
        if hasattr(self, 'rubberBand'):
            self.rubberBand.setRect(QRectF(self.origin, event.pos()).normalized())

    def mouseReleaseEvent(self, event):
        if hasattr(self, 'rubberBand'):
            rect = self.rubberBand.rect()
            rect = rect.normalized()
            rect = QRectF(self.mapToScene(rect.topLeft()), self.mapToScene(rect.bottomRight()))
            print(rect.x(), rect.y(), rect.width(), rect.height())
            self.scene.removeItem(self.rubberBand)
            del self.rubberBand

class MainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.view = GraphicsView(self)
        self.setCentralWidget(self.view)
        self.view.setImage('image.jpg')
        self.show()

if __name__ == '__main__':
    import sys

    app = QApplication(sys.argv)
    window = MainWindow()
    sys.exit(app.exec_())

在上面的代码中，我们使用QGraphicsView来显示图片，鼠标按下时在场景中添加了一个QGraphicsRectItem，然后在鼠标移动时更新QGraphicsRectItem的大小，最后在释放鼠标时将QGraphicsRectItem的坐标转换成图片上的坐标并输出。