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 完整代码

好的，下面是一个完整的示例代码，可以实现你的需求：

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


class GraphicsView(QGraphicsView):
    def __init__(self, parent=None):
        super(GraphicsView, self).__init__(parent)
        self.scene = QGraphicsScene(self)
        self.setScene(self.scene)
        self.setSceneRect(0, 0, 800, 600)
        self.image_item = None
        self.rect_item = None
        self.start_pos = None
        self.end_pos = None

    def load_image(self, filename):
        self.scene.clear()
        pixmap = QPixmap(filename)
        self.image_item = self.scene.addPixmap(pixmap)

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

    def mouseMoveEvent(self, event):
        if self.start_pos is not None:
            self.end_pos = self.mapToScene(event.pos())
            self.draw_rect()

    def mouseReleaseEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.end_pos = self.mapToScene(event.pos())
            self.draw_rect()
            self.start_pos = None
            self.end_pos = None

    def draw_rect(self):
        if self.rect_item is not None:
            self.scene.removeItem(self.rect_item)
        x = min(self.start_pos.x(), self.end_pos.x())
        y = min(self.start_pos.y(), self.end_pos.y())
        w = abs(self.start_pos.x() - self.end_pos.x())
        h = abs(self.start_pos.y() - self.end_pos.y())
        self.rect_item = self.scene.addRect(QRectF(x, y, w, h), QPen(QColor("red"), 2, Qt.SolidLine))

    def get_rect_coordinates(self):
        if self.rect_item is not None:
            rect = self.rect_item.rect()
            x = rect.x()
            y = rect.y()
            w = rect.width()
            h = rect.height()
            return x, y, w, h
        else:
            return None


if __name__ == "__main__":
    app = QApplication(sys.argv)
    view = GraphicsView()
    view.load_image("test.jpg")
    view.show()
    sys.exit(app.exec_())

在这个示例代码中，我们创建了一个继承自 `QGraphicsView` 的类 `GraphicsView`，并重写了其鼠标事件。其中，`load_image` 方法用于加载图片，`draw_rect` 方法用于绘制红色矩形，`get_rect_coordinates` 方法用于获取矩形的坐标信息。

你只需要在 `load_image` 方法中传入你要加载的图片路径，然后运行程序即可。在程序运行时，你可以使用鼠标在图片上框选红色矩形，矩形的坐标信息可以通过 `get_rect_coordinates` 方法获取。