从图像保存区域并另存为新图像

Question

我有LabelTool类，可以在图像上创建一个矩形，这是可行的，但是我不知道如何将所选区域另存为新图像，我还想知道该矩形的高度和宽度，我需要此参数用于为另一个项目创建txt文件。

import sys
from PyQt5 import QtCore, QtWidgets, QtGui
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import QApplication, QScrollArea
from PyQt5.uic import loadUi

class LabelTool(QtWidgets.QLabel):
        def __init__(self, parent=None):
            QtWidgets.QLabel.__init__(self,parent)
            self.selection = QtWidgets.QRubberBand(QtWidgets.QRubberBand.Rectangle, self)


        def mousePressEvent(self, event):
            if event.button() == QtCore.Qt.LeftButton:
                position = QtCore.QPoint(event.pos())
                if self.selection.isVisible():

                    print(self.upper_left.manhattanLength())
                    if (self.upper_left - position).manhattanLength() < 20:

                        self.mode = "drag_upper_left"
                    elif (self.lower_right - position).manhattanLength() < 20:

                        self.mode = "drag_lower_right"
                    else:

                        self.selection.hide()
                else:

                    self.upper_left = position
                    self.lower_right = position
                    self.mode = "drag_lower_right"
                    self.selection.show()

        def mouseMoveEvent(self, event):
            '''
                Mouse moved. If selection is visible, drag it according to drag mode.
            '''

            if self.selection.isVisible():
                # visible selection
                if self.mode is "drag_lower_right":
                    self.lower_right = QtCore.QPoint(event.pos())
                    print(str(self.lower_right))
                elif self.mode is "drag_upper_left":
                    self.upper_left = QtCore.QPoint(event.pos())
                    print(str(self.upper_left))
                # update geometry
                self.selection.setGeometry(QtCore.QRect(self.upper_left, self.lower_right).normalized())

这是主窗口，由qgraphicsview小部件和一些按钮组成

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        loadUi('GUI/gui.ui', self)


        kpe_window = LabelTool()
        pixmap = QtGui.QPixmap("image.JPG")
        kpe_window.setPixmap(pixmap)
        kpe_window.setFocusPolicy(QtCore.Qt.StrongFocus)
        self.setFocusProxy(self.grafic)
        kpe_window.setFocus(True)
        lay = QtWidgets.QVBoxLayout(self.grafic)
        lay.addWidget(kpe_window)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    mainWin = MainWindow()
    mainWin.show()
    sys.exit(app.exec_())

这是ui文件：

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>GUI</class>
 <widget class="QMainWindow" name="GUI">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>770</width>
    <height>527</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MetaxaReborn</string>
  </property>
  <widget class="QWidget" name="centralWidget">
   <layout class="QGridLayout" name="gridLayout">
    <item row="0" column="2">
     <widget class="QGraphicsView" name="grafic"/>
    </item>
    <item row="0" column="3">
     <layout class="QGridLayout" name="gridLayout_2">
      <item row="0" column="0">
       <widget class="QPushButton" name="loadFile_btn">
        <property name="text">
         <string/>
        </property>
        <property name="icon">
         <iconset>
          <normaloff>icons/file.png</normaloff>icons/file.png</iconset>
        </property>
        <property name="iconSize">
         <size>
          <width>32</width>
          <height>32</height>
         </size>
        </property>
       </widget>
      </item>
      <item row="0" column="1">
       <widget class="QPushButton" name="loadFolder_btn">
        <property name="text">
         <string/>
        </property>
        <property name="icon">
         <iconset>
          <normaloff>icons/folder.png</normaloff>icons/folder.png</iconset>
        </property>
        <property name="iconSize">
         <size>
          <width>32</width>
          <height>32</height>
         </size>
        </property>
       </widget>
      </item>
      <item row="1" column="0">
       <widget class="QPushButton" name="clear_btn">
        <property name="text">
         <string>clear</string>
        </property>
       </widget>
      </item>
     </layout>
    </item>
   </layout>
  </widget>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <resources/>
 <connections/>
</ui>