Python QT findChildren 未从 UI 文件中找到任何子项

Question

我有一个这样的 UI 文件

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>RoverPlanner</class>
 <widget class="QWidget" name="RoverPlanner">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>752</width>
    <height>555</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>RoverPlanner</string>
  </property>
  <widget class="QWidget" name="horizontalLayoutWidget_6">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>10</y>
     <width>641</width>
     <height>501</height>
    </rect>
   </property>
   <layout class="QHBoxLayout" name="hl_rover_planner">
    <item>
     <layout class="QVBoxLayout" name="vl_path_config">
      <item>
       <layout class="QHBoxLayout" name="hl_rover_select">
        <item>
         <widget class="QLabel" name="lbl_rover">
          <property name="text">
           <string>Rover : </string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QComboBox" name="cb_rover">
          <item>
           <property name="text">
            <string>Husky</string>
           </property>
          </item>
          <item>
           <property name="text">
            <string>ArgoJ5</string>
           </property>
          </item>
          <item>
           <property name="text">
            <string>Husky (Simulated)</string>
           </property>
          </item>
         </widget>
        </item>
       </layout>
      </item>
      <item>
       <layout class="QHBoxLayout" name="hl_path_creator">
        <item>
         <widget class="QLabel" name="lbl_path_creator">
          <property name="text">
           <string>Path Creator</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QPushButton" name="btn_add_to_path">
          <property name="text">
           <string>Add to path</string>
          </property>
         </widget>
        </item>
       </layout>
      </item>
      <item>
       <layout class="QHBoxLayout" name="hl_segment_options">
        <item>
         <layout class="QVBoxLayout" name="vl_segment_type">
          <item>
           <widget class="QRadioButton" name="radio_circle">
            <property name="text">
             <string>Circle</string>
            </property>
            <property name="checked">
             <bool>true</bool>
            </property>
           </widget>
          </item>
          <item>
           <widget class="QRadioButton" name="radio_line">
            <property name="text">
             <string>Line</string>
            </property>
           </widget>
          </item>
         </layout>
        </item>
        <item>
         <layout class="QVBoxLayout" name="vl_segment_extra_options">
          <item>
           <widget class="QCheckBox" name="chk_backwards">
            <property name="text">
             <string>Backwards</string>
            </property>
           </widget>
          </item>
          <item>
           <widget class="QCheckBox" name="chk_clockwise">
            <property name="text">
             <string>Clockwise</string>
            </property>
            <property name="checked">
             <bool>true</bool>
            </property>
           </widget>
          </item>
         </layout>
        </item>
       </layout>
      </item>
      <item>
       <layout class="QHBoxLayout" name="hl_radius">
        <item>
         <widget class="QLabel" name="lbl_radius">
          <property name="text">
           <string>Circle Radius (m)</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QDoubleSpinBox" name="spin_radius">
          <property name="singleStep">
           <double>0.010000000000000</double>
          </property>
          <property name="value">
           <double>1.000000000000000</double>
          </property>
         </widget>
        </item>
       </layout>
      </item>
      <item>
       <layout class="QHBoxLayout" name="hl_arc_angle">
        <item>
         <widget class="QLabel" name="lbl_arc_angle">
          <property name="text">
           <string>Arc Angle (rad)</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QDoubleSpinBox" name="spin_arc_angle">
          <property name="decimals">
           <number>5</number>
          </property>
          <property name="singleStep">
           <double>0.010000000000000</double>
          </property>
          <property name="value">
           <double>0.785400000000000</double>
          </property>
         </widget>
        </item>
       </layout>
      </item>
     </layout>
    </item>
    <item>
     <layout class="QVBoxLayout" name="vl_segments">
      <item>
       <widget class="QLabel" name="lbl_path">
        <property name="text">
         <string>Paths</string>
        </property>
       </widget>
      </item>
      <item>
       <widget class="QTreeView" name="tree_paths"/>
      </item>
      <item>
       <layout class="QHBoxLayout" name="horizontalLayout">
        <item>
         <widget class="QPushButton" name="btn_save_paths">
          <property name="text">
           <string>Save Paths</string>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QPushButton" name="btn_load_paths">
          <property name="text">
           <string>Load Paths</string>
          </property>
         </widget>
        </item>
       </layout>
      </item>
     </layout>
    </item>
   </layout>
  </widget>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <resources/>
 <connections/>
</ui>

下面是一些 Python 代码，用于 RQT ROS 插件。

import os
import rospy
import rospkg
from PySide2.QtWidgets import QTreeView, QPushButton, QFileDialog
from python_qt_binding import loadUi

from qt_gui.plugin import Plugin
from python_qt_binding.QtWidgets import QWidget
from argparse import ArgumentParser

def get_file():
    print("Hello World!")
    dlg = QFileDialog()
    dlg.setFileMode(QFileDialog.AnyFile)
    dlg.setFilter("XML files (*.xml)")

    if dlg.exec_():
        filenames = dlg.selectedFiles()
        f = open(filenames[0], 'r')

        with f:
            data = f.read()
            # self.contents.setText(data)


class RoverPlanner(Plugin):
    def __init__(self, context):
        super(RoverPlanner, self).__init__(context)
        self.setObjectName('RoverPlanner')
        parser = ArgumentParser()
        parser.add_argument("-q", "--quiet", action="store_true",
                            dest="quiet",
                            help="Put plugin in silent mode")
        args, unknowns = parser.parse_known_args(context.argv())
        if not args.quiet:
            print('arguments: ', args)
            print('unknowns: ', unknowns)

        self.widget = QWidget()
        ui_file = os.path.join(rospkg.RosPack().get_path('cuarl-rover-planner'), 'resource', 'rover_planner_widget.ui')
        loadUi(ui_file, self.widget)
        self.widget.setObjectName('RoverPlannerUI')
        # Show widget.windowTitle on left-top of each plugin (when
        # it's set in widget). This is useful when you open multiple
        # plugins at once. Also if you open multiple instances of your
        # plugin at once, these lines add number to make it easy to
        # tell from pane to pane.
        if context.serial_number() > 1:
            self.widget.setWindowTitle(self.widget.windowTitle() + (' (%d)' % context.serial_number()))
        # Add widget to the user interface
        context.add_widget(self.widget)
        self.tree_paths = self.widget.findChild(QTreeView)
        self.btn_load_paths = self.widget.findChildren(QPushButton)
        print(self.tree_paths)
        print(self.btn_load_paths)

    def shutdown_plugin(self):
        # TODO unregister all publishers here
        pass

    def save_settings(self, plugin_settings, instance_settings):
        # TODO save intrinsic configuration, usually using:
        # instance_settings.set_value(k, v)
        pass

    def restore_settings(self, plugin_settings, instance_settings):
        # TODO restore intrinsic configuration, usually using:
        # v = instance_settings.value(k)
        pass

根据文档，似乎我的代码应该找到这些 child 。但是这段代码的输出是

('arguments: ', Namespace(quiet=False))
('unknowns: ', [])
None
[]

我不知道我是否没有正确使用 findChildren/findChild 函数，或者我遗漏了什么

Answer 1

我曾经遇到过类似的问题，原因是该库使用了一些像 python_qt_binding 这样的包装器，但另一部分代码使用了 PyQt5 或 PySide2。为什么会这样？因为包装器创建了使用相同代码库的新类，但最终它们是不同的类。

我的建议是，如果您打算使用 python_qt_binding 则不再直接使用 pyqt5 或 pyside2 而是使用包装器，在您的情况下，您应该使用以下内容:

import os

from argparse import ArgumentParser

import rospy
import rospkg

from qt_gui.plugin import Plugin

from python_qt_binding.QtWidgets import QWidget, QTreeView, QPushButton, QFileDialog
from python_qt_binding import loadUi

# ....