PyQt5在QWidget窗体中显示Qwidget的自定义类（补：完美解决）

【概览】

1、显示原生Qwidget

1)不使用布局（绝对定位）

2)使用布局

2、显示Qwidget的自定义类

1)不使用布局（绝对定位）

      2)使用布局

【知识点】

1、显示原生Qwidget

1)不使用布局（绝对定位）

这种情况下，原生QWidget部件在实例化时必须带parent参数，当然parent = self，即：  self.widget = QWidget(self)

 class MyWindow(QWidget):
     def __init__(self, parent=None):
         super(MyWindow,self).__init__(parent)
         self.resize(400, 300)

         # 添加原生QWidget
         self.widget = QWidget(self) # 注意QWidget(self) 内的self!!
         self.widget.setGeometry(10,10,380,250)
         self.widget.setStyleSheet("background-color:grey;")

         # 添加编辑框（QLineEdit）
         self.lineEdit = QLineEdit("",self) # 注意QLineEdit("0",self) 内的self!!
         self.lineEdit.setGeometry(10,270,380,20)

【效果图】

2)使用布局

这种情况下，原生QWidget部件在实例化时可以不带parent参数，parent =None / self都行，即： self.widget = QWidget()或 self.widget = QWidget(self)

class MyWindow(QWidget):
    def __init__(self, parent=None):
        super(MyWindow,self).__init__(parent)
        self.resize(400, 300)
        layout = QGridLayout()

        # 添加原生QWidget
        self.widget = QWidget()  # 注意QWidget() 内可以没有self!!
        self.widget.setStyleSheet("background-color:grey;")

        # 添加编辑框（QLineEdit）
        self.lineEdit = QLineEdit("") # 注意QLineEdit("0") 内可以没self!!

        # 放入布局内
        layout.addWidget(self.widget,0,0)
        layout.addWidget(self.lineEdit,1,0)
        self.setLayout(layout)

【效果图】

2、显示Qwidget的自定义类

1)不使用布局（绝对定位）

这种情况下，原生QWidget自定义类里面要放个东西！！不放东西的话，我也不会:(

 class MyWidget(QWidget):
     def __init__(self, parent=None):
         super(MyWidget,self).__init__(parent)

         #QWidget自定义类里面要放个东西！！（不放东西的话，我也不会）
         self.gb = QGroupBox(self)
         self.gb.setGeometry(0,0,200,200) #一定要有个东西把它撑起来！！不然看不到
         self.setStyleSheet("background-color:grey;")

         self.do_something()

     def do_something(self):
         pass

 class MyWindow(QWidget):
     def __init__(self, parent=None):
         super(MyWindow,self).__init__(parent)
         self.resize(400,300)

         # 添加自定义部件（MyWidget）
         self.widget = MyWidget(self)
         self.widget.setGeometry(10,10,380,240)

         # 添加编辑框（QLineEdit）
         self.lineEdit = QLineEdit("",self)
         self.lineEdit.setGeometry(10,260,380,20)

【效果图】

2)使用布局

这种情况下，原生QWidget部件在实例化时可以不带parent参数，parent =None / self都行，即： self.widget = QWidget()或 self.widget = QWidget(self)

 class MyWindow(QWidget):
     def __init__(self, parent=None):
         super(MyWindow,self).__init__(parent)
         self.resize(400,300)
         layout = QGridLayout()

         # 添加自定义部件（MyWidget）
         self.widget = MyWidget()

         # 添加编辑框（QLineEdit）
         self.lineEdit = QLineEdit("")

         # 放入布局内
         layout.addWidget(self.widget,0,0)
         layout.addWidget(self.lineEdit,1,0)
         self.setLayout(layout)

         self.setWindowTitle("4、QWidget的自定义类")

【效果图】

【源代码】（依次）

 from PyQt5.QtCore import *
 from PyQt5.QtGui import *
 from PyQt5.QtWidgets import *

 class MyWindow(QWidget):
     def __init__(self):
         super(MyWindow,self).__init__()
         self.resize(400, 300)

         # 添加原生QWidget
         self.widget = QWidget(self) # 注意QWidget(self) 内的self!!
         self.widget.setGeometry(10,10,380,250)
         self.widget.setStyleSheet("background-color:grey;")

         # 添加编辑框（QLineEdit）
         self.lineEdit = QLineEdit("",self) # 注意QLineEdit("0",self) 内的self!!
         self.lineEdit.setGeometry(10,270,380,20)

         self.setWindowTitle("1、原生QWidget")

 if __name__ == '__main__':
     import sys
     app = QApplication(sys.argv)
     dialog = MyWindow()
     dialog.show();
     sys.exit(app.exec_())   

 from PyQt5.QtCore import *
 from PyQt5.QtGui import *
 from PyQt5.QtWidgets import *

 class MyWindow(QWidget):
     def __init__(self):
         super(MyWindow,self).__init__()
         self.resize(400, 300)
         layout = QGridLayout()

         # 添加原生QWidget
         self.widget = QWidget()
         self.widget.setStyleSheet("background-color:grey;")

         # 添加编辑框（QLineEdit）
         self.lineEdit = QLineEdit("")

         # 放入布局内
         layout.addWidget(self.widget,0,0)
         layout.addWidget(self.lineEdit,1,0)
         self.setLayout(layout)

         self.setWindowTitle("2、原生QWidget")

 if __name__ == '__main__':
     import sys
     app = QApplication(sys.argv)
     dialog = MyWindow()
     dialog.show();
     sys.exit(app.exec_())   

 from PyQt5.QtCore import *
 from PyQt5.QtGui import *
 from PyQt5.QtWidgets import *

 class MyWidget(QWidget):
     def __init__(self, parent=None):
         super(MyWidget,self).__init__(parent)

         #QWidget派生类里面要放个东西！！（不放东西的话，我也不会）
         self.gb = QGroupBox(self)
         self.gb.setGeometry(0,0,200,200) #一定要有个东西把它撑起来！！不然看不到
         self.setStyleSheet("background-color:grey;")

         self.do_something()

     def do_something(self):
         pass

 class MyWindow(QWidget):
     def __init__(self, parent=None):
         super(MyWindow,self).__init__(parent)
         self.resize(400,300)

         # 添加自定义部件（MyWidget）
         self.widget = MyWidget(self)
         self.widget.setGeometry(10,10,380,240)

         # 添加编辑框（QLineEdit）
         self.lineEdit = QLineEdit("",self)
         self.lineEdit.setGeometry(10,260,380,20)

         self.setWindowTitle("3、QWidget的派生类")

 if __name__ == '__main__':
     import sys
     app = QApplication(sys.argv)
     window = MyWindow()
     window.show();
     sys.exit(app.exec_())   

 from PyQt5.QtCore import *
 from PyQt5.QtGui import *
 from PyQt5.QtWidgets import *

 class MyWidget(QWidget):
     def __init__(self, parent=None):
         super(MyWidget,self).__init__(parent)

         #QWidget派生类里面要放个东西！！（不放东西的话，我也不会）
         self.gb = QGroupBox(self)
         self.gb.setGeometry(0,0,200,200) #一定要有个东西把它撑起来！！不然看不到
         self.setStyleSheet("background-color:red;")
         self.do_something()

     def do_something(self):
         pass

 class MyWindow(QWidget):
     def __init__(self):
         super(MyWindow,self).__init__()
         self.resize(400,300)
         layout = QGridLayout()

         # 添加自定义部件（MyWidget）
         self.widget = MyWidget(self) # sizeHint() = QSize(-1, -1)
         self.widget.setStyleSheet("background-color:red;")

         # 添加编辑框（QLineEdit）
         self.lineEdit = QLineEdit("",self) # sizeHint() = QSize(75, 20)

         # 放入布局内
         layout.addWidget(self.widget,0,0)
         layout.addWidget(self.lineEdit,1,0)
         self.setLayout(layout)

 if __name__ == '__main__':
     import sys
     app = QApplication(sys.argv)
     window = MyWindow()
     window.show();
     sys.exit(app.exec_())   

【增补】

皇天不负苦心人，终于完美解决了。

问题出在自定义的QWidget类里面，加上下面三句即可：

         self.setPalette(QPalette(Qt.red)) # 这一句是辅助！着色，区分背景。这一句与self.setStyleSheet("background-color:red;")咋看一样，影响不一样
         self.setAutoFillBackground(True) # 这一句是关键！！！自动填充背景
         self.setMinimumSize(100,100) # 这一句是辅助！！因为这个自定义的QWidget默认大小（sizeHint()）是0，看不到！

其中，第一句与 self.setBackgroundRole(QPalette.Midlight) 及 self.setStyleSheet("background-color:red;") 的第一感觉是等效的 ??? 各位自己体会吧:(

         self.setPalette(QPalette(Qt.red))

         self.setBackgroundRole(QPalette.Midlight)

         self.setStyleSheet("background-color:red;")

完整自定义的QWidget类：

 class MyWidget(QWidget):
     def __init__(self, parent=None):
         super(MyWidget,self).__init__(parent)

         self.setPalette(QPalette(Qt.red)) # 这一句是辅助！着色，区分背景。这一句与self.setStyleSheet("background-color:red;")咋看一样，影响不一样
         self.setAutoFillBackground(True) #这一句是关键！！！自动填充背景
         self.setMinimumSize(100,100) # 这一句是辅助！！因为这个自定义的QWidget默认大小（sizeHint()）是0，看不到！
         #self.setMaximumSize(500, 500)
         #self.setFixesSize(400,200)

         # 做一些别的事情......
         self.do_something()

     def do_something(self):
         pass

     # 如果需要的话，就覆写属性函数：sizeHint（默认尺寸）
     #def sizeHint(self):
     #    return QSize(400, 200)
     # 如果需要的话，就覆写属性函数：minimumSizeHint（最小尺寸）
     #def minimumSizeHint(self):
     #    return QSize(100, 100)

【效果图】

【完整代码】

 from PyQt5.QtCore import *
 from PyQt5.QtGui import *
 from PyQt5.QtWidgets import *

 class MyWidget(QWidget):
     def __init__(self, parent=None):
         super(MyWidget,self).__init__(parent)

         self.setPalette(QPalette(Qt.red)) # 这一句是辅助！着色，区分背景。这一句与self.setStyleSheet("background-color:red;")咋看一样，影响不一样
         self.setAutoFillBackground(True) #这一句是关键！！！自动填充背景
         self.setMinimumSize(100,100) # 这一句是辅助！！因为这个自定义的QWidget默认大小（sizeHint()）是0，看不到！ 不过主窗体使用了布局的话，此句可省略
         #self.setMaximumSize(500, 500)
         #self.setFixesSize(400,200)

         # 做一些别的事情......
         self.do_something()

     def do_something(self):
         pass

     # 如果需要的话，就覆写属性函数：sizeHint（默认尺寸）
     #def sizeHint(self):
     #    return QSize(400, 200)
     # 如果需要的话，就覆写属性函数：minimumSizeHint（最小尺寸）
     #def minimumSizeHint(self):
     #    return QSize(100, 100)

 class MyWindow(QWidget):
     def __init__(self, parent=None):
         super(MyWindow,self).__init__(parent)
         self.resize(400,300)
         layout = QGridLayout()

         # 添加自定义部件（MyWidget）
         self.widget = MyWidget() # 这里可以不要self

         # 添加编辑框（QLineEdit）
         self.lineEdit = QLineEdit("") # 这里可以不要self

         # 放入布局内
         layout.addWidget(self.widget,0,0)
         layout.addWidget(self.lineEdit,1,0)
         self.setLayout(layout)

         self.setWindowTitle("5、完美显示QWidget的派生类")

 if __name__ == '__main__':
     import sys
     app = QApplication(sys.argv)
     window = MyWindow()
     window.show();
     sys.exit(app.exec_())   

再另外补充一个PyQt5应用实例： 飘动的文字

【效果图】

【源代码】

 #!/usr/bin/env python

 #############################################################################
 ##
 ## Copyright (C) 2013 Riverbank Computing Limited.
 ## Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
 ## All rights reserved.
 ##
 ## This file is part of the examples of PyQt.
 ##
 ## $QT_BEGIN_LICENSE:BSD$
 ## You may use this file under the terms of the BSD license as follows:
 ##
 ## "Redistribution and use in source and binary forms, with or without
 ## modification, are permitted provided that the following conditions are
 ## met:
 ##   * Redistributions of source code must retain the above copyright
 ##     notice, this list of conditions and the following disclaimer.
 ##   * Redistributions in binary form must reproduce the above copyright
 ##     notice, this list of conditions and the following disclaimer in
 ##     the documentation and/or other materials provided with the
 ##     distribution.
 ##   * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
 ##     the names of its contributors may be used to endorse or promote
 ##     products derived from this software without specific prior written
 ##     permission.
 ##
 ## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 ## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 ## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 ## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 ## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 ## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 ## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 ## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 ## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 ## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 ## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
 ## $QT_END_LICENSE$
 ##
 #############################################################################

 from PyQt5.QtCore import QBasicTimer
 from PyQt5.QtGui import QColor, QFontMetrics, QPainter, QPalette
 from PyQt5.QtWidgets import (QApplication, QDialog, QLineEdit, QVBoxLayout,
         QWidget)

 class WigglyWidget(QWidget):
     def __init__(self, parent=None):
         super(WigglyWidget, self).__init__(parent)

         self.setBackgroundRole(QPalette.Midlight)
         self.setAutoFillBackground(True)

         newFont = self.font()
         newFont.setPointSize(newFont.pointSize() + 20)
         self.setFont(newFont)

         self.timer = QBasicTimer()
         self.text = ''

         self.step = 0;
         self.timer.start(60, self)   

     def paintEvent(self, event):
         sineTable = (0, 38, 71, 92, 100, 92, 71, 38, 0, -38, -71, -92, -100, -92, -71, -38)

         metrics = QFontMetrics(self.font())
         x = (self.width() - metrics.width(self.text)) / 2
         y = (self.height() + metrics.ascent() - metrics.descent()) / 2
         color = QColor()

         painter = QPainter(self)

         for i, ch in enumerate(self.text):
             index = (self.step + i) % 16
             color.setHsv((15 - index) * 16, 255, 191)
             painter.setPen(color)
             painter.drawText(x, y - ((sineTable[index] * metrics.height()) / 400), ch)
             x += metrics.width(ch)

     def setText(self, newText):
         self.text = newText

     def timerEvent(self, event):
         if event.timerId() == self.timer.timerId():
             self.step += 1
             self.update()
         else:
             super(WigglyWidget, self).timerEvent(event)

 class Dialog(QDialog):
     def __init__(self, parent=None):
         super(Dialog, self).__init__(parent)

         wigglyWidget = WigglyWidget()
         lineEdit = QLineEdit()

         layout = QVBoxLayout()
         layout.addWidget(wigglyWidget)
         layout.addWidget(lineEdit)
         self.setLayout(layout)

         lineEdit.textChanged.connect(wigglyWidget.setText)

         lineEdit.setText("Hello world!")

         self.setWindowTitle("Wiggly")
         self.resize(360, 145)

 if __name__ == '__main__':

     import sys

     app = QApplication(sys.argv)
     dialog = Dialog()
     dialog.show();
     sys.exit(app.exec_())