PyQt QHboxLayout具有调整大小的小部件，没有左对齐

Question

I have a HboxLayout with a number of widgets. I set the size of the widgets manually, to dynamically fit the height of the window, and to have a certain aspect ratio. Initially, the widgets appear correctly, left aligned (as I set it). But when I then eg make the window smaller, and the widgets also shrink, spacing appears between them. They no longer appear 'glued' to the left side of the window. The position of the widgets doesn't seem to be updated in the way I expect. The 'left align' only holds initially. Positions seem to be fixed. Is this a feature or a bug? How to fix this? I searched around extensively, but to no avail. See code below.

    #!/usr/bin/python
    import sys
    from PyQt4.QtCore import *
    from PyQt4.QtGui import *
    from PyQt4 import QtCore, QtGui

    #After launching the app try and resize the window to
    #make the height smaller. Buttons shrink but stay in the 
    #same position. No left align
    #Run the app after uncommenting the app.setStyle("motif").
    #Make the widow less high and click the buttons. They will move
    #to the left!
    class DynButton(QtGui.QWidget):
       def __init__(self, parent=None):
          super(DynButton, self).__init__(parent)
          layout = QVBoxLayout()
          self.button = QtGui.QPushButton('Bouton', self)
          layout.addWidget(self.button)
          self.setLayout(layout)
          self.initUI()
       def paintEvent(self, e):
          self.initUI()
       def resizeEvent(self, e):
          self.initUI()
       def sizeHint(self):
          return QSize(self.h,self.h)
       def initUI(self):
          self.h=self.height()
          self.button.resize(self.h,self.h)
          self.button.move(0,0)
          self.resize(self.h,self.h) 

    class TestHbox(QtGui.QWidget):
       def __init__(self, parent=None):
          super(TestHbox, self).__init__(parent)
          layout = QtGui.QHBoxLayout()
          layout.setSpacing(0)
          layout.setMargin(0)
          self.b1 = DynButton()
          layout.addWidget(self.b1)
          self.b2 = DynButton()
          layout.addWidget(self.b2)
          self.b3 = DynButton()
          layout.addWidget(self.b3)
          layout.setAlignment(QtCore.Qt.AlignLeft)
          self.setLayout(layout)
       def sizeHint(self):
            return QSize(600, 140)

    def main():
       app = QApplication(sys.argv)
       #app.setStyle("motif")
       ex = TestHbox()
       ex.show()
       sys.exit(app.exec_())

    if __name__ == '__main__':
       main()

--EDIT--

For now I managed to solve it by adding some manual positioning to 'TestHbox'.

def resizeEvent(self, e):
   items = (self.layout.itemAt(i) for i in range(self.layout.count())) 
   X=0
   for w in items:
       w.widget().move(X,0)
       X+=w.widget().width()

Answer 1

I think you are looking for this. I added this line to your code : self.button.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Preferred)

#!/usr/bin/python
import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4 import QtCore, QtGui

class DynButton(QtGui.QWidget):
   def __init__(self, parent=None):
      super(DynButton, self).__init__(parent)
      layout = QVBoxLayout()
      self.button = QtGui.QPushButton('Bouton', self)
      self.button.setSizePolicy(QSizePolicy.Minimum, QSizePolicy.Preferred)
      layout.addWidget(self.button)
      self.setLayout(layout)

class TestHbox(QtGui.QWidget):
   def __init__(self, parent=None):
      super(TestHbox, self).__init__(parent)
      layout = QtGui.QHBoxLayout()
      layout.setSpacing(0)
      layout.setMargin(0)
      self.b1 = DynButton()
      layout.addWidget(self.b1)
      self.b2 = DynButton()
      layout.addWidget(self.b2)
      self.b3 = DynButton()
      layout.addWidget(self.b3)
      layout.setAlignment(QtCore.Qt.AlignLeft)
      self.setLayout(layout)

def main():
   app = QApplication(sys.argv)
   #app.setStyle("motif")
   ex = TestHbox()
   ex.show()
   sys.exit(app.exec_())

if __name__ == '__main__':
   main()

There are other option that you can tryout for size policy. Fixed, Minimum, Maximum, preferred, Expanding, Ignored, MinimumExpanding...