布局不会扩展超过使用设计器设置的初始大小

Question

我正在尝试根据 GUI window 大小调整我的小部件的大小，但卡住了。

首先，我使用设计器放置了一些小部件，包括 QVBoxLayout，并使用 PyQt5.uic.loadUi() 加载它。

之后我尝试通过 resizeEvent:

调整一些小部件的大小

def resizeEvent(self, event):
    print("Resized")
    QtWidgets.QMainWindow.resizeEvent(self, event)
    self.resize_widget(self.label, 'both', self.ratio_label)
    self.resize_widget(self.slider_cv2, 'width', self.ratio_slider_cv2)
    self.resize_widget(self.graph_layout, 'both', self.ratio_graph_layout)

def resize_widget(self, widget, mode, ratio):
    if mode == 'width':
        widget.resize(int(self.size().width() * ratio), widget.geometry().height())
    elif mode == 'height':
        widget.resize(widget.geometry().width(), int(self.size().height() * ratio))
    else:
        try:
            widget.resize(int(self.size().width() * ratio[0]), int(self.size().height() * ratio[1]))
        except AttributeError:
            widget.setGeometry(QtCore.QRect(widget.geometry().left(), widget.geometry().top(), int(self.geometry().width() * ratio[0]), int(self.geometry().height() * ratio[1])))

self.label、self.slider_cv2和self.graph_layout分别是Qlabel、QSlider和QVBoxLayout的实例。

self.label 和 self.slider_cv2 的大小如我所料动态变化，但 self.graph_layout 没有。当 GUI window 变小时，它会变小，但不会增长到大于其初始大小。

添加了最少的可重现代码：

from PyQt5 import QtWidgets, uic, QtCore
from PyQt5.QtMultimedia import QMediaPlayer, QMediaContent, QVideoFrame
from PyQt5.QtCore import QUrl, QTimer
from PyQt5.QtGui import QPixmap, QImage
import sys
import os
import threading
app = QtWidgets.QApplication(sys.argv)
import cv2
import matplotlib.pyplot as plt
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
from time import sleep
import numpy as np


class UI(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()
        uic.loadUi('/workspace/demo_cv2_load_entire_layout.ui', self)

        self.fig = plt.Figure()
        self.canvas = FigureCanvas(self.fig)
        self.graph_layout.addWidget(self.canvas)

        #---------For resizeing widget-----------
        w, h = self.size().width(), self.size().height()
        self.graph_layout.activate()
        self.ratio_graph_layout = (self.graph_layout.geometry().width() / w, self.graph_layout.geometry().height() / h)
        self.ratio_label = (self.label.size().width() / w, self.label.size().height() / h)
        self.ratio_slider_cv2 = self.slider_cv2.size().width() / w
        self.initial_wh = (w, h)
        #----------------------------------------
        self.show()
        
    def resizeEvent(self, event):
        print("Resized")
        QtWidgets.QMainWindow.resizeEvent(self, event)
        self.resize_widget(self.label, 'both', self.ratio_label)
        self.resize_widget(self.slider_cv2, 'width', self.ratio_slider_cv2)
        self.resize_widget(self.graph_layout, 'both', self.ratio_graph_layout)
    
    def resize_widget(self, widget, mode, ratio):
        if mode == 'width':
            widget.resize(int(self.size().width() * ratio), widget.geometry().height())
        elif mode == 'height':
            widget.resize(widget.geometry().width(), int(self.size().height() * ratio))
        else:
            try:
                widget.resize(int(self.size().width() * ratio[0]), int(self.size().height() * ratio[1]))
            except AttributeError:
                widget.setGeometry(QtCore.QRect(widget.geometry().left(), widget.geometry().top(), int(self.geometry().width() * ratio[0]), int(self.geometry().height() * ratio[1])))
        print(widget.geometry())


if __name__ == "__main__":
    window = UI()
    app.exec_()

和.UI文件：

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>1018</width>
    <height>814</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QWidget" name="verticalLayoutWidget">
    <property name="geometry">
     <rect>
      <x>240</x>
      <y>410</y>
      <width>291</width>
      <height>151</height>
     </rect>
    </property>
    <layout class="QVBoxLayout" name="graph_layout">
     <property name="sizeConstraint">
      <enum>QLayout::SetMaximumSize</enum>
     </property>
    </layout>
   </widget>
   <widget class="QSlider" name="slider_cv2">
    <property name="geometry">
     <rect>
      <x>220</x>
      <y>620</y>
      <width>349</width>
      <height>15</height>
     </rect>
    </property>
    <property name="orientation">
     <enum>Qt::Horizontal</enum>
    </property>
   </widget>
   <widget class="QLabel" name="label">
    <property name="geometry">
     <rect>
      <x>90</x>
      <y>0</y>
      <width>711</width>
      <height>371</height>
     </rect>
    </property>
    <property name="frameShape">
     <enum>QFrame::Box</enum>
    </property>
    <property name="text">
     <string>Video</string>
    </property>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>1018</width>
     <height>20</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

Answer 1

如果您想手动调整元素的大小，则不应使用布局。在此您必须使用 QWidget 作为容器，然后使用布局将 FigureCanvas 放置在该容器中。

另一方面，我实现了一种逻辑，可以简化并允许轻松处理调整大小功能，而无需覆盖 resizeEvent。

*.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>1018</width>
    <height>814</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QSlider" name="slider_cv2">
    <property name="geometry">
     <rect>
      <x>220</x>
      <y>620</y>
      <width>349</width>
      <height>15</height>
     </rect>
    </property>
    <property name="orientation">
     <enum>Qt::Horizontal</enum>
    </property>
   </widget>
   <widget class="QLabel" name="label">
    <property name="geometry">
     <rect>
      <x>90</x>
      <y>0</y>
      <width>711</width>
      <height>371</height>
     </rect>
    </property>
    <property name="frameShape">
     <enum>QFrame::Box</enum>
    </property>
    <property name="text">
     <string>Video</string>
    </property>
   </widget>
   <widget class="QWidget" name="graph_container" native="true">
    <property name="geometry">
     <rect>
      <x>240</x>
      <y>390</y>
      <width>291</width>
      <height>151</height>
     </rect>
    </property>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>1018</width>
     <height>28</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

*.py

import os
import sys
from dataclasses import dataclass
from enum import IntFlag, auto
from pathlib import Path


from PyQt5 import QtWidgets, uic, QtCore

from matplotlib.figure import Figure
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas


class ModeRatio(IntFlag):
    NONE = auto()
    WIDTH = auto()
    HEIGHT = auto()
    BOTH = WIDTH | HEIGHT


@dataclass
class SizeManager(QtCore.QObject):
    widget: QtWidgets.QWidget
    mode: ModeRatio

    def __post_init__(self):
        super().__init__(self.widget)
        self.widget.window().installEventFilter(self)
        self._width_ratio = self.widget.width() * 1.0 / self.widget.window().width()
        self._height_ratio = self.widget.height() * 1.0 / self.widget.window().height()

    def eventFilter(self, obj, event):
        if obj is self.widget.window():
            if event.type() == QtCore.QEvent.Resize:
                self.apply_resize()
        return super().eventFilter(obj, event)

    def apply_resize(self):
        width = self.widget.width()
        height = self.widget.height()
        if self.mode & ModeRatio.WIDTH:
            width = self.widget.window().width() * self._width_ratio
        if self.mode & ModeRatio.HEIGHT:
            height = self.widget.window().height() * self._height_ratio
        self.widget.resize(QtCore.QSizeF(width, height).toSize())


class UI(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()

        filename = os.fspath(
            Path(__file__).resolve().parent / "demo_cv2_load_entire_layout.ui"
        )
        uic.loadUi(filename, self)

        self.fig = Figure()
        self.canvas = FigureCanvas(self.fig)

        lay = QtWidgets.QVBoxLayout(self.graph_container)
        lay.addWidget(self.canvas)

        self.label_size_manager = SizeManager(widget=self.label, mode=ModeRatio.BOTH)
        self.slider_size_manager = SizeManager(
            widget=self.slider_cv2, mode=ModeRatio.WIDTH
        )
        self.graph_size_manager = SizeManager(
            widget=self.graph_container, mode=ModeRatio.BOTH
        )


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)

    window = UI()
    window.show()

    app.exec_()

├── demo_cv2_load_entire_layout.ui
└── main.py

Answer 2

首先，感谢@eyllanesc 为问题提供了直接而优雅的解决方案。

这是使用 qt-designer 设置类似属性的方法：将布局放在 QWidget.

内

之前尝试过直接修改layout或者mainwindow的centralwidget，但是都失败了

很奇怪 self.graph_layout.geometry() returns 类似 (0, 0, 200, 100) 的东西，尽管它在主窗口的视角下远低于 (0, 0)。所以我认为有一个不可见的父对象（即使 self.graph_layout.parent() returns mainwindow 的 centralwidget），并通过明确地将布局放在一个小部件中来替换这个幽灵父对象。

此外，用户必须将小部件的布局（通过右键单击）设置为Layout Horizontally或Layout Vertically等，以使布局的大小自动跟随小部件。

布局不会扩展超过使用设计器设置的初始大小

Layout doesn't expand more than initial size it was set using designer

python

pyqt

qt-designer

pyqt5