使用 takeAt() 时小部件故障

Question

我在 QListWidgetItem 中有一个小部件，其中有 5 个元素：

QLabel
SpacerItem
QWidget（包含QLabel和QLineEdit）
SpacerItem
QWidget（包含QLabel和QLineEdit）

我想访问外部小部件，为此我使用 QWidget* selectedWidget = dynamic_cast<QWidget*>(ui->listWidget->itemWidget(ui->listWidget->item(1))); 然后 QWidget* SelectedEdit = selectedWidget->layout()->takeAt(2)->widget(); 访问内部小部件（包含 QLineEdit），最后访问 lineEdit i'我使用 QLineEdit* ThisEdit = dynamic_cast<QLineEdit*>(SelectedEdit->layout()->takeAt(1)->widget());。每次选择后，我都会读取主小部件内的元素数量，并在执行 SelectedEdit 后将数字变为 4

header代码：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_pushButton_clicked();

private:
    Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

源代码：

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QListWidgetItem>
#include <QLabel>
#include <QLineEdit>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QListWidgetItem* list = new QListWidgetItem();
    QWidget* listwidget = new QWidget;
    QHBoxLayout* listLayout = new QHBoxLayout(listwidget);
    listwidget->setMaximumSize(QSize(ui->listWidget->width(), 20));
    listwidget->setMinimumSize(QSize(ui->listWidget->width(), 20));
    QLabel* NameLabel = new QLabel("Test Name");
    NameLabel->setMaximumWidth(200);
    NameLabel->setMinimumWidth(200);
    QFrame* line = new QFrame();
    line->setFrameShape(QFrame::VLine);
    line->setFrameShadow(QFrame::Sunken);
    QLabel* MaxLabel = new QLabel("Max");
    QFrame* line2 = new QFrame();
    line2->setFrameShape(QFrame::VLine);
    line2->setFrameShadow(QFrame::Sunken);
    QLabel* MinLabel = new QLabel("Min");
    listLayout->addWidget(NameLabel);
    listLayout->addWidget(line);
    listLayout->addWidget(MaxLabel);
    listLayout->addWidget(line2);
    listLayout->addWidget(MinLabel);
    listLayout->setSizeConstraint(QLayout::SetMinAndMaxSize);
    list->setSizeHint(listwidget->sizeHint());
    listLayout->setMargin(0);
    list->setSizeHint(QSize(listwidget->width(), listwidget->height()));
    ui->listWidget->addItem(list);
    ui->listWidget->setItemWidget(list, listwidget);
    ui->listWidget->item(0)->setFlags(ui->listWidget->item(0)->flags() & ~Qt::ItemIsSelectable);
    ui->listWidget->item(0)->setFlags(ui->listWidget->item(0)->flags() & ~Qt::ItemIsEnabled);

    for(int i = 0; i < 10; i++){
        list = new QListWidgetItem();
        QWidget* wid = new QWidget();
        wid->setMaximumSize(QSize(ui->listWidget->width(), 20));
        wid->setMinimumSize(QSize(ui->listWidget->width(), 20));
        QHBoxLayout* lay = new QHBoxLayout(wid);
        lay->setMargin(0);
        QLabel* lab = new QLabel("Name " + QString::number(i + 1));
        lab->setMaximumWidth(NameLabel->width());
        lab->setMinimumWidth(NameLabel->width());
        QWidget* maxContainer = new QWidget();
        maxContainer->setObjectName("MaxWidget" + QString::number(i));
        QHBoxLayout* maxLay = new QHBoxLayout(maxContainer);
        maxLay->setMargin(0);
        QLabel* maxLab = new QLabel("Max: ");
        QLineEdit* maxedit = new QLineEdit();
        maxedit->setObjectName("MaxEdit" + QString::number(i));
        maxedit->setText("1000");
        maxedit->setMinimumWidth(60);
        maxedit->setMaximumWidth(60);
        maxLay->addWidget(maxLab);
        maxLay->addWidget(maxedit);
        maxLay->setSizeConstraint(QLayout::SetMinAndMaxSize);
        QWidget* minContainer = new QWidget();
        minContainer->setObjectName("MinWidget");
        QHBoxLayout* minLay = new QHBoxLayout(minContainer);
        minLay->setMargin(0);
        QLabel* minLab = new QLabel("Min: ");
        QLineEdit* minedit = new QLineEdit();
        minedit->setText("50");
        minedit->setMinimumWidth(60);
        minedit->setMaximumWidth(60);
        minLay->addWidget(minLab);
        minLay->addWidget(minedit);
        minLay->setSizeConstraint(QLayout::SetMinAndMaxSize);
        maxContainer->setMaximumWidth(MaxLabel->width());
        maxContainer->setMinimumWidth(MaxLabel->width());
        minContainer->setMaximumWidth(MinLabel->width());
        minContainer->setMinimumWidth(MinLabel->width());
        QSpacerItem* FirstSpace = new QSpacerItem(line->width(), 1, QSizePolicy::Fixed, QSizePolicy::Fixed);
        QSpacerItem* SecondSpace = new QSpacerItem(line2->width(), 1, QSizePolicy::Fixed, QSizePolicy::Fixed);
        lay->addWidget(lab);
        lay->addSpacerItem(FirstSpace);
        lay->addWidget(maxContainer);
        lay->addSpacerItem(SecondSpace);
        lay->addWidget(minContainer);
        lay->setSizeConstraint(QLayout::SetMinAndMaxSize);
        list->setSizeHint(QSize(wid->width(), wid->height()));
        ui->listWidget->addItem(list);
        ui->listWidget->setItemWidget(list, wid);
    }
}

MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::on_pushButton_clicked()
{
    int numwid = ui->listWidget->count();
    QWidget* selectedWidget = dynamic_cast<QWidget*>(ui->listWidget->itemWidget(ui->listWidget->item(1)));
    int selectednum = selectedWidget->layout()->count(); // selectednum = 5
    QWidget* SelectedEdit = selectedWidget->layout()->takeAt(2)->widget();
    selectednum = selectedWidget->layout()->count(); // selectednum = 4
    QLineEdit* ThisEdit = dynamic_cast<QLineEdit*>(SelectedEdit->layout()->takeAt(1)->widget());
    selectednum = selectedWidget->layout()->count(); selectednum = 4
    ThisEdit->setText("600");
    selectednum = selectedWidget->layout()->count(); selectednum = 4
}

ui代码：

<?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>445</width>
    <height>358</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
     <widget class="QListWidget" name="listWidget"/>
    </item>
    <item>
     <widget class="QPushButton" name="pushButton">
      <property name="text">
       <string>PushButton</string>
      </property>
     </widget>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>445</width>
     <height>21</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

初始状态：

最终状态：

如您所见，最大和最小标签彼此重叠

Answer 1

您正在使用 QLayout::takeAt，从布局中删除 小部件。我不认为你有意这样做...

改用QLayout::itemAt。

使用 takeAt() 时小部件故障

Widget malfunction when use takeAt()

qt