children().count() of QGroupBox returns 值超过预期

Question

我正在测试 Qt 文档的以下要点。

When you use a layout, you do not need to pass a parent when constructing the child widgets. The layout will automatically reparent the widgets (using QWidget::setParent()) so that they are children of the widget on which the layout is installed.

我使用 QDesigner 创建了五个 QPushButton 和一个 QGroupbox。然后我将这些按钮添加到 QGridLayout 并将其设置为组框的布局。

然后我尝试检查groupbox的children。但它显示 6 children 而不是 5。一个是空的，其他是按钮。

这是我的代码。

QGridLayout *grd = new QGridLayout();
grd->addWidget(ui->pushButton,0,0);
grd->addWidget(ui->pushButton_2,0,1);
grd->addWidget(ui->pushButton_3,1,0,1,3);
grd->addWidget(ui->pushButton_4,2,0);
grd->addWidget(ui->pushButton_5,2,1);

ui->groupBox->setLayout(grd);

qDebug() << ui->groupBox->children().count();

foreach (QObject *button, ui->groupBox->children())
{
    qDebug() << "obj name" << button->objectName();
    QPushButton *push_button = qobject_cast<QPushButton *>(button) ;
    if(push_button)
    {
        qDebug() << push_button->text();
    }
}

我得到的结果。

6 
obj name "" 
obj name "pushButton" 
"button 1" 
obj name "pushButton_2" 
"button 2" 
obj name "pushButton_3" 
"button 3" 
obj name "pushButton_4" 
"button 4" 
obj name "pushButton_5" 
"button 5"

谁能告诉我为什么 children().count() 等于 6 而不是 5？

Answer 1

执行以下操作：

qDebug() << "Class name:" << button->metaObject()->className();

你会看到一个 child 是 QGridLayout

或者：

grd->setObjectName("GridLayout");

并且名称应该显示在空字符串的位置

什么意思：widget的布局变成了widget的child。

children().count() of QGroupBox returns 值超过预期

children().count() of QGroupBox returns value more than expected

c++

qt

qgroupbox