qt - 无法从 MainWindow 显示 QGridLayout 中的小部件

Question

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
{
    reminderTextEdit     = new QTextEdit("");
    reminderTextEdit->setPlaceholderText("What do you want to be reminded of?");
    /// Setting parent is necessary otherwise it will be created in a window of its own.
    reminderTextEdit->setParent(this);
    reminderTextEdit->show();

    dateComboBox         = new QComboBox();
    dateComboBox->setParent(this);
    dateComboBox->show();

    monthComboBox        = new QComboBox();
    monthComboBox->setParent(this);
    monthComboBox->show();

    yearComboBox         = new QComboBox();
    yearComboBox->setParent(this);
    yearComboBox->show();

    doneAndAddMoreButton = new QPushButton();
    doneAndAddMoreButton->setParent(this);
    doneAndAddMoreButton->show();

    doneAndQuitButton    = new QPushButton();
    doneAndQuitButton->setParent(this);
    doneAndQuitButton->show();

    gridLayout           = new QGridLayout;
    gridLayout->addWidget(reminderTextEdit, 0, 0, 0, 0);
    gridLayout->addWidget(dateComboBox, 1, 0);
    gridLayout->addWidget(monthComboBox, 1, 1);
    gridLayout->addWidget(yearComboBox, 1, 2);
    gridLayout->addWidget(doneAndAddMoreButton, 2, 0);
    gridLayout->addWidget(doneAndQuitButton, 2, 1);
}

这段代码只是生成一个父窗口和一个子窗口。

在其末尾添加 setLayout(gridLayout); 会产生以下错误:

QWidget::setLayout:尝试在主窗口“”上设置 QLayout“”，该窗口已经有布局

错误的地方请指出。

Answer 1

QMainWindow 已经有固定的布局。所以你不能重新分配一个。参见这里:http://doc.qt.io/qt-5/qmainwindow.html#details

QMainWindow has its own layout to which you can add QToolBars, QDockWidgets, a QMenuBar, and a QStatusBar. The layout has a center area that can be occupied by any kind of widget.

您可以做的是将“空”小部件设置为中心小部件并为其指定布局。

QWidget *centralWidget = new QWidget(); //set parent to this
//...
reminderTextEdit = new QTextEdit("");
reminderTextEdit->setPlaceholderText("What do you want to be reminded of?");
//...

centralWidget->setLayout(gridLayout);    
setCentralWidget(window);

编辑:

正如 @thuga 在评论中提到的:当您将小部件添加到布局中时，它将承担该项目的责任(重新设置它们的父级)。因此，当您将项目添加到布局时，您不需要首先需要声明父级。

您提供给 setCentralWidget 的小部件也是如此