Vs - Qt - 下拉窗口示例

下列代码定义了一个窗口，窗口采用竖直布局：一个按钮及一个label。按下按钮时候，窗口扩张，显示label控件。再次按下按钮时，窗口收缩，隐藏label控件。

详细代码如下：

#include <QApplication>
#include <QWidget>
#include <QHBoxLayout>
#include <QTimer>
#include <QLabel>
#include <QVBoxLayout>
#include <QPushButton>
#include <QDebug>class MyWidget : public QWidget
{//Q_OBJECT
public:MyWidget(QWidget* parent = nullptr) : QWidget(parent), m_bD(true){setFixedWidth(100);//	setStyleSheet("background-color:red;");m_vLayout = new QVBoxLayout();m_vLayout->setContentsMargins(0, 0, 0, 0);setLayout(m_vLayout);m_hLayout = new QHBoxLayout();m_pushBtn = new QPushButton("d!", this);m_pushBtn->setFixedSize(20, 20);m_hLayout->addStretch(1);m_hLayout->addWidget(m_pushBtn);m_vLayout->addLayout(m_hLayout);m_label = new QLabel(this);m_label->setText("just a label text!");m_vLayout->addWidget(m_label);m_vLayout->addStretch(1);//setFixedHeight(m_pushBtn->height() + m_label->height());setFixedHeight(m_pushBtn->height());m_label->hide();QObject::connect(m_pushBtn, &QPushButton::clicked, [=]() {if (m_bD){//m_vLayout->addWidget(m_label);m_label->show();m_pushBtn->setText("d!");qDebug() << "push btn h:" << m_pushBtn->height() << ", label h:" << m_label->height();setFixedHeight(m_pushBtn->height() + m_label->height());m_bD = false;}else{m_bD = true;//m_vLayout->removeWidget(m_label);m_label->hide();m_pushBtn->setText("p!");qDebug() << "push btn h:" << m_pushBtn->height() << ", label h:" << m_label->height();setFixedHeight(m_pushBtn->height());}});}private:QHBoxLayout* m_hLayout;QPushButton* m_pushBtn;bool m_bD;QVBoxLayout* m_vLayout;QLabel *m_label;
};int main(int argc, char** argv)
{QApplication app(argc, argv);MyWidget w;w.show();return app.exec();
}

页面效果如下：