QT 自定义界面布局要诀

1. 问题：有三个UI 子界面在一个主界面UI 上组合，那么三个子界面需要从主界面传递QSize子区域大小吗？

如下：

MonitorWnd::MonitorWnd(QSzie size, QWidget* parent)
    :ViewBaseWnd(parent){

        setFixedSize(size);

}

 实践所得：不需要设置大小，只需要设置伸缩比例即可 setStretchFactor   

void ViewWnd::InitUi()
{
	QVBoxLayout* view_layout = new QVBoxLayout(this);
	view_layout->setMargin(0);
	view_layout->setContentsMargins(QMargins(0, 0, 0, 0));
	view_layout->addSpacing(0);
	setLayout(view_layout);

	//view 标题栏
	m_title_wnd.reset(new ViewTitleWnd(this));
	m_title_wnd->setFixedHeight(VIEWTITLE_BUTTON_HEIGHT);

	view_layout->addWidget(m_title_wnd.get());
	//view_layout->addStretch();
	//view播放区域
	m_stacked_layout.reset(new QStackedLayout(view_layout));
	//QSize view_size(this->width(), this->height()- m_title_wnd->height());
	if (!m_monitor_wnd) {
		m_monitor_wnd.reset(new MonitorWnd(this));

		m_stacked_layout->addWidget(m_monitor_wnd.get());
		m_stacked_layout->setCurrentWidget(m_monitor_wnd.get());
		m_title_wnd->SetBtnStatusType(TitleTabType::TitleTabType_Monitor);//初始化显示监视器
		m_module_map[TitleTabType::TitleTabType_Monitor] = m_monitor_wnd;
	}
	if (!m_emap_wnd) {
		m_emap_wnd.reset(new EMapWnd(this));
		m_stacked_layout->addWidget(m_emap_wnd.get());
		m_module_map[TitleTabType::TitleTabType_EMap] = m_emap_wnd;
	}
	if (!m_terminal_wnd) {
		m_terminal_wnd.reset(new TerminalPreviewWnd(this));
		m_stacked_layout->addWidget(m_terminal_wnd.get());
		m_module_map[TitleTabType::TitleTabType_TerminalPreView] = m_terminal_wnd;
	}
	connect(m_title_wnd.get(), &ViewTitleWnd::sig_tabIndex, this, &ViewWnd::slot_TitleClicked);
}

 以上 m_monitor_wnd 、m_emap_wnd、m_terminal_wnd为三个子界面的对象。

void MonitorWnd::InitUi()
{
	QHBoxLayout* main_layout = new QHBoxLayout(this);
	main_layout->setMargin(0);
	main_layout->setContentsMargins(QMargins(0, 0, 0, 0));
	main_layout->setSpacing(0);

	QWidget* play_wnd = new QWidget(this);
	play_wnd->setObjectName("MonitorPlayWnd");

	QVBoxLayout* play_layout = new QVBoxLayout(play_wnd);
	play_layout->setMargin(0);
	play_layout->setContentsMargins(QMargins(0, 0, 0, 0));
	play_layout->setSpacing(0);

	play_wnd->setLayout(play_layout);
	//play_layout->addStretch();
	{
		m_monitor_name.reset( new QLabel(this));
		m_monitor_name->setFixedHeight(MONITOR_NAME_H);
		play_layout->addWidget(m_monitor_name.get(), 0, Qt::AlignVCenter);

		m_playpannel.reset(new PlayPannel(false, true, true, true, true, true, true, true, MAX_WND_VIDEO, this));
		//int height = this->height();
		//m_playpannel->setFixedHeight(this->height() - m_monitor_name->height() - MONITOR_CTROLAREA_H);

		QWidget* ctr_area = new QWidget(play_wnd);
		ctr_area->setObjectName("MonitorCtrArea");
		ctr_area->setFixedHeight(MONITOR_CTROLAREA_H);
		play_layout->addWidget(m_playpannel.get());
		play_layout->addWidget(ctr_area);
    }
    //右侧设备显示区
	//QWidget* list_monitors = new QWidget(this);
	//QSize monitorlist_size = QSize(this->width()/5, this->height());
	m_monitorlist_wnd.reset(new MonitorListWnd(this));

	main_layout->addWidget(play_wnd,4);
	main_layout->addWidget(m_monitorlist_wnd.get(), 1);
	this->setLayout(main_layout);
}

 //play_layout->addStretch();这个是空白间隔符，不要随意添加，显示异常还难以排查。

总结： 使用QHBoxLayout QVBoxLayout  然后 addWidget,  有时候会用到addSpacing(), addStrech(),但是要谨慎；添加子界面不需要设置固定大小setFixSize(.....),只需要在添加到Layout时设置伸缩比例即可：

main_layout->addWidget(play_wnd,4);
main_layout->addWidget(m_monitorlist_wnd.get(), 1);