QT5 custom Widgth cannot be displayed

zj.liu

I added four play Windows using QWidgth, which worked fine with the QWidgth class, but failed to display when replaced with custom widgth,

The desired effect:

code:

            m_layout->setSpacing(0);
            m_layout->setContentsMargins(0,0,0,0);
            QWidget *w1= new QWidget(video_window);
            QWidget *w2= new QWidget(video_window);
            QWidget *w3= new QWidget(video_window);
            QWidget *w4= new QWidget(video_window);
            m_layout->addWidget(w1,0,0,1,1);
            m_layout->addWidget(w2,0,1,1,1);
            m_layout->addWidget(w3,1,0,1,1);
            m_layout->addWidget(w4,1,1,1,1);
            video_window->setLayout(m_layout);

But it doesn't show when I replace widgth with my custom widgth:

custom widgth:

Video_play::Video_play(QWidget *parent) : QWidget(parent)
{

    this->init();
}


void Video_play::init()
{
    Act_stop=new QAction(tr("停止预览"),this);
    Act_preview=new QAction(tr("预览"),this);

    Act_cut1=new QAction(tr("全屏"),this);
    Act_cut4=new QAction(tr("切换4画面"),this);
    Act_cut8=new QAction(tr("切换8画面"),this);
    Act_cut16=new QAction(tr("切换16画面"),this);

    connect(Act_stop, SIGNAL(triggered()), this, SLOT(stop_preview()));
    connect(Act_preview, SIGNAL(triggered()), this, SLOT(action_preview()));

    connect(Act_cut1, SIGNAL(triggered()), this, SLOT(cut_1()));
    connect(Act_cut4, SIGNAL(triggered()), this, SLOT(cut_4()));
    connect(Act_cut8, SIGNAL(triggered()), this, SLOT(cut_8()));
    connect(Act_cut16, SIGNAL(triggered()), this, SLOT(cut_16()));
   this->setStyleSheet("QMenu {background-color:rgba(255,255,255,1);border:1px solid rgba(82,130,164,1);}QMenu::item:selected {background:rgba(82,130,164,1);border:1px solid rgba(82,130,164,1);}");
}
void Video_play::contextMenuEvent(QContextMenuEvent *event)
{

    QCursor cur=this->cursor();
    QMenu *menu=new QMenu(this);

    menu->addAction(Act_preview);
    menu->addAction(Act_stop);
    menu->addAction(Act_cut1);
    menu->addAction(Act_cut4);
    menu->addAction(Act_cut8);
    menu->addAction(Act_cut16);
    menu->exec(cur.pos());
}

mrjj

@zj-liu said in QT5 custom Widgth cannot be displayed:

What's the difference between a class that inherits from QWidget and QWidget

In terms of using stylesheet, you need to have a paintEvent for the custom widget
that respect the stylesheet.
This allows a custom QWidget to use stylesheet.

 void CustomWidget::paintEvent(QPaintEvent *)
 {
     QStyleOption opt;
     opt.init(this);
     QPainter p(this);
     style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
 }

SGaist

Hi and welcome to devnet,

What exactly is not working ?

zj.liu

@SGaist I want four Windows like those in Figure 1 to appear, but they don't

SGaist

Your Alpha values are 1, which AFAIK, means almost fully transparent.

zj.liu

@SGaist

I removing the subclass's style sheet,but hasn't changed,

In addition, the parent class has a set style sheet:

video_window->setStyleSheet("background:transparent;border:2px solid red;");

then,I replaced one of the custom QWidgth with QWidgth:

            m_layout->setSpacing(0);
            m_layout->setContentsMargins(0,0,0,0);
            Video_play *w1= new Video_play(video_window);
            QWidget *w2= new QWidget(video_window);
            Video_play *w3= new Video_play(video_window);
            Video_play *w4= new Video_play(video_window);
            m_layout->addWidget(w1,0,0,1,1);
            m_layout->addWidget(w2,0,1,1,1);
            m_layout->addWidget(w3,1,0,1,1);
            m_layout->addWidget(w4,1,1,1,1);
            video_window->setLayout(m_layout);

run:

so,What's the difference between a class that inherits from QWidget and QWidget

mrjj

@zj-liu said in QT5 custom Widgth cannot be displayed:

What's the difference between a class that inherits from QWidget and QWidget

In terms of using stylesheet, you need to have a paintEvent for the custom widget
that respect the stylesheet.
This allows a custom QWidget to use stylesheet.

 void CustomWidget::paintEvent(QPaintEvent *)
 {
     QStyleOption opt;
     opt.init(this);
     QPainter p(this);
     style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
 }

zj.liu

@mrjj
Thanks，After I added paintEvent, I successfully solved the problem