Render child widget relative to paint event rectangles

[jmalicke]

We want to paint some custom rectangles and then put a QPushButton in them.

Capture.PNG

Let's say we want to put the QPushButton in the top rectangle. How do we do it?

Here's our paint event:

void ChannelAxisList::paintEvent(QPaintEvent* pEvent)
{
    QPainter painter(this);
 
    QRect rt = pEvent->rect();
    painter.setBrush(QBrush(QColor(255, 255, 255, 0)));
    painter.setPen(QPen(QColor(255, 255, 255), 1));
 
    rt.setRight(rt.right() - 1);
    rt.setBottom(rt.bottom() - 1);
 
    painter.drawRect(rt);
 
    rt.setTopLeft(QPoint(0, 0));
    calculateLayout(rt);
 
 
    painter.setBrush(QBrush(QColor(255, 255, 255, 0)));
    painter.setPen(QPen(QColor(255, 255, 255), 1));
 
    painter.drawRect(m_mainRect);
 
    painter.setBrush(QBrush(QColor(255, 0, 0)));
    painter.setPen(QPen(QColor(0, 255, 0), 1));
    painter.setRenderHint(QPainter::Antialiasing, false);
 
    painter.drawRoundedRect(m_header, 2, 2);
    painter.drawRoundedRect(m_list, 2, 2); 
}

void ChannelAxisList::paintEvent(QPaintEvent* pEvent)
{
    QPainter painter(this);

    QRect rt = pEvent->rect();
    painter.setBrush(QBrush(QColor(255, 255, 255, 0)));
    painter.setPen(QPen(QColor(255, 255, 255), 1));

    rt.setRight(rt.right() - 1);
    rt.setBottom(rt.bottom() - 1);

    painter.drawRect(rt);

    rt.setTopLeft(QPoint(0, 0));
    calculateLayout(rt);


    painter.setBrush(QBrush(QColor(255, 255, 255, 0)));
    painter.setPen(QPen(QColor(255, 255, 255), 1));

    painter.drawRect(m_mainRect);

    painter.setBrush(QBrush(QColor(255, 0, 0)));
    painter.setPen(QPen(QColor(0, 255, 0), 1));
    painter.setRenderHint(QPainter::Antialiasing, false);

    painter.drawRoundedRect(m_header, 2, 2);
    painter.drawRoundedRect(m_list, 2, 2); 
}

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[kmy]

Creating QPusuButton code isn't in paintEvent, but in constructor.

It seems you already prepared 'm_header'.
Hou about use QPushButton::setGeometry() ?

ChannelAxisList()
{
    this->m_button = new QPushButton(this);
}
 
void ChannelAxisList::otherMethod()
{
    // m_header is changed here...
    this->m_header = QRect(QPoint(), this->size());    // sample
 
    this->m_button->setGeometry(this->m_header);
}

ChannelAxisList()
{
    this->m_button = new QPushButton(this);
}

void ChannelAxisList::otherMethod()
{
    // m_header is changed here...
    this->m_header = QRect(QPoint(), this->size());    // sample

    this->m_button->setGeometry(this->m_header);
}

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[jmalicke]

Very bizarre things happen when I move() or setGeometry() inside a paintEvent(). It appears in the right place until the mouse hovers over it. Then the widget jumps away from the mouse and leaves a trailing rectangle behind.

[anda_skoa]

Very bizarre things happen when I move() or setGeometry() inside a paintEvent(). It appears in the right place until the mouse hovers over it. Then the widget jumps away from the mouse and leaves a trailing rectangle behind.

Why would you move a widget in its parent's paintEvent()?
That is where you paint.

Cheers,
_