Reimplemented QHeaderView paints wrong on scrolling

[coyoteazul]

Hi. I've reimplemented QHeaderView to rotate text on the vertical header of my table (a QStandardItem through a QSortProxyModel)
Whenever i scroll to the sides, the painting goes wrong. Like it couldn't paint the new column headers. Also if i do something to fire the paint event, it only paints right if i'm on the initial position. How can i get it to paint properly?
Thanks in advance for your help.


Initial position


Scroll to the furthest right


Scroll back to initial position



This is my reimplementation

#include <QObject>
#include <QHeaderView>
#include <QPainter>
 
class QHeaderViewR : public QHeaderView
{
QStringList heads;
 
public:
    QHeaderViewR(QStringList _heads):QHeaderView(Qt::Horizontal)
    {
        heads = _heads;
        this->setSectionResizeMode(QHeaderView::Fixed);
        this->setSectionsClickable(true);
    }
 
    void paintSection(QPainter * painter, const QRect & rect, int logicalIndex) const
    {
        QPen pen(Qt::black);
        painter->setPen(pen);
 
        painter->rotate(90);
        painter->translate(0,-rect.width()+1);
 
        QRect copy = rect;
 
        copy.setWidth(rect.height());
        copy.setHeight(rect.width());
        copy.moveTo(0,-this->sectionPosition(logicalIndex));
 
        if (logicalIndex == 0) //Show a line on the left
        {
            copy.setHeight(rect.width()-1);
            painter->drawText(copy,Qt::AlignCenter, heads.at(logicalIndex));
        }
        else
        {
            painter->drawText(copy,Qt::AlignCenter ,heads.at(logicalIndex));
        }
 
        painter->drawRect(copy);
    }
signals:
    void sectionPressed(int logicalIndex());
};

#include <QObject>
#include <QHeaderView>
#include <QPainter>

class QHeaderViewR : public QHeaderView
{
QStringList heads;

public:
    QHeaderViewR(QStringList _heads):QHeaderView(Qt::Horizontal)
    {
        heads = _heads;
        this->setSectionResizeMode(QHeaderView::Fixed);
        this->setSectionsClickable(true);
    }

    void paintSection(QPainter * painter, const QRect & rect, int logicalIndex) const
    {
        QPen pen(Qt::black);
        painter->setPen(pen);

        painter->rotate(90);
        painter->translate(0,-rect.width()+1);

        QRect copy = rect;

        copy.setWidth(rect.height());
        copy.setHeight(rect.width());
        copy.moveTo(0,-this->sectionPosition(logicalIndex));

        if (logicalIndex == 0) //Show a line on the left
        {
            copy.setHeight(rect.width()-1);
            painter->drawText(copy,Qt::AlignCenter, heads.at(logicalIndex));
        }
        else
        {
            painter->drawText(copy,Qt::AlignCenter ,heads.at(logicalIndex));
        }

        painter->drawRect(copy);
    }
signals:
    void sectionPressed(int logicalIndex());
};

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[wysota]

What happens if in paintSection you comment out all of your code and call the superclass implementation of the method? Do the problems with repainting go away?

[coyoteazul]

I didn't know you could do that. Yes, if i do that the repainting is done correctly, but the text is not rotated anymore

void paintSection(QPainter * painter, const QRect & rect, int logicalIndex) const
{
    QHeaderView::paintSection(painter,rect,logicalIndex);
        //old code commented out
}

void paintSection(QPainter * painter, const QRect & rect, int logicalIndex) const
{
    QHeaderView::paintSection(painter,rect,logicalIndex);
        //old code commented out
}

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[wysota]

This works for me just fine:

#include <QtWidgets>
 
class MyHeader : public QHeaderView {
public:
  MyHeader(QWidget*parent = 0) : QHeaderView(Qt::Horizontal, parent) {
 
  }
protected:
  QSize sectionSizeFromContents(int logicalIndex) const {
    QSize s = QHeaderView::sectionSizeFromContents(logicalIndex);
    return QSize(s.height(), std::max(100, s.width()));
  }
 
  void paintSection(QPainter *painter, const QRect & rect, int logicalIndex) const {
    if (logicalIndex % 2) {
      painter->save();
      painter->translate(rect.left(), rect.bottom());
      painter->rotate(-90);
      QRect r(0, 0, rect.height(), rect.width());
      painter->setBrush(Qt::red);
      painter->drawRect(r);
      painter->drawText(r, Qt::AlignCenter, QString::number(logicalIndex+1));
      painter->restore();
    } else QHeaderView::paintSection(painter, rect, logicalIndex);
  }
}; 
 
int main(int argc, char**argv) {
  QApplication app(argc, argv); 
  QTableView view;
  QStandardItemModel model(800,400);
  view.setModel(&model);
  view.setHorizontalHeader(new MyHeader);
  view.show();
  return app.exec();
}

#include <QtWidgets>

class MyHeader : public QHeaderView {
public:
  MyHeader(QWidget*parent = 0) : QHeaderView(Qt::Horizontal, parent) {

  }
protected:
  QSize sectionSizeFromContents(int logicalIndex) const {
    QSize s = QHeaderView::sectionSizeFromContents(logicalIndex);
    return QSize(s.height(), std::max(100, s.width()));
  }

  void paintSection(QPainter *painter, const QRect & rect, int logicalIndex) const {
    if (logicalIndex % 2) {
      painter->save();
      painter->translate(rect.left(), rect.bottom());
      painter->rotate(-90);
      QRect r(0, 0, rect.height(), rect.width());
      painter->setBrush(Qt::red);
      painter->drawRect(r);
      painter->drawText(r, Qt::AlignCenter, QString::number(logicalIndex+1));
      painter->restore();
    } else QHeaderView::paintSection(painter, rect, logicalIndex);
  }
}; 
   
int main(int argc, char**argv) {
  QApplication app(argc, argv); 
  QTableView view;
  QStandardItemModel model(800,400);
  view.setModel(&model);
  view.setHorizontalHeader(new MyHeader);
  view.show();
  return app.exec();
}

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[anda_skoa]

Right, I would have also recommended saving and restoring the painter

Cheers,
_

[coyoteazul]

It worked!. I tried using save and restoring when i first reimplemented this class, but it wouldn't work as expected for some reason (dumb me probably)
Thanks a lot!