QStyledItemDelegate events are not called

**PinTxO** · 13th October 2015, 15:51

Hi everyone.

This is my first post in this comunity and hopefully not the last.

My problem is the next, I've created a custom delegated for a QComboBox but I don't see the items, I mean, when I click in the combo I can see deployed items but not the information(a image with a text and two more images). Debugging I've noticed that the paint event never is called. The curious thing is that the info in the items exists because when I click one of them, the info shows in the combo. My code:

delegates.h

Qt Code:

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class ComboUpDownDelegate : public QStyledItemDelegate {
  Q_OBJECT
 
public:
  static const int SESSION_DATA_ROLE;
  static const int ICON1_ROLE;
  static const int ICON2_ROLE;
  static const int ICON3_ROLE;
 
  static const char* COMBO_TYPE;
  static const QString COMBO_ICON_TEXT;
  static const QString COMBO_ICON_TEXT_ICONS;
  static const QString COMBO_ICON_RICHTEXT_COUNTER;
 
public:
  ComboUpDownDelegate(QObject* parent);
  ~ComboUpDownDelegate();
 
  void initCombo(QComboBox* combo);
 
  virtual QSize sizeHint(const QStyleOptionViewItem & option, const QModelIndex & index) const override;
  virtual void paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const override;
  virtual bool eventFilter(QObject *object, QEvent *event) override;
 
  void setTitle(const QString& title);
  QString title() const;
 
  virtual QWidget* createEditor(QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index) const override  {
    return nullptr;
  }
 
protected:
  void drawIconRichTextCounter(QPainter* painter, const CUDSession& data, const QPoint& topLeft, int row, int width) const;
 
private:
  QString m_title;
  QPixmap m_icon1, m_icon2, m_icon3;
};

class ComboUpDownDelegate : public QStyledItemDelegate {
  Q_OBJECT

public:
  static const int SESSION_DATA_ROLE;
  static const int ICON1_ROLE;
  static const int ICON2_ROLE;
  static const int ICON3_ROLE;

  static const char* COMBO_TYPE;
  static const QString COMBO_ICON_TEXT;
  static const QString COMBO_ICON_TEXT_ICONS;
  static const QString COMBO_ICON_RICHTEXT_COUNTER;

public:
  ComboUpDownDelegate(QObject* parent);
  ~ComboUpDownDelegate();

  void initCombo(QComboBox* combo);

  virtual QSize sizeHint(const QStyleOptionViewItem & option, const QModelIndex & index) const override;
  virtual void paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const override;
  virtual bool eventFilter(QObject *object, QEvent *event) override;

  void setTitle(const QString& title);
  QString title() const;

  virtual QWidget* createEditor(QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index) const override  {
    return nullptr;
  }

protected:
  void drawIconRichTextCounter(QPainter* painter, const CUDSession& data, const QPoint& topLeft, int row, int width) const;

private:
  QString m_title;
  QPixmap m_icon1, m_icon2, m_icon3;
};

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delegates.cpp

Qt Code:

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namespace {
  QPoint drawText(QPainter* painter, const QPoint& point, const QString& text, const QFont& font) {
    painter->setFont(font);
 
    QFontMetrics fm(font);
    const int w = fm.width(text);
    painter->drawText(point, text);
 
    return QPoint(point.x() + w, point.y());
  }
}
 
const int ComboUpDownDelegate::SESSION_DATA_ROLE = Qt::UserRole + 1;
const int ComboUpDownDelegate::ICON1_ROLE = Qt::UserRole + 1;
const int ComboUpDownDelegate::ICON2_ROLE = Qt::UserRole + 2;
const int ComboUpDownDelegate::ICON3_ROLE = Qt::UserRole + 3;
 
const char* ComboUpDownDelegate::COMBO_TYPE = "combo_type";
const QString ComboUpDownDelegate::COMBO_ICON_TEXT = "icon_text";
const QString ComboUpDownDelegate::COMBO_ICON_TEXT_ICONS = "icon_text_icons";
const QString ComboUpDownDelegate::COMBO_ICON_RICHTEXT_COUNTER = "icon_richtext_counter";
 
ComboUpDownDelegate::ComboUpDownDelegate(QObject* parent)
  : QStyledItemDelegate(parent) {
  initCombo(qobject_cast<QComboBox*>(parent));
 
  // Icons
  m_icon1 = Customisation::getImage("time", QSize(16, 16), QColor("#C8C8C8"));
  m_icon2 = Customisation::getImage("warning", QSize(16, 16), QColor("#C8C8C8"));
  m_icon3 = Customisation::getImage("warning", QSize(16, 16), QColor("#FF0000"));
}
 
ComboUpDownDelegate::~ComboUpDownDelegate() {
}
 
void ComboUpDownDelegate::initCombo(QComboBox* combo) {
  if (combo != nullptr) {
    combo->view()->setEditTriggers(QAbstractItemView::CurrentChanged);
    combo->installEventFilter(this);
  }
}
 
QSize ComboUpDownDelegate::sizeHint(const QStyleOptionViewItem & option, const QModelIndex & index) const {
  auto combo = static_cast<QComboBox*>(this->parent());
 
  const auto text = index.data(Qt::DisplayRole).toString();
  const auto style = QApplication::style();
 
  QStyleOptionButton opt;
  opt.text = text;
  opt.rect = option.rect;
  opt.icon = index.data(Qt::DecorationRole).value<QIcon>();
  if (combo != nullptr) {
    opt.iconSize = combo->iconSize();
  }
 
  return style->sizeFromContents(QStyle::CT_CheckBox, &opt, QSize());
  //return style->sizeFromContents(QStyle::CT_PushButton, &opt, QSize());
}
 
void ComboUpDownDelegate::paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const {
  QComboBox* combo = static_cast<QComboBox*>(this->parent());
 
  // Basic style
  QStyleOptionViewItemV4 modifiedOption(option);
  modifiedOption.text.clear();
  modifiedOption.icon = QIcon();
  QApplication::style()->drawControl(QStyle::CE_ItemViewItem, &modifiedOption, painter);
 
  const auto topLeft = option.rect.topLeft();
  const int margin = 3;
  const int fontHeight = QFontMetrics(painter->font()).height();
 
  painter->setPen(combo->palette().color(QPalette::Text));
 
  if (combo->property(COMBO_TYPE) == COMBO_ICON_TEXT)
  {
    const bool state1 = index.data(ICON1_ROLE).toBool();
    QPixmap icon1(state1 ? m_icon1 : m_icon2);
    painter->drawPixmap(margin, topLeft.y() + margin, icon1);
 
    const QString text = index.data(Qt::DisplayRole).toString();
    painter->drawText(icon1.width() + 2 * margin, topLeft.y() + fontHeight + 3, text);
 
    const bool state2 = index.data(ICON2_ROLE).toBool();
    QPixmap icon2(state2 ? m_icon1 : m_icon2);
    int w = option.rect.width() - icon2.width() - margin;
    painter->drawPixmap(w, topLeft.y() + margin, icon2);
  }
  else if (combo->property(COMBO_TYPE) == COMBO_ICON_TEXT_ICONS)
  {
    const bool state1 = index.data(ICON1_ROLE).toBool();
    QPixmap icon1(state1 ? m_icon1 : m_icon2);
    painter->drawPixmap(margin, topLeft.y() + margin, icon1);
 
    const QString text = index.data(Qt::DisplayRole).toString();
    painter->drawText(icon1.width() + 2 * margin, topLeft.y() + fontHeight + 3, text);
 
    const bool state3 = index.data(ICON3_ROLE).toBool();
    QPixmap icon3(state3 ? m_icon1 : m_icon2);
    int w = option.rect.width() - icon3.width() - margin;
    painter->drawPixmap(w, topLeft.y() + margin, icon3);
 
    const bool state2 = index.data(ICON2_ROLE).toBool();
    QPixmap icon2(state2 ? m_icon1 : m_icon2);
    w -= icon2.width();
    painter->drawPixmap(w, topLeft.y() + margin, icon2);
  }
  else if (combo->property(COMBO_TYPE) == COMBO_ICON_RICHTEXT_COUNTER)
  {
    const CUDSession data = index.data(SESSION_DATA_ROLE).value<CUDSession>();
    drawIconRichTextCounter(painter, data, topLeft, index.row(), option.rect.width());
  }
}
 
void ComboUpDownDelegate::drawIconRichTextCounter(QPainter* painter, const CUDSession& data, const QPoint& topLeft, int row, int width) const {
  const int margin = 15;
 
  QPixmap icon1(m_icon1);
  painter->drawPixmap(margin, topLeft.y() + margin, icon1);
 
  QFont normalFont(painter->font());
  QFont boldFont(normalFont);
  boldFont.setBold(true);
  QFontMetrics fm(normalFont);
 
  QPoint p(topLeft + QPoint(icon1.width() + 1.5 * margin, fm.height() + 11));
  if (row == 0)
  {
    p = drawText(painter, p, QString("ALL SESSIONS"), boldFont);
  }
  else
  {
    QString strRow = QString::number(row);
    if(strRow.length() < 2)
    {
        strRow = "0" + strRow;
    }
    p = drawText(painter, p, QString("SESSION %1").arg(strRow), boldFont);
    painter->setPen(QColor("#C8C8C8"));
    p = drawText(painter, p, QString(" | "), normalFont);
    p = drawText(painter, p, QString("START:"), boldFont);
    p = drawText(painter, p, QString(" %1  -  ").arg(data.StartStr()), normalFont);
    p = drawText(painter, p, QString("END:"), boldFont);
    if(data.End().isValid())
    {
        p = drawText(painter, p, QString(" %1").arg(data.EndStr()), normalFont);
    }
    else
    {
        p = drawText(painter, p, QString(" %1").arg(tr("Running")), normalFont);
    }
 
    const QString errorCounter(QString::number(data.Errors()));
    p.setX(width - fm.width("888") - margin);
    painter->drawText(p, errorCounter);
 
    QPixmap icon2(data.Errors() > 0 ? m_icon3 : m_icon2);
    painter->drawPixmap(p.x() - icon2.width() - 3, topLeft.y() + margin, icon2);
  }
 
}
 
bool ComboUpDownDelegate::eventFilter(QObject *object, QEvent *event) {
  auto combo = static_cast<QComboBox*>(object);
 
  if (combo != nullptr && object == this->parent() && event->type() == QEvent::Paint) {
    QStylePainter painter(combo);
 
    painter.setPen(combo->palette().color(QPalette::Text));
 
    QStyleOptionComboBox opt;
    opt.initFrom(combo);
    opt.editable = combo->isEditable();
    opt.frame = combo->hasFrame();
    if (combo->hasFocus() && !opt.editable) {
      opt.state |= QStyle::State_Selected;
    }
    opt.subControls = QStyle::SC_All;
 
    if (m_title.isEmpty()) {
      opt.currentText = combo->currentText();
    } else {
      opt.currentText = m_title.arg(combo->count());
    }
    painter.drawComplexControl(QStyle::CC_ComboBox, opt);
    painter.drawControl(QStyle::CE_ComboBoxLabel, opt);
 
    if (combo->property(COMBO_TYPE) == COMBO_ICON_RICHTEXT_COUNTER) {
      drawIconRichTextCounter(&painter, combo->currentData(SESSION_DATA_ROLE).value<CUDSession>(),
                              QPoint(0, 0), combo->currentIndex(), combo->width() - 16);
    }
 
    return true;
  }
  return QStyledItemDelegate::eventFilter(object, event);
}
 
void ComboUpDownDelegate::setTitle(const QString& title) {
  m_title = title;
}
 
QString ComboUpDownDelegate::title() const {
  return m_title;
}

namespace {
  QPoint drawText(QPainter* painter, const QPoint& point, const QString& text, const QFont& font) {
    painter->setFont(font);

    QFontMetrics fm(font);
    const int w = fm.width(text);
    painter->drawText(point, text);

    return QPoint(point.x() + w, point.y());
  }
}

const int ComboUpDownDelegate::SESSION_DATA_ROLE = Qt::UserRole + 1;
const int ComboUpDownDelegate::ICON1_ROLE = Qt::UserRole + 1;
const int ComboUpDownDelegate::ICON2_ROLE = Qt::UserRole + 2;
const int ComboUpDownDelegate::ICON3_ROLE = Qt::UserRole + 3;

const char* ComboUpDownDelegate::COMBO_TYPE = "combo_type";
const QString ComboUpDownDelegate::COMBO_ICON_TEXT = "icon_text";
const QString ComboUpDownDelegate::COMBO_ICON_TEXT_ICONS = "icon_text_icons";
const QString ComboUpDownDelegate::COMBO_ICON_RICHTEXT_COUNTER = "icon_richtext_counter";

ComboUpDownDelegate::ComboUpDownDelegate(QObject* parent)
  : QStyledItemDelegate(parent) {
  initCombo(qobject_cast<QComboBox*>(parent));

  // Icons
  m_icon1 = Customisation::getImage("time", QSize(16, 16), QColor("#C8C8C8"));
  m_icon2 = Customisation::getImage("warning", QSize(16, 16), QColor("#C8C8C8"));
  m_icon3 = Customisation::getImage("warning", QSize(16, 16), QColor("#FF0000"));
}

ComboUpDownDelegate::~ComboUpDownDelegate() {
}

void ComboUpDownDelegate::initCombo(QComboBox* combo) {
  if (combo != nullptr) {
    combo->view()->setEditTriggers(QAbstractItemView::CurrentChanged);
    combo->installEventFilter(this);
  }
}

QSize ComboUpDownDelegate::sizeHint(const QStyleOptionViewItem & option, const QModelIndex & index) const {
  auto combo = static_cast<QComboBox*>(this->parent());

  const auto text = index.data(Qt::DisplayRole).toString();
  const auto style = QApplication::style();

  QStyleOptionButton opt;
  opt.text = text;
  opt.rect = option.rect;
  opt.icon = index.data(Qt::DecorationRole).value<QIcon>();
  if (combo != nullptr) {
    opt.iconSize = combo->iconSize();
  }

  return style->sizeFromContents(QStyle::CT_CheckBox, &opt, QSize());
  //return style->sizeFromContents(QStyle::CT_PushButton, &opt, QSize());
}

void ComboUpDownDelegate::paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const {
  QComboBox* combo = static_cast<QComboBox*>(this->parent());

  // Basic style
  QStyleOptionViewItemV4 modifiedOption(option);
  modifiedOption.text.clear();
  modifiedOption.icon = QIcon();
  QApplication::style()->drawControl(QStyle::CE_ItemViewItem, &modifiedOption, painter);

  const auto topLeft = option.rect.topLeft();
  const int margin = 3;
  const int fontHeight = QFontMetrics(painter->font()).height();

  painter->setPen(combo->palette().color(QPalette::Text));

  if (combo->property(COMBO_TYPE) == COMBO_ICON_TEXT)
  {
    const bool state1 = index.data(ICON1_ROLE).toBool();
    QPixmap icon1(state1 ? m_icon1 : m_icon2);
    painter->drawPixmap(margin, topLeft.y() + margin, icon1);

    const QString text = index.data(Qt::DisplayRole).toString();
    painter->drawText(icon1.width() + 2 * margin, topLeft.y() + fontHeight + 3, text);

    const bool state2 = index.data(ICON2_ROLE).toBool();
    QPixmap icon2(state2 ? m_icon1 : m_icon2);
    int w = option.rect.width() - icon2.width() - margin;
    painter->drawPixmap(w, topLeft.y() + margin, icon2);
  }
  else if (combo->property(COMBO_TYPE) == COMBO_ICON_TEXT_ICONS)
  {
    const bool state1 = index.data(ICON1_ROLE).toBool();
    QPixmap icon1(state1 ? m_icon1 : m_icon2);
    painter->drawPixmap(margin, topLeft.y() + margin, icon1);

    const QString text = index.data(Qt::DisplayRole).toString();
    painter->drawText(icon1.width() + 2 * margin, topLeft.y() + fontHeight + 3, text);

    const bool state3 = index.data(ICON3_ROLE).toBool();
    QPixmap icon3(state3 ? m_icon1 : m_icon2);
    int w = option.rect.width() - icon3.width() - margin;
    painter->drawPixmap(w, topLeft.y() + margin, icon3);

    const bool state2 = index.data(ICON2_ROLE).toBool();
    QPixmap icon2(state2 ? m_icon1 : m_icon2);
    w -= icon2.width();
    painter->drawPixmap(w, topLeft.y() + margin, icon2);
  }
  else if (combo->property(COMBO_TYPE) == COMBO_ICON_RICHTEXT_COUNTER)
  {
    const CUDSession data = index.data(SESSION_DATA_ROLE).value<CUDSession>();
    drawIconRichTextCounter(painter, data, topLeft, index.row(), option.rect.width());
  }
}

void ComboUpDownDelegate::drawIconRichTextCounter(QPainter* painter, const CUDSession& data, const QPoint& topLeft, int row, int width) const {
  const int margin = 15;

  QPixmap icon1(m_icon1);
  painter->drawPixmap(margin, topLeft.y() + margin, icon1);

  QFont normalFont(painter->font());
  QFont boldFont(normalFont);
  boldFont.setBold(true);
  QFontMetrics fm(normalFont);

  QPoint p(topLeft + QPoint(icon1.width() + 1.5 * margin, fm.height() + 11));
  if (row == 0)
  {
    p = drawText(painter, p, QString("ALL SESSIONS"), boldFont);
  }
  else
  {
    QString strRow = QString::number(row);
    if(strRow.length() < 2)
    {
        strRow = "0" + strRow;
    }
    p = drawText(painter, p, QString("SESSION %1").arg(strRow), boldFont);
    painter->setPen(QColor("#C8C8C8"));
    p = drawText(painter, p, QString(" | "), normalFont);
    p = drawText(painter, p, QString("START:"), boldFont);
    p = drawText(painter, p, QString(" %1  -  ").arg(data.StartStr()), normalFont);
    p = drawText(painter, p, QString("END:"), boldFont);
    if(data.End().isValid())
    {
        p = drawText(painter, p, QString(" %1").arg(data.EndStr()), normalFont);
    }
    else
    {
        p = drawText(painter, p, QString(" %1").arg(tr("Running")), normalFont);
    }

    const QString errorCounter(QString::number(data.Errors()));
    p.setX(width - fm.width("888") - margin);
    painter->drawText(p, errorCounter);

    QPixmap icon2(data.Errors() > 0 ? m_icon3 : m_icon2);
    painter->drawPixmap(p.x() - icon2.width() - 3, topLeft.y() + margin, icon2);
  }

}

bool ComboUpDownDelegate::eventFilter(QObject *object, QEvent *event) {
  auto combo = static_cast<QComboBox*>(object);

  if (combo != nullptr && object == this->parent() && event->type() == QEvent::Paint) {
    QStylePainter painter(combo);

    painter.setPen(combo->palette().color(QPalette::Text));

    QStyleOptionComboBox opt;
    opt.initFrom(combo);
    opt.editable = combo->isEditable();
    opt.frame = combo->hasFrame();
    if (combo->hasFocus() && !opt.editable) {
      opt.state |= QStyle::State_Selected;
    }
    opt.subControls = QStyle::SC_All;

    if (m_title.isEmpty()) {
      opt.currentText = combo->currentText();
    } else {
      opt.currentText = m_title.arg(combo->count());
    }
    painter.drawComplexControl(QStyle::CC_ComboBox, opt);
    painter.drawControl(QStyle::CE_ComboBoxLabel, opt);

    if (combo->property(COMBO_TYPE) == COMBO_ICON_RICHTEXT_COUNTER) {
      drawIconRichTextCounter(&painter, combo->currentData(SESSION_DATA_ROLE).value<CUDSession>(),
                              QPoint(0, 0), combo->currentIndex(), combo->width() - 16);
    }

    return true;
  }
  return QStyledItemDelegate::eventFilter(object, event);
}

void ComboUpDownDelegate::setTitle(const QString& title) {
  m_title = title;
}

QString ComboUpDownDelegate::title() const {
  return m_title;
}

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Where I create the combo:

Qt Code:

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auto comboSesiones = new QComboBox();
comboSesiones->setProperty(ComboUpDownDelegate::COMBO_TYPE, ComboUpDownDelegate::COMBO_ICON_RICHTEXT_COUNTER);
comboSesiones->setSizeAdjustPolicy(QComboBox::SizeAdjustPolicy::AdjustToContents);
comboSesiones->setMinimumWidth(525);
auto delegate = new ComboUpDownDelegate(comboSesiones);
comboSesiones->setItemDelegate(delegate);
connect(comboSesiones, SIGNAL(currentIndexChanged(int)), SLOT(onSesionCurrentChanged(int)));
comboSesiones->setVisible(false);
comboSesiones->addItem("");
int index = comboSesiones->count() - 1;
comboSesiones->setItemData(index, QVariant(), ComboUpDownDelegate::SESSION_DATA_ROLE);

auto comboSesiones = new QComboBox();
comboSesiones->setProperty(ComboUpDownDelegate::COMBO_TYPE, ComboUpDownDelegate::COMBO_ICON_RICHTEXT_COUNTER);
comboSesiones->setSizeAdjustPolicy(QComboBox::SizeAdjustPolicy::AdjustToContents);
comboSesiones->setMinimumWidth(525);
auto delegate = new ComboUpDownDelegate(comboSesiones);
comboSesiones->setItemDelegate(delegate);
connect(comboSesiones, SIGNAL(currentIndexChanged(int)), SLOT(onSesionCurrentChanged(int)));
comboSesiones->setVisible(false);
comboSesiones->addItem("");
int index = comboSesiones->count() - 1;
comboSesiones->setItemData(index, QVariant(), ComboUpDownDelegate::SESSION_DATA_ROLE);

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Thank you very much.