inserting custom Widget to listview

[axeljaeger]

If you go with setIndexWidget, YES, if you use a delegate, it depends. You can only use your widget for the edit state. You have to fake drawing of that widget in delegate:aint. It depends on how clever you do that. For example, if you instantiate a widget, take a screenshot of it and blit it to the cell, it is not clever.

[faldzip]

as I understand from the picture all you need from the widgets are 3 buttons, the rest are labels, so you can draw it all by yourself in delegate.
int QAbstractItemDelegate::sizeHint() you should return required size hint, and in QAbstractItemDelegate::paint() you can draw all you want width painter. Drawing text is simple (see QPainter::drawText()) and drawing buttons is also simple: QStyle::drawControl()
Here is a code snippet from my code painting a button in one cell at column number = ButtonColumn:

void MyDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
	QStyledItemDelegate::paint(painter, option, index);
	if (!index.isValid() || index.column() != ButtonColumn) {
		return;
	}
 
	QStyleOptionButton opt;
	State s = (State)(index.data(Qt::UserRole).toInt());
	if (s == Hovered)
		opt.state |= QStyle::State_MouseOver;
	if (s == Pressed)
		opt.state |= QStyle::State_Sunken;
	opt.state |= QStyle::State_Enabled;
	opt.rect = option.rect.adjusted(1, 1, -1, -1);
	opt.text = trUtf8("Button text");
	QApplication::style()->drawControl(QStyle::CE_PushButton, &opt, painter, 0);
}

void MyDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
	QStyledItemDelegate::paint(painter, option, index);
	if (!index.isValid() || index.column() != ButtonColumn) {
		return;
	}

	QStyleOptionButton opt;
	State s = (State)(index.data(Qt::UserRole).toInt());
	if (s == Hovered)
		opt.state |= QStyle::State_MouseOver;
	if (s == Pressed)
		opt.state |= QStyle::State_Sunken;
	opt.state |= QStyle::State_Enabled;
	opt.rect = option.rect.adjusted(1, 1, -1, -1);
	opt.text = trUtf8("Button text");
	QApplication::style()->drawControl(QStyle::CE_PushButton, &opt, painter, 0);
}

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As you see the state of the button is stored in model cause there is one button for each index (in this column ButtonColumn) so the best way to store the state is to store it in model :] (State is my own enum).

but then you have do your own event handling for hover and push events. I geting quite compicated, because you have to implement it in QAbstractItemDelegate::editorEvent() and in event filter installed on view's viewport. And view's viewport has to have mouse tracking enabled. So for my button's in columns here is there relevant, example code:

bool HistoryDelegate::editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index)
{
	if (event->type() == QEvent::MouseMove) {
		if (index != m_lastUnderMouse) {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Normal, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
			}
			if (index.isValid() && index.column() == ButtonColumn) {
				model->setData(index, (int)Hovered, Qt::UserRole);
				emit needsUpdate(index);
				m_lastUnderMouse = index;
			} else {
				m_lastUnderMouse = QModelIndex();
			}
		}
	}
	if (event->type() == QEvent::MouseButtonPress || event->type() == QEvent::MouseButtonDblClick) {
		if (index != m_lastUnderMouse) {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Normal, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
			}
			if (index.isValid() && index.column() == ButtonColumn) {
				model->setData(index, (int)Pressed, Qt::UserRole);
				emit needsUpdate(index);
				emit clicked(index);
				m_lastUnderMouse = index;
			} else {
				m_lastUnderMouse = QModelIndex();
			}
		} else {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Pressed, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
				emit clicked(m_lastUnderMouse);
			}
		}
	}
	if (event->type() == QEvent::MouseButtonRelease) {
		if (index != m_lastUnderMouse) {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Normal, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
			}
			if (index.isValid() && index.column() == ButtonColumn) {
				model->setData(index, (int)Hovered, Qt::UserRole);
				emit needsUpdate(index);
				m_lastUnderMouse = index;
			} else {
				m_lastUnderMouse = QModelIndex();
			}
		} else {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Hovered, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
			}
		}
	}
	return QStyledItemDelegate::editorEvent(event, model, option, index);
}

bool HistoryDelegate::editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index)
{
	if (event->type() == QEvent::MouseMove) {
		if (index != m_lastUnderMouse) {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Normal, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
			}
			if (index.isValid() && index.column() == ButtonColumn) {
				model->setData(index, (int)Hovered, Qt::UserRole);
				emit needsUpdate(index);
				m_lastUnderMouse = index;
			} else {
				m_lastUnderMouse = QModelIndex();
			}
		}
	}
	if (event->type() == QEvent::MouseButtonPress || event->type() == QEvent::MouseButtonDblClick) {
		if (index != m_lastUnderMouse) {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Normal, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
			}
			if (index.isValid() && index.column() == ButtonColumn) {
				model->setData(index, (int)Pressed, Qt::UserRole);
				emit needsUpdate(index);
				emit clicked(index);
				m_lastUnderMouse = index;
			} else {
				m_lastUnderMouse = QModelIndex();
			}
		} else {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Pressed, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
				emit clicked(m_lastUnderMouse);
			}
		}
	}
	if (event->type() == QEvent::MouseButtonRelease) {
		if (index != m_lastUnderMouse) {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Normal, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
			}
			if (index.isValid() && index.column() == ButtonColumn) {
				model->setData(index, (int)Hovered, Qt::UserRole);
				emit needsUpdate(index);
				m_lastUnderMouse = index;
			} else {
				m_lastUnderMouse = QModelIndex();
			}
		} else {
			if (m_lastUnderMouse.isValid()) {
				model->setData(m_lastUnderMouse, (int)Hovered, Qt::UserRole);
				emit needsUpdate(m_lastUnderMouse);
			}
		}
	}
	return QStyledItemDelegate::editorEvent(event, model, option, index);
}

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m_lastUnderMouse is QPersistentModelIndex storing which index was last under mouse to know that we have to for example remove the hover highlight because now we are highlightind another index.
needsUpdate() is connected to view and call update(QModelIndex) to call MyDelegate:aint() which will paint new button state.

bool MyWidgetContainingView::eventFilter(QObject *obj, QEvent *event)
{
	if (obj != ui->treeView->viewport())
		return QWidget::eventFilter(obj, event);
	switch (event->type()) {
	case QEvent::Leave:
		m_delegate->notifyMouseLeave();
		break;
	case QEvent::MouseMove:
		QModelIndex index = ui->treeView->indexAt(static_cast<QMouseEvent *>(event)->pos());
		if (!index.isValid())
			m_delegate->notifyMouseLeave();
		break;
	}
	return QWidget::eventFilter(obj, event);
}

bool MyWidgetContainingView::eventFilter(QObject *obj, QEvent *event)
{
	if (obj != ui->treeView->viewport())
		return QWidget::eventFilter(obj, event);
	switch (event->type()) {
	case QEvent::Leave:
		m_delegate->notifyMouseLeave();
		break;
	case QEvent::MouseMove:
		QModelIndex index = ui->treeView->indexAt(static_cast<QMouseEvent *>(event)->pos());
		if (!index.isValid())
			m_delegate->notifyMouseLeave();
		break;
	}
	return QWidget::eventFilter(obj, event);
}

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notifyMouseLeave() is the delegate method to notify delegate that mouse left view's viewport so it has to for example remove the hover highlight from m_lastUnderMouse if it is valid index.

Hope this helps :]


Notice that this solution is very efficient because there is no single real button, they are just drawn by delegate :]

[MarkoSan]

So, these are two ways of implementing my task?

[faldzip]

My whole previous post is one solution, and the last sentence was about it's performance advantage compared to setIndexWidget()

[MarkoSan]

Well, as seen from my attached pic, I must display several strings and a pic. How do send this data to model, using custom roles?

[faldzip]

Well, as seen from my attached pic, I must display several strings and a pic. How do send this data to model, using custom roles?

It depends on your model. If you use QStandardItemModel then every QStandardItem has setData() method which you can use like this:

QStandardItem *item = new QStandardItem;
item->setData("Label 1 text", Qt::UserRole);
item->setData("Label 2 text", Qt::UserRole+1);
item->setData("Label 3 text", Qt::UserRole+2);
item->setData(false, Qt::UserRole+3); // button 1 pressed?

QStandardItem *item = new QStandardItem;
item->setData("Label 1 text", Qt::UserRole);
item->setData("Label 2 text", Qt::UserRole+1);
item->setData("Label 3 text", Qt::UserRole+2);
item->setData(false, Qt::UserRole+3); // button 1 pressed?

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and so on.

If you have your own mode implementation then you need to return proper value in YourMode::data():

QVariant YourModel::data(const QModelIndex &index, int role) const
{
    // ...
    if (role == Qt::UserRole + 2) {
        QString s = "Label 3 text"; // should take proper text for given index from your underlaying data structure
        return s; 
    }
    // ...
}

QVariant YourModel::data(const QModelIndex &index, int role) const
{
    // ...
    if (role == Qt::UserRole + 2) {
        QString s = "Label 3 text"; // should take proper text for given index from your underlaying data structure
        return s; 
    }
    // ...
}

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and so on.

[pancake]

Hi faldżip,

Just wanted to say thanks for such a great code example of a button delegate in a view. It has helped me a lot! Maybe it should be included in the Qt documentation, because their delegate examples do not cover all of this.

Dan

[JuanMO]

Is too bad idea to create a widget with the QCreator an use it to render all I need? (To avoid doing it manually)
Here is an example

class CustomItemDelegate : public QStyledItemDelegate
{
	WidgetItem * witem;
public:
 
	CustomItemDelegate()
	{
		witem = new 	WidgetItem ();
	}
 
	~CustomItemDelegate()
	{
		delete witem;
	}
 
 
	void paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const
	{
		witem->resize(option.rect.size());
 
		/*
               Here update the witem with some method with the real item data
               Update labels, icons, and so on
               */
 
		painter->save();
		painter->translate(option.rect.topLeft());
		witem->render(painter);
		painter->restore();				
	}
}

class CustomItemDelegate : public QStyledItemDelegate
{
	WidgetItem * witem;
public:

	CustomItemDelegate()
	{
		witem = new 	WidgetItem ();
	}

	~CustomItemDelegate()
	{
		delete witem;
	}


	void paint(QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index) const
	{
		witem->resize(option.rect.size());

		/*
               Here update the witem with some method with the real item data
               Update labels, icons, and so on
               */
				
		painter->save();
		painter->translate(option.rect.topLeft());
		witem->render(painter);
		painter->restore();				
	}
}

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Note that the widget is create just once and then all its components updated

[JuanMO]

If I have two buttons in an item, how can I know which one was press?