Word wrap in QListView

[jiveaxe]

Hi,
have used the code of marcel creating a qtrewidget with word-wrap function and it works nice. The next step should be display html text instead of plain text like now. I have used the following code in overridden paint():

painter->save();
QTextDocument doc;
doc.setHtml(index.data().toString());
QAbstractTextDocumentLayout::PaintContext context;
doc.setPageSize(option.rect.size());
painter->translate(option.rect.x(), option.rect.y());
doc.documentLayout()->draw(painter, context);
painter->restore();

painter->save();
QTextDocument doc;
doc.setHtml(index.data().toString());
QAbstractTextDocumentLayout::PaintContext context;
doc.setPageSize(option.rect.size());
painter->translate(option.rect.x(), option.rect.y());
doc.documentLayout()->draw(painter, context);
painter->restore();

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( instead of painter->drawText() ) but with no luck: the treeWidget is illegible.

Any hint?

Some code:
delegate.cpp

void delegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
	painter->save();
	QTextDocument doc;
	doc.setHtml(index.data().toString());
	QAbstractTextDocumentLayout::PaintContext context;
	doc.setPageSize(option.rect.size());
	painter->translate(option.rect.x(), option.rect.y());
	doc.documentLayout()->draw(painter, context);
	painter->restore();
//	painter->drawText(option.rect, Qt::AlignLeft | Qt::TextWordWrap, index.data().toString());
}
 
QSize delegate::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const
{
	QTreeWidget *p = (QTreeWidget*)parent();
	QFontMetrics fm(p->font());
 
	float rw = float(p->viewport()->size().width());
	float tw = fm.width(index.data().toString());
	float ratio = tw/rw;
	int lines = int(ratio) + 1;
	return QSize(rw,lines*fm.height());
}

void delegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
	painter->save();
	QTextDocument doc;
	doc.setHtml(index.data().toString());
	QAbstractTextDocumentLayout::PaintContext context;
	doc.setPageSize(option.rect.size());
	painter->translate(option.rect.x(), option.rect.y());
	doc.documentLayout()->draw(painter, context);
	painter->restore();
//	painter->drawText(option.rect, Qt::AlignLeft | Qt::TextWordWrap, index.data().toString());
}

QSize delegate::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const
{
	QTreeWidget *p = (QTreeWidget*)parent();
	QFontMetrics fm(p->font());

	float rw = float(p->viewport()->size().width());
	float tw = fm.width(index.data().toString());
	float ratio = tw/rw;
	int lines = int(ratio) + 1;
	return QSize(rw,lines*fm.height());
}

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Thanks

[jiveaxe]

Hi,
I'm planning use two different delegate to draw items so I choose QListWidget. For providing support to the two delegates I created a new class, named ListWidgetItemDelegate (like StarDelegate example in the manual). Now from the MainDialog I can decide which delegate using. All works fine. I then decided to modify one of the delegate for supporting the marcel's word-wrap solution:

QSize SectionItem::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const
{
	QListWidget *p = (QListWidget*)parent();
	QString text = index.data().toString();
	QFontMetrics fm(p->font());
	float rw = float(p->viewport()->size().width());
	float tw = fm.width(text);
	float ratio = tw/rw;
	int lines = int(ratio) + 1;
	return QSize(rw,lines*fm.height());
}

QSize SectionItem::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const
{
	QListWidget *p = (QListWidget*)parent();
	QString text = index.data().toString();
	QFontMetrics fm(p->font());
	float rw = float(p->viewport()->size().width());
	float tw = fm.width(text);
	float ratio = tw/rw;
	int lines = int(ratio) + 1;
	return QSize(rw,lines*fm.height());
}

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but i get an error during compiling because parent is not declared in the scope. Now from maindialog passing by ListWidgetItemDelegate to SectionItem I'm little lost and i don't know which row modify for passing the right parent.

Here the code that have used hoping someone, read marcel, can help me:

listwidgetitemdelegate.cpp

#include "listwidgetitemdelegate.h"
#include "headeritem.h"
#include "sectionitem.h"
 
void ListWidgetItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
	if (qVariantCanConvert<HeaderItem>(index.data()))
	{
		HeaderItem headerItem = qVariantValue<HeaderItem>(index.data());
		headerItem.paint(painter, option, index);
	}
	else if (qVariantCanConvert<SectionItem>(index.data()))
	{
		SectionItem sectionItem = qVariantValue<SectionItem>(index.data());
		sectionItem.paint(painter, option, index);
	}
	else
	{
		QItemDelegate::paint(painter, option, index);
	}
}
 
QSize ListWidgetItemDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     if (qVariantCanConvert<SectionItem>(index.data())) {
         SectionItem sectionItem = qVariantValue<SectionItem>(index.data());
         return sectionItem.sizeHint(option, index);
     } else {
         return QItemDelegate::sizeHint(option, index);
     }
 }

#include "listwidgetitemdelegate.h"
#include "headeritem.h"
#include "sectionitem.h"

void ListWidgetItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
	if (qVariantCanConvert<HeaderItem>(index.data()))
	{
		HeaderItem headerItem = qVariantValue<HeaderItem>(index.data());
		headerItem.paint(painter, option, index);
	}
	else if (qVariantCanConvert<SectionItem>(index.data()))
	{
		SectionItem sectionItem = qVariantValue<SectionItem>(index.data());
		sectionItem.paint(painter, option, index);
	}
	else
	{
		QItemDelegate::paint(painter, option, index);
	}
}

QSize ListWidgetItemDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     if (qVariantCanConvert<SectionItem>(index.data())) {
         SectionItem sectionItem = qVariantValue<SectionItem>(index.data());
         return sectionItem.sizeHint(option, index);
     } else {
         return QItemDelegate::sizeHint(option, index);
     }
 }

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sectionitem.cpp

#include "sectionitem.h"
 
SectionItem::SectionItem(QString text)
{
	itemText = text;
}
 
SectionItem::~SectionItem()
{
}
 
void SectionItem::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
	painter->save();
	painter->setPen(QPen(Qt::darkGreen));
	painter->drawText(option.rect, Qt::AlignLeft | Qt::TextWordWrap, itemText);
	painter->restore();
}
 
QSize SectionItem::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const
{
	QListWidget *p = (QListWidget*)parent();
	QFontMetrics fm(p->font());
 
	float rw = float(p->viewport()->size().width());
	float tw = fm.width(itemText);
	float ratio = tw/rw;
	int lines = int(ratio) + 1;
	return QSize(rw,lines*fm.height());
}

#include "sectionitem.h"

SectionItem::SectionItem(QString text)
{
	itemText = text;
}

SectionItem::~SectionItem()
{
}

void SectionItem::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
	painter->save();
	painter->setPen(QPen(Qt::darkGreen));
	painter->drawText(option.rect, Qt::AlignLeft | Qt::TextWordWrap, itemText);
	painter->restore();
}

QSize SectionItem::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const
{
	QListWidget *p = (QListWidget*)parent();
	QFontMetrics fm(p->font());

	float rw = float(p->viewport()->size().width());
	float tw = fm.width(itemText);
	float ratio = tw/rw;
	int lines = int(ratio) + 1;
	return QSize(rw,lines*fm.height());
}

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maindialog.cpp

...
listWidget = new QListWidget;
listWidget->setItemDelegate(new ListWidgetItemDelegate);
listWidget->setAlternatingRowColors(true);
listWidget->setResizeMode(QListWidget::Adjust);
 
QStringList list;
list << "New Section"
     << "The <b>QListWidgetItem</b> class provides an item for use with the QListWidget item view class."
     << "The <b>QObject</b> class is the base class of all Qt objects."
     << "Qt's <b>drag and drop</b> infrastructure is fully supported by the model/view framework. Items in lists, tables, and trees can be dragged within the views, and data can be imported and exported as MIME-encoded data. ciao da giuseppe";
 
QListWidgetItem *item1 = new QListWidgetItem;
item1->setData(0, qVariantFromValue(HeaderItem(list.at(0))));
listWidget->insertItem(0, item1);
 
for(int i = 1; i < list.size(); i++)
{
	QListWidgetItem *item = new QListWidgetItem;
	item->setData(0, qVariantFromValue(SectionItem(list.at(i))));
	listWidget->insertItem(i, item);
}
...

...
listWidget = new QListWidget;
listWidget->setItemDelegate(new ListWidgetItemDelegate);
listWidget->setAlternatingRowColors(true);
listWidget->setResizeMode(QListWidget::Adjust);

QStringList list;
list << "New Section"
     << "The <b>QListWidgetItem</b> class provides an item for use with the QListWidget item view class."
     << "The <b>QObject</b> class is the base class of all Qt objects."
     << "Qt's <b>drag and drop</b> infrastructure is fully supported by the model/view framework. Items in lists, tables, and trees can be dragged within the views, and data can be imported and exported as MIME-encoded data. ciao da giuseppe";

QListWidgetItem *item1 = new QListWidgetItem;
item1->setData(0, qVariantFromValue(HeaderItem(list.at(0))));
listWidget->insertItem(0, item1);

for(int i = 1; i < list.size(); i++)
{
	QListWidgetItem *item = new QListWidgetItem;
	item->setData(0, qVariantFromValue(SectionItem(list.at(i))));
	listWidget->insertItem(i, item);
}
...

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Regards

[marcel]

In ListWidgetItemDelegate::sizeHint you can pass parent() to SectionItem::sizeHint(). All you have to do is to add another parameter to SectionItem's sizeHint method.
SectionItem is not a QAbstractItemDelegate, isn't it?

Regards

[jiveaxe]

No marcel, SectionItem is not a QAbstractItemDelegate. Now I edit the code and then tell you the result.

Thanks

[marcel]

Yes. Just make sure you pass the parent of ListWidgetItemDelegate.

Regards

[jiveaxe]

I'm making some sort of mistake because i got errors during compiling; here the modifications:

listwidgetitemdelegate.cpp

...
return sectionItem.sizeHint(parent, option, index);
...

...
return sectionItem.sizeHint(parent, option, index);
...

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sectionitem.h

...
QSize sizeHint(QWidget *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const;
...

...
QSize sizeHint(QWidget *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const;
...

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sectionitem.cpp

QSize SectionItem::sizeHint(QWidget *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
{...}

QSize SectionItem::sizeHint(QWidget *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
{...}

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For clearness here the code for the header files:
listwidgetitemdelegate.h

class ListWidgetItemDelegate : public QItemDelegate
{
	Q_OBJECT
 
	public:
		ListWidgetItemDelegate(QWidget *parent = 0) : QItemDelegate(parent) {}
 
		void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const;
 
		QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const;
};

class ListWidgetItemDelegate : public QItemDelegate
{
	Q_OBJECT

	public:
		ListWidgetItemDelegate(QWidget *parent = 0) : QItemDelegate(parent) {}

		void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const;

		QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const;
};

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sectionitem.h

class SectionItem
{
	public:
 
		SectionItem(QString text = "");
		~SectionItem();
 
		void paint(QPainter*, const QStyleOptionViewItem&, const QModelIndex&) const;
		QSize sizeHint(QObject *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const;
 
	private:
		QString itemText;
};
 
Q_DECLARE_METATYPE(SectionItem)

class SectionItem
{
	public:

		SectionItem(QString text = "");
		~SectionItem();

		void paint(QPainter*, const QStyleOptionViewItem&, const QModelIndex&) const;
		QSize sizeHint(QObject *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const;

	private:
		QString itemText;
};

Q_DECLARE_METATYPE(SectionItem)

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Bye

[marcel]

Who is parent? The one that you pass to SectionItem::sizeHint().
It should be (QListWidget*)parent().

And in maindialog.cpp, it should be:

listWidget->setItemDelegate(new ListWidgetItemDelegate(listWidget));

listWidget->setItemDelegate(new ListWidgetItemDelegate(listWidget));

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[jiveaxe]

Ok marcel, now works! Here the modifications I made:

maindialog.cpp

listWidget->setItemDelegate(new ListWidgetItemDelegate(listWidget));

listWidget->setItemDelegate(new ListWidgetItemDelegate(listWidget));

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listwidgetitemdelegate.cpp

...
return sectionItem.sizeHint(parent(), option, index);
...

...
return sectionItem.sizeHint(parent(), option, index);
...

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sectionitem.h

QSize sizeHint(QObject *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const;

QSize sizeHint(QObject *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const;

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sectionitem.cpp

QSize SectionItem::sizeHint(QObject *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
{
	QListWidget *p = (QListWidget*)parent;
...
}

QSize SectionItem::sizeHint(QObject *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
{
	QListWidget *p = (QListWidget*)parent;
...
}

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Thanks a lot

[jiveaxe]

I would like rendering html text instead of plain text; changing SectionItem:aint like this:

void SectionItem::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
	painter->save();
	QTextDocument doc;
	doc.setHtml(itemText);
	QAbstractTextDocumentLayout::PaintContext context;
	doc.setPageSize(option.rect.size());
	painter->translate(option.rect.x(), option.rect.y());
	doc.documentLayout()->draw(painter, context);
	painter->restore();
//  painter->drawText(option.rect, Qt::AlignLeft | Qt::TextWordWrap, index.data().toString());
}

void SectionItem::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
	painter->save();
	QTextDocument doc;
	doc.setHtml(itemText);
	QAbstractTextDocumentLayout::PaintContext context;
	doc.setPageSize(option.rect.size());
	painter->translate(option.rect.x(), option.rect.y());
	doc.documentLayout()->draw(painter, context);
	painter->restore();
//  painter->drawText(option.rect, Qt::AlignLeft | Qt::TextWordWrap, index.data().toString());
}

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It renders html text but the last row of each phrase (when wrapped) is always drawn in the following item and a blank row remains in own item (see the attached image for better explanation).

Any hint?

Cheers

[jiveaxe]

I have found a possible solution even if for some widths it renders not optimally. Attached are 2 images, one with correct draw and one with the unwanted behavior.

Here the new code for SectionItem:aint

void SectionItem::paint(QObject *parent, QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
	QListWidget *p = (QListWidget*)parent;
 
	painter->save();
	QTextDocument doc;
	doc.setHtml(itemText);
	QAbstractTextDocumentLayout::PaintContext context;
	doc.setPageSize(QSize(option.rect.size().width(), option.rect.size().height() + p->viewport()->size().height()));
	painter->translate(option.rect.x(), option.rect.y());
	doc.documentLayout()->draw(painter, context);
	painter->restore();
}

void SectionItem::paint(QObject *parent, QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
	QListWidget *p = (QListWidget*)parent;

	painter->save();
	QTextDocument doc;
	doc.setHtml(itemText);
	QAbstractTextDocumentLayout::PaintContext context;
	doc.setPageSize(QSize(option.rect.size().width(), option.rect.size().height() + p->viewport()->size().height()));
	painter->translate(option.rect.x(), option.rect.y());
	doc.documentLayout()->draw(painter, context);
	painter->restore();
}

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Regards

[marcel]

It might have to do with the HTML itself. Do you have any <p> tags or any other tag that enforces spacings around it?

Can you paste the html?

BTW: don't tell me that you too are working on (yet another) IDE.

Regards

[jiveaxe]

There aren't <p> tags in the html, only <b> and </b>, but here the code:

QStringList list;
list << "New Section"
     << "The <b>QListWidgetItem</b> class provides an item for use with the QListWidget item view class. The <b>QListWidgetItem</b> class provides an item for use with the QListWidget item view class. The <b>QListWidgetItem</b> class provides an item for use with the QListWidget item view class."
     << "The <b>QObject</b> class is the base class of all Qt objects."
     << "Qt's <b>drag and drop</b> infrastructure is fully supported by the model/view framework. Items in lists, tables, and trees can be dragged within the views, and data can be imported and exported as MIME-encoded data.";

QStringList list;
list << "New Section"
     << "The <b>QListWidgetItem</b> class provides an item for use with the QListWidget item view class. The <b>QListWidgetItem</b> class provides an item for use with the QListWidget item view class. The <b>QListWidgetItem</b> class provides an item for use with the QListWidget item view class."
     << "The <b>QObject</b> class is the base class of all Qt objects."
     << "Qt's <b>drag and drop</b> infrastructure is fully supported by the model/view framework. Items in lists, tables, and trees can be dragged within the views, and data can be imported and exported as MIME-encoded data.";

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...and not, I am not working on a new ide.

Bye

[marcel]

void SectionItem::paint(QObject *parent, QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
    QListWidget *p = (QListWidget*)parent;
 
    painter->save();
    QTextDocument doc;
    doc.setHtml(itemText);
    doc.setTextWidth(option.rect.size().width());
    QAbstractTextDocumentLayout::PaintContext context;
    painter->translate(option.rect.x(), option.rect.y());
    doc.documentLayout()->draw(painter, context);
    painter->restore();
}
 
 
QSize SectionItem::sizeHint(QObject *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
{
    QListWidget *p = (QListWidget*)parent;
    QFontMetrics fm(p->font());
 
    float rw = float(p->viewport()->size().width());
    float tw = fm.width(itemText);
    float ratio = tw/rw;
    int lines = 0;
    if(ratio - int(ratio) < 0.1f)
        lines = int(ratio);
    else
        lines = int(ratio) + 1;
    return QSize(rw,lines*fm.height());
}

void SectionItem::paint(QObject *parent, QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex & index) const
{
    QListWidget *p = (QListWidget*)parent;

    painter->save();
    QTextDocument doc;
    doc.setHtml(itemText);
    doc.setTextWidth(option.rect.size().width());
    QAbstractTextDocumentLayout::PaintContext context;
    painter->translate(option.rect.x(), option.rect.y());
    doc.documentLayout()->draw(painter, context);
    painter->restore();
}


QSize SectionItem::sizeHint(QObject *parent, const QStyleOptionViewItem& option, const QModelIndex& index) const
{
    QListWidget *p = (QListWidget*)parent;
    QFontMetrics fm(p->font());

    float rw = float(p->viewport()->size().width());
    float tw = fm.width(itemText);
    float ratio = tw/rw;
    int lines = 0;
    if(ratio - int(ratio) < 0.1f)
        lines = int(ratio);
    else
        lines = int(ratio) + 1;
    return QSize(rw,lines*fm.height());
}

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Problem 1: don't give the height to the text document. you already set it with the size hint.

Problem 2: ocassionaly, due to rounding errors, you got 1 extra line of text that remained empty( the +1 in the sizeHint).

Regards

[jiveaxe]

Thank for your tips, marcel, helpful as usual; I have corrected the code.

Regards