'Annotation' of lines in a QTextEdit

[fullmetalcoder]

FMC: If you managed to insert a "margin widget" into a scroll area, could you please present a minimal code that accomplishes that? We might be going in circles here and I'm really interested in finding a solution.

Minimal? well... my code is not really minimal because the layout used has some complexities and I use a custom class, QPanel (inheriting from QWidget). As I don't feel like spending too much time on trimming down my code so I'll give you a layout-less sample... Fell free to ask for the layout code if you want something a little more flexible but then don't expect something that will work out of box...

So here comes the minimum (not very handy nor fully functionnal but works...) :

#include <QPainter>
#include <QPaintEvent>
 
#include <QTextEdit>
#include <QTextBlock>
#include <QTextLayout>
 
#include <QScrollBar>
#include <QApplication>
 
class SampleArea : public QTextEdit
{
	public:
		SampleArea(QWidget *p = 0)
		 : QTextEdit(p)
		{
			QString txt =  "eat me...\ndrink me...\n";
 
			for ( int i = 0; i < 8; ++i )
				txt += txt;
 
			document()->setPlainText(txt);
		}
 
		inline void setMargins(int l, int r, int t, int b)
		{ setViewportMargins(l, r, t, b); }
};
 
class SamplePanel : public QWidget
{
	public:
		SamplePanel(SampleArea *a)
		 : QWidget(a), m_area(a)
		{
			setFixedWidth(50);
			setFixedHeight(a->height());
 
			connect(a->verticalScrollBar()	, SIGNAL( valueChanged(int) ),
					this					, SLOT  ( update() ));
 
			a->setMargins(50, 0, 0, 0);
		}
 
	protected:
		virtual void paintEvent(QPaintEvent *e)
		{
			e->accept();
 
			QPainter p(this);
 
			int m_lineNumber = 1;
			const QFontMetrics fm = fontMetrics();
			const int ascent = fontMetrics().ascent() + 1;
			QTextBlock block = m_area->document()->begin();
			int contentsY = m_area->verticalScrollBar()->value();
			qreal pageBottom = contentsY + m_area->viewport()->height();
 
			for ( ; block.isValid(); block = block.next(), ++m_lineNumber )
			{
				QTextLayout* layout = block.layout();
				QPointF position = layout->position();
				const QRectF boundingRect = layout->boundingRect();
 
				if ( position.y() + boundingRect.height() < contentsY )
					continue;
 
				if ( position.y() > pageBottom )
					break;
 
				const QString txt = QString::number( m_lineNumber );
 
				p.drawText(width() - fm.width(txt) - 2, qRound(position.y()) - contentsY + ascent, txt);
			}
		}
 
	private:
		SampleArea *m_area;
};
 
int main (int argc, char **argv)
{
	QApplication app(argc, argv);
 
	SampleArea area;
	SamplePanel panel(&area);
 
	area.show();
 
	return app.exec();
}

#include <QPainter>
#include <QPaintEvent>

#include <QTextEdit>
#include <QTextBlock>
#include <QTextLayout>

#include <QScrollBar>
#include <QApplication>

class SampleArea : public QTextEdit
{
	public:
		SampleArea(QWidget *p = 0)
		 : QTextEdit(p)
		{
			QString txt =  "eat me...\ndrink me...\n";
			
			for ( int i = 0; i < 8; ++i )
				txt += txt;
			
			document()->setPlainText(txt);
		}
		
		inline void setMargins(int l, int r, int t, int b)
		{ setViewportMargins(l, r, t, b); }
};

class SamplePanel : public QWidget
{
	public:
		SamplePanel(SampleArea *a)
		 : QWidget(a), m_area(a)
		{
			setFixedWidth(50);
			setFixedHeight(a->height());
			
			connect(a->verticalScrollBar()	, SIGNAL( valueChanged(int) ),
					this					, SLOT  ( update() ));
			
			a->setMargins(50, 0, 0, 0);
		}
		
	protected:
		virtual void paintEvent(QPaintEvent *e)
		{
			e->accept();
			
			QPainter p(this);
			
			int m_lineNumber = 1;
			const QFontMetrics fm = fontMetrics();
			const int ascent = fontMetrics().ascent() + 1;
			QTextBlock block = m_area->document()->begin();
			int contentsY = m_area->verticalScrollBar()->value();
			qreal pageBottom = contentsY + m_area->viewport()->height();
			
			for ( ; block.isValid(); block = block.next(), ++m_lineNumber )
			{
				QTextLayout* layout = block.layout();
				QPointF position = layout->position();
				const QRectF boundingRect = layout->boundingRect();
				
				if ( position.y() + boundingRect.height() < contentsY )
					continue;
				
				if ( position.y() > pageBottom )
					break;
				
				const QString txt = QString::number( m_lineNumber );
		
				p.drawText(width() - fm.width(txt) - 2, qRound(position.y()) - contentsY + ascent, txt);
			}
		}
		
	private:
		SampleArea *m_area;
};

int main (int argc, char **argv)
{
	QApplication app(argc, argv);
	
	SampleArea area;
	SamplePanel panel(&area);
	
	area.show();
	
	return app.exec();
}

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