[Interest] Scaling QTextDocument into a drawing region

[Bob Hood]

I want to wrangle HTML-formatted text contained in a QTextDocument into a 
specific drawing region, but I want it drawn there scaled-to-fit instead of 
broken-to-fit.  I'm not gettingthat, and I'm scratching my head.

Some code for discussion:

     ...
     QTextDocument td;
     td.setDocumentMargin(0);
     td.setPageSize(QSize(bounds.width(), bounds.height()));
     td.setTextWidth(bounds.width());
     td.setHtml(tr("<center>This is just a long line of text I want to 
display</center>"));

     painter.save();
     painter.translate(bounds.left(), bounds.top());

     QAbstractTextDocumentLayout::PaintContext ctx;
     ctx.palette.setColor(QPalette::Text, painter.pen().color());
     td.documentLayout()->draw(&painter, ctx);

     painter.restore();
     ...

Now, if the width of "bounds" is smaller than the document's layout, it of 
course breaks the line to make it fit.  However, what I want it to do is 
/scale/ the text to fit the width of "bounds" so that it all appears on a 
single line without breakage.

I've tried a number of different approaches to get the QTextDocument to 
actually scale to "bounds" if it exceeds it, including inserting " ", 
which just causes breakage in non-obvious locations, and using the QPainter to 
try scaling the drawing area, but that gives me ugly text, even with small 
scaling factors.

The one I've seemed to have the most success with is:

     ...
     QFont f = td.defaultFont();
     for(;;)
     {
         doc_size = td.documentLayout()->documentSize();
         if(doc_size.width() < new_bounds.width())
             break;

         f.setPointSizeF(f.pointSizeF() - .1);
         td.setDefaultFont(f);
     }
     ...

But of course the font size can only go so low before setPointSizeF() starts 
failing, so I have to lock the lowest font size, even if it doesn't result in 
the text fitting within "bounds".

Is this approach of manipulating the font size the best way of getting a 
QTextDocument to scale within an arbitrary boundary, or is there something 
else I might try manipulating (QAbstractTextDocumentLayout?) to get me closer 
to my goal?
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