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List:       koffice-devel
Subject:    Re: karbon, kpainter and kword
From:       "Dirk Schönberger" <dirk.schoenberger () sz-online ! de>
Date:       2003-06-17 14:22:51
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Thomas Zander schreibt:

> On Tue, Jun 17, 2003 at 12:37:22PM +0000, Dirk Sch?nberger wrote:
> > I have left text support out of KPainter because I wasn't sure about the
> > requirements.
> > Would it be ok if we collect the requirements and I implement a first
> > version incl. the frontend / backend communication operators.
> > After that we could see how this API could be implemented by the KPainter
> > backends.
> > 
> > > 1) give me the width (+ height and baseline) of an "A" in font foo size 
> > > 12pt (with decimals, not just in pixels) 
> > 
> > something like
> > 
> > KFontMetric &fontMetrics (QString &string);
> > KFontMetric &fontMetrics (QChar &string);
> 
> The real thing needed for the painter is a bit more high-level that might
> give different low-level specs.
> 
> KWord needs to find out where a sentence breaks on the page. Or in other
> words; how much text (glyphs) fit in x milimeters.

That's why I introduced text model in my design ideas. a text model managed
the conversion of a high level text description (e.g. simple text or KWord)
into a set of KPainter calls (drawGlyph, drawString, drawChar).
It uses its own metrics, but it can also use KPainter generated metrics for
real fonts.

> 
> This sounds similar, but it is not.
> Anyone familiar with TeX recongnizes the last solution since it is what gives
> TeX the power to insert a word somewhere on the page without making the
> paragraph take an extra line; they just 'shrink' the font a little bit over
> the horizontal line.

But this means you need the actual font outline in the text model, no?

> 
> Anyway; to render fonts in KWord correctly I think the following approuch
> should be taken:
> 
> 1) take a big line (paragraph of QtRT) and a rectangle (in mm) and ask the
> painter where the line would break.

or the font metrics?

> 2) repeat for rest of paragraph.
> 
> Using the line-breakings data-structure for painting.
> 
> 1) Give array of glyphs and size (in pixels) to the renderer for painting.

drawGlyph() calls?

> 2) KPainter figures out what size (in pixels) the string is and scales the
> text horizontally and vertically (both, but independend) to make it fit. [1]

If you call drawGlyph(), KPainter doesn't know anymore that it is supposed
to render a text string.

Regards
Dirk
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