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Re: The future of draw_axes (was: Freetype font warning)


From: logari81
Subject: Re: The future of draw_axes (was: Freetype font warning)
Date: Sat, 22 Jan 2011 22:36:41 +0100

On Sat, 2011-01-22 at 22:22 +0100, David Bateman wrote:
> Ben Abbott wrote:
> > On Jan 22, 2011, at 5:58 AM, logari81 <address@hidden> wrote:
> >
> >   
> >> I think that freetype will be at some point in the future a prerequisite
> >> for octave anyway, even when using gnuplot, just for estimating text
> >> extents.
> >>     
> >
> > Good point.
> >
> >   
> This is what I tried with the legend code. Trying to estimate the text
> extents with FreeType when for example gnuplot is using something else
> (gd, etc) gives pretty poor results. This is why I ended up treating the
> gnuplot legends  with the gnuplot legend functionality rather than using
> an overlaid axis with appropriate line and text objects.
> 
> Kostas, if you figure out a way to get good text extents for gnuplot
> I'll applaud and then go and make the gnuplot legend code much simpler.
> However, I think it'll be really hard to get it right, and probably the
> only way is to have gnuplot modified to supply the means to give them to us.
> 
> D.
> 

My idea is to split the job currently done in draw_axes into two parts:

1. Preparing the layout: calculation of objects (ticks, labels, etc.)
positions relatively to the axes.

2. Drawing the objects at the pre-calculated positions. Pure openGL
operations.

I would like to have (1) in graphics.cc so that it can possibly (but not
necessarily) be used by gnuplot as well.

I would leave (2) in draw_axes, keeping in it only the pure OpenGL part.

My main motivation is not the improvement of the gnuplot backend (this
could be a side effect). My real objective is to solve the
position/outerposition/tightinset synchronization problem in fltk.

I think my recent changes have tided up draw_axes a bit, so that
separating the layout calculation from the drawing operation would now
be easier than before.

BR

Kostas



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