Re: writing a text widget with pango

[Martyn Plummer <plummer iarc fr>]

On 23-May-2002 Havoc Pennington wrote:
> Martyn Plummer <plummer iarc fr> writes:
> > This would be most welcome. I maintain the GNOME GUI for the R project
> > (a language for data analysis and graphics http://www.r-project.org ).
> > Part of the GUI is a graphics device using the GTK+ API, which can be
> > used to plot graphs.  I want to do simple things like draw axis labels,
> > titles for graphs, and so on, on a GtkDrawable.  The absence of a simple
> > draw-string API in GTK+ 2.0 has made this rather more difficult, so
> > please seriously consider bringing it back.
>
> See, now you're discouraging us though. ;-) There's no reason graph
> titles should have broken i18n just to save 5 lines of code... there's
> little extra complexity to get that simple case right.

Let me try and re-encourage you then!  I suggest you try the graphics
demo of R to see the sort of things it can do

You can get an RPM (signed by me) from
ftp://calvin.iarc.fr/pub/R/RedHat/7.x/i386/R-base-1.5.0-2.i386.rpm

Type "R" to start R, "q()" to quit.  To see the graphics demo type
"demo(graphics)" at the R prompt.

R does its own layout when plotting graphics.  I don't
need a high-level layout engine.  I do need a low-level function that
answers the question "I want to plot this text string, in this font,
what are its extents?"  In gtk+ 1.2 this was easy, since gdk was just
a wrapper around Xlib.  In gtk+ 2.0 the low level functions I needed
are deprecated, and I'm trying not to use them. This simple question
no longer has a simple answer, apparently.  If I can do it in five
lines of code then excuse me while I break down and weep, but I
couldn't piece this together from the documentation.  Eventually
I adapted the code from gdk_text_extents() in the linux-fb port of
gdk, This works, except plotting of mathematical formulae is broken.

Martyn