Re: Difference in font layout heights?

[Lars Clausen <lrclause cs uiuc edu>]

[Resending this to the list, and casting a vote for having Reply-To: list]

On Mon, 24 Feb 2003, Havoc Pennington wrote:
> On Mon, Feb 24, 2003 at 10:36:37AM -0600, Lars Clausen wrote:
>> 
>> In working on using a TextView widget for editing text in Dia, I notice
>> that there's a significant difference in the height of multi-line text,
>> about 12%.  We use the FT2 backend for internal Dia rendering, but the
>> TextView of course uses either the gdk renderer or xft, depending on the
>> GDK_USE_XFT setting.  The length of the text is unaffected.  We use
>> pango_ft2_render_layout to do the whole rendering, while GtkTextView
>> uses gtk_text_layout_draw, which does line-by-line rendering.  Is the
>> line space wrong in one or the other of these?
>> 
> 
> TextView has settings for the amount of inter-paragraph and inter-line
> spacing, that default to nonzero.

If you're referring to gtk_text_view_get_pixels_[above|below]_lines, they
default to zero.

Upon further investigation, it looks like PangoFT2 ignores font metrics for
line distance, and just uses the height given, while PangoXFT and PangoX
use either ascent+descent or baselineskip or some other amount found in the
font.  FT2's method has the advantage that when I ask for a 1cm high font,
I know there'll be 1cm between lines, if nothing else.  The other method
probably looks better, though, as the line distance is font dependant.

-Lars

-- 
Lars Clausen (http://shasta.cs.uiuc.edu/~lrclause)| Hårdgrim of Numenor
"I do not agree with a word that you say, but I   |----------------------------
will defend to the death your right to say it."   | Where are we going, and
    --Evelyn Beatrice Hall paraphrasing Voltaire  | what's with the handbasket?