Re: Hyphenation support in Pango ( / Cairo )

[Alex Kerr <alex phonething com>]

Just a thought, assuming I've understood correctly - can't you use the 
PangoLogAttr structure (i.e. check what's in it) while people are typing 
their input (as you can use Pango for rendering and cursor placement etc 
in this context anyway) and then generate a hyphen when and where you 
want (e.g. mid word, or when line wraps etc) based on the is_char_break 
or is_line_break values in PangoLogAttr?

I guess you'd be checking these values in real time as someone typed the 
input. pango_layou_get_log_attrs() is one API giving access to the 
structure, not sure if there are others? Might be worth checking the 
different Pango API pages for this 
http://developer.gnome.org/pango/stable/index.html

Cheers
Alex

On 10/05/2011 16:41, Roland Schwarz wrote:
> Dear subscribers,
>
> I hope that my following question is not too far away from the common
> discussion context in this list, I have a question regarding  the Pango
> library and hyphenation of textual input.
>
> At the moment I am working on a project that deals with the typesetting
> of so called 'critical editions' from language and literature studies.
> Our goal is to build a tool that can process given XML input with some
> user definable stylesheets into a - primarily - PDF output.
> The coding platform is F# with the .net framework, and I have to keep in
> mind only using the features that are available on mono too, as this
> should be kind of platform independent ;-)
>
> To avoid reinventing the wheel we tried out parts of the Cairo/Pango
> library, and got good results with the output in PDF format, basic line
> breaking and text formatting. As our development continues, we have the
> problem that we need to support a kind of hyphenation for our textual
> input, and that is the core of my current problem: Is there any kind of
> useable hyphenation support in the Pango library ?
>
> I have found several discussions about this point, some of them 8 years
> old, but nothing so far that looks like a code example or a 'how to'
> e.g. plug in some hyphenation patterns known from teX or something 
> similar.
>
> To explain the current approach and why we are looking for a kind of
> automatic hyphenation, there is a small code extract from the current
> 'playground prototype' ;-) .
> (Yes, thats C#, even if I wrote F#. The source is currently a
> combination of (C&F)#Libraries)
>
>                  Pango.Layout pgLayout2 =
> Pango.CairoHelper.CreateLayout(ctx);
>                  pgLayout2.Wrap = Pango.WrapMode.Word;
>                  pgLayout2.Alignment = Pango.Alignment.Left;
>                  pgLayout2.SingleParagraphMode = true;
>                  pgLayout2.Justify = true;
>                  pgLayout2.Width = Convert.ToInt32(GlobalPageWidth *
> Pango.Scale.PangoScale);
>                  pgLayout2.Spacing = Convert.ToInt32(5 *
> Pango.Scale.PangoScale);
>                  pgLayout2.FontDescription =
> Pango.FontDescription.FromString("Linux Libertine 8");
>                  pgLayout2.SetMarkup("..some longer raw text input...");
>                  var resultlines = pgLayout2.Lines
>
> So, what we are doing is using the Layout Class of Pango, pass some
> formatting attributes to it and let the layout-class do the work to
> split the given text into Layoutlines. Those layout lines are then used
> for the current pagination algorithm, as they also include the most
> relevant geometric information and can be just placed in the pdf output
> using a Context.moveto(x,y) and the showLayoutline-function. The 
> feature we are now looking for is a build-in hyphenation with the 
> Layout-class.
>
> So, the question is: Is there anything like this ?
>
> Thanks alot for any information about this !
> This text will be also posted on the Cairo mailing list as well as 
> there are two different mailing lists given for Cairo and Pango. I 
> hope not to offend someone with this procedure.
>
> Greetings !
>
> roland schwarz
>
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