Re: [gnome-print] Serializing a PangoFont

[Chema Celorio <chema ximian com>]

On Mon, 2002-07-08 at 14:12, Owen Taylor wrote:
> 
> [ I'm phrasing this reply in terms of Pango HEAD and fontconfig,
>   since that's what any development targetted beyond the next
>   few months will need to deal with. I've also CC'ed Keith Packard
>   in case he has any relevant thoughts ]

<nod> I was looking at pango head too.

> But what is relevant really depends on what the metafile is going
> to be used for and how long it will be stored.
> 
>  - Do you want the exact same font file on disk?

Yes. This is what i want.

>  - Do you want a font with exactly the same name and an error
>    if it doesn't exist?
>  - Do you want the closest matching font?
>  - Do you want the font that would have been loaded if the
>    same PangoFontDescription 
> 
> If you want close to pixel-for-pixel results, and you want to
> transport a metafile file between computers, then the only real
> way you are going to do that is by embedding the font information
> inside your file.

I am unsure of the long term usage of the metafile but since everything
is working fine as it is I don't want to touch that code right now. So
about sharing a metafile between computers, not for the visible future.
It is just an intermediate format for now which will go away if i ever
find a reason to do so (i.e. performance hit)

> > The only viable alternative that i see right now is getting a
> > PangoFontDescription from the font and when playing back the stream
> > create a font from a description, however this is currently not possible
> > unless i create a PangoLayout again, but i already know the layout I
> > have the glyph and the position.
> 
>  pango_context_load_font (context, pango_font_describe(font)) 
> 
> Should give you a font that's reasonably similar to the original font.
> (Unless the font is missing, in which case it will give you a 
> "random" other font without any indication of error; one of the
> deficiencies of FontConfig.)
> 
> Note, however, that there is no guarantee at all that the glyph indices in 
> the new font will correspond to the original glyph indices in the
> PangoGlyphString. 

Right, this was happening to me before.

> (Even if the filename is the same, there is no guarantee; a new version
> of the font could rearrange the glyphs.)
> 
> Really, unless you are sure that you are going to have *exactly* the
> same font, you need to redo the layout

Yes, I am sure we are going to have the exactly same font. It will be
ran on the same box immediately after the user prints.

thanks,
Chema