font-selection-strategy

[Victor Mote <vi...@outfitr.com>]

FOP-devs:

WRT font-selection-strategy, I think the new aXSL methods provide the means
to client applications to implement the "character-by-character" option.

My current reading of the spec is that the "auto" option is merely an
opportunity, a hook if you will, for an implementation to do something
fancier than "character-by-character". This whole attribute is actually an
extension to CSS, which only does character-by-character. The definition of
"auto" is "The selection criterion given by the contextual characters is
used in an implementation defined manner." That seems to cover almost
anything doesn't it? Including character-by-character. The "Note" under
"auto" seems to confirm this.

Nevertheless, the example given in the "Note" provides some ideas for other
algorithms, and seems to suggest that there is room for more than one. So,
the general framework would seem to include the definition of one or more
such algorithms, naming each one, and then providing that name through some
global-ish mechanism like a font-configuration file or other configuration
option. The font system can then implement the algorithm, perhaps with the
help of call-back methods to provide, for example, the various pieces of
contextual text.

Now, I suggest that the creation and definition of such algorithms should be
driven by the user base. IOW, if a user wishes to suggest an algorithm for
font-selection that provides something useful to them, it should be
considered. I say this partly because I don't seem to have a need for any
such thing. My general approach is going to be to provide a list of exactly
one font-family and then (by perusing the log!!) make sure that font-family
actually got used. If it did not, I'm going to consider my stylesheet to be
deficient as opposed to the font selection algorithm. In other words, I am
going to implement my own manual algorithm.

The other wrinkle that the standard seems to present is qualitative
judgments like "better quality fonts" and "match each other badly
stylistically". I know of no way to get this information other than asking
the user for it. So it is likely that some algorithms will require
additional information in font-configuration.

This post does not require any response from anyone. I realize you are
trying to get a release out the door. I just wanted to document my thoughts
on the matter for you before they escaped.

Victor Mote

Re: font-selection-strategy

[Jeremias Maerki <de...@jeremias-maerki.ch>]

I must say (from a pure FOP-POV), that I'm looking forward to see what
Vincent will come up with with your help. WRT font-selection-strategy I
believe that character-by-character will be a huge step forward for our
two FO processors and should cover 98% of all use cases. If anyone needs
more we can always look at it when this happens. I wouldn't think too
much about that, yet, especially since we don't know the exact
requirements that would come up. But I fully share your interpretation
of the issues here.

On 09.09.2005 19:54:38 Victor Mote wrote:
> FOP-devs:
> 
> WRT font-selection-strategy, I think the new aXSL methods provide the means
> to client applications to implement the "character-by-character" option.
> 
> My current reading of the spec is that the "auto" option is merely an
> opportunity, a hook if you will, for an implementation to do something
> fancier than "character-by-character". This whole attribute is actually an
> extension to CSS, which only does character-by-character. The definition of
> "auto" is "The selection criterion given by the contextual characters is
> used in an implementation defined manner." That seems to cover almost
> anything doesn't it? Including character-by-character. The "Note" under
> "auto" seems to confirm this.
> 
> Nevertheless, the example given in the "Note" provides some ideas for other
> algorithms, and seems to suggest that there is room for more than one. So,
> the general framework would seem to include the definition of one or more
> such algorithms, naming each one, and then providing that name through some
> global-ish mechanism like a font-configuration file or other configuration
> option. The font system can then implement the algorithm, perhaps with the
> help of call-back methods to provide, for example, the various pieces of
> contextual text.
> 
> Now, I suggest that the creation and definition of such algorithms should be
> driven by the user base. IOW, if a user wishes to suggest an algorithm for
> font-selection that provides something useful to them, it should be
> considered. I say this partly because I don't seem to have a need for any
> such thing. My general approach is going to be to provide a list of exactly
> one font-family and then (by perusing the log!!) make sure that font-family
> actually got used. If it did not, I'm going to consider my stylesheet to be
> deficient as opposed to the font selection algorithm. In other words, I am
> going to implement my own manual algorithm.
> 
> The other wrinkle that the standard seems to present is qualitative
> judgments like "better quality fonts" and "match each other badly
> stylistically". I know of no way to get this information other than asking
> the user for it. So it is likely that some algorithms will require
> additional information in font-configuration.
> 
> This post does not require any response from anyone. I realize you are
> trying to get a release out the door. I just wanted to document my thoughts
> on the matter for you before they escaped.
> 
> Victor Mote



Jeremias Maerki