RE: [cgmo-webcgm] Action Item: PROPOSAL: setStyleProperty - text-font

[Lofton Henderson <lofton@rockynet.com>]

Dieter,

I do understand the proposed algorithm for text-font.  According to
your proposed algorithm, one of two things will happen:  

A.) either you'll get the font you asked for in the text-font Style
Property; 

B.) or, you'll get "no change", i.e., what was asked for in the
WebCGM instance (Adobe13, or "other+FontProperties"). 

In the context of technical graphics requirements, this is already much
better than the CSS font-matching, which can lead to a wide range of
results.

But ... I'm still unconvinced that the introduction of potential
variability in the behavior of graphical text is worth the use cases [1]
that are gained by introducing the text-font SP, with no font
restrictions, and allowing it in WebCGM 2.0's  cgm+xcf  content
packages.

[1]
http://lists.oasis-open.org/archives/cgmo-webcgm/200505/msg00091.html

Back to my example case (below).  As you pointed out, there was one
flawed assumption in my example.  So I'll separate two
scenarios.

1.)  behavior on different platforms:  e.g., WinXP, linux, mac,
...  The requested font (e.g., lucidaConsole) may be routinely
available on one, but not on another.  So two different systems on
Dave's desktop, each running an appropriate version of the same vendor's
CGM viewer, might give different results.  Correct?

2.)  different viewers on same platform:  I guess I was
implicitly thinking, here, of some past experience where the graphic
system (e.g., CGM viewer) shipped some font resources as part of the
system (e.g., for software text simulation).  That probably is not
nearly as common nowadays as using the font resources on the system,
which tend to be prodigious.

So to summarize my concern ... we're potentially introducing some text
unpredictability, and I'm not yet convinced that's a good idea.  As
the august graphics experts Weidenbrueck & Henderson wrote [2] about
WebCGM (compared to SVG), "Predictability of text model 
--  completely constrained and predictable -- ..."  

[2]
http://www.cgmopen.org/technical/webcgm_svg.htm#S3.3

[Btw, another issue to resolve if we were to include text-font SP: 
unless a text-font SP that replaces the font in the CGM is chosen *very*
carefully, it will not likely work well with the text restriction box of
the RESTRICTED TEXT elements.  How would we address this? 
]

Regards,
-Lofton.

At 06:18 PM 6/20/2005 +0200, Dieter  Weidenbrück wrote:

Lofton,
 
I am not sure whether I understand your concern:

-----Original Message-----

From: Lofton Henderson [mailto:lofton@rockynet.com]

Sent: Monday, June 20, 2005 5:42 PM

To: dieter@itedo.com; cgmo-webcgm@lists.oasis-open.org

Subject: Re: [cgmo-webcgm] Action Item: PROPOSAL: setStyleProperty - text-font

I'm uncomfortable with one aspect of this proposal:  two different applications processing the same WebCGM 2.0 content could mysteriously get very different results.  This is not supposed to happen in WebCGM.  For example, let's suppose this link occurs in a HTML + WebCGM parts list application:

<a href=""pump.cgm#xcf(pump-styles.xml)">Pump" subassembly</a>

and the XCF contains:

<webcgm ... text-font="Lofton_Calligraphic" >

[DW] following my proposal, the application would do the following (in pseudo-code):

 

if "Lofton_Calligraphic" is available then

    for each text element in the selected APS

        if "Lofton_Calligraphic" contains all glyphs needed to represent the text

            set text font to "Lofton_Calligraphic"

    end for

end if

 

As I assume that the font does not exist, the first check would fail, and hence the application

would not do anything.

If a font with that name really exists, the next test would detect whether it covers the glyphs

needed for the text elements. If this is not the case, nothing will happen either.

I do not understand how two different applications would come to different results other than

if they run in two different environments, one with this font installed, and the other one without?

 

Please let me know if I am missing anything.

Regards,

Dieter

 

I know that it is not part of Dieter's design intent, but this in fact provides a loophole to completely evade the tight text restrictions and highly predictable graphical text results of WebCGM 1.0.

I am not yet convinced that this is a wise thing to do.

-Lofton.

At 12:28 PM 6/20/2005 +0200, Dieter  Weidenbrück wrote:

All,

 

here is my proposal regarding the text-font style property:

 

"text-font: The text-font style property redefines the text font that is used for drawing graphical text within the APS to which it is applied. Text-font corresponds to the font set inside a CGM using the FONT LIST and TEXT FONT INDEX elements. The required behavior is as follows: the application needs to check first whether the specified font resource exists. If so, it has to further ensure that all glyphs of the text it will be applied to exist in that font. If both checks are successful, the application shall apply the font to the text. In all other cases the text remains unchanged."

 

 

Comment: I wanted to specify a simply yet clear way for a successful font change. By restricting it to the cases where the font is installed and appropriate I think this can be accomplished.

 

Regards,

Dieter