Path: utzoo!utgpu!water!watmath!clyde!rutgers!gatech!gtss!chas
From: chas@gtss.UUCP (Charles Cleveland)
Newsgroups: comp.sys.amiga
Subject: font structures
Message-ID: <196@gtss.UUCP>
Date: 19 Jan 88 05:17:17 GMT
Reply-To: chas@gtss.UUCP (Charles Cleveland)
Organization: Georgia Tech School of Physics
Lines: 50

This is about fonts and structures which indicate them.

Here is a newly opened Window.  Its structure has a pointer to a Rastport
structure which contains a pointer to a TextFont structure.

The Window also contains a pointer to its parent Screen's structure.  This
structure contains a pointer to a TextAttr structure along with a pointer
to the Screen's Rastport structure which of course also contains a pointer
to a TextFont structure.

Perhaps there are other related TextAttr/TextFont structures I have
overlooked.  If so, I would like to know of them.

I am interested in knowing how the values of these structures are related
to one another.  What determines Window's Rastport's TextFont when it is
opened?  Are the Screen's TextAttr and its Rastport's TextFont related,
perhaps only during the latter's initialization?  In what (possibly
independent) ways are the Screen's TextAttr & its RastPort's TextFont used?
For example, my Addison-Wesley Intuition Reference Manual says that a string
gadget "inherits ... the font of the screen in which it appears."  Well,
which font is that?  Can I in any way change the font for my String
Gadgets without changing a default font for my entire Screen?

Apart from a desire to understand the relations between these structures
for future use, I simply want to set the font used by Text() in the window
(ala SetFont) to that which will be use by Intuition string gadgets,
regardless of the mindless antics someone may have played with SetFont or
its equivalents.  I would also like to know which font structure has been
thereby set (or which structure it was set from) so that I can determine its
size for scaling purposes.
-------------
I have had embarrassingly inordinate difficulty opening a TextFont from the
Screen's TextAttr structure.  Apparently, (from memory)

  tf = (struct TextFont *)OpenFont(WindowPointer->WScreen->Font);

results in a Guru with an illegal instruction error.  I will shortly explore
this further.  Undoubtedly I am doing something stupid that invokes the Guru,
but it keeps me from testing out some of the alternatives which might enable
me to sort this out by myself [Lattice 3.03 -- I promise I'll upgrade
soon :-)].  In the meantime I would appreciate any info about how these
structures relate to one another and their uses.  Perhaps that will inspire
comprehension as to why my OpenFont call fails.

Best regards to all.
-- 
-Life would be so much easier if we could just look at the source code.-

Charles Cleveland    Georgia Tech School of Physics    Atlanta, GA 30332
UUCP: ...!gatech!gtss!chas         INTERNET:  chas@ss.physics.gatech.edu