On 31.10.2011 23:39, Eric Wasylishen wrote:
My idea of how to proceed is something like this:
- add a method to NSLayoutManager for getting a range of glyphs and their
advances as efficiently as possible, which should not be difficult (or maybe we
already have that?). I'm not sure if I advertised it well, but I made a
change in NSLayoutManager several months ago so that we store advancements
along with the glyphs in the glyph run data structure (previously, the
advancements were not stored.The reason for this change is so in the future we
can implement a glyph generator which does complex text layout, by calling a
library such as harfbuzz or icu, since these take a character run and output a
glpyh run with advancements.)
- properly implement GSShowGlyphsWithAdvances in the backends. easy for cairo,
at least.
- for cairo, it would be nice to use real glyphs by importing the code from
Opal that Neils and I wrote.
Sounds great.
Let us talk in detail how to integrate these two implementations. I
think that most of the FreeType code you wrote there would fit perfectly
into a FontInfo subclass, but I also remember there was a part that
didn't. That is, you did override some code from NSFont, but I am not
that sure which bit.
Maybe the best way to start this rewrite is to use a font descriptor in
the creation of a FontInfo instead of the font name we currently use. If
this descriptor contains a font name everything stays the same for the
old backend, if it doesn't they will have to use some methods on
NSFontManager to get the font name.
We will need two additional flags in the descriptor for the role and
whether we want a screen font. The descriptor could be used instead of
GSFontMapKey to cache the currently used fonts.
The pseudocode for -drawGlyphsForGlyphRange:atPoint: should look something like
this:
for the range to be drawn:
- get the first subrange with the same colour
- get the glyphs in that subrange and their advances as efficiently as
possible
- set the colour, and send the glyphs and advances to the backend with
GSShowGlyphsWithAdvances
- start the next loop iteration, starting at the end of the current
subrange
Again, sounds correct to me.
_______________________________________________
Discuss-gnustep mailing list
[email protected]
https://lists.gnu.org/mailman/listinfo/discuss-gnustep
