Font variations.

src/ports/SkFontConfigParser_android.cpp

Index: src/ports/SkFontConfigParser_android.cpp
diff --git a/src/ports/SkFontConfigParser_android.cpp b/src/ports/SkFontConfigParser_android.cpp
index ffc60427f47a0d841288f8c9ff997e057f793385..3770c3d7876eab20caacbe59f59bc2c4b3e5b1e1 100644
--- a/src/ports/SkFontConfigParser_android.cpp
+++ b/src/ports/SkFontConfigParser_android.cpp
@@ -163,6 +163,10 @@ static void font_element_handler(FamilyData* self, FontFileInfo* file, const cha
             if (!parse_non_negative_integer(value, &file->fIndex)) {
                 SkDebugf("---- Font index %s (INVALID)", value);
             }
+        } else if (MEMEQ("axis", name, nameLen)) {

[bungeman-skia, 2015/04/01 20:38:28]

Need support for multiple axes. By index, id (four char tag), or name? Note that
this already currently assumes the user knows the font here. As a result index
is easy and nice.

Axis space. Normalized or design? Prefer design.

Need to be able to specify in something other than 'SkFixed' in base 10.

Possibilities for 400 weight, slightly greater than normal width, no slant:

axis="400 1.2 0"

axis="wght:400 wdth:1.2 slnt:0" (also 'opsz' is standard)

axis="weight:400 width:1.2 slant:0" (also 'optical-size')

axis-wght="400" axis-wdth="1.2" axis-slnt="0"

axis-weight="400" axis-width="1.2" axis-slant="0"

'weight' is easier to read, but 'wght' maps directly to the underlying data in
the font, meaning that it is easy to use non-standard variation ids (since no
translation is needed). Using positional indexes here isn't very clear at all,
but is very simple to implement and extend, 'wght' means we have to do string
matching at some point. In theory though, we could do this string matching up
front based on the font scan. However, it's not clear how to specify all four
byte codes like this. In css this would look something like

font-axis-settings: 'wght' 800, 'wdth' 1.2, 'slnt' 0;

with the grammar:

<axis-tag-value>#
axis-tag-value: <string> <number>

on the other hand, I don't want to write too many parsers here.

+            if (!parse_non_negative_integer(value, &file->fAxes.push_back())) {
+                SkDebugf("---- Font axis %s (INVALID)", value);
+            }
         }
     }
     XML_SetCharacterDataHandler(self->fParser, font_file_name_handler);