GF Axis Registry setup (#2541)

* Add GF Axis Registry files to git repo.

* Update root README.md with a description of the axisregistry/ subdir.

* Update root README.md with a description of the axisregistry/ subdir.

* Revise the axis registry README file to be simpler and also descrie the metadata fields of the axis textprotos.

README.md

@@ -9,6 +9,8 @@ Each family subdirectory contains the  `.ttf` font files served by Google Fonts,
 
 The `/catalog` subdirectory contains additional metadata, such as profile texts and portrait/avatar images of font designers, and this is open for contributions and corrections from anyone via Github.
 
+The `/axisregistry` subdirectory contains metadata for the GF Axis Registry, containing information on variable font axes that can be found in the collection, including experimental axes.
+
 ## Bug reports and improvement requests
 
 If you find a problem with a font file or have a request for the future development of a font project, please [create a new issue in this project's issue tracker](https://github.com/google/fonts/issues).

axisregistry/README.md

@@ -0,0 +1,33 @@
+# GF Axis Registry
+
+This package contains a collection of metadata files that collectivefly form the
+GF Axis Registry.
+
+## Why does Fonts have its own Axis Registry?
+
+We plan to support a superset of the OpenType axis registry and additional
+metadata. Individual variable fonts support a subset of our axis registry. Axes
+not in our registry will not function via our API.
+
+## Axis Metadata Fields
+
+*   `tag`
+    *   Tag for the axis used to specify an axis in `font-variation-settings`
+        and CSS API requests.
+*   `display_name`
+    *   Readable name for the axis, generally the expanded form of `tag`.
+*   `min_value`
+    *   Lower bound of the axis. Inclusive.
+*   `max_value`
+    *   Upper bound of the axis. Inclusive.
+*   `default_value`
+    *   Default position of the aixs.
+*   `precision`
+    *   Describes the specificity at which an axis position can be specified.
+        For example, `0` means values must be specified as whole numbers while
+        `-1` means values can be as precise as one decimal place.
+*   `fallback` (repeated)
+    *   Important positions along the axis. For weight, these are positions like
+        Regular, Medium, and Bold.
+*   `description`   
+    *   A description of the axis.

axisregistry/casual.textproto

@@ -0,0 +1,19 @@
+# CASL based on https://github.com/arrowtype/Recursive#variable-axes
+tag: "CASL"
+display_name: "Casual"
+min_value: 0
+max_value: 1
+default_value: 0
+precision: -2
+fallback {
+  name: "Linear"
+  value: 0
+}
+fallback {
+  name: "Casual"
+  value: 1
+}
+description:
+  "Along this axis, letterforms adjust in stroke curvature, contrast, and"
+  " terminals to go from a sturdy, rational 'Linear' style to a friendly,"
+  " energetic 'Casual' style."

axisregistry/cursive.textproto

@@ -0,0 +1,24 @@
+# CRSV based on https://github.com/arrowtype/Recursive#variable-axes
+tag: "CRSV"
+display_name: "Cursive"
+min_value: 0
+max_value: 1
+default_value: 0.5
+precision: -1
+fallback {
+  name: "Roman"
+  value: 0
+}
+fallback {
+  name: "Auto"
+  value: 0.5
+}
+fallback {
+  name: "Cursive"
+  value: 1
+}
+description:
+  "Controls the substitution of cursive forms along the Slant axis. 'Off' (0)"
+  " maintains Roman letterforms such as a double-story a and g, 'Auto' (0.5)"
+  " allows for Cursive substitution, and 'On' (1) asserts cursive forms even"
+  " in upright text with a Slant of 0."

axisregistry/expression.textproto

@@ -0,0 +1,20 @@
+# FOR TESTING ONLY [for now anyway]
+# Added for initial releases of Recursive::XPRN (https://recursive.design)
+tag: "XPRN"
+display_name: "Expression"
+min_value: 0
+max_value: 1
+default_value: 0
+precision: -1
+fallback {
+  name: "Inexpressive"
+  value: 0
+}
+fallback {
+  name: "Expressive"
+  value: 1
+}
+description:
+  "Axis used first in Recursive development, intended as a general purpose"
+  " axis for any expressive variation; GF team requested a different approach"
+  " to expressive axes, with more specificity."

axisregistry/grade.textproto

@@ -0,0 +1,33 @@
+# GRAD based on https://github.com/TypeNetwork/Opentype-1.8-Axis-Proposal/blob/gh-pages/proposal/Grade/ProposalSummary.md
+tag: "GRAD"
+display_name: "Grade"
+min_value: -1
+max_value: 1
+default_value: 0
+precision: -1
+fallback {
+  name: "Full Negative"
+  value: -1
+}
+fallback {
+  name: "Half Negative"
+  value: -0.5
+}
+fallback {
+  name: "Normal"
+  value: 0
+}
+fallback {
+  name: "Half Positive"
+  value: 0.5
+}
+fallback {
+  name: "Full Positive"
+  value: 1
+}
+description:
+  "Finesse the style from lighter to bolder in typographic color, by varying"
+  " stroke thicknesses or other forms, without any changes overall width,"
+  " inter-letter spacing, or kerning, so there are no changes to line breaks"
+  " or page layout. Negative grade makes the style lighter, while positive"
+  " grade makes it bolder. "

axisregistry/italic.textproto

@@ -0,0 +1,19 @@
+# ital based on https://docs.microsoft.com/en-us/typography/opentype/spec/dvaraxistag_ital
+tag: "ital"
+display_name: "Italic"
+min_value: 0
+max_value: 1
+default_value: 0
+precision: -1
+fallback {
+  name: "Roman"
+  value: 0
+}
+fallback {
+  name: "Italic"
+  value: 1
+}
+description:
+  "Adjust the style from roman to italic. This can be provided as"
+  " a continuous range within a single font file, like most axes, or as a"
+  " toggle between two roman and italic files that form a family as a pair."

axisregistry/monospace.textproto

@@ -0,0 +1,23 @@
+# FOR TESTING ONLY [for now anyway]
+# MONO based on https://github.com/arrowtype/Recursive#variable-axes
+tag: "MONO"
+display_name: "Monospace"
+min_value: 0
+max_value: 1
+default_value: 0
+precision: -2
+fallback {
+  name: "Proportional"
+  value: 0
+}
+fallback {
+  name: "Monospace"
+  value: 1
+}
+description:
+  "Adjust the style from proportional (natural widths, default) to"
+  " monospace (fixed width). Monospace is when all glyphs have the same"
+  " total character width, and more wide or narrow letter proportions to fill"
+  " the space such as a narrower 'w' or wider 'r.' Proportionally spaced"
+  "fonts have letters drawn with more typical proportions, and each glyph"
+  "takes up a unique amount of space on a line."

axisregistry/optical_size.textproto

@@ -0,0 +1,93 @@
+# opsz based on https://docs.microsoft.com/en-us/typography/opentype/spec/dvaraxistag_opsz
+# fallbacks based on https://en.wikipedia.org/wiki/Traditional_point-size_names
+# plus discussion with dcrossland@
+tag: "opsz"
+display_name: "Optical size"
+min_value: 6
+max_value: 144
+default_value: 14
+precision: -1
+fallback {
+  name: "6pt"
+  value: 6
+}
+fallback {
+  name: "7pt"
+  value: 7
+}
+fallback {
+  name: "8pt"
+  value: 8
+}
+fallback {
+  name: "9pt"
+  value: 9
+}
+fallback {
+  name: "10pt"
+  value: 10
+}
+fallback {
+  name: "11pt"
+  value: 11
+}
+fallback {
+  name: "12pt"
+  value: 12
+}
+fallback {
+  name: "14pt"
+  value: 14
+}
+fallback {
+  name: "18pt"
+  value: 18
+}
+fallback {
+  name: "20pt"
+  value: 20
+}
+fallback {
+  name: "24pt"
+  value: 24
+}
+fallback {
+  name: "28pt"
+  value: 28
+}
+fallback {
+  name: "36pt"
+  value: 36
+}
+fallback {
+  name: "48pt"
+  value: 48
+}
+fallback {
+  name: "60pt"
+  value: 60
+}
+fallback {
+  name: "72pt"
+  value: 72
+}
+fallback {
+  name: "96pt"
+  value: 96
+}
+fallback {
+  name: "120pt"
+  value: 120
+}
+fallback {
+  name: "144pt"
+  value: 144
+}
+description:
+  "Adapt the style to specific text sizes, specified in Points. At smaller"
+  " sizes, letters typically become optimized for more legibility, with loose"
+  " spacing/kerning and thicker strokes with less detail. At larger sizes,"
+  " letters are typically optimized for headlines with thinner strokes and"
+  " more detailed forms, and more extreme weights and widths. When used in"
+  " CSS, this axis is activated by default, but not all products/platforms"
+  " use it automatically."

axisregistry/slant.textproto

@@ -0,0 +1,15 @@
+# slnt based on https://docs.microsoft.com/en-us/typography/opentype/spec/dvaraxistag_slnt
+tag: "slnt"
+display_name: "Slant"
+min_value: -90
+max_value: 90
+default_value: 0
+precision: 0
+fallback {
+  name: "Default"
+  value: 0
+}
+description:
+  "Adjust the style from upright to slanted, also known to typographers"
+  " as an 'oblique' style. Rarely, slant can work in the other direction,"
+  " called a 'backslanted' or 'reverse oblique' style."

axisregistry/softness.textproto

@@ -0,0 +1,16 @@
+# SOFT based on https://github.com/undercasetype/Fraunces#variable-axes
+tag: "SOFT"
+display_name: "Softness"
+min_value: 0
+max_value: 100
+default_value: 0
+precision: -1
+fallback {
+  name: "Normal"
+  value: 0
+}
+fallback {
+  name: "Soft"
+  value: 100
+}
+description: "Along this axis, letterforms become more soft and rounded."

axisregistry/weight.textproto

@@ -0,0 +1,48 @@
+# wght based on https://docs.microsoft.com/en-us/typography/opentype/spec/dvaraxistag_wght
+tag: "wght"
+display_name: "Weight"
+min_value: 1
+max_value: 1000
+default_value: 400
+precision: 0
+fallback {
+  name: "Thin"
+  value: 100
+}
+fallback {
+  name: "Extra Light"
+  value: 200
+}
+fallback {
+  name: "Light"
+  value: 300
+}
+fallback {
+  name: "Regular"
+  value: 400
+}
+fallback {
+  name: "Medium"
+  value: 500
+}
+fallback {
+  name: "Semi Bold"
+  value: 600
+}
+fallback {
+  name: "Bold"
+  value: 700
+}
+fallback {
+  name: "Extra Bold"
+  value: 800
+}
+fallback {
+  name: "Black"
+  value: 900
+}
+description:
+  "Adjust the style from lighter to bolder in typographic color, by varying"
+  " stroke thicknesses or other forms. This typically changes overall width,"
+  " and so may be used in conjunction with axes for Width and Grade (if"
+  " present)."

axisregistry/width.textproto

@@ -0,0 +1,50 @@
+# wdth based on https://docs.microsoft.com/en-us/typography/opentype/spec/dvaraxistag_wdth
+tag: "wdth"
+display_name: "Width"
+min_value: 50
+max_value: 200
+default_value: 100
+precision: -1
+# Instance values based on https://docs.microsoft.com/en-us/typography/opentype/spec/os2#uswidthclass
+fallback {
+  name: "Ultra Condensed"
+  value: 50
+}
+fallback {
+  name: "Extra Condensed"
+  value: 62.5
+}
+fallback {
+  name: "Condensed"
+  value: 75
+}
+fallback {
+  name: "Semi Condensed"
+  value: 87.5
+}
+fallback {
+  name: "Normal"
+  value: 100
+}
+fallback {
+  name: "Semi Expanded"
+  value: 112.5
+}
+fallback {
+  name: "Expanded"
+  value: 125
+}
+fallback {
+  name: "Extra Expanded"
+  value: 150
+}
+fallback {
+  name: "Ultra Expanded"
+  value: 200
+}
+description:
+  "Adjust the style from narrower to wider, by varying the proportions of"
+  " counters, stems, and other forms including overall spacinig and kerning."
+  " This typically changes the apparent weight (what typographers call"
+  " 'typographic color') in a subtle way, and so may be used in conjunction"
+  " with axes for Width and Grade (if present)."

axisregistry/wonkiness.textproto

@@ -0,0 +1,20 @@
+# WONK based on https://github.com/undercasetype/Fraunces#variable-axes
+tag: "WONK"
+display_name: "Wonkiness"
+min_value: 0
+max_value: 1
+default_value: 0
+precision: 0
+fallback {
+  name: "Normal"
+  value: 0
+}
+fallback {
+  name: "Wonky"
+  value: 1
+}
+description:
+  "Controls the subsitution of wonky forms along the Optical Size axis. 'Off'"
+  " (0) maintains more normalized letterforms, such as the leaning n/m/h in"
+  " Roman, or the bulbous flags in the b/d/h/k/l of the Italic. In"
+  " static fonts, this is also available as an OpenType Stylistic Set."