VF-first feature writers

README.md

@@ -9,53 +9,70 @@ AFDKO Python Modules
 pip3 install git+https://github.com/adobe-type-tools/python-modules
 ```
 
+## `goadbWriter`
+The goadbWriter extracts a UFO’s glyph order into a GlyphOrderAndAliasDB file. In the `makeotf`-workflow, this file is essential for assignment of glyph order and code points. The GOADB can also be used to filter non-exporting glyphs. [Read more about the GOADB](https://adobe-type-tools.github.io/afdko/MakeOTFUserGuide.html#glyphorderandaliasdb-goadb)
 
-## `kernFeatureWriter.py`
-This tool exports the kerning and groups data within a UFO to a
+#### Usage:
+```zsh
+
+    # simple, really
+    goadbWriter font.ufo
+
+```
+
+
+
+## `kernFeatureWriter`
+The kernFeatureWriter exports the kerning and groups data within a UFO to a
 `makeotf`-compatible GPOS kern feature file.
 
 #### Default functionality:
 
--   writing of a sorted kern.fea file, which organizes pairs in order of
-    specificity (exceptions first, then glyph-to-glyph, then group pairs)
--   filtering of small pairs (often results of interpolation).  
-    Exceptions (even though they may be small) are not filtered.
--   processing of right-to-left pairs (given that kerning groups containing
-    those glyphs are suffixed with `_ARA`, `_HEB`, or `_RTL`)
+-   write a sorted kern.fea file. Pairs are organized in order of specificity:  
+        - glyph-glyph  
+        - glyph-glyph exceptions  
+        - glyph-group exceptions  
+        - group-glyph exceptions  
+        - glyph-group
+        - glyph-group
+        - group-glyph and group-group
+
+-   filter low-value pairs (<3 or custom value), which are often results of interpolation (exceptions are not filtered)
+-   process right-to-left pairs (given that kerning groups containing
+    those glyphs are suffixed with `_ARA`, `_HEB`, or `_RTL`, or RTL glyphs are in a `RTL_KERNING` group)
 
 #### Optional functionality:
 
--   dissolving single-element groups into glyph pairs – this helps with
+-   dissolve single-element groups into glyph pairs – this helps with
     subtable optimization, and can be seen as a means to avoid kerning overflow
 -   subtable measuring and automatic insertion of subtable breaks
--   specifying a maximum subtable size
--   identification of glyph-to-glyph RTL pairs by way of a global `RTL_KERNING`
+-   specify a maximum subtable size
+-   identify of glyph-to-glyph RTL pairs by way of a global `RTL_KERNING`
     reference group
--   specifying a glyph name suffix for glyphs to be ignored when writing the
+-   specify a glyph name suffix for glyphs to be ignored when writing the
     kern feature
 
 #### Usage:
 ```zsh
 
     # write a basic kern feature file
-    python kernFeatureWriter.py font.ufo
+    kernFeatureWriter font.ufo
 
     # write a kern feature file with minimum absolute kerning value of 5
-    python kernFeatureWriter.py -min 5 font.ufo
+    kernFeatureWriter -min 5 font.ufo
 
     # write a kern feature with subtable breaks
-    python kernFeatureWriter.py -s font.ufo
+    kernFeatureWriter -s font.ufo
 
     # further usage information
-    python kernFeatureWriter.py -h
+    kernFeatureWriter -h
 
 ```
 
 ----
 
-## `markFeatureWriter.py`
-This tool interprets glyphs and anchor points within a UFO to write a
-`makeotf`-compatible GPOS mark feature file.
+## `markFeatureWriter`
+The markFeatureWriter interprets glyphs and anchor points within a UFO to write a `makeotf`-compatible GPOS mark feature file.
 
 The input UFO file needs to have base glyphs and zero-width combining
 marks. Base- and mark glyphs attach via anchor pairs (e.g. `above` and
@@ -64,22 +81,22 @@ Combining marks must be members of a `COMBINING_MARKS` reference group.
 
 #### Default functionality:
 
--   writing a `mark.fea` file, which contains mark classes/groups, and
+-   write a `mark.fea` file, which contains mark classes/groups, and
     per-anchor mark-to-base positioning lookups (GPOS lookup type 4)
--   writing mark-to-ligature positioning lookups (GPOS lookup type 5).
+-   write mark-to-ligature positioning lookups (GPOS lookup type 5).  
     This requires anchor names to be suffixed with an ordinal (`1ST`, `2ND`,
     `3RD`, etc). For example – if a mark with an `_above` anchor is to be
     attached to a ligature, the ligature’s anchor names would be `above1ST`,
     `above2ND`, etc – depending on the amount of ligature elements.
 
 #### Optional functionality:
 
--   writing `mkmk.fea`, for mark-to-mark positioning (GPOS lookup type 6)
--   writing `abvm.fea`/`blwm.fea` files, as used in Indic scripts (anchor pairs
+-   write `mkmk.fea`, for mark-to-mark positioning (GPOS lookup type 6)
+-   write `abvm.fea`/`blwm.fea` files, as used in Indic scripts (anchor pairs
     are `abvm`, `_abvm`, and `blwm`, `_blwm`, respectively)
--   writing mark classes into a separate file (in case classes need to be
+-   write mark classes into a separate file (in case classes need to be
     shared across multiple lookup types)
--   trimming casing tags (`UC`, `LC`, or `SC`)
+-   trim casing tags (`UC`, `LC`, or `SC`)
 
     Trimming tags is a somewhat specific feature, but it is quite essential:
     In a UFO, anchors can be used to build composite glyphs – for example
@@ -99,16 +116,16 @@ Combining marks must be members of a `COMBINING_MARKS` reference group.
 ```zsh
 
     # write a basic mark feature
-    python markFeatureWriter.py font.ufo
+    markFeatureWriter font.ufo
 
     # write mark and mkmk feature files
-    python markFeatureWriter.py -m font.ufo
+    markFeatureWriter -m font.ufo
 
     # trim casing tags
-    python markFeatureWriter.py -t font.ufo
+    markFeatureWriter -t font.ufo
 
     # further usage information
-    python markFeatureWriter.py -h
+    markFeatureWriter -h
 
 ```
 
@@ -123,31 +140,31 @@ feature kern{
 } kern;
 ```
 
-The benefit of this is that different feature flags can be used ([example](https://github.com/adobe-fonts/source-serif/blob/main/familyGPOS.fea#L12-L13)), or that mark groups can be shared across `mark`/`mkmk` features. Also, the (sometimes volatile) GPOS feature data can be re-generated periodically without affecting the overall structure of the feature tree.
+The benefit of this approach is that different feature flags can be used ([example](https://github.com/adobe-fonts/source-serif/blob/main/familyGPOS.fea#L12-L13)), or that mark groups can be shared across `mark`/`mkmk` features. Also, the (sometimes volatile) GPOS feature data can be re-generated periodically without affecting the overall structure of the feature tree.
 
 
 ----
 
 ## [utilities (folder `/utilities`)](/utilities)
 
-* `flKernExport.py`  
+* `flKernExport`  
 FLS5 script to export class kerning to UFO. Superseded by [vfb3ufo](https://github.com/LucasFonts/vfbLib).
 
 
 ## [other modules (folder `/vintage`)](/vintage)
 
 Other modules are FontLab scripts which were used in pre-UFO days in a FLS5 environment. Those modules are not in active development.
 
-* `AdobeFontLabUtils.py`  
+* `AdobeFontLabUtils`  
 Support module for FontLab scripts. Defines commonly used functions and globals.
 
-* `BezChar.py`  
+* `BezChar`  
 This module converts between a FontLab glyph and a bez file data string. Used
 by the OutlineCheck and AutoHint scripts, to convert FL glyphs to bez programs 
 as needed by C libraries that do the hard work.
 
-* `WriteFeaturesKernFDK.py`  
+* `WriteFeaturesKernFDK`  
 Former kern feature writer. 
 
-* `WriteFeaturesMarkFDK.py`  
+* `WriteFeaturesMarkFDK`  
 Former mark feature writer.