From ae1fafa2f9a0e4a097434f9634c47b9fc9437d2c Mon Sep 17 00:00:00 2001 From: Werner Lemberg Date: Mon, 10 Sep 2012 13:31:25 +0200 Subject: [PATCH] [doc] Improve hint set documentation. With help from Adam. --- doc/ttfautohint-1.pandoc | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/doc/ttfautohint-1.pandoc b/doc/ttfautohint-1.pandoc index db3070e..f29f805 100644 --- a/doc/ttfautohint-1.pandoc +++ b/doc/ttfautohint-1.pandoc @@ -493,11 +493,16 @@ Hint Sets In ttfautohint terminology, a *hint set* is the *optimal* configuration for a given PPEM (pixel per EM) value. -Internally, ttfautohint creates hint sets for every PPEM value in the range -given by the `--hinting-range-min` and `--hinting-range-max` options (this -is a per-glyph operation). If it differs to the current one, a new set is -emitted. For some glyphs it is possible that one set covers, say, the range -8px-1000px, while other glyphs need 10 or more such sets. +In the range given by the `--hinting-range-min` and `--hinting-range-max` +options, ttfautohint creates hint sets for every PPEM value. For each +glyph, ttfautohint automatically determines if a new set should be emitted +for a PPEM value if it finds that it differs from a previous one. For some +glyphs it is possible that one set covers, say, the range 8px-1000px, while +other glyphs need 10 or more such sets. + +In the PPEM range below `--hinting-range-min`, ttfautohint always uses just +one set, in the PPEM range between `--hinting-range-max` and +`--hinting-limit`, it also uses just one set. One of the hinting configuration parameters is the decision which segments form an edge. For example, let us assume that two segments get aligned on a @@ -534,6 +539,14 @@ more hint sets without any noticeable hinting effects. Similar arguments hold for `--hinting-range-min` except that there is no lower limit at which hinting is switched off. +An example. Let's assume that we have a hinting range 10\ <= ppem <=\ 100, +and the hinting limit is set to 250. For a given glyph, ttfautohint finds +out that four hint sets must be computed to exactly cover thes hinting +range: 10-15, 16-40, 41-80, and 81-100. For ppem values below 10ppem, the +hint set covering 10-15ppem is used, for ppem values larger than 100 the +hint set covering 81-100ppem is used. For ppem values larger than 250, no +hinting gets applied. + The '\.ttfautohint' Glyph ------------------------- -- 2.11.4.GIT