From f37875c6c4e42055735f1cda9fdbcb7ab11b80bc Mon Sep 17 00:00:00 2001
From: Sam Atman
Date: Fri, 13 Dec 2024 15:14:15 -0500
Subject: Add c0 and c1 control width options

This allows a build of DisplayWidth to give characters in those classes
a width, for cases where they'll be printed with a substitute in the
final display.  It also raises the size of possible characters from an
i3 to an i4, to accommodate printing C1s as e.g. <80> or \u{80}.
---
 README.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'README.md')

diff --git a/README.md b/README.md
index bad64fc..c4227a2 100644
--- a/README.md
+++ b/README.md
@@ -441,7 +441,7 @@ test "Display width" {
 }
 ```
 
-This has a build option, `"cjk"`, which will consider [ambiguous characters](https://www.unicode.org/reports/tr11/tr11-6.html) as double-width.
+This module has build options.  The first is `cjk`, which will consider [ambiguous characters](https://www.unicode.org/reports/tr11/tr11-6.html) as double-width.
 
 To choose this option, add it to the dependency like so:
 
@@ -451,6 +451,8 @@ const zg = b.dependency("zg", .{
 });
 ```
 
+The other options are `c0_width` and `c1_width`.  The standard behavior is to treat C0 and C1 control codes as zero-width, except for delete and backspace, which are -1 (the logic ensures that a `strWidth` is always at least 0).  If printing control codes with replacement characters, it's necessary to assign these a width, hence the options.  When provided these values must fit in an `i4`, this allows for C1s to be printed as `\u{80}` if desired.
+
 ## Scripts
 
 Unicode categorizes code points by the Script in which they belong. A Script
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