Add support for html named colors

Quill deltas often contain named colors from the standard HTML color palette. This is especially true if the delta was created using Quill on web.

These named colors could not be handled by flutter_quill, and so an exception was thrown.

This change adds dart contants for the 140 named html colors. It modifies `stringToColor` to check if the input is one of the named colors, and returns the value if found. Web colors are case insensitive.

Author: MichaelMarner

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fixed `View.of(context)` calls throwing when used with the `screenshot` package [#2662](https://github.com/singerdmx/flutter-quill/pull/2662).
+- Fixed support for html named colors [#2675](https://github.com/singerdmx/flutter-quill/pull/2675)
 
 ### Added
 

lib/src/common/utils/color.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'web_colors.dart';
 
 import '../../editor/widgets/default_styles.dart';
 
@@ -115,7 +116,12 @@ Color stringToColor(String? s,
       return Colors.brown;
   }
 
-  if (s!.startsWith('rgba')) {
+  // is it an html named color?
+  if (WebColors.namedColors.containsKey(s!.toLowerCase())) {
+    return WebColors.namedColors[s.toLowerCase()]!;
+  }
+
+  if (s.startsWith('rgba')) {
     s = s.substring(5); // trim left 'rgba('
     s = s.substring(0, s.length - 1); // trim right ')'
     final arr = s.split(',').map((e) => e.trim()).toList();
@@ -129,7 +135,7 @@ Color stringToColor(String? s,
   }
 
   if (!s.startsWith('#')) {
-    throw UnsupportedError('Color code not supported');
+    throw UnsupportedError('Color code not supported: $s');
   }
 
   var hex = s.replaceFirst('#', '');