Handle color black

app/assets/sample_data.json

@@ -74,7 +74,8 @@
    },
    {
       "attributes":{
-         "strike":true
+         "strike":true,
+         "color":"black"
       },
       "insert":"web"
    },

lib/widgets/text_line.dart

@@ -108,6 +108,13 @@ class TextLine extends StatelessWidget {
   }
 
   Color _hexStringToColor(String s) {
+    switch (s.toLowerCase()) {
+      case 'transparent':
+        return Colors.transparent;
+      case 'black':
+        return Colors.black;
+    }
+
     if (s.startsWith('rgba')) {
       s = s.substring(5); // trim left 'rgba('
       s = s.substring(0, s.length - 1); // trim right ')'
@@ -115,9 +122,7 @@ class TextLine extends StatelessWidget {
       return Color.fromRGBO(int.parse(arr[0]), int.parse(arr[1]),
           int.parse(arr[2]), double.parse(arr[3]));
     }
-    if (s == 'transparent') {
-      return Colors.transparent;
-    }
+
     String hex = s.replaceFirst('#', '');
     hex = hex.length == 6 ? 'ff' + hex : hex;
     int val = int.parse(hex, radix: 16);