Support alpha modifier on color

mark-nicepants · May 5, 2024 · d5c4092 · d5c4092
1 parent cee9aeb
commit d5c4092
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Showing 3 changed files with 53 additions and 0 deletions.
diff --git a/lib/models/color_value.dart b/lib/models/color_value.dart
@@ -36,6 +36,14 @@ class ColorValue {
     return ColorValue._(rgb[0], rgb[1], rgb[2], a);
   }
 
+  /// cascades this amount alpha on the existing alpha
+  /// ignores any space info
+  /// Should throw Exception for any value (1.0 < amount) or (amount < 0.0)
+  ColorValue alphainate(double amount) {
+    final newA = ((a / 255) * (amount * 255)).round();
+    return ColorValue._(r, g, b, newA);
+  }
+
   ColorValue mix(String value, double amount) {
     final other = maybeParse(value)!;
 

diff --git a/lib/transformers/color_transformer.dart b/lib/transformers/color_transformer.dart
@@ -51,6 +51,8 @@ class ColorTransformer extends SingleTokenTransformer {
             colorValue = colorValue.lighten(value / 2);
           } else if (type == 'darken') {
             colorValue = colorValue.darken(value / 2);
+          } else if (type == 'alpha') {
+            colorValue = colorValue.alphainate(value);
           } else if (color != null && type == 'mix' && color.startsWith('#')) {
             colorValue = colorValue.mix(color, value);
           }

diff --git a/test/transformers/color_transformer_test.dart b/test/transformers/color_transformer_test.dart
@@ -79,6 +79,33 @@ final colorModifiers = '''
         }
       }
     }
+  },
+
+  "srgb-1-0-test": {
+    "value": "{purple}",
+    "type": "color",
+    "\$extensions": {
+      "studio.tokens": {
+        "modify": {
+          "type": "alpha",
+          "value": "1.0",
+          "space": "srgb"
+        }
+      }
+    }
+  },
+  "srgb-0-5-test": {
+    "value": "{purple}",
+    "type": "color",
+    "\$extensions": {
+      "studio.tokens": {
+        "modify": {
+          "type": "alpha",
+          "value": "0.5",
+          "space": "srgb"
+        }
+      }
+    }
   }
 }
 ''';
@@ -173,4 +200,20 @@ void main() {
       equals('const Color(0xFFB200E3)'),
     );
   });
+
+  test('Color modifiers alpha', () {
+    final parsed = json.decode(colorModifiers) as Map<String, dynamic>;
+    final parser = TokenParser()..parse(parsed);
+
+    final transformer = ColorTransformer();
+
+    expect(
+      transformer.transform(parser.resolve('srgb-1-0-test')!),
+      equals('const Color(0xFF6400FF)'),
+    );
+    expect(
+      transformer.transform(parser.resolve('srgb-0-5-test')!),
+      equals('const Color(0x806400FF)'),
+    );
+  });
 }