Feat: Add withOpacity to gradient (flutter#150670)

Feat: Add withOpacity to gradient because sometimes it's required to call withOpacity directly on gradient Resolves flutter#150501 This adds a `withOpacity` feature to a gradient, given user has given colors this will override opacity to given opacity for them.
engine-flutter-autoroll · Jul 3, 2024 · fbd6890 · fbd6890
1 parent 56835d6
commit fbd6890
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diff --git a/packages/flutter/lib/src/painting/gradient.dart b/packages/flutter/lib/src/painting/gradient.dart
@@ -240,6 +240,9 @@ abstract class Gradient {
   /// Typically this is the same as interpolating from null (with [lerp]).
   Gradient scale(double factor);
 
+  /// Returns a new [Gradient] with each color set to the given opacity.
+  Gradient withOpacity(double opacity);
+
   /// Linearly interpolates from another [Gradient] to `this`.
   ///
   /// When implementing this method in subclasses, return null if this class
@@ -556,6 +559,19 @@ class LinearGradient extends Gradient {
 
     return '${objectRuntimeType(this, 'LinearGradient')}(${description.join(', ')})';
   }
+
+  @override
+  LinearGradient withOpacity(double opacity) {
+    return LinearGradient(
+      begin: begin,
+      end: end,
+      colors: <Color>[
+        for (final Color color in colors) color.withOpacity(opacity)
+      ],
+      stops: stops,
+      tileMode: tileMode,
+    );
+  }
 }
 
 /// A 2D radial gradient.
@@ -843,6 +859,21 @@ class RadialGradient extends Gradient {
 
     return '${objectRuntimeType(this, 'RadialGradient')}(${description.join(', ')})';
   }
+
+  @override
+  RadialGradient withOpacity(double opacity) {
+    return RadialGradient(
+      center: center,
+      radius: radius,
+      colors: <Color>[
+        for (final Color color in colors) color.withOpacity(opacity)
+      ],
+      stops: stops,
+      tileMode: tileMode,
+      focal: focal,
+      focalRadius: focalRadius,
+    );
+  }
 }
 
 /// A 2D sweep gradient.
@@ -1106,4 +1137,18 @@ class SweepGradient extends Gradient {
 
     return '${objectRuntimeType(this, 'SweepGradient')}(${description.join(', ')})';
   }
+
+  @override
+  SweepGradient withOpacity(double opacity) {
+    return SweepGradient(
+      center: center,
+      startAngle: startAngle,
+      endAngle: endAngle,
+      colors: <Color>[
+        for (final Color color in colors) color.withOpacity(opacity)
+      ],
+      stops: stops,
+      tileMode: tileMode,
+    );
+  }
 }
diff --git a/packages/flutter/test/painting/gradient_test.dart b/packages/flutter/test/painting/gradient_test.dart
@@ -306,6 +306,29 @@ void main() {
     );
   });
 
+  test('LinearGradient withOpacity test', () {
+    const LinearGradient testGradient = LinearGradient(
+      begin: Alignment.bottomRight,
+      end: Alignment.topCenter,
+      colors: <Color>[
+        Color(0xFFFFFFFF),
+        Color(0xAF777777),
+        Color(0x44444444),
+      ],
+    );
+    final LinearGradient actual = testGradient.withOpacity(0.5);
+
+    expect(actual, const LinearGradient(
+       begin: Alignment.bottomRight,
+      end: Alignment.topCenter,
+      colors: <Color>[
+        Color(0x80FFFFFF),
+        Color(0x80777777),
+        Color(0x80444444),
+      ],
+    ),);
+  });
+
   test('RadialGradient with AlignmentDirectional', () {
     expect(
       () {
@@ -596,6 +619,33 @@ void main() {
     ));
   });
 
+
+  test('RadialGradient withOpacity test', () {
+    const RadialGradient testGradient = RadialGradient(
+      center: Alignment.topLeft,
+      focal: Alignment.centerLeft,
+      radius: 20.0,
+      focalRadius: 10.0,
+      colors: <Color>[
+        Color(0xFFFFFFFF),
+        Color(0xAF777777),
+        Color(0x44444444),
+      ],
+    );
+    final RadialGradient actual = testGradient.withOpacity(0.5);
+
+    expect(actual, const RadialGradient(
+      center: Alignment.topLeft,
+      focal: Alignment.centerLeft,
+      radius: 20.0,
+      focalRadius: 10.0,
+      colors: <Color>[
+        Color(0x80FFFFFF),
+        Color(0x80777777),
+        Color(0x80444444),
+      ],
+    ));
+  });
   test('SweepGradient lerp test', () {
     const SweepGradient testGradient1 = SweepGradient(
       center: Alignment.topLeft,
@@ -806,6 +856,28 @@ void main() {
     ));
   });
 
+  test('SweepGradient withOpacity test', () {
+    const SweepGradient testGradient = SweepGradient(
+      center: Alignment.topLeft,
+      endAngle: math.pi / 2,
+      colors: <Color>[
+        Color(0xFFFFFFFF),
+        Color(0xAF777777),
+        Color(0x44444444),
+      ],
+    );
+    final SweepGradient actual = testGradient.withOpacity(0.5);
+
+    expect(actual, const SweepGradient(
+      center: Alignment.topLeft,
+      endAngle: math.pi / 2,
+      colors: <Color>[
+        Color(0x80FFFFFF),
+        Color(0x80777777),
+        Color(0x80444444),
+      ],
+    ));
+  });
   test('Gradient lerp test (with RadialGradient)', () {
     const RadialGradient testGradient1 = RadialGradient(
       center: Alignment.topLeft,