Add Size Effect

example/lib/examples/everything_view.dart

@@ -4,6 +4,7 @@
 import 'dart:math';
 import 'dart:ui' as ui;
 
+import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_animate/flutter_animate.dart';
 
@@ -20,8 +21,8 @@ class EverythingView extends StatelessWidget {
         childAspectRatio: 0.85,
         children: [
           /***
-          A few fun / interesting examples
-          ***/
+                  A few fun / interesting examples
+               ***/
           tile(
             'fade+tint+blur+scale',
             a
@@ -103,9 +104,9 @@ class EverythingView extends StatelessWidget {
           ),
 
           /***
-          Catalog of minimal examples for all visual effects.
-          In alphabetic order of the effect's class name.
-          ***/
+                  Catalog of minimal examples for all visual effects.
+                  In alphabetic order of the effect's class name.
+               ***/
 
           tile('align', a.align()),
 
@@ -175,6 +176,10 @@ class EverythingView extends StatelessWidget {
           tile('scaleY', a.scaleY()),
           tile('scaleXY', a.scaleXY()),
 
+          tile('sizeX', a.sizeX()),
+          tile('sizeY', a.sizeY()),
+          tile('sizeXY', a.size()),
+
           tile('shake', a.shake()),
           tile('shakeX', a.shakeX()),
           tile('shakeY', a.shakeY()),

lib/src/effects/effects.dart

@@ -26,3 +26,4 @@ export 'then_effect.dart';
 export 'tint_effect.dart';
 export 'toggle_effect.dart';
 export 'visibility_effect.dart';
+export 'size_effect.dart';

lib/src/effects/size_effect.dart

@@ -0,0 +1,130 @@
+import 'dart:math' as math;
+import 'package:flutter/widgets.dart';
+import 'package:flutter_animate/flutter_animate.dart';
+
+/// An effect that adjust the size of target between the specified [begin] and [end]
+/// offset values. unlike [ScaleEffect], this effect does affect the real size
+/// of the widget.
+/// Defaults to `begin=0.0, end=1.0`.
+@immutable
+class SizeEffect extends Effect<double> {
+  static const double neutralValue = 1.0;
+  static const double defaultValue = 0.0;
+  static const double defaultAxisAlignment = 0.0;
+
+  const SizeEffect({
+    super.delay,
+    super.duration,
+    super.curve,
+    double? begin,
+    double? end,
+    this.fixedWidthFactor,
+    this.fixedHeightFactor,
+    this.alignment,
+  }) : super(
+          begin: begin ?? (end == null ? defaultValue : neutralValue),
+          end: end ?? neutralValue,
+        );
+
+  final AlignmentGeometry? alignment;
+  final double? fixedWidthFactor;
+  final double? fixedHeightFactor;
+
+  @override
+  Widget build(
+    BuildContext context,
+    Widget child,
+    AnimationController controller,
+    EffectEntry entry,
+  ) {
+    final animation = buildAnimation(controller, entry);
+    return getOptimizedBuilder<double>(
+      animation: animation,
+      builder: (_, __) {
+        return ClipRect(
+          child: Align(
+            alignment: alignment ?? Alignment.center,
+            widthFactor: fixedWidthFactor ?? math.max(animation.value, 0.0),
+            heightFactor: fixedHeightFactor ?? math.max(animation.value, 0.0),
+            child: child,
+          ),
+        );
+      },
+    );
+  }
+}
+
+/// Adds [SizeEffect] related extensions to [AnimateManager].
+extension SizeEffectExtensions<T extends AnimateManager<T>> on T {
+  /// Adds a [SizeEffect] that adjust the size of target between
+  /// the specified [begin] and [end] offset values.
+  ///
+  T size({
+    Duration? delay,
+    Duration? duration,
+    Curve? curve,
+    double? begin,
+    double? end,
+    double? fixedWidthFactor,
+    double? fixedHeightFactor,
+    AlignmentGeometry? alignment,
+  }) =>
+      addEffect(SizeEffect(
+        delay: delay,
+        duration: duration,
+        curve: curve,
+        begin: begin,
+        end: end,
+        alignment: alignment,
+        fixedWidthFactor: fixedWidthFactor,
+        fixedHeightFactor: fixedHeightFactor,
+      ));
+
+  /// Adds a [SizeEffect] that adjust the size of target horizontally between
+  /// the specified [begin] and [end] values.
+  ///
+  /// [axisAlignment] describes how to align the child along the horizontal axis
+  /// that [sizeFactor] is modifying.
+  T sizeX({
+    Duration? delay,
+    Duration? duration,
+    Curve? curve,
+    double? begin,
+    double? end,
+    double? axisAlignment,
+  }) =>
+      addEffect(SizeEffect(
+          delay: delay,
+          duration: duration,
+          curve: curve,
+          begin: begin,
+          end: end,
+          fixedHeightFactor: 1.0,
+          alignment: AlignmentDirectional(
+              axisAlignment ?? SizeEffect.defaultAxisAlignment, -1.0)));
+
+  /// Adds a [SizeEffect] that adjust the size of target vertically between
+  /// the specified [begin] and [end] values.
+  ///
+  /// [axisAlignment] describes how to align the child along the vertical axis
+  /// that [sizeFactor] is modifying.
+  T sizeY({
+    Duration? delay,
+    Duration? duration,
+    Curve? curve,
+    double? begin,
+    double? end,
+    double? axisAlignment,
+  }) =>
+      addEffect(SizeEffect(
+          delay: delay,
+          duration: duration,
+          curve: curve,
+          begin: begin,
+          end: end,
+          fixedWidthFactor: 1.0,
+          alignment: AlignmentDirectional(
+            -1.0,
+            axisAlignment ?? SizeEffect.defaultAxisAlignment,
+          )));
+}

test/effects/size_test.dart

@@ -0,0 +1,61 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter_animate/flutter_animate.dart';
+
+import '../tester_extensions.dart';
+
+void main() {
+  testWidgets('SizeEffect: size', (tester) async {
+    final animation = const FlutterLogo().animate().size(
+          duration: 1000.ms,
+          begin: 1.0,
+          end: 0.0,
+        );
+
+    await tester.pumpAnimation(MaterialApp(home: animation),
+        initialDelay: 500.ms);
+    _verifySize(tester, 0.5, 0.5);
+  });
+
+  testWidgets('SizeEffect: size', (tester) async {
+    final animation =
+        const FlutterLogo().animate().size(duration: 1000.ms, end: 2);
+
+    // Check halfway,
+    await tester.pumpAnimation(MaterialApp(home: animation),
+        initialDelay: 500.ms);
+    _verifySize(tester, 1.5, 1.5);
+  });
+
+  testWidgets('SizeEffect: sizeX', (tester) async {
+    final animation =
+        const FlutterLogo().animate().sizeX(duration: 1000.ms, end: 2);
+
+    // Check halfway,
+    await tester.pumpAnimation(MaterialApp(home: animation),
+        initialDelay: 500.ms);
+    _verifySize(tester, 1.5, 1);
+  });
+
+  testWidgets('SizeEffect: sizeY', (tester) async {
+    final animation =
+        const FlutterLogo().animate().sizeY(duration: 1000.ms, end: 2);
+
+    // Check halfway,
+    await tester.pumpAnimation(MaterialApp(home: animation),
+        initialDelay: 500.ms);
+    _verifySize(tester, 1, 1.5);
+  });
+}
+
+_verifySize(
+    WidgetTester tester, double widthFactor, double heightFactor) async {
+  tester.widget(find.byType(Align));
+  expect(
+      tester.widget(find.byType(Align)),
+      isA<Align>()
+          .having(
+              (Align align) => align.widthFactor, 'widthFactor', widthFactor)
+          .having((Align align) => align.heightFactor, 'heightFactor',
+              heightFactor));
+}