Add reverseCurve parameter

README.md

@@ -64,10 +64,10 @@ Text("Hello World!").animate().fade().scale()
 > **NOTE:** The shortform style is used in this README, but all functionality is
 > available in either format.
 
-Delay, duration, curve
+Delay, duration, curve, reverseCurve
 ----------------------------------------
 
-Effects have optional `delay`, `duration`, and `curve` parameters. Effects run
+Effects have optional `delay`, `duration`, `curve`, and `reverseCurve` parameters. Effects run
 in parallel, but you can use a `delay` to run them sequentially:
 
 ``` dart

lib/src/animate.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/widgets.dart';
 import 'package:flutter_animate/src/warn.dart';
+
 import '../flutter_animate.dart';
 
 /// The Flutter Animate library makes adding beautiful animated effects to your widgets
@@ -250,6 +251,7 @@ class Animate extends StatefulWidget with AnimateManager<Animate> {
       delay: delay,
       duration: effect.duration ?? prior?.duration ?? Animate.defaultDuration,
       curve: effect.curve ?? prior?.curve ?? Animate.defaultCurve,
+      reverseCurve: effect.reverseCurve ?? prior?.reverseCurve,
       owner: this,
     );
 

lib/src/effects/blur_effect.dart

@@ -1,4 +1,5 @@
 import 'dart:ui';
+
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 
@@ -20,12 +21,14 @@ class BlurEffect extends Effect<Offset> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     Offset? begin,
     Offset? end,
   }) : super(
           delay: delay,
           duration: duration,
           curve: curve,
+          reverseCurve: reverseCurve,
           begin: begin ?? neutralValue,
           end: end ?? (begin == null ? defaultValue : neutralValue),
         );
@@ -87,6 +90,7 @@ extension BlurEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
     double? end,
   }) {
@@ -96,6 +100,7 @@ extension BlurEffectExtensions<T> on AnimateManager<T> {
       delay: delay,
       duration: duration,
       curve: curve,
+      reverseCurve: reverseCurve,
       begin: BlurEffect.neutralValue.copyWith(dx: begin),
       end: BlurEffect.neutralValue.copyWith(dx: end),
     ));
@@ -107,6 +112,7 @@ extension BlurEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
     double? end,
   }) {
@@ -116,6 +122,7 @@ extension BlurEffectExtensions<T> on AnimateManager<T> {
       delay: delay,
       duration: duration,
       curve: curve,
+      reverseCurve: reverseCurve,
       begin: BlurEffect.neutralValue.copyWith(dy: begin),
       end: BlurEffect.neutralValue.copyWith(dy: end),
     ));
@@ -127,6 +134,7 @@ extension BlurEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
     double? end,
   }) {
@@ -136,6 +144,7 @@ extension BlurEffectExtensions<T> on AnimateManager<T> {
       delay: delay,
       duration: duration,
       curve: curve,
+      reverseCurve: reverseCurve,
       begin: Offset(begin, begin),
       end: Offset(end, end),
     ));

lib/src/effects/box_shadow_effect.dart

@@ -21,13 +21,15 @@ class BoxShadowEffect extends Effect<BoxShadow> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     BoxShadow? begin,
     BoxShadow? end,
     this.borderRadius,
   }) : super(
           delay: delay,
           duration: duration,
           curve: curve,
+          reverseCurve: reverseCurve,
           begin: begin ?? neutralValue,
           end: end ?? (begin == null ? defaultValue : neutralValue),
         );
@@ -61,6 +63,7 @@ extension BoxShadowEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     BoxShadow? begin,
     BoxShadow? end,
     BorderRadius? borderRadius,
@@ -69,6 +72,7 @@ extension BoxShadowEffectExtensions<T> on AnimateManager<T> {
         delay: delay,
         duration: duration,
         curve: curve,
+        reverseCurve: reverseCurve,
         begin: begin,
         end: end,
         borderRadius: borderRadius,

lib/src/effects/color_effect.dart

@@ -31,13 +31,15 @@ class ColorEffect extends Effect<Color?> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     Color? begin,
     Color? end,
     this.blendMode,
   }) : super(
           delay: delay,
           duration: duration,
           curve: curve,
+          reverseCurve: reverseCurve,
           begin: begin ?? neutralValue,
           end: end ?? (begin == null ? defaultValue : neutralValue),
         );
@@ -72,6 +74,7 @@ extension ColorEffectExtension<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     Color? begin,
     Color? end,
     BlendMode? blendMode,
@@ -80,6 +83,7 @@ extension ColorEffectExtension<T> on AnimateManager<T> {
         delay: delay,
         duration: duration,
         curve: curve,
+        reverseCurve: reverseCurve,
         begin: begin,
         end: end,
         blendMode: blendMode,

lib/src/effects/crossfade_effect.dart

@@ -17,12 +17,14 @@ class CrossfadeEffect extends Effect<double> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     required this.builder,
     this.alignment,
   }) : super(
           delay: delay,
           duration: duration,
           curve: curve,
+          reverseCurve: reverseCurve,
           begin: 0,
           end: 1,
         );
@@ -54,13 +56,15 @@ extension CrossfadeEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     required WidgetBuilder builder,
     Alignment? alignment,
   }) =>
       addEffect(CrossfadeEffect(
         delay: delay,
         duration: duration,
         curve: curve,
+        reverseCurve: reverseCurve,
         builder: builder,
         alignment: alignment,
       ));

lib/src/effects/custom_effect.dart

@@ -27,13 +27,16 @@ class CustomEffect extends Effect<double> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
     double? end,
   }) : super(
           delay: delay,
           duration: duration,
           curve: curve,
-          begin: begin ?? 0.0, // Should this use "smart" defaults?
+          reverseCurve: reverseCurve,
+          begin: begin ?? 0.0,
+          // Should this use "smart" defaults?
           end: end ?? 1.0,
         );
 
@@ -61,6 +64,7 @@ extension CustomEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
     double? end,
   }) =>
@@ -69,6 +73,7 @@ extension CustomEffectExtensions<T> on AnimateManager<T> {
         delay: delay,
         duration: duration,
         curve: curve,
+        reverseCurve: reverseCurve,
         begin: begin,
         end: end,
       ));

lib/src/effects/effect.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
+
 import '../../flutter_animate.dart';
 
 /// An empty effect that all other effects extend.
@@ -23,6 +24,10 @@ class Effect<T> {
   /// previous effect, or use [Animate.defaultCurve] if this is the first effect.
   final Curve? curve;
 
+  /// The specified easing curve for the effect. If null, will inherit the curve from the
+  /// previous effect, or use [Animate.defaultCurve] if this is the first effect.
+  final Curve? reverseCurve;
+
   /// The begin value for the effect. If null, effects should use a reasonable
   /// default value when appropriate.
   final T? begin;
@@ -31,7 +36,14 @@ class Effect<T> {
   /// default value when appropriate.
   final T? end;
 
-  const Effect({this.delay, this.duration, this.curve, this.begin, this.end});
+  const Effect({
+    this.delay,
+    this.duration,
+    this.curve,
+    this.reverseCurve,
+    this.begin,
+    this.end,
+  });
 
   /// Builds the widgets that implement the effect on the target [child],
   /// based on the provided [AnimationController] and [EffectEntry].

lib/src/effects/elevation_effect.dart

@@ -18,6 +18,7 @@ class ElevationEffect extends Effect<double> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
     double? end,
     Color? color,
@@ -27,6 +28,7 @@ class ElevationEffect extends Effect<double> {
           delay: delay,
           duration: duration,
           curve: curve,
+          reverseCurve: reverseCurve,
           begin: begin ?? neutralValue,
           end: end ?? (begin == null ? defaultValue : neutralValue),
         );
@@ -61,6 +63,7 @@ extension ElevationEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
     double? end,
     Color? color,
@@ -70,6 +73,7 @@ extension ElevationEffectExtensions<T> on AnimateManager<T> {
         delay: delay,
         duration: duration,
         curve: curve,
+        reverseCurve: reverseCurve,
         begin: begin,
         end: end,
         color: color,

lib/src/effects/fade_effect.dart

@@ -14,12 +14,14 @@ class FadeEffect extends Effect<double> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
     double? end,
   }) : super(
           delay: delay,
           duration: duration,
           curve: curve,
+          reverseCurve: reverseCurve,
           begin: begin ?? (end == null ? defaultValue : neutralValue),
           end: end ?? neutralValue,
         );
@@ -44,13 +46,15 @@ extension FadeEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
     double? end,
   }) =>
       addEffect(FadeEffect(
         delay: delay,
         duration: duration,
         curve: curve,
+        reverseCurve: reverseCurve,
         begin: begin,
         end: end,
       ));
@@ -61,12 +65,14 @@ extension FadeEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
   }) =>
       addEffect(FadeEffect(
         delay: delay,
         duration: duration,
         curve: curve,
+        reverseCurve: reverseCurve,
         begin: begin ?? FadeEffect.defaultValue,
         end: 1.0,
       ));
@@ -77,12 +83,14 @@ extension FadeEffectExtensions<T> on AnimateManager<T> {
     Duration? delay,
     Duration? duration,
     Curve? curve,
+    Curve? reverseCurve,
     double? begin,
   }) =>
       addEffect(FadeEffect(
         delay: delay,
         duration: duration,
         curve: curve,
+        reverseCurve: reverseCurve,
         begin: begin ?? FadeEffect.neutralValue,
         end: 0.0,
       ));