feat: Add overlay animation duration and curve for showcase barrier

CHANGELOG.md

@@ -1,3 +1,7 @@
+## Unreleased
+
+- Feature [#616](https://github.com/SimformSolutionsPvtLtd/showcaseview/issues/616) - Add overlay animation duration and curve for showcase barrier. Fixed by @[vasu-nageshri](https://github.com/vasu-nageshri)
+
 ## 5.1.0
 
 - Fixed [#650](https://github.com/SimformSolutionsPvtLtd/showcaseview/issues/650) - Fix null-check crash in ShowcaseService.getController during didUpdateWidget. Fixed by @[vatsaltanna-simformsolutions](https://github.com/vatsaltanna-simformsolutions)
@@ -6,7 +10,7 @@
 - Fixed [#645](https://github.com/SimformSolutionsPvtLtd/showcaseview/issues/645) -  Prevent re-entrant calls to _onComplete during rapid barrier taps. Fixed by @[apizon](https://github.com/apizon)
 - Fixed [#639](https://github.com/SimformSolutionsPvtLtd/showcaseview/issues/639) - Add null-safety guards for async sequence transitions. Fixed by @[vasu-nageshri](https://github.com/vasu-nageshri)
 - Fixed [#622](https://github.com/SimformSolutionsPvtLtd/showcaseview/issues/622) - Resolve Semantics issue when using `go_router` and `showSemanticsDebugger` flag. Fixed by @[Sahil-Simform](https://github.com/Sahil-Simform)
-- Fix [#620](https://github.com/SimformSolutionsPvtLtd/showcaseview/pull/620)- Set MouseRegion opaque property to false for improved interaction in TargetWidget, TooltipWrapper, and FloatingActionWidget. Fixed by @[RuslanTsitser](https://github.com/RuslanTsitser)
+- Fixed [#620](https://github.com/SimformSolutionsPvtLtd/showcaseview/pull/620)- Set MouseRegion opaque property to false for improved interaction in TargetWidget, TooltipWrapper, and FloatingActionWidget. Fixed by @[RuslanTsitser](https://github.com/RuslanTsitser)
 
 ## [5.0.2]
 

doc/documentation.md

@@ -130,6 +130,10 @@ Reference](https://pub.dev/documentation/showcaseview/latest/showcaseview/).
 ShowcaseView.register(
   autoPlayDelay: const Duration(seconds: 3),
   semanticEnable: true, // Enable accessibility support globally
+  // Overlay barrier fades in when showcase first appears (default 200ms).
+  // Set overlayAnimationDuration to Duration.zero to disable.
+  overlayAnimationDuration: const Duration(milliseconds: 200),
+  overlayAnimationCurve: Curves.easeInOut,
   globalFloatingActionWidget: (showcaseContext) => FloatingActionWidget(
     left: 16,
     bottom: 16,

lib/src/showcase/showcase_view.dart

@@ -79,6 +79,8 @@ class ShowcaseView {
     this.blurValue = 0,
     this.overlayColor,
     this.overlayOpacity,
+    this.overlayAnimationDuration = Constants.defaultOverlayAnimationDuration,
+    this.overlayAnimationCurve = Constants.defaultOverlayAnimationCurve,
     this.globalTooltipActionConfig,
     this.globalTooltipActions,
     this.globalFloatingActionWidget,
@@ -161,6 +163,24 @@ class ShowcaseView {
   /// Opacity apply on [overlayColor] (which ranges from 0.0 to 1.0)
   final double? overlayOpacity;
 
+  /// Duration of the fade-in animation applied to the overlay barrier
+  /// (background color, opacity and blur) when the showcase first appears.
+  ///
+  /// This animates only the initial appearance of the barrier and not the
+  /// transition between individual showcase steps.
+  ///
+  /// Defaults to 200 milliseconds. Set to [Duration.zero] to show the barrier
+  /// instantly.
+  final Duration overlayAnimationDuration;
+
+  /// Curve used for the overlay barrier fade-in animation.
+  ///
+  /// Only applies when [overlayAnimationDuration] is greater than
+  /// [Duration.zero].
+  ///
+  /// Defaults to [Curves.easeInOut].
+  final Curve overlayAnimationCurve;
+
   /// Whether to enable semantic properties for accessibility.
   ///
   /// When set to true, semantic widgets will be added to improve

lib/src/utils/constants.dart

@@ -66,4 +66,12 @@ class Constants {
 
   static const Duration defaultAutoPlayDelay = Duration(milliseconds: 2000);
   static const Duration defaultScrollDuration = Duration(milliseconds: 300);
+
+  /// Default duration for the overlay barrier fade-in animation.
+  /// Set to [Duration.zero] to make the barrier appear instantly.
+  static const Duration defaultOverlayAnimationDuration =
+      Duration(milliseconds: 200);
+
+  /// Default curve for the overlay barrier fade-in animation.
+  static const Curve defaultOverlayAnimationCurve = Curves.easeInOut;
 }

lib/src/utils/overlay_manager.dart

@@ -29,6 +29,7 @@ import '../showcase/showcase.dart';
 import '../showcase/showcase_controller.dart';
 import '../showcase/showcase_service.dart';
 import '../showcase/showcase_view.dart';
+import '../widget/animated_overlay_barrier.dart';
 import 'extensions.dart';
 import 'shape_clipper.dart';
 
@@ -181,30 +182,57 @@ class OverlayManager {
       child: const Align(),
     );
 
+    Widget barrier = GestureDetector(
+      onTap: firstController.handleBarrierTap,
+      child: ClipPath(
+        clipper: ShapeClipper(
+          linkedObjectData: _getLinkedShowcasesData(controllers),
+        ),
+        child: firstController.blur <= 0.2
+            ? backgroundContainer
+            : BackdropFilter(
+                filter: ImageFilter.blur(
+                  sigmaX: firstController.blur,
+                  sigmaY: firstController.blur,
+                ),
+                child: backgroundContainer,
+              ),
+      ),
+    );
+
+    final overlayAnimationDuration =
+        firstController.showcaseView.overlayAnimationDuration;
+    if (overlayAnimationDuration > Duration.zero) {
+      // The barrier is kept outside the per-step keyed stack and given a stable
+      // key so its fade-in animation runs only once when the showcase first
+      // appears, instead of restarting (and flickering) on every step.
+      barrier = AnimatedOverlayBarrier(
+        key: const ValueKey('showcase_overlay_barrier'),
+        duration: overlayAnimationDuration,
+        curve: firstController.showcaseView.overlayAnimationCurve,
+        child: barrier,
+      );
+    }
+
     final overlayChild = Stack(
-      // This key is used to force rebuild the overlay when needed.
-      // this key enables `_overlayEntry?.markNeedsBuild();` to detect that
-      // output of the builder has changed.
-      key: ValueKey(firstController.id),
       children: [
-        GestureDetector(
-          onTap: firstController.handleBarrierTap,
-          child: ClipPath(
-            clipper: ShapeClipper(
-              linkedObjectData: _getLinkedShowcasesData(controllers),
-            ),
-            child: firstController.blur <= 0.2
-                ? backgroundContainer
-                : BackdropFilter(
-                    filter: ImageFilter.blur(
-                      sigmaX: firstController.blur,
-                      sigmaY: firstController.blur,
-                    ),
-                    child: backgroundContainer,
-                  ),
+        barrier,
+        // Tooltips are kept in their own stack so the barrier (and its
+        // optional fade-in) lives outside this keyed subtree. `Positioned.fill`
+        // is required because the inner stack has only `Positioned` children
+        // and would otherwise collapse, clipping the tooltips.
+        Positioned.fill(
+          child: Stack(
+            // This key forces the tooltips to rebuild when needed. It enables
+            // `_overlayEntry?.markNeedsBuild();` to detect that the output of
+            // the builder has changed and restarts the per-step tooltip
+            // animations between showcase steps.
+            key: ValueKey(firstController.id),
+            children: [
+              ...controllers.expand((object) => object.tooltipWidgets),
+            ],
           ),
         ),
-        ...controllers.expand((object) => object.tooltipWidgets),
       ],
     );
 

lib/src/widget/animated_overlay_barrier.dart

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2021 Simform Solutions
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+import 'package:flutter/material.dart';
+
+/// Fades the showcase overlay barrier (background color, opacity and blur) in
+/// when the showcase first appears.
+///
+/// The fade only runs once for the lifetime of this widget's [State]. The
+/// overlay rebuilds on every showcase step to reposition the highlight cut-out,
+/// so this widget is kept outside the per-step keyed subtree in
+/// `OverlayManager` to preserve its animation state across steps and avoid the
+/// barrier flickering between showcases.
+class AnimatedOverlayBarrier extends StatefulWidget {
+  const AnimatedOverlayBarrier({
+    required this.duration,
+    required this.curve,
+    required this.child,
+    super.key,
+  });
+
+  /// Duration of the fade-in animation.
+  final Duration duration;
+
+  /// Curve of the fade-in animation.
+  final Curve curve;
+
+  /// The barrier widget (background color/blur) to fade in.
+  final Widget child;
+
+  @override
+  State<AnimatedOverlayBarrier> createState() => _AnimatedOverlayBarrierState();
+}
+
+class _AnimatedOverlayBarrierState extends State<AnimatedOverlayBarrier>
+    with SingleTickerProviderStateMixin {
+  late final AnimationController _controller = AnimationController(
+    vsync: this,
+    duration: widget.duration,
+  );
+
+  late final Animation<double> _opacity = CurvedAnimation(
+    parent: _controller,
+    curve: widget.curve,
+  );
+
+  @override
+  void initState() {
+    super.initState();
+    _controller.forward();
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return FadeTransition(
+      opacity: _opacity,
+      child: widget.child,
+    );
+  }
+}

lib/src/widget/floating_action_widget.dart

@@ -172,9 +172,10 @@ class FloatingActionWidget extends StatelessWidget {
       width: width,
       height: height,
       child: Material(
-          type: MaterialType.transparency,
-          color: Colors.transparent,
-          child: child),
+        type: MaterialType.transparency,
+        color: Colors.transparent,
+        child: child,
+      ),
     );
   }
 }