Added onStart and onShowStep callbacks

lib/src/onboarding_widget.dart

@@ -16,6 +16,7 @@ class Onboarding extends StatefulWidget {
     this.initialIndex = 0,
     this.onChanged,
     this.onEnd,
+    this.onStart,
     this.autoSizeTexts = false,
     required this.steps,
     required this.child,
@@ -35,6 +36,8 @@ class Onboarding extends StatefulWidget {
   /// A callback that signal when the `Onboarding` is finished or stopped
   final ValueChanged<int>? onEnd;
 
+  final VoidCallback? onStart;
+
   /// By default, the value used is false
   /// Sometimes the `titleText` and the `bodyText` might not fit well in the constrained label box,
   /// because of the long texts, longer translations or smaller screens.
@@ -178,6 +181,7 @@ class OnboardingState extends State<Onboarding> {
             debugBoundaries: widget.debugBoundaries,
             scaleWidth: widget.scaleWidth,
             scaleHeight: widget.scaleHeight,
+            onStart: widget.onStart,
             onChanged: (int index) {
               controller.setCurrentIndex(index);
               widget.onChanged?.call(index);

lib/src/step.dart

@@ -96,6 +96,7 @@ class OnboardingStep {
     this.showPulseAnimation = false,
     this.pulseInnerColor = defaultInnerPulseColor,
     this.pulseOuterColor = defaultOuterPulseColor,
+    this.onShowStep,
     this.onTapCallback,
   })  : assert(() {
           if (titleTextColor == null && titleTextStyle == null) {
@@ -135,6 +136,8 @@ class OnboardingStep {
   /// is required
   final FocusNode focusNode;
 
+  final void Function(VoidCallback nextStep)? onShowStep;
+
   /// By default, the value used is `TextAlign.start`
   final TextAlign textAlign;
 
@@ -292,6 +295,7 @@ class OnboardingStep {
     Color? pulseInnerColor,
     Color? pulseOuterColor,
     TapCallback? onTapCallback,
+    Function(VoidCallback nextStep)? onShowStep,
   }) {
     return OnboardingStep(
       key: key ?? this.key,
@@ -320,6 +324,7 @@ class OnboardingStep {
       pulseInnerColor: pulseInnerColor ?? this.pulseInnerColor,
       pulseOuterColor: pulseOuterColor ?? this.pulseOuterColor,
       onTapCallback: onTapCallback ?? this.onTapCallback,
+      onShowStep: onShowStep ?? this.onShowStep,
     );
   }
 
@@ -352,6 +357,7 @@ class OnboardingStep {
       pulseInnerColor: $pulseInnerColor,
       pulseOuterColor: $pulseOuterColor,
       onTapCallback: $onTapCallback,
+      onShowStep: $onShowStep,
     )''';
   }
 
@@ -385,6 +391,7 @@ class OnboardingStep {
         other.showPulseAnimation == showPulseAnimation &&
         other.pulseInnerColor == pulseInnerColor &&
         other.pulseOuterColor == pulseOuterColor &&
+        other.onShowStep == onShowStep &&
         other.onTapCallback == onTapCallback;
   }
 
@@ -415,6 +422,7 @@ class OnboardingStep {
         showPulseAnimation.hashCode ^
         pulseInnerColor.hashCode ^
         pulseOuterColor.hashCode ^
+      onShowStep.hashCode ^
         onTapCallback.hashCode;
   }
 }

lib/src/stepper.dart

@@ -33,6 +33,7 @@ class OnboardingStepper extends StatefulWidget {
     this.pulseDuration = const Duration(milliseconds: 1000),
     this.onChanged,
     this.onEnd,
+    this.onStart,
     this.autoSizeTexts = false,
     this.stepIndexes = const <int>[],
     this.debugBoundaries = false,
@@ -60,6 +61,8 @@ class OnboardingStepper extends StatefulWidget {
   /// By default stepIndexes os an empty array
   final List<int> stepIndexes;
 
+  final VoidCallback? onStart;
+
   /// `onChanged` is called every time when the previous step has faded out,
   ///
   /// before the next step is shown with a value of the step index on which the user was
@@ -200,6 +203,14 @@ class OnboardingStepperState extends State<OnboardingStepper>
       await Future<void>.delayed(step.delay);
     }
 
+    if (widget.onStart != null) {
+      widget.onStart!();
+    }
+
+    if (step.onShowStep != null) {
+      step.onShowStep!(_nextStep);
+    }
+
     setTweensAndAnimate(step);
     step.focusNode.requestFocus();
   }
@@ -234,6 +245,9 @@ class OnboardingStepperState extends State<OnboardingStepper>
       if (stepperIndex > 0) {
         await Future<void>.delayed(step.delay);
       }
+      if (step.onShowStep != null) {
+        step.onShowStep!(_nextStep);
+      }
       if (stepperIndex < widget.steps.length && stepperIndex >= 0) {
         setTweensAndAnimate(step);
         step.focusNode.requestFocus();
@@ -258,6 +272,11 @@ class OnboardingStepperState extends State<OnboardingStepper>
       final OnboardingStep step = widget.steps[stepperIndex];
       await Future<void>.delayed(step.delay);
 
+      if (step.onShowStep != null) {
+        step.onShowStep!(_nextStep);
+      }
+
+
       if (widget.stepIndexes.indexWhere((int el) => el == stepperIndex) != -1) {
         setTweensAndAnimate(step);
         step.focusNode.requestFocus();