Merge pull request #2050 from jonataslaw/4.5.1

Circular reveal

+import 'dart:math' show sqrt, max;
+import 'dart:ui' show lerpDouble;
+
+import 'package:flutter/material.dart';
+
+class CircularRevealClipper extends CustomClipper<Path> {
+  final double fraction;
+  final Alignment? centerAlignment;
+  final Offset? centerOffset;
+  final double? minRadius;
+  final double? maxRadius;
+
+  CircularRevealClipper({
+    required this.fraction,
+    this.centerAlignment,
+    this.centerOffset,
+    this.minRadius,
+    this.maxRadius,
+  });
+
+  @override
+  Path getClip(Size size) {
+    final Offset center = this.centerAlignment?.alongSize(size) ??
+        this.centerOffset ??
+        Offset(size.width / 2, size.height / 2);
+    final minRadius = this.minRadius ?? 0;
+    final maxRadius = this.maxRadius ?? calcMaxRadius(size, center);
+
+    return Path()
+      ..addOval(
+        Rect.fromCircle(
+          center: center,
+          radius: lerpDouble(minRadius, maxRadius, fraction)!,
+        ),
+      );
+  }
+
+  @override
+  bool shouldReclip(CustomClipper<Path> oldClipper) => true;
+
+  static double calcMaxRadius(Size size, Offset center) {
+    final w = max(center.dx, size.width - center.dx);
+    final h = max(center.dy, size.height - center.dy);
+    return sqrt(w * w + h * h);
+  }
+}
+

@@ -184,3 +184,26 @@ class SizeTransitions {
     );
   }
 }
+
+
+class CircularRevealTransition {
+  Widget buildTransitions(
+      BuildContext context,
+      Curve? curve,
+      Alignment? alignment,
+      Animation<double> animation,
+      Animation<double> secondaryAnimation,
+      Widget child) {
+    return ClipPath(
+      clipper: CircularRevealClipper(
+        fraction: animation.value,
+        centerAlignment:  Alignment.center,
+        centerOffset: Offset.zero,
+        minRadius: 0,
+        maxRadius: 800,
+      ),
+      child: child,
+    );
+  }
+}
+

@@ -619,6 +619,22 @@ Cannot read the previousTitle for a route that has not yet been installed''',
                       onStartPopGesture: () => _startPopGesture<T>(route),
                       child: child)
                   : child);
+          
+        case Transition.ciruclarReveal:
+          return CircularRevealTransition().buildTransitions(
+              context,
+              route.curve,
+              route.alignment,
+              animation,
+              secondaryAnimation,
+              route.popGesture ?? Get.defaultPopGesture
+                  ? CupertinoBackGestureDetector<T>(
+                  gestureWidth: route.gestureWidth?.call(context) ??
+                      _kBackGestureWidth,
+                  enabledCallback: () => _isPopGestureEnabled<T>(route),
+                  onStartPopGesture: () => _startPopGesture<T>(route),
+                  child: child)
+                  : child);
 
         default:
           if (Get.customTransition != null) {