Add breakpoint extension to get the current active breakpoint

packages/flutter_adaptive_scaffold/lib/src/breakpoints.dart

@@ -216,3 +216,49 @@ class Breakpoint {
     return isWidthActive && isHeightActive && isRightPlatform;
   }
 }
+
+/// An extension on [BuildContext] that returns the active [Breakpoint] based on
+/// an available [SlotLayout] ancestor or the default breakpoints.
+extension BreakpointExtension on BuildContext {
+  /// Returns the currently active [Breakpoint].
+  Breakpoint get activeBreakpoint {
+    final SlotLayout? slotLayout = findAncestorWidgetOfExactType<SlotLayout>();
+    if (slotLayout != null) {
+      for (final MapEntry<Breakpoint, SlotLayoutConfig?> config
+          in slotLayout.config.entries) {
+        if (config.key.isActive(this)) {
+          return config.key;
+        }
+      }
+    }
+
+    final TargetPlatform platform = Theme.of(this).platform;
+
+    if (Breakpoint.desktop.contains(platform)) {
+      if (Breakpoints.extraLarge.isActive(this)) {
+        return Breakpoints.extraLargeDesktop;
+      } else if (Breakpoints.large.isActive(this)) {
+        return Breakpoints.largeDesktop;
+      } else if (Breakpoints.mediumLarge.isActive(this)) {
+        return Breakpoints.mediumLargeDesktop;
+      } else if (Breakpoints.medium.isActive(this)) {
+        return Breakpoints.mediumDesktop;
+      } else if (Breakpoints.small.isActive(this)) {
+        return Breakpoints.smallDesktop;
+      }
+    } else if (Breakpoint.mobile.contains(platform)) {
+      if (Breakpoints.extraLarge.isActive(this)) {
+        return Breakpoints.extraLargeMobile;
+      } else if (Breakpoints.large.isActive(this)) {
+        return Breakpoints.largeMobile;
+      } else if (Breakpoints.mediumLarge.isActive(this)) {
+        return Breakpoints.mediumLargeMobile;
+      } else if (Breakpoints.medium.isActive(this)) {
+        return Breakpoints.mediumMobile;
+      } else if (Breakpoints.small.isActive(this)) {
+        return Breakpoints.smallMobile;
+      }
+    }
+    return Breakpoints.standard;
+  }
+}