## 2.0.0-dev

* Fix Null check operator used on a null value

CHANGELOG.md

@@ -1,53 +1,56 @@
-## [2.0.0]
+## 2.0.0-dev
+
+* Fix Null check operator used on a null value
+## 2.0.0
 
 * Breaking change: add clipBehavior and restorationId
 * Merge flutter/issues/29264(SliverAppBar's flexibleSpace glitch on iOS when NestedScrollView's body is a ScrollView)
 
-## [1.0.1]
+## 1.0.1
 
 * Merge flutter/flutter#59187(Support floating the header slivers of a NestedScrollView)
 
-## [1.0.0]
+## 1.0.0
 
 * Merge code from 1.17.0
 * Fix analysis_options
 
-## [0.4.1]
+## 0.4.1
 
 * add demo to show how to change pinned header height dynamically.
 
-## [0.4.0]
+## 0.4.0
 
 * web support
 
-## [0.3.8]
+## 0.3.8
 
 * add NestedScrollViewState key to get currentInnerPosition/innerScrollPositions instead of ScrollController
 * due to we can't set ScrollController for list in NestedScrollView's body(it will breaking behaviours of InnerScrollController in NestedScrollView), provide demos('PullToRefresh','LoadMore' and 'ScrollToTop') to show how to do it without ScrollController
 
-## [0.3.6]
+## 0.3.6
 
 * fix api error base on Flutter SDK v1.7.8+hotfix.2
 
-## [0.3.5]
+## 0.3.5
 
 * New ExtendedNestedScrollView still has some issues in special layout, make it as obsolete for now till find a better solution
 
-## [0.3.3]
+## 0.3.3
 
 * fix issue that Caught error: type 'Future<void>' is not a subtype of type 'Future<Null>'
  for old extended_nested_scroll_view
 
-## [0.2.9]
+## 0.2.9
 
-* fix issue [0.2.5] for old extended_nested_scroll_view
+* fix issue 0.2.5 for old extended_nested_scroll_view
 
-## [0.2.7]
+## 0.2.7
 
 * fix issue for quick change page
 * handle unavailable page change(no actived nested positions in it)
 
-## [0.2.5]
+## 0.2.5
 
 * fix issue that ut postion is not overscroll actually,it get minimal value
   and will scroll inner positions
@@ -60,58 +63,58 @@
      }
    }
 
-## [0.2.0]
+## 0.2.0
 
 * update new extended_nested_scroll_view demo
 
-## [0.1.9]
+## 0.1.9
 
 * set keepOnlyOneInnerNestedScrollPositionActive default value: false
 
-## [0.1.8]
+## 0.1.8
 
 * update new ExtendedNestedScrollView readme
 
-## [0.1.7]
+## 0.1.7
 
 * add assert for keepOnlyOneInnerNestedScrollPositionActive
-    ///when ExtendedNestedScrollView body has [TabBarView]/[PageView] and children have
+    ///when ExtendedNestedScrollView body has TabBarView/PageView and children have
     ///AutomaticKeepAliveClientMixin or PageStorageKey,
-    ///[_innerController.nestedPositions] will have more one,
+    ///_innerController.nestedPositions will have more one,
     ///when you scroll, it will scroll all of nestedPositions
-    ///set [keepOnlyOneInnerNestedScrollPositionActive] true to avoid it.
-    ///notice: only for Axis.horizontal [TabBarView]/[PageView] and
-    ///[scrollDirection] must be Axis.vertical.
+    ///set keepOnlyOneInnerNestedScrollPositionActive true to avoid it.
+    ///notice: only for Axis.horizontal TabBarView/PageView and
+    ///scrollDirection must be Axis.vertical.
 assert(!(widget.keepOnlyOneInnerNestedScrollPositionActive && widget.scrollDirection == Axis.horizontal));
 
-## [0.1.6]
+## 0.1.6
 
-* fix issue: Actived [_NestedScrollPosition] is not right for multiple
+* fix issue: Actived _NestedScrollPosition is not right for multiple
 
-## [0.1.5]
+## 0.1.5
 
 * add new ExtendedNestedScrollView to slove issue more smartly.
 
-## [0.1.4]
+## 0.1.4
 
 * Update readme.
 
-## [0.1.3]
+## 0.1.3
 
 * Update demo.
 
-## [0.1.2]
+## 0.1.2
 
 * Remove unused method.
 
-## [0.1.1]
+## 0.1.1
 
 * Update demo.
 
-## [0.1.0]
+## 0.1.0
 
 * Upgrade Some Commments.
 
-## [0.0.1]
+## 0.0.1
 
 * Initial Open Source release.

lib/src/old_extended_nested_scroll_view.dart

@@ -613,7 +613,7 @@ class _NestedScrollCoordinator
 
   bool get hasScrolledBody {
     for (final _NestedScrollPosition position in _currentInnerPositions) {
-      assert(position.minScrollExtent != null && position.pixels != null);
+      assert(position.hasContentDimensions && position.hasPixels);
       if (position.pixels > position.minScrollExtent) {
         return true;
       }
@@ -899,6 +899,64 @@ class _NestedScrollCoordinator
     goBallistic(0.0);
   }
 
+  void pointerScroll(double delta) {
+    assert(delta != 0.0);
+
+    goIdle();
+    updateUserScrollDirection(
+        delta < 0.0 ? ScrollDirection.forward : ScrollDirection.reverse);
+
+    if (_innerPositions.isEmpty) {
+      // Does not enter overscroll.
+      _outerPosition.applyClampedPointerSignalUpdate(delta);
+    } else if (delta > 0.0) {
+      // Dragging "up" - delta is positive
+      // Prioritize getting rid of any inner overscroll, and then the outer
+      // view, so that the app bar will scroll out of the way asap.
+      double outerDelta = delta;
+      for (final _NestedScrollPosition position in _currentInnerPositions) {
+        if (position.pixels < 0.0) {
+          // This inner position is in overscroll.
+          final double potentialOuterDelta =
+              position.applyClampedPointerSignalUpdate(delta);
+          // In case there are multiple positions in varying states of
+          // overscroll, the first to 'reach' the outer view above takes
+          // precedence.
+          outerDelta = math.max(outerDelta, potentialOuterDelta);
+        }
+      }
+      if (outerDelta != 0.0) {
+        final double innerDelta =
+            _outerPosition.applyClampedPointerSignalUpdate(outerDelta);
+        if (innerDelta != 0.0) {
+          for (final _NestedScrollPosition position in _currentInnerPositions)
+            position.applyClampedPointerSignalUpdate(innerDelta);
+        }
+      }
+    } else {
+      // Dragging "down" - delta is negative
+      double innerDelta = delta;
+      // Apply delta to the outer header first if it is configured to float.
+      if (_floatHeaderSlivers)
+        innerDelta = _outerPosition.applyClampedPointerSignalUpdate(delta);
+
+      if (innerDelta != 0.0) {
+        // Apply the innerDelta, if we have not floated in the outer scrollable,
+        // any leftover delta after this will be passed on to the outer
+        // scrollable by the outerDelta.
+        double outerDelta = 0.0; // it will go negative if it changes
+        for (final _NestedScrollPosition position in _currentInnerPositions) {
+          final double overscroll =
+              position.applyClampedPointerSignalUpdate(innerDelta);
+          outerDelta = math.min(outerDelta, overscroll);
+        }
+        if (outerDelta != 0.0)
+          _outerPosition.applyClampedPointerSignalUpdate(outerDelta);
+      }
+    }
+    goBallistic(0.0);
+  }
+
   @override
   double setPixels(double newPixels) {
     assert(false);
@@ -947,7 +1005,7 @@ class _NestedScrollCoordinator
       // Prioritize getting rid of any inner overscroll, and then the outer
       // view, so that the app bar will scroll out of the way asap.
       double outerDelta = delta;
-      for (final _NestedScrollPosition position in _innerPositions) {
+      for (final _NestedScrollPosition position in _currentInnerPositions) {
         if (position.pixels < 0.0) {
           // This inner position is in overscroll.
           final double potentialOuterDelta =
@@ -1183,7 +1241,7 @@ class _NestedScrollPosition extends ScrollPosition
           oldPosition: oldPosition,
           debugLabel: debugLabel,
         ) {
-    if (pixels == null && initialPixels != null) {
+    if (!hasPixels && initialPixels != null) {
       correctPixels(initialPixels);
     }
     if (activity == null) {
@@ -1333,6 +1391,30 @@ class _NestedScrollPosition extends ScrollPosition
     return 0.0;
   }
 
+  // Returns the amount of delta that was not used.
+  //
+  // Negative delta represents a forward ScrollDirection, while the positive
+  // would be a reverse ScrollDirection.
+  //
+  // The method doesn't take into account the effects of [ScrollPhysics].
+  double applyClampedPointerSignalUpdate(double delta) {
+    assert(delta != 0.0);
+
+    final double min =
+        delta > 0.0 ? -double.infinity : math.min(minScrollExtent, pixels);
+    // The logic for max is equivalent but on the other side.
+    final double max =
+        delta < 0.0 ? double.infinity : math.max(maxScrollExtent, pixels);
+    final double newPixels = (pixels + delta).clamp(min, max) as double;
+    final double clampedDelta = newPixels - pixels;
+    if (clampedDelta == 0.0) {
+      return delta;
+    }
+    forcePixels(newPixels);
+    didUpdateScrollPositionBy(clampedDelta);
+    return delta - clampedDelta;
+  }
+
   @override
   ScrollDirection get userScrollDirection => coordinator.userScrollDirection;
 
@@ -1412,6 +1494,11 @@ class _NestedScrollPosition extends ScrollPosition
     return coordinator.jumpTo(coordinator.unnestOffset(value, this));
   }
 
+  @override
+  void pointerScroll(double delta) {
+    return coordinator.pointerScroll(delta);
+  }
+
   @override
   void jumpToWithoutSettling(double value) {
     assert(false);

pubspec.yaml

@@ -1,11 +1,11 @@
 name: extended_nested_scroll_view
 description: extended nested scroll view to fix pinned header and inner scrollables sync issues.
-version: 2.0.0
+version: 2.0.0-dev
 homepage: https://github.com/fluttercandies/extended_nested_scroll_view
 
 environment:
   sdk: ">=2.6.0 <3.0.0"
-  flutter: ">=1.22.0-2.0"
+  flutter: ">1.22.4"
 
 dependencies:
   flutter: