fix: ScrollMetrics.minScrollExtent != 0.0, offset calculation error (#581).

Author: xuelongqy

CHANGELOG.md

@@ -1,3 +1,7 @@
+## V 3.0.4
+> fix: ScrollMetrics.minScrollExtent != 0.0, offset calculation error.  
+> feat: Supported [ScrollView.center] [#581](https://github.com/xuelongqy/flutter_easy_refresh/pull/581).  
+
 ## V 3.0.3+1
 > docs: NestedScrollView example.   
 

example/pubspec.yaml

@@ -7,7 +7,7 @@ description: EasyRefresh example.
 # Both the version and the builder number may be overridden in flutter
 # build by specifying --build-name and --build-number, respectively.
 # Read more about versioning at semver.org.
-version: 3.0.3+48
+version: 3.0.4+49
 
 environment:
   sdk: ">=2.13.0 <3.0.0"

lib/src/notifier/indicator_notifier.dart

@@ -827,28 +827,30 @@ class HeaderNotifier extends IndicatorNotifier {
         !(clamping && _offset > 0)) {
       return 0;
     }
+    // Moving distance
+    final move = position.minScrollExtent - value;
     if (clamping) {
       if (value > position.minScrollExtent) {
         // Rollback first minus offset.
-        return math.max(_offset > 0 ? (-value + _offset) : 0, 0);
+        return math.max(_offset > 0 ? (move + _offset) : 0, 0);
       } else {
         // Overscroll accumulated offset.
-        final mOffset = -value + _offset;
+        final mOffset = move + _offset;
         if (hasSecondary && mOffset > secondaryDimension) {
           // Cannot exceed secondary offset.
           return secondaryDimension;
         }
         return mOffset;
       }
     } else {
-      return value > position.minScrollExtent ? 0 : -value;
+      return value > position.minScrollExtent ? 0 : move;
     }
   }
 
   /// See [IndicatorNotifier.calculateOffsetWithPixels].
   @override
   double calculateOffsetWithPixels(ScrollMetrics position, double pixels) =>
-      math.max(-pixels - position.minScrollExtent, 0.0);
+      math.max(position.minScrollExtent - pixels, 0.0);
 
   /// See [IndicatorNotifier.createBallisticSimulation].
   @override

lib/src/physics/scroll_physics.dart

@@ -376,7 +376,6 @@ class _ERScrollPhysics extends BouncingScrollPhysics {
         }
       }
     }
-
     // Update offset
     _updateIndicatorOffset(position, value, value);
     return bounds;

pubspec.yaml

@@ -1,6 +1,6 @@
 name: easy_refresh
 description: A flutter widget that provides pull-down refresh and pull-up load.
-version: 3.0.3+1
+version: 3.0.4
 homepage: https://xuelongqy.github.io/flutter_easy_refresh
 repository: https://github.com/xuelongqy/flutter_easy_refresh
 issue_tracker: https://github.com/xuelongqy/flutter_easy_refresh/issues