不知道什么原因引起的

导致第一行最后一个item下陷一个位置

日志:

The following NoSuchMethodError was thrown during performLayout():
The getter 'parentData' was called on null.
Receiver: null
Tried calling: parentData

The relevant error-causing widget was: 
  LoadingMoreSliverList<GoodsItem> file:///C:/Users/lvccz/AndroidStudioProjects/demo1/lib/pages/index_page/index_home.dart:149:12
When the exception was thrown, this was the stack: 
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)
#1      CrossAxisItems.insertLeading (package:waterfall_flow/src/rendering/sliver_waterfall_flow.dart:569:48)
#2      RenderSliverWaterfallFlow.performLayout (package:waterfall_flow/src/rendering/sliver_waterfall_flow.dart:199:28)
#3      RenderObject.layout (package:flutter/src/rendering/object.dart:1724:7)
#4      RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:134:11)
...
The following RenderObject was being processed when the exception was fired: RenderSliverWaterfallFlow#aacb0 relayoutBoundary=up2 NEEDS-LAYOUT NEEDS-COMPOSITING-BITS-UPDATE
...  needs compositing
...  parentData: paintOffset=Offset(13.6, 0.0) (can use size)
...  constraints: SliverConstraints(AxisDirection.down, GrowthDirection.forward, ScrollDirection.forward, scrollOffset: 522.5, remainingPaintExtent: 768.9, crossAxisExtent: 365.5, crossAxisDirection: AxisDirection.right, viewportMainAxisExtent: 768.9, remainingCacheExtent: 1268.9 cacheOrigin: -250.0 )
...  geometry: SliverGeometry(scrollExtent: 8346.8, paintExtent: 768.9, maxPaintExtent: 8346.8, hasVisualOverflow: true, cacheExtent: 1268.9)
...    scrollExtent: 8346.8
...    paintExtent: 768.9
...    maxPaintExtent: 8346.8
...    hasVisualOverflow: true
...    cacheExtent: 1268.9
...  currently live children: 0 to 9
RenderObject: RenderSliverWaterfallFlow#aacb0 relayoutBoundary=up2 NEEDS-LAYOUT NEEDS-COMPOSITING-BITS-UPDATE
  needs compositing
  parentData: paintOffset=Offset(13.6, 0.0) (can use size)
  constraints: SliverConstraints(AxisDirection.down, GrowthDirection.forward, ScrollDirection.forward, scrollOffset: 522.5, remainingPaintExtent: 768.9, crossAxisExtent: 365.5, crossAxisDirection: AxisDirection.right, viewportMainAxisExtent: 768.9, remainingCacheExtent: 1268.9 cacheOrigin: -250.0 )
  geometry: SliverGeometry(scrollExtent: 8346.8, paintExtent: 768.9, maxPaintExtent: 8346.8, hasVisualOverflow: true, cacheExtent: 1268.9)
    scrollExtent: 8346.8
    paintExtent: 768.9
    maxPaintExtent: 8346.8
    hasVisualOverflow: true
    cacheExtent: 1268.9
  currently live children: 0 to 9
...  child with index 0: RenderIndexedSemantics#51a2e relayoutBoundary=up3 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: crossAxisIndex=0;crossAxisOffset=0.0;trailingLayoutOffset=316.77886977886976; index=0; layoutOffset=-16.9 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 333.7)
...    index: 0
...    child: RenderRepaintBoundary#ab28e relayoutBoundary=up4 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      size: Size(175.7, 333.7)
...      usefulness ratio: no metrics collected yet (never painted)
...      child: RenderSemanticsAnnotations#b7eb5 relayoutBoundary=up5 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 333.7)
...        child: RenderMouseRegion#9e5e6 relayoutBoundary=up6 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 333.7)
...          listeners: enter, exit
...  child with index 1: RenderIndexedSemantics#ef0b5 relayoutBoundary=up3 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: crossAxisIndex=1;crossAxisOffset=189.77886977886982;trailingLayoutOffset=315.8550368550368; index=1; layoutOffset=-16.9 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 332.8)
...    index: 1
...    child: RenderRepaintBoundary#fefb4 relayoutBoundary=up4 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      size: Size(175.7, 332.8)
...      usefulness ratio: no metrics collected yet (never painted)
...      child: RenderSemanticsAnnotations#b7613 relayoutBoundary=up5 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 332.8)
...        child: RenderMouseRegion#93d8d relayoutBoundary=up6 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 332.8)
...          listeners: enter, exit
...  child with index 2: RenderIndexedSemantics#6341c relayoutBoundary=up3
...    needs compositing
...    parentData: crossAxisIndex=1;crossAxisOffset=189.77886977886982;trailingLayoutOffset=646.2702702702702; index=2; layoutOffset=329.5 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 316.8)
...    index: 2
...    child: RenderRepaintBoundary#4ffd8 relayoutBoundary=up4
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      layer: OffsetLayer#efcd0
...        offset: Offset(203.4, -284.6)
...      size: Size(175.7, 316.8)
...      metrics: 99.6% useful (2 bad vs 475 good)
...      diagnosis: this is an outstandingly useful repaint boundary and should definitely be kept
...      child: RenderSemanticsAnnotations#ff3d2 relayoutBoundary=up5
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 316.8)
...        child: RenderMouseRegion#6c37d relayoutBoundary=up6
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 316.8)
...          listeners: enter, exit
...  child with index 3: RenderIndexedSemantics#00e2f relayoutBoundary=up3
...    needs compositing
...    parentData: crossAxisIndex=0;crossAxisOffset=0.0;trailingLayoutOffset=647.1941031941031; index=3; layoutOffset=330.4 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 316.8)
...    index: 3
...    child: RenderRepaintBoundary#dd151 relayoutBoundary=up4
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      layer: OffsetLayer#18673
...        offset: Offset(13.6, -283.7)
...      size: Size(175.7, 316.8)
...      metrics: 99.6% useful (2 bad vs 474 good)
...      diagnosis: this is an outstandingly useful repaint boundary and should definitely be kept
...      child: RenderSemanticsAnnotations#03a6d relayoutBoundary=up5
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 316.8)
...        child: RenderMouseRegion#694cc relayoutBoundary=up6
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 316.8)
...          listeners: enter, exit
...  child with index 4: RenderIndexedSemantics#e61b8 relayoutBoundary=up3
...    needs compositing
...    parentData: crossAxisIndex=1;crossAxisOffset=189.77886977886982;trailingLayoutOffset=976.6855036855036; index=4; layoutOffset=659.9 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 316.8)
...    index: 4
...    child: RenderRepaintBoundary#680a7 relayoutBoundary=up4
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      layer: OffsetLayer#acd76
...        offset: Offset(203.4, 45.8)
...      size: Size(175.7, 316.8)
...      metrics: 98.3% useful (3 bad vs 177 good)
...      diagnosis: this is an outstandingly useful repaint boundary and should definitely be kept
...      child: RenderSemanticsAnnotations#38e2f relayoutBoundary=up5
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 316.8)
...        child: RenderMouseRegion#2fe33 relayoutBoundary=up6
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 316.8)
...          listeners: enter, exit
...  child with index 5: RenderIndexedSemantics#51375 relayoutBoundary=up3
...    needs compositing
...    parentData: crossAxisIndex=0;crossAxisOffset=0.0;trailingLayoutOffset=977.6093366093365; index=5; layoutOffset=660.8 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 316.8)
...    index: 5
...    child: RenderRepaintBoundary#56717 relayoutBoundary=up4
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      layer: OffsetLayer#3c9b2
...        offset: Offset(13.6, 46.7)
...      size: Size(175.7, 316.8)
...      metrics: 98.3% useful (3 bad vs 175 good)
...      diagnosis: this is an outstandingly useful repaint boundary and should definitely be kept
...      child: RenderSemanticsAnnotations#28fa0 relayoutBoundary=up5
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 316.8)
...        child: RenderMouseRegion#bf370 relayoutBoundary=up6
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 316.8)
...          listeners: enter, exit
...  child with index 6: RenderIndexedSemantics#aa09b relayoutBoundary=up3
...    needs compositing
...    parentData: crossAxisIndex=1;crossAxisOffset=189.77886977886982;trailingLayoutOffset=1307.100737100737; index=6; layoutOffset=990.3 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 316.8)
...    index: 6
...    child: RenderRepaintBoundary#d6555 relayoutBoundary=up4
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      layer: OffsetLayer#8273a
...        offset: Offset(203.4, 376.2)
...      size: Size(175.7, 316.8)
...      metrics: 98.7% useful (1 bad vs 75 good)
...      diagnosis: this is an outstandingly useful repaint boundary and should definitely be kept
...      child: RenderSemanticsAnnotations#fb511 relayoutBoundary=up5
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 316.8)
...        child: RenderMouseRegion#85d40 relayoutBoundary=up6
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 316.8)
...          listeners: enter, exit
...  child with index 7: RenderIndexedSemantics#4c1ee relayoutBoundary=up3
...    needs compositing
...    parentData: crossAxisIndex=0;crossAxisOffset=0.0;trailingLayoutOffset=1308.02457002457; index=7; layoutOffset=991.2 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 316.8)
...    index: 7
...    child: RenderRepaintBoundary#6734c relayoutBoundary=up4
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      layer: OffsetLayer#a8f86
...        offset: Offset(13.6, 377.1)
...      size: Size(175.7, 316.8)
...      metrics: 98.7% useful (1 bad vs 75 good)
...      diagnosis: this is an outstandingly useful repaint boundary and should definitely be kept
...      child: RenderSemanticsAnnotations#a757a relayoutBoundary=up5
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 316.8)
...        child: RenderMouseRegion#6b9e8 relayoutBoundary=up6
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 316.8)
...          listeners: enter, exit
...  child with index 8: RenderIndexedSemantics#10f69 relayoutBoundary=up3
...    needs compositing
...    parentData: crossAxisIndex=1;crossAxisOffset=189.77886977886982;trailingLayoutOffset=1636.5921375921375; index=8; layoutOffset=1320.7 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 315.9)
...    index: 8
...    child: RenderRepaintBoundary#a713a relayoutBoundary=up4
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      layer: OffsetLayer#ac017
...        offset: Offset(203.4, 706.6)
...      size: Size(175.7, 315.9)
...      metrics: 80.0% useful (1 bad vs 4 good)
...      diagnosis: this is a useful repaint boundary and should be kept
...      child: RenderSemanticsAnnotations#d0c4e relayoutBoundary=up5
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 315.9)
...        child: RenderMouseRegion#a5fb3 relayoutBoundary=up6
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 315.9)
...          listeners: enter, exit
...  child with index 9: RenderIndexedSemantics#27f00 relayoutBoundary=up3
...    needs compositing
...    parentData: crossAxisIndex=0;crossAxisOffset=0.0;trailingLayoutOffset=1638.4398034398037; index=9; layoutOffset=1321.7 (can use size)
...    constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...    semantic boundary
...    size: Size(175.7, 316.8)
...    index: 9
...    child: RenderRepaintBoundary#de1e4 relayoutBoundary=up4
...      needs compositing
...      parentData: <none> (can use size)
...      constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...      layer: OffsetLayer#b5394
...        offset: Offset(13.6, 707.6)
...      size: Size(175.7, 316.8)
...      metrics: 80.0% useful (1 bad vs 4 good)
...      diagnosis: this is a useful repaint boundary and should be kept
...      child: RenderSemanticsAnnotations#8b50f relayoutBoundary=up5
...        parentData: <none> (can use size)
...        constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...        size: Size(175.7, 316.8)
...        child: RenderMouseRegion#d3951 relayoutBoundary=up6
...          parentData: <none> (can use size)
...          constraints: BoxConstraints(w=175.7, 0.0<=h<=Infinity)
...          size: Size(175.7, 316.8)
...          listeners: enter, exit
════════════════════════════════════════════════════════════════════════════════════════════════════

这是我的瀑布流wiget

首页商品列表
  Widget _buildGoodsList() {
    return LoadingMoreSliverList(SliverListConfig<GoodsItem>(
      waterfallFlowDelegate: WaterfallFlowDelegate(
          crossAxisCount: 2, crossAxisSpacing: ScreenUtil().setHeight(50), mainAxisSpacing: ScreenUtil().setWidth(50)),
      itemBuilder: (context, item, index) {
        return WaterfallGoodsCard(item);
      },
      sourceList: indexGoodsRepository,
      padding: EdgeInsets.only(left: ScreenUtil().setWidth(50),right: ScreenUtil().setWidth(50)),
      lastChildLayoutType: LastChildLayoutType.foot,
      indicatorBuilder: (context, state) {
        return LoadingMoreListCostumIndicator(state, isSliver: true);
      },
//      collectGarbage: (List<int> indexes) {
//        indexes.forEach((index) {
//          final item = indexGoodsRepository[index];
//          final provider = ExtendedNetworkImageProvider(
//            item.mainPic,
//          );
//          provider.evict();
//        });
//      },
    ));
  }

https://user-images.githubusercontent.com/19726808/125303985-cadfe080-e35f-11eb-94ce-f619168154c2.mp4

大佬又遇到这个问题吗？ 就是waterfall_flow和extended_nested_scroll_view一起使用再往上滚动的时候可能会出现无法滚上去(或者不流畅)的BUG

Hi and thanks for this useful plugin.

I am using the latest version as of 1st Nov 2020.,

I notice that when I show a mixture of TEXT and images approx 60 cells (30 text cells and 30 image cells of different sizes) and scroll through - the cells appear to jump from 1 side to the next - I am testing this on a live device and get this issue on ANDROID and iOS. Its as if each scroll gesture forces the rebuild of the grid and then the cells get re-shuffled.

I have tested using a normal gridView and do not get this behaviour.

When the grid cells are the same size - the issue does not appear . When we have different sized IMAGES - we get the issue.

The code I use is :

WaterfallFlow.custom(
        padding: EdgeInsets.all(10),
        gridDelegate: SliverWaterfallFlowDelegateWithFixedCrossAxisCount(
            crossAxisCount: crossAxis, crossAxisSpacing: 5, mainAxisSpacing: 5),
        childrenDelegate: SliverChildBuilderDelegate((context, index) {
          var model = items[index].item2;
          var comp = items[index].item1;

          if (model.pictureUrl == null) {
           /// Display a TEXT widget
            return Container(height: 100, width: 100, child: comp);
          } else {
          /// Display an Image widget
            return comp;
          }
        }, childCount: items.length),
      );

Flutter doctor info: [✓] Flutter (Channel unknown, v1.14.6, on Mac OS X 10.14.6 18G84, locale zh-Hans-CN) • Flutter version 1.14.6 at /Users/huangyumeng/flutter/sdk/flutter • Framework revision fabeb2a16f (4 months ago), 2020-01-28 07:56:51 -0800 • Engine revision c4229bfbba • Dart version 2.8.0 (build 2.8.0-dev.5.0 fc3af737c7)

[!] Android toolchain - develop for Android devices (Android SDK version 29.0.0) • Android SDK at /Users/huangyumeng/Library/Android/sdk • Android NDK location not configured (optional; useful for native profiling support) • Platform android-29, build-tools 29.0.0 • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b4-5784211) ! Some Android licenses not accepted. To resolve this, run: flutter doctor --android-licenses

[✓] Xcode - develop for iOS and macOS (Xcode 11.3.1) • Xcode at /Applications/Xcode.app/Contents/Developer • Xcode 11.3.1, Build version 11C504 • CocoaPods version 1.7.4

[✓] Android Studio (version 3.6) • Android Studio at /Applications/Android Studio.app/Contents • Flutter plugin version 45.1.1 • Dart plugin version 192.8052 • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b4-5784211)

[✓] Connected device (1 available) • Redmi Note 8 Pro • 192.168.1.53:5555 • android-arm64 • Android 9 (API 28)

! Doctor found issues in 1 category.

问题描述： 产品瀑布流默认为两列，会偶现第二列某一个区域为空白的情况，滑动后第二列整个消失，第一列的布局会挤在一起。布局代码：

SliverPadding(
          padding: EdgeInsets.all(kMomentWaterfallCrossAxisSpacing),
          sliver: SliverWaterfallFlow(
            gridDelegate: SliverWaterfallFlowDelegate(
                crossAxisCount: kMomentWaterfallCrossAxisCount,
                mainAxisSpacing: kMomentWaterfallMainAxisSpacing,
                crossAxisSpacing: kMomentWaterfallCrossAxisSpacing,
                lastChildLayoutTypeBuilder: (idx) {
                  return idx == _model.momentList.length
                      ? LastChildLayoutType.foot
                      : LastChildLayoutType.none;
                },
                viewportBuilder: (firstIdx, lastIdx) {},
                collectGarbage: (List<int> collectIdxList) {
                  for (int idx in collectIdxList) {
                    dataList[idx].evictImageInfo();
                  }
                }),
            delegate: SliverChildBuilderDelegate((context, idx) {
              return ItemTile();
            }, childCount: dataList.length),
          ),
        )

Bugly报错： NoSuchMethodError: The getter 'parentData' was called on null. Receiver: null Tried calling: parentData

#0 CrossAxisItems.insertLeading (package:waterfall_flow/src/rendering/sliver_waterfall_flow.dart:569)

2 #1 RenderSliverWaterfallFlow.performLayout (package:waterfall_flow/src/rendering/sliver_waterfall_flow.dart:199) 3 #2 RenderObject.layout (package:flutter/src/rendering/object.dart:1767) 4 #3 RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:134) 5 #4 RenderSliverPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:373) 6 #5 RenderObject.layout (package:flutter/src/rendering/object.dart:1767) 7 #6 RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:452) 8 #7 RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1444) 9 #8 RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1353) 10 #9 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1628) 11 #10 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:888) 12 #11 RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:401) 13 #12 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:797) 14 #13 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:283) 15 #14 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1109) 16 #15 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1048) 17 #16 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:964) 18 #17 _rootRun (dart:async/zone.dart:1126) 19 #18 _CustomZone.run (dart:async/zone.dart:1023) 20 #19 _CustomZone.runGuarded (dart:async/zone.dart:925) 21 #20 _invoke (dart:ui/hooks.dart:260) 22 #21 _drawFrame (dart:ui/hooks.dart:218)

I have a SliverWaterfallFlowDelegateWithMaxCrossAxisExtent that creates a Waterfall grid of elements.

When the device is rotated from a longer list (portrait) to a shorter list (landscape), the bottom of the list goes empty and you have to scroll up to reach to latest items.

Reproduction:

1. When the device starts is portrait, the list is rendered as a 1 item list in the cross axis
2. Scroll to the bottom of list.
3. Turn the device to landscape.

Expected:

• The list rebuilds having 2 items in the cross axis and showing the latest 2 or 1 items

Happening:

• The list rebuilds but the latest items are way up high in the list. You have to scroll up to get to the latest items.

Also, this error is thrown:

════════ Exception caught by rendering library ═════════════════════════════════
The following NoSuchMethodError was thrown during performLayout():
The getter 'minTrailingIndex' was called on null.
Receiver: null
Tried calling: minTrailingIndex

The relevant error-causing widget was
SliverWaterfallFlow
 lib/…/components/flageventlistscaffold.dart
When the exception was thrown, this was the stack
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
#1      RenderSliverWaterfallFlow.performLayout
 package:waterfall_flow/…/rendering/sliver_waterfall_flow.dart
#2      RenderObject.layout
 package:flutter/…/rendering/object.dart
#3      RenderSliverEdgeInsetsPadding.performLayout
 package:flutter/…/rendering/sliver_padding.dart
#4      RenderSliverPadding.performLayout
 package:flutter/…/rendering/sliver_padding.dart
...
The following RenderObject was being processed when the exception was fired: RenderSliverWaterfallFlow#aa835 relayoutBoundary=up3 NEEDS-LAYOUT NEEDS-COMPOSITING-BITS-UPDATE
RenderObject: RenderSliverWaterfallFlow#aa835 relayoutBoundary=up3 NEEDS-LAYOUT NEEDS-COMPOSITING-BITS-UPDATE
    needs compositing
    parentData: paintOffset=Offset(4.0, 0.0) (can use size)
    constraints: SliverConstraints(AxisDirection.down, GrowthDirection.forward, ScrollDirection.idle, scrollOffset: 6661.4, remainingPaintExtent: 334.0, crossAxisExtent: 742.0, crossAxisDirection: AxisDirection.right, viewportMainAxisExtent: 334.0, remainingCacheExtent: 834.0, cacheOrigin: -246.0)
    geometry: SliverGeometry(scrollExtent: 7229.4, paintExtent: 568.0, maxPaintExtent: 7229.4, hasVisualOverflow: true, cacheExtent: 814.0)
        scrollExtent: 7229.4
        paintExtent: 568.0
        maxPaintExtent: 7229.4
        hasVisualOverflow: true
        cacheExtent: 814.0
    currently live children: 0 to 17
    child with index 0: RenderIndexedSemantics#f7bcb relayoutBoundary=up4 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
        parentData: crossAxisIndex=0;crossAxisOffset=0.0;trailingLayoutOffset=407.9;indexes[0, 2, 4, 6, 8, 10, 12, 14]; index=0; layoutOffset=0.0 (can use size)
        constraints: BoxConstraints(w=368.5, 0.0<=h<=Infinity)
        semantic boundary
        size: Size(368.5, 407.9)
        index: 0
        child: RenderRepaintBoundary#69a4b relayoutBoundary=up5 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
            needs compositing
            parentData: <none> (can use size)
            constraints: BoxConstraints(w=368.5, 0.0<=h<=Infinity)
            size: Size(368.5, 407.9)
            usefulness ratio: no metrics collected yet (never painted)
            child: RenderPadding#8344e relayoutBoundary=up6 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
                parentData: <none> (can use size)
                constraints: BoxConstraints(w=368.5, 0.0<=h<=Infinity)
                size: Size(368.5, 407.9)
                padding: EdgeInsets.zero
                textDirection: ltr
                child: RenderSemanticsGestureHandler#2854f relayoutBoundary=up7 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
                    parentData: offset=Offset(0.0, 0.0) (can use size)
                    constraints: BoxConstraints(w=368.5, 0.0<=h<=Infinity)
                    size: Size(368.5, 407.9)
                    gestures: tap
...
════════════════════════════════════════════════════════════════════════════════

• 表现一：TabBarView滚动时无法整体滚动
• 表现二：如果把TabBarView的physics改为Never，则loadmore失效

请问这种带TabBarView的瀑布流如何做到整体滚动并刷新正常啊？

###6# 录屏

https://user-images.githubusercontent.com/20849786/171082914-9accec76-4b56-480b-ad72-a19f26e93bd2.mov

最简实现

import 'package:app/business/tuchong_item.dart';
import 'package:extended_image/extended_image.dart';
import 'package:flutter/material.dart';
import 'package:loading_more_list/loading_more_list.dart';
import 'dart:async';
import 'dart:convert';
import 'package:http/http.dart';
import 'package:http_client_helper/http_client_helper.dart';
import 'package:loading_more_list_library/loading_more_list_library.dart';

class ListWithTab extends StatefulWidget {
  const ListWithTab({Key? key}) : super(key: key);

  @override
  _ListWithTabState createState() => _ListWithTabState();
}

class _ListWithTabState extends State<ListWithTab> with SingleTickerProviderStateMixin {
  final List<Widget> myTabs = [
    Tab(text: 'tab1'),
    Tab(text: 'tab2'),
    Tab(text: 'tab3'),
  ];
  TabController? _tabController;
  List<int> dataSource = List.generate(100, (index) => index);
  int pageNumber = 1;

  @override
  void initState() {
    _tabController = TabController(length: 3, vsync: this);
    super.initState();
  }

  @override
  void dispose() {
    _tabController?.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: LoadingMoreCustomScrollView(
        slivers: [
          SliverToBoxAdapter(child: Container(height: 300, color: Colors.red)),
          buildTabs(context),
          buildTabBarView(),
        ],
      ),
    );
  }

  SliverFillRemaining buildTabBarView() {
    return SliverFillRemaining(
      child: TabBarView(
        controller: _tabController,
        children: myTabs
            .map((e) => LoadingMoreList<TuChongItem>(
                  ListConfig<TuChongItem>(
                    itemBuilder: buildWaterfallFlowItem,
                    sourceList: TuChongRepository(),
                    padding: const EdgeInsets.all(5.0),
                    primary: false,
                    extendedListDelegate: const SliverWaterfallFlowDelegateWithMaxCrossAxisExtent(
                      maxCrossAxisExtent: 300,
                      crossAxisSpacing: 5,
                      mainAxisSpacing: 5,
                    ),
                    lastChildLayoutType: LastChildLayoutType.foot,
                  ),
                ))
            .toList(),
      ),
    );
  }

  SliverToBoxAdapter buildTabs(BuildContext context) {
    return SliverToBoxAdapter(
      child: Container(
        padding: EdgeInsets.symmetric(vertical: 20),
        child: Align(
          alignment: Alignment.centerLeft,
          child: TabBar(
            isScrollable: true,
            padding: EdgeInsets.zero,
            controller: _tabController,
            tabs: myTabs,
            indicatorWeight: 3,
            indicatorColor: Theme.of(context).primaryColor,
            indicatorSize: TabBarIndicatorSize.label,
            labelColor: Theme.of(context).primaryColor,
            overlayColor: MaterialStateProperty.all(Colors.transparent),
          ),
        ),
      ),
    );
  }

  Widget buildWaterfallFlowItem(BuildContext c, TuChongItem item, int index) {
    return AspectRatio(
      aspectRatio: item.imageSize.width / item.imageSize.height,
      child: ExtendedImage.network(
        item.imageUrl,
        shape: BoxShape.rectangle,
        //clearMemoryCacheWhenDispose: true,
        border: Border.all(color: Colors.grey.withOpacity(0.4), width: 1.0),
        borderRadius: const BorderRadius.all(
          Radius.circular(10.0),
        ),
        loadStateChanged: (ExtendedImageState value) {
          if (value.extendedImageLoadState == LoadState.loading) {
            Widget loadingWidget = Container(
              alignment: Alignment.center,
              color: Colors.grey.withOpacity(0.8),
              child: CircularProgressIndicator(
                strokeWidth: 2.0,
                valueColor: AlwaysStoppedAnimation<Color>(Theme.of(c).primaryColor),
              ),
            );
            return loadingWidget;
          } else if (value.extendedImageLoadState == LoadState.completed) {
            item.imageRawSize = Size(value.extendedImageInfo!.image.width.toDouble(), value.extendedImageInfo!.image.height.toDouble());
          }
          return null;
        },
      ),
    );
  }
}

class TuChongRepository extends LoadingMoreBase<TuChongItem> {
  TuChongRepository({this.maxLength = 40});

  int _pageIndex = 1;
  bool _hasMore = true;
  bool forceRefresh = false;

  @override
  bool get hasMore => (_hasMore && length < maxLength) || forceRefresh;
  final int maxLength;

  @override
  Future<bool> refresh([bool notifyStateChanged = false]) async {
    _hasMore = true;
    _pageIndex = 1;
    //force to refresh list when you don't want clear list before request
    //for the case, if your list already has 20 items.
    forceRefresh = !notifyStateChanged;
    final bool result = await super.refresh(notifyStateChanged);
    forceRefresh = false;
    return result;
  }

  @override
  Future<bool> loadData([bool isloadMoreAction = false]) async {
    String url = '';
    if (isEmpty) {
      url = 'https://api.tuchong.com/feed-app';
    } else {
      final int? lastPostId = this[length - 1].postId;
      url = 'https://api.tuchong.com/feed-app?post_id=$lastPostId&page=$_pageIndex&type=loadmore';
    }
    bool isSuccess = false;
    try {
      //to show loading more clearly, in your app,remove this
      // await Future.delayed(const Duration(milliseconds: 500));
      List<TuChongItem>? feedList;
      final Response result = await HttpClientHelper.get(Uri.parse(url)) as Response;
      feedList = TuChongSource.fromJson(json.decode(result.body) as Map<String, dynamic>).feedList;

      if (_pageIndex == 1) {
        clear();
      }

      for (final TuChongItem item in feedList!) {
        if (item.hasImage && !contains(item) && hasMore) {
          add(item);
        }
      }
      _hasMore = feedList.isNotEmpty;
      _pageIndex++;
      isSuccess = true;
    } catch (exception, stack) {
      isSuccess = false;
      print(exception);
      print(stack);
    }
    return isSuccess;
  }
}

Hi, is there a way to extend fullCrossAxisExtent to the first item? Imagine a loader on the top of the grid or a button to reload content in case of errors ...

      lastChildLayoutTypeBuilder: (index) {
        if ((index == 0 && reloadRequired) ||
            ((index == 0 && isLoadingAll) ||
                (index == dataLength - 1 && isLoadingMore)) ||
            (index == dataLength - 1 && !isLoadingAll)) {
          return LastChildLayoutType.fullCrossAxisExtent;
        }

        return LastChildLayoutType.none;
      },

Thanks, Andrea

I am getting a noSuchMethod error when running on a Simulator (iOS).

The issue seems similar to what has been raised here :

https://github.com/fluttercandies/waterfall_flow/issues/16

because I dont always get this error. It happens on scrolling (when there is more than 1 page of images).

When I look at the line 479 in sliver_waterfall_flow it shows :

if (data.layoutOffset < -precisionErrorTolerance) {

If I scroll very fast up and down I get the error and my list of (say) 20 items either gets cleared or goes down to 1 or two items (Only 1 or 2 items are shown).

My images were small (20k) apart from a few that were very large (5mb). When I remove the large images from the list - I dont get the issue at all.

Additionally - I am also experiencing jumping of images within the Masonary view.

Why flutter version must be >= 1.17.0 environment: sdk: ">=2.6.0 <3.0.0" flutter: ">=1.17.0"

log: depends on flutter_staggered_grid_view >=0.3.2 which requires Flutter SDK version >=1.17.0, version solving failed. pub upgrade failed (1; Because flutter_demo depends on flutter_staggered_grid_view >=0.3.2 which requires Flutter SDK version >=1.17.0, version solving failed.)

in this code i get visible error and how can i have WaterfallFlow into ListView?

The getter 'visible' was called on null. Receiver: null Tried calling: visible

class SampleCode extends StatelessWidget {
  List<Color> colors = <Color>[];

  @override
  Widget build(BuildContext context) {
    final double screenWidthSize = MediaQuery.of(context).size.width;

    return Scaffold(
      appBar: AppBar(
        title: const Text('RandomSized'),
      ),
      body: ListView(
        children: <Widget>[
          Container(
            height: 100.0,
            child: Text('TEST'),
          ),
          LayoutBuilder(
              builder: (BuildContext context, BoxConstraints constraints){
                int _crossAxisCount = 0;
                if (screenWidthSize > 720) {
                  _crossAxisCount = 3;
                } else if (screenWidthSize > 520) {
                  _crossAxisCount = 2;
                } else {
                  _crossAxisCount = 1;
                }
                return Expanded(
                  child: WaterfallFlow.builder(
                    padding: const EdgeInsets.all(5.0),
                    shrinkWrap: false,
                    gridDelegate: SliverWaterfallFlowDelegateWithFixedCrossAxisCount(
                      crossAxisCount: _crossAxisCount,
                      crossAxisSpacing: 4,
                      mainAxisSpacing: 4,
                    ),
                    itemBuilder: (BuildContext c, int index) {
                      final Color color = getRandomColor(index);
                      return Container(
                        decoration: BoxDecoration(
                            border: Border.all(color: Colors.black),
                            color: getRandomColor(index)),
                        alignment: Alignment.center,
                        child: Text(
                          '$index ' + 'TestString' * 10 * (index % 3 + 1),
                          style: TextStyle(
                              color: color.computeLuminance() < 0.5
                                  ? Colors.white
                                  : Colors.black),
                        ),
                        //height: ((index % 3) + 1) * 100.0,
                      );
                    },
                    itemCount: 22,
                  ),
                );
              }
          )
        ],
      ),
    );
  }

  Color getRandomColor(int index) {
    if (index >= colors.length) {
      colors.add(Color.fromARGB(255, Random.secure().nextInt(255),
          Random.secure().nextInt(255), Random.secure().nextInt(255)));
    }

    return colors[index];
  }
}

I have All exceptions turned on and it always crashes.

double get maxLeadingLayoutOffset { try { return leadingItems .reduce( // <=================== here (WaterfallFlowParentData curr, WaterfallFlowParentData next) => curr.layoutOffset >= next.layoutOffset ? curr : next) .layoutOffset; } catch (e) { return 0.0; } }

越滚到底部性能越差，似乎窗口大小改变会重建当前位置之前所有的组件 ListView 和 GridView 无此问题

以下演示运行于 Release 模式

https://user-images.githubusercontent.com/181192/186556514-6382ecde-30d6-47e7-a939-d56c3a0fad82.mp4

线上出现几百个异常日志，本地测试无法复现。

872行代码片段截图

堆栈信息： #0 ListMixin.reduce (dart:collection/list.dart:222) #1 _CrossAxisChildrenData.insert (package:waterfall_flow/src/rendering/sliver_waterfall_flow.dart:872) #2 RenderSliverWaterfallFlow.performLayout (package:waterfall_flow/src/rendering/sliver_waterfall_flow.dart:537) #3 RenderObject.layout (package:flutter/src/rendering/object.dart:1915) #4 RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:137) #5 RenderSliverPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:371) #6 RenderObject.layout (package:flutter/src/rendering/object.dart:1915) #7 RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:510) #8 RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1580) #9 RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1489) #10 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1757) #11 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:887) #12 RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:504) #13 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:892) #14 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:370) #15 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1146) #16 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1083) #17 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:997) #18 _rootRun (dart:async/zone.dart:1426) #19 _CustomZone.run (dart:async/zone.dart:1328) #20 _CustomZone.runGuarded (dart:async/zone.dart:1236) #21 _invoke (dart:ui/hooks.dart:151) #22 PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:308) #23 _drawFrame (dart:ui/hooks.dart:115)