flutter_staggered_grid_view包导致出现的错误
App中用到了瀑布流插件
flutter_staggered_grid_view: ^0.4.1
每次调用瀑布流模块的时候,都会报如下错误,之前是没有问题的,最近出现了这个问题,请帮各位看下,谢谢
======== Exception caught by scheduler library =====================================================
The following assertion was thrown during a scheduler callback:
Updated layout information required for RenderIndexedSemantics#eabc3 NEEDS-LAYOUT to calculate semantics.
'package:flutter/src/rendering/object.dart':
Failed assertion: line 2747 pos 12: '!_needsLayout'
Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
https://github.com/flutter/flutter/issues/new?template=2_bug.md
When the exception was thrown, this was the stack:
#2 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2747:12)
#3 RenderObject._getSemanticsForParent.<anonymous closure> (package:flutter/src/rendering/object.dart:2769:61)
#4 Iterable.forEach (dart:core/iterable.dart:279:35)
#5 RenderSliverVariableSizeBoxAdaptor.visitChildren (package:flutter_staggered_grid_view/src/rendering/sliver_variable_size_box_adaptor.dart:296:29)
#6 RenderObject.visitChildrenForSemantics (package:flutter/src/rendering/object.dart:2854:5)
#7 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2764:5)
#8 RenderObject._getSemanticsForParent.<anonymous closure> (package:flutter/src/rendering/object.dart:2769:61)
#9 RenderObjectWithChildMixin.visitChildren (package:flutter/src/rendering/object.dart:3146:14)
#10 RenderObject.visitChildrenForSemantics (package:flutter/src/rendering/object.dart:2854:5)
#11 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2764:5)
#12 RenderObject._getSemanticsForParent.<anonymous closure> (package:flutter/src/rendering/object.dart:2769:61)
#13 Iterable.forEach (dart:core/iterable.dart:279:35)
#14 RenderViewportBase.visitChildrenForSemantics (package:flutter/src/rendering/viewport.dart:222:10)
#15 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2764:5)
#16 RenderObject._getSemanticsForParent.<anonymous closure> (package:flutter/src/rendering/object.dart:2769:61)
#17 RenderIgnorePointer.visitChildrenForSemantics (package:flutter/src/rendering/proxy_box.dart:3318:14)
#18 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2764:5)
#19 RenderObject._getSemanticsForParent.<anonymous closure> (package:flutter/src/rendering/object.dart:2769:61)
#20 RenderObjectWithChildMixin.visitChildren (package:flutter/src/rendering/object.dart:3146:14)
#21 RenderObject.visitChildrenForSemantics (package:flutter/src/rendering/object.dart:2854:5)
#22 RenderSemanticsAnnotations.visitChildrenForSemantics (package:flutter/src/rendering/proxy_box.dart:4715:11)
#23 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2764:5)
#24 RenderObject._getSemanticsForParent.<anonymous closure> (package:flutter/src/rendering/object.dart:2769:61)
#25 RenderObjectWithChildMixin.visitChildren (package:flutter/src/rendering/object.dart:3146:14)
#26 RenderObject.visitChildrenForSemantics (package:flutter/src/rendering/object.dart:2854:5)
#27 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2764:5)
#28 RenderObject._getSemanticsForParent.<anonymous closure> (package:flutter/src/rendering/object.dart:2769:61)
#29 RenderObjectWithChildMixin.visitChildren (package:flutter/src/rendering/object.dart:3146:14)
#30 RenderObject.visitChildrenForSemantics (package:flutter/src/rendering/object.dart:2854:5)
#31 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2764:5)
#32 RenderObject._getSemanticsForParent.<anonymous closure> (package:flutter/src/rendering/object.dart:2769:61)
#33 RenderObjectWithChildMixin.visitChildren (package:flutter/src/rendering/object.dart:3146:14)
#34 RenderObject.visitChildrenForSemantics (package:flutter/src/rendering/object.dart:2854:5)
#35 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2764:5)
#36 RenderObject._getSemanticsForParent.<anonymous closure> (package:flutter/src/rendering/object.dart:2769:61)
#37 RenderObjectWithChildMixin.visitChildren (package:flutter/src/rendering/object.dart:3146:14)
#38 RenderObject.visitChildrenForSemantics (package:flutter/src/rendering/object.dart:2854:5)
#39 RenderObject._getSemanticsForParent (package:flutter/src/rendering/object.dart:2764:5)
#40 RenderObject._updateSemantics (package:flutter/src/rendering/object.dart:2725:41)
#41 PipelineOwner.flushSemantics (package:flutter/src/rendering/object.dart:1080:16)
#42 RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:458:21)
#43 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:883:13)
#44 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1143:15)
#45 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1080:9)
#49 _invoke (dart:ui/hooks.dart:166:10)
#50 PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:270:5)
#51 _drawFrame (dart:ui/hooks.dart:129:31)
(elided 5 frames from class _AssertionError and dart:async)
====================================================================================================
相关推荐
零基础App开发入门:2024年用Flutter快速构建你的第一款应用
移动应用开发已成为连接用户与服务的重要桥梁,其核心在于通过代码构建可在智能手机上运行的软件。跨平台开发框架通过一套代码同时生成Android和iOS应用,大幅提升了开发效率并降低了维护成本。在众多技术方案中,Flutter以其高性能的渲染引擎和热重载特性,为开发者提供了接近原生的体验与高效的开发流程。对于初学者而言,从构建一个具备核心功能的简易应用入手,是理解状态管理、UI组件和数据交互等基础概念的最佳实践。本文将以Flutter为例,结合**环境搭建**和**组件化开发**等关键热词,手把手指导零基础开发
mongodb-linux-x86_64-ubuntu2004-8.0.13.tgz
mongodb-linux-x86_64-ubuntu2004-8.0.13
chromedriver-linux64-159.0.8135.0(Canary).zip
chromedriver-linux64-159.0.8135.0(Canary).zip
三相四桥臂电压不对称跌落补偿动态电压恢复器DVR(Simulink仿真实现)
内容概要:本文围绕三相四桥臂动态电压恢复器(DVR)在电压不对称跌落情况下的补偿能力展开,重点介绍了基于Simulink平台构建的仿真模型,用于研究和验证DVR对电网电压不平衡的动态补偿性能。系统采用三相四桥臂逆变器结构,利用其独立的中性线控制能力有效处理零序分量,结合多准PR(Proportional Resonant)控制策略实现对正负序电压分量的精确跟踪与快速响应,从而提升在不平衡负载或电网故障条件下DVR的补偿精度与系统稳定性。文中提供了完整的仿真模型及相关参考文献,涵盖控制算法设计、系统建模与参数整定等关键技术环节,适用于复杂电能质量问题的研究与教学演示。; 适合人群:电气工程、电力电子与电力系统相关专业的研究生、科研人员及从事电能质量治理的技术工程师;具备一定的电路理论、自动控制原理和Simulink仿真基础者更佳。; 使用场景及目标:①研究动态电压恢复器在三相电压不对称跌落工况下的补偿机制与控制策略;②掌握三相四桥臂逆变器在不平衡条件下的建模与控制方法;③深入理解多准PR控制器在正负序分离控制中的应用,提升对电能质量调节装置的设计与仿真能力; 阅读建议:建议结合提供的参考文献与说明文档,逐步搭建并调试Simulink仿真模型,重点关注控制器参数设计与系统动态响应特性,通过设置不同类型的电压跌落场景(如单相跌落、两相短路等)来验证控制策略的有效性与鲁棒性。
【MIMO无线编码】在瑞利衰落信道中比较2x2和4x4的BPSK调制系统(Matlab代码实现)
内容概要:本文通过Matlab代码实现,在瑞利衰落信道环境下对2x2和4x4 MIMO系统采用BPSK调制的性能进行仿真与比较,重点分析不同天线配置下的误码率(BER)表现,旨在探讨MIMO系统中天线数量增加对无线通信可靠性和传输性能的影响。研究涵盖了信道建模、信号调制解调、接收端检测算法等关键环节,并通过蒙特卡洛仿真获得统计结果,直观展示了MIMO技术在对抗多径衰落方面的优势。; 适合人群:具备通信原理基础知识和Matlab编程能力的高校学生、科研人员及从事无线通信系统设计的工程技术人员。; 使用场景及目标:①理解MIMO系统在瑞利衰落信道中的工作原理与性能评估方法;②掌握BPSK调制解调及典型MIMO检测技术的Matlab实现;③通过仿真对比不同规模MIMO系统的性能差异,为系统设计提供参考依据。; 阅读建议:建议读者结合Matlab代码逐段运行并观察仿真结果,深入理解各模块功能,同时可尝试修改参数(如信噪比范围、仿真次数、天线数目)以探究其对系统性能的影响,从而加深对MIMO无线编码技术的认知。


