[Bug report] extended_text/lib/src/extended/text_overflow_mixin.dart:461:16 range.end != maxOffset "can' find no overflow"

[msxenon]

Version

15.0.0

Platforms

Web

Device Model

Mac

flutter info

[✓] Flutter (Channel stable, 3.29.2, on macOS 15.3.1 24D70 darwin-arm64, locale en-US) [1,846ms]
    • Flutter version 3.29.2 on channel stable at fvm/versions/3.29.2
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision c236373904 (18 hours ago), 2025-03-13 16:17:06 -0400
    • Engine revision 18b71d647a
    • Dart version 3.7.2
    • DevTools version 2.42.3

How to reproduce?

1. Open the example/lib/pages/custom_text_overflow_demo.dart L50, and paste this _buildText(position: TextOverflowPosition.middle, maxLines: 1),. or just set maxLines to 1.
2. now start the example on web and try to resize from full screen to minimum available width.
3. check the text is truncated and not returning back even when there is available width.

Logs

Example code (optional)

Contact

No response

[zmtzawqlp]

please update to 15.0.1 or 14.2.1,reopen if still has problem

[msxenon]

@zmtzawqlp the bug is still there on 15.0.1

The following assertion was thrown during performLayout():
'package:extended_text/src/extended/text_overflow_mixin.dart': Failed assertion: line 1303 pos 45:
'start <= end': is not true.

The relevant error-causing widget was:
  ExtendedRichText
  ExtendedRichText:file:///xxx/.pub-cache/hosted/pub.dev/extended_text-15.0.1/lib/src/extended/widgets/text.dart:169:16

When the exception was thrown, this was the stack:
#2      new _TextRange (package:extended_text/src/extended/text_overflow_mixin.dart:1303:45)
#3      _TextRange.copyWith (package:extended_text/src/extended/text_overflow_mixin.dart:1313:50)
#4      TextOverflowMixin._findNoOverflow (package:extended_text/src/extended/text_overflow_mixin.dart:485:38)
#5      TextOverflowMixin.layoutOverflow (package:extended_text/src/extended/text_overflow_mixin.dart:120:29)
#6      ExtendedRenderParagraph.performLayout (package:extended_text/src/extended/rendering/paragraph.dart:175:5)
#7      RenderObject.layout (package:flutter/src/rendering/object.dart:2715:7)

[zmtzawqlp]

i didn't reproduce it at my side.

[Anemony22]

I am getting this same issue with the failed assertion as @msxenon . Also during perform layout of a custom widget. I am using the ExtendedText widget in a custom table widget. Inside the table cell, it's within an Expanded in a Row. When I resize the column to be small enough (although still with a good amount of the text showing) I get the error. Nothing visually is broken as far as I can see, it just triggers the assertion.

SEVERE: 2025-06-13 15:43:59.223240: 'package:extended_text/src/extended/text_overflow_mixin.dart': Failed assertion: line 1309 pos 45: 'start <= end': is not true.

[ananya-pathak-sndk]

I am getting a similar issue. Following are the logs recorded.

The following assertion was thrown during performLayout():
'package:extended_text/src/extended/text_overflow_mixin.dart': Failed assertion: line 1309 pos 45:
'start <= end': is not true.

The relevant error-causing widget was:
  ExtendedRichText
  ExtendedRichText:file:///[xxxx]/.pub-cache/hosted/pub.dev/extended_text-15.0.2/lib/src/extended/widgets/text.dart:169:16

When the exception was thrown, this was the stack:
#2      new _TextRange (package:extended_text/src/extended/text_overflow_mixin.dart:1309:45)
#3      _TextRange.copyWith (package:extended_text/src/extended/text_overflow_mixin.dart:1319:50)
#4      TextOverflowMixin._findNoOverflow (package:extended_text/src/extended/text_overflow_mixin.dart:491:38)
#5      TextOverflowMixin.layoutOverflow (package:extended_text/src/extended/text_overflow_mixin.dart:126:29)
#6      ExtendedRenderParagraph.performLayout (package:extended_text/src/extended/rendering/paragraph.dart:175:5)
#7      RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#8      RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:115:18)
#9      RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#10     RenderPadding.performLayout (package:flutter/src/rendering/shifted_box.dart:243:12)
#11     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#12     ChildLayoutHelper.layoutChild (package:flutter/src/rendering/layout_helper.dart:62:11)
#13     RenderFlex._computeSizes (package:flutter/src/rendering/flex.dart:1161:28)
#14     RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:1257:32)
#15     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#16     ChildLayoutHelper.layoutChild (package:flutter/src/rendering/layout_helper.dart:62:11)
#17     RenderFlex._computeSizes (package:flutter/src/rendering/flex.dart:1203:26)
#18     RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:1257:32)
#19     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#20     ChildLayoutHelper.layoutChild (package:flutter/src/rendering/layout_helper.dart:62:11)
#21     RenderFlex._computeSizes (package:flutter/src/rendering/flex.dart:1203:26)
#22     RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:1257:32)
#23     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#24     RenderPadding.performLayout (package:flutter/src/rendering/shifted_box.dart:243:12)
#25     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#26     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:115:18)
#27     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#28     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:115:18)
#29     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#30     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:115:18)
#31     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#32     ChildLayoutHelper.layoutChild (package:flutter/src/rendering/layout_helper.dart:62:11)
#33     RenderFlex._computeSizes (package:flutter/src/rendering/flex.dart:1161:28)
#34     RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:1257:32)
#35     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#36     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:115:18)
#37     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#38     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:115:18)
#39     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#40     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:115:18)
#41     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#42     RenderSliverFixedExtentBoxAdaptor.performLayout (package:flutter/src/rendering/sliver_fixed_extent_list.dart:354:19)
#43     _RenderSliverPrototypeExtentList.performLayout (package:flutter/src/widgets/sliver_prototype_extent_list.dart:273:11)
#44     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#45     RenderProxySliver.performLayout (package:flutter/src/rendering/proxy_sliver.dart:63:12)
#46     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#47     RenderMultiSliver.layoutChild (package:sliver_tools/src/rendering/multi_sliver.dart:292:13)
#48     RenderMultiSliver._layoutChildSequence (package:sliver_tools/src/rendering/multi_sliver.dart:154:31)
#49     RenderMultiSliver.performLayout (package:sliver_tools/src/rendering/multi_sliver.dart:90:24)
#50     RenderObject.layout (package:flutter/src/rendering/object.dart:2762:7)
#51     RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:673:13)
#52     RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1684:12)
#53     RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1575:20)
#54     RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:2610:7)
#55     PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:1157:18)
#56     PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:1170:15)
#57     RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:629:23)
#58     WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:1261:13)
#59     RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:495:5)
#60     SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1434:15)
#61     SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1347:9)
#62     SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:1200:5)
#66     _invoke (dart:ui/hooks.dart:332:10)
#67     PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:444:5)
#68     _drawFrame (dart:ui/hooks.dart:302:31)
(elided 5 frames from class _AssertionError and dart:async)

The following RenderObject was being processed when the exception was fired: ExtendedRenderParagraph#23217 relayoutBoundary=up10 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE:
  creator: ExtendedRichText ← ExtendedText-[<'199y1201 Letter from Amy Hunter.jpg'>] ← Semantics ←
    BodyText ← EntityMetadataBuilder ← FileEntityNameBuilder ← FileItemName ← Padding ← Flex ←
    Expanded ← Row ← Expanded ← ⋯
  parentData: <none> (can use size)
  constraints: BoxConstraints(0.0<=w<=274.0, 0.0<=h<=Infinity)
  size: Size(274.0, 20.0)
  textAlign: start
  textDirection: ltr
  softWrap: wrapping at box width
  overflow: clip
  textScaler: SystemTextScaler (no scaling) clamped [0.0, 1.5]
  locale: en
  maxLines: 1
This RenderObject had the following child:
    text: TextSpan

[cherry98]

I am getting a similar issue.

Additional reproduction (extended_text 15.0.2, macOS desktop)

We hit the same start <= end assertion in text_overflow_mixin.dart:1309 with TextOverflowPosition.middle.

Trigger: text is exactly "Photo Print" (two equal-length words), with a medium-narrow max width (~70–90px at fontSize: 14). Not only at extremely narrow widths.

Does NOT reproduce with the same layout: "New Project", "New ProjectProject", or other strings of similar/greater length.

Minimal case:

SizedBox(
  width: 83,
  child: ExtendedText.rich(
    TextSpan(text: 'Photo Print'),
    maxLines: 1,
    style: TextStyle(fontSize: 14),
    overflowWidget: TextOverflowWidget(
      position: TextOverflowPosition.middle,
      child: Text('...'),
    ),
  ),
)

@zmtzawqlp Please help handle it.

[ggvle]

For the same issue, AI says the reason is a bug in the TextOverflowPosition.middle algorithm in extended_text 15.0.2: it calculates the character range on either side of the ellipsis by subtracting the width already used by each line from the total line width, and when this available width gets very small (even smaller than the ellipsis itself), the calculated start ends up greater than end, which triggers an assert(start <= end) in the _TextRange constructor and throws an exception.