fix(splitter): preserve pane sizes after collapse - 22.1.x - #17554
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kdinev
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🟢 Approval recommended
The behavioral change is narrowly scoped to collapse/expand sizing, aligns with the reported issue/acceptance criteria, and is covered by targeted unit tests for the key scenarios.
Pull request overview
This PR fixes IgxSplitterPane collapse/expand behavior so panes retain their configured sizes (and min/max constraints) after being collapsed and then expanded, addressing #17545 and preventing sibling panes from being reset to size="auto".
Changes:
- Removed the “reset all pane sizes when any pane is collapsed” initialization behavior in
IgxSplitterComponent. - Updated
IgxSplitterPaneComponentcollapse handling to preserve configured sizes, clear only temporarydragSize, and allow adjacent fixed-size panes to flex-grow while a sibling is collapsed. - Added/updated unit tests to cover horizontal/vertical splitters, fixed-size behavior during collapse, initially-collapsed panes, and drag-size cleanup.
File summaries
| File | Description |
|---|---|
| projects/igniteui-angular/splitter/src/splitter/splitter.component.ts | Stops resetting pane sizes during pane initialization when panes are collapsed, enabling size preservation across collapse/expand. |
| projects/igniteui-angular/splitter/src/splitter/splitter.component.spec.ts | Adds coverage validating size preservation, fixed-size fill behavior during collapse, initial-collapse constraints, and dragSize cleanup. |
| projects/igniteui-angular/splitter/src/splitter/splitter-pane/splitter-pane.component.ts | Preserves size on collapse, clears only sibling dragSize, and adjusts flex-grow logic to let adjacent panes fill released space while collapsed. |
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- Files reviewed: 3/3 changed files
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- Review effort level: Lite
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kdinev
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Sep 8, 2026
kdinev
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Sep 8, 2026
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Closes #17545
Description
This PR prevents
IgxSplitterPanefrom losing its configured size after being collapsed and expanded.Previously, collapsing a pane reset its siblings to
size="auto", which caused horizontal panes to lose their previous width. The updated behavior:Testing
Added coverage for horizontal and vertical splitters, fixed-size panes, initial collapse, and temporary drag-size cleanup.
Motivation / Context
Type of Change (check all that apply):
Component(s) / Area(s) Affected:
How Has This Been Tested?
Test Configuration:
Screenshots / Recordings
Checklist:
feature/README.MDupdates for the feature docsREADME.MDCHANGELOG.MDupdates for newly added functionalityng updatemigrations for the breaking changes (migrations guidelines)