Srajan-Sanjay-Saxena opened a new pull request, #21376:
URL: https://github.com/apache/echarts/pull/21376
fix(axis): honor showMinLabel/showMaxLabel for broken axis with time/value
scales
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## Brief Information
This pull request is in the type of:
- [x] bug fixing
- [ ] new feature
- [ ] others
### What does this PR do?
Fixes broken axis ignoring showMinLabel/showMaxLabel options on time/value
axes, causing extent boundary labels to disappear when breaks are positioned
nearby.
### Fixed issues
- Fixes issue where axisLabel.showMinLabel: true was not honored on broken
axes
- Resolves 00:00 label disappearing with time axis when break starts at 02:00
## Details
### Before: What was the problem?
When using a line chart with a broken axis (time or value scale):
- Setting `axisLabel: { showMinLabel: true }` had no effect
- Extent boundary labels (e.g., 00:00) would disappear when breaks were
positioned close to them
- Example: axis from 00:00 to 23:59:59 with break from 02:00 to 09:00 would
not show the 00:00 label
- Moving the break to 03:00 would make 00:00 appear (inconsistent behavior)
- Only affected time/value axes; category axes worked correctly
**Root Cause:**
The makeRealNumberLabels() function in axisTickLabelBuilder.ts lacked the
logic to honor showMinLabel/showMaxLabel options, unlike the category axis
implementation (makeLabelsByNumericCategoryInterval). When pruneTicksByBreak()
executed during scale.getTicks(), it removed ticks within a gap distance
(interval * 3/4) of break boundaries to prevent visual overlap with zigzag
break indicators. This pruning could inadvertently remove extent boundary ticks
when breaks were positioned near the axis start or end.
**Example Issue Breakdown:**
- Axis extent: 00:00 to 23:59:59 with 2-hour interval
- Break: 02:00 to 09:00
- Pruning gap: 2h * 3/4 = 1.5 hours
- Buffer zone: (02:00 - 1.5h = 00:30) to (02:00 + 1.5h = 03:30)
- Result: 00:00 label disappeared because it fell within the pruning gap
- Workaround: Setting break at 03:00 would show 00:00 (falls outside gap)
### After: How does it behave after the fixing?
- `showMinLabel` and `showMaxLabel` options are now properly respected on
time and value axes with breaks
- Extent boundary labels display consistently regardless of break positioning
- The fix uses `pruneByBreak: 'preserve_extent_bound'` mode which protects
extent boundary ticks from removal
- Defensively adds min/max labels if they're missing or if first/last tick
is a break marker
- Time axis metadata is preserved for proper label formatting
- Behavior now matches category axis implementation
**Solution Implementation:**
1. Added showMinLabel/showMaxLabel option checking in makeRealNumberLabels()
2. Pass pruneByBreak: 'preserve_extent_bound' to scale.getTicks() when these
options are enabled, instructing the pruning logic to skip extent boundary
ticks even if they fall within the gap zone
3. Defensively add missing min/max labels if the first/last tick is a break
marker or not positioned at the extent boundary
4. Preserve time metadata when adding extent labels for proper formatting on
time axes
This aligns real number/time axis behavior with the existing category axis
implementation and ensures consistent label display regardless of break
positioning.
## Document Info
One of the following should be checked.
- [x] This PR doesn't relate to document changes
- [ ] The document should be updated later
- [ ] The document changes have been made in apache/echarts-doc#xxx
## Misc
### Security Checking
- [x] This PR uses security-sensitive Web APIs.
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### ZRender Changes
- [x] This PR depends on ZRender changes (ecomfe/zrender#xxx).
### Related test cases or examples to use the new APIs
Test case: Line chart with time axis (00:00 to 23:59:59), break from 02:00
to 09:00, axisLabel.showMinLabel: true should display 00:00 label.
### Merging options
- [x] Please squash the commits into a single one when merging.
### Other information
This fix aligns the real number/time axis implementation with the existing
category axis behavior, ensuring feature parity across all axis types. The
change is backward compatible and only affects behavior when
showMinLabel/showMaxLabel is explicitly set with broken axes.
## I am attaching a video of the fix
https://github.com/user-attachments/assets/c94e784f-f623-4ffb-b0bf-47a2fc17eee6
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