SakshamSinghal20 opened a new pull request, #21503:
URL: https://github.com/apache/echarts/pull/21503
## Brief Information
This pull request is in the type of:
- [x] bug fixing
- [ ] new feature
- [ ] others
### What does this PR do?
Fixes label positioning bugs in heatmap series when using
`labelLayout.moveOverlap`, ensuring labels only shift when overlapping and stay
within coordinate system bounds.
### Fixed issues
- #21461: When using the moveOverLap attribute for label overlap, the
position should remain within the coordinate system, and in some cases, offsets
are applied unnecessarily
## Details
### Before: What was the problem?
When using `series.labelLayout: { moveOverlap: 'shiftX' | 'shiftY' }` on
Heatmap series with value or time axes, two issues occurred:
1. **Unnecessary shifts**: Labels were shifted even when they had no overlap
2. **Out-of-bounds positioning**: Labels moved outside the coordinate system
instead of staying within axis bounds
**Root causes:**
- `LabelManager.layout()` used canvas dimensions instead of coordinate
system bounds
- `shiftLayoutOnXY()` always eliminated gaps, shifting labels even without
overlaps
### After: How does it behave after the fixing?
**Fixed behavior:**
1. Labels only shift when they actually overlap
2. Labels stay within the coordinate system's plotting area
3. Non-overlapping labels remain in original positions
**Implementation:**
- Modified `LabelManager.ts` to detect Cartesian systems and use plotting
area bounds via `getArea()`
- Modified `labelLayoutHelper.ts` to add overlap detection; if no overlaps,
only clamp to bounds
- Falls back to canvas dimensions for non-Cartesian systems (backward
compatible)
**Changes:**
- `src/label/LabelManager.ts`: Added `getCoordSysBounds()` helper (28 lines)
- `src/label/labelLayoutHelper.ts`: Added overlap detection (35 lines)
- `test/heatmap-label-moveOverlap.html`: New test file
## Document Info
- [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.
### ZRender Changes
- [ ] This PR depends on ZRender changes (ecomfe/zrender#xxx).
### Related test cases or examples to use the new APIs
- `test/heatmap-label-moveOverlap.html`
- `test/issue-21461-fix-demo.html`
### Merging options
- [x] Please squash the commits into a single one when merging.
### Other information
Fully backward compatible, minimal changes (63 lines), tested with
value/time/category axes.
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