eschutho opened a new pull request, #35806:
URL: https://github.com/apache/superset/pull/35806
### SUMMARY
Fixes the "Clipped area is either empty or outside the resulting image"
error that occurs when generating tiled screenshots for large dashboards (50+
charts).
**Root Cause:**
When scrolling through tall dashboards to capture tiles,
`getBoundingClientRect()` returns negative Y coordinates for elements scrolled
above the viewport. Playwright rejects these invalid clip coordinates, causing
the screenshot to fail.
**Solution:**
- Add comprehensive viewport bounds tracking and validation
- Clamp clip coordinates to always be within viewport (≥0)
- Calculate visible portions when elements are partially scrolled off-screen
- Skip invalid tiles with warnings instead of crashing
- Validate all clip dimensions before calling `page.screenshot()`
**Changes:**
- `superset/utils/screenshot_utils.py`: Enhanced clip validation logic
(lines 142-205)
- `tests/unit_tests/utils/test_screenshot_utils.py`: Added 6 new edge case
tests
**Test Coverage:**
All 21 unit tests passing, including new tests for:
- Negative element positions (scrolled above viewport)
- Elements extending beyond viewport boundaries
- Invalid clip dimensions (zero/negative width/height)
- Elements completely scrolled out of view
- Zero-width elements
### BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF
**BEFORE:**
```
playwright._impl._errors.Error: Page.screenshot: Clipped area is either
empty or outside the resulting image
Call log:
taking page screenshot
- waiting for fonts to load...
- fonts loaded
```
Tiled screenshot fails → Falls back to single screenshot → Empty PDF for
large dashboards
**AFTER:**
- Tiled screenshots complete successfully for dashboards with 50+ charts
- No more clip validation errors
- Invalid tiles are gracefully skipped with warnings
### TESTING INSTRUCTIONS
1. **Unit Tests:**
```bash
pytest tests/unit_tests/utils/test_screenshot_utils.py -v
```
All 21 tests should pass
2. **Manual Testing (requires large dashboard):**
- Create a dashboard with 50+ charts (one per row)
- Enable tiled screenshots:
```python
SCREENSHOT_TILED_ENABLED = True
SCREENSHOT_TILED_CHART_THRESHOLD = 20
```
- Generate a screenshot/report for the dashboard
- Verify: No "Clipped area" errors in logs
- Verify: PDF/image is generated correctly (not empty)
3. **Verify Logs:**
- Should see "Large dashboard detected" and "Using tiled screenshots"
messages
- Should NOT see clip validation errors
- May see "Skipping tile X/Y - invalid clip dimensions" warnings
(expected for edge cases)
### ADDITIONAL INFORMATION
- [ ] Has associated issue:
- [ ] Required feature flags: `SCREENSHOT_TILED_ENABLED=True` (optional, for
testing)
- [ ] Changes UI
- [ ] Includes DB Migration (follow approval process in
[SIP-59](https://github.com/apache/superset/issues/13351))
- [ ] Migration is atomic, supports rollback & is backwards-compatible
- [ ] Confirm DB migration upgrade and downgrade tested
- [ ] Runtime estimates and downtime expectations provided
- [ ] Introduces new feature or API
- [ ] Removes existing feature or API
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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