sfirke opened a new issue, #45488:
URL: https://github.com/apache/superset/issues/45488
### Bug description
(I found this issue by hand, then wrote it up with Claude AI. I edited and
am posting this by hand having read it all)
In 7.0.0rc2, a Timeseries chart whose Legend Type is **List** and Legend
Orientation is **Top** or **Bottom** draws every legend item as the same filled
12px square. That includes data series and annotation layers, and solid and
dashed lines alike. In 6.1.0 the legend icon reflected the series: a line with
its marker, drawn in the series' line style.
The practical loss is the line style. Our chart of PFAS concentrations has
two Formula annotation layers: a solid red line for a regulatory limit (8 ppt)
and a dashed gold line for the lab reporting limit (2 ppt). In 6.1.0 the legend
showed the dashed one as dashed, so readers could match legend to line by style
as well as color. In 7.0.0rc2 both are plain colored squares, and so is the
data series.
This comes from #43314, which renders List Top/Bottom legends as HTML
outside the ECharts canvas
(`superset-frontend/plugins/plugin-chart-echarts/src/Timeseries/TimeseriesLegend.tsx`).
The swatch is a fixed square that only knows the series color:
```ts
const Swatch = styled.span<{ color: string; selected: boolean }>`
${({ color, selected }) => `
background: ${selected ? color : 'transparent'};
border: 1px solid ${color};
...
height: 12px;
width: 12px;
`}
`;
```
The PR fixes a real problem (long legends painting over the plot), and I'm
not suggesting reverting it. But its testing instructions say a chart with only
a few legend entries should be "unaffected". The icons are a visible change for
every such chart. Other legend types (Scroll), Left/Right orientation, and
other chart plugins still use the ECharts legend, so legend icons are now
inconsistent between charts on the same dashboard depending on a legend setting.
This affects ~99 charts in my deployment.
**How to reproduce**
1. Create a Line Chart with a metric and a Formula annotation layer with
Style "Dashed" (e.g. value `2`).
2. Under Customize, set Legend Type to List and Legend Orientation to Top.
3. The legend shows a filled square for the metric and for the annotation;
the annotation isn't shown as dashed.
4. Switch Legend Type to Scroll: the legend shows ECharts' usual line-series
icons again. (Sam: I confirmed this)
5. Compare with 6.1.0, where the List legend shows the same icons as Scroll.
**Expected behavior**
The legend icon reflects the series it labels, as in 6.1.0 and as the Scroll
legend still does: at least the line style (solid/dashed/dotted) and ideally
the symbol. Ideally line series (including annotation lines) show as a short
line segment in their style, so a dashed annotation line is recognizable in the
legend.
**Proposed fix**
`buildTimeseriesCustomLegend` already receives the final series. It could
pass each item's series type, symbol and `lineStyle.type` to
`TimeseriesLegend`, and `Swatch` could render a small inline SVG (a line
segment in the right dash style, plus the symbol) instead of a fixed square.
Bar and area series could keep a filled square.
### Screenshots/recordings
6.1.0 has the right symbol/line weight and dashing:
<img width="1540" height="477" alt="Image"
src="https://github.com/user-attachments/assets/432eaf93-ff73-4603-9058-0a1e1f43aac3";
/>
7.0.0rc2 is missing it:
<img width="1552" height="505" alt="Image"
src="https://github.com/user-attachments/assets/651b416e-1401-402e-a632-09260e59db38";
/>
### Superset version
master / latest-dev
### Python version
Not applicable
### Node version
Not applicable
### Browser
Not applicable
### Additional context
- Superset 7.0.0rc2, Docker image built from the release. Works as expected
on 6.1.0.
- Introduced by #43314 (render Plain Timeseries legends as HTML, not canvas).
- Annotation layers aren't the trigger; a chart with no annotations and a
Plain Top legend also gets squares.
### Checklist
- [ ] I have searched Superset docs and Slack and didn't find a solution to
my problem.
- [x] I have searched the GitHub issue tracker and didn't find a similar bug
report.
- [x] I have checked Superset's logs for errors and if I found a relevant
Python stacktrace, I included it here as text in the "additional context"
section.
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