Apply data label font properties to scatter chart dLbls XML (#1348)

[rupivbluegreen]

Change Summary

Fixes #1348. Scatter charts now respect dataLabelFontSize / dataLabelFontFace / dataLabelColor / dataLabelFontBold / dataLabelFontItalic in PowerPoint by emitting populated <a:defRPr> blocks where the code previously emitted bare <a:defRPr/>.

Change Type

• Bug fix
• New feature
• Documentation update

Related Issue

Closes #1348 — Scatter plot data label font size not working

Motivation and Context

In src/gen-charts.ts, the scatter chart's data-label section emits four <a:pPr> blocks containing bare <a:defRPr/> elements:

1. main label paragraph (dataLabelFormatScatter: 'custom' | 'customXY')
2. X-value field paragraph (customXY)
3. Y-value field paragraph (customXY)
4. XY-format dLbls txPr paragraph ('XY')

With these <a:defRPr/> empty, PowerPoint falls back to its own defaults for the scatter label rich text — ignoring the user-supplied dataLabel* chart options. Line/bar/pie data labels in the same file already emit a populated defRPr (see gen-charts.ts:882-886, 1003-1005, 1303-1305, etc.); the scatter chart was the only remaining holdout.

A user attached the same diff in a comment on the issue page.

Change Description

Each of the four bare <a:defRPr/> emissions is replaced with the populated form already used elsewhere in this file:

strXml += `<a:defRPr sz="${Math.round((opts.dataLabelFontSize || DEF_FONT_SIZE) * 100)}" b="${opts.dataLabelFontBold ? 1 : 0}" i="${opts.dataLabelFontItalic ? 1 : 0}" u="none" strike="noStrike">`
strXml += `    <a:solidFill>${createColorElement(opts.dataLabelColor || DEF_FONT_COLOR)}</a:solidFill>`
strXml += `    <a:latin typeface="${opts.dataLabelFontFace || 'Arial'}"/>`
strXml += `</a:defRPr>`

When the user doesn't specify these options, the result is identical to the previous behavior (font size = DEF_FONT_SIZE, font face = Arial, color = DEF_FONT_COLOR, bold/italic = off, underline/strike = none) — no regression for callers that don't set the options.

Verification

Generated a scatter chart with both customXY and XY label formats, all five dataLabel* font options set, and inspected the produced chart XML:

PASS  #1348 dataLabelFontSize=6 surfaces as sz="600"
PASS  #1348 dataLabelFontBold surfaces as b="1"
PASS  #1348 dataLabelFontItalic surfaces as i="1"
PASS  #1348 dataLabelColor surfaces as solidFill srgbClr FF0000
PASS  #1348 dataLabelFontFace surfaces as latin typeface="Courier New"
PASS  #1348 no bare empty <a:defRPr/> remain in scatter dLbls block

On master (without the fix) the bare <a:defRPr/> check fails — 16 empty defRPr instances remain across the two charts, matching the source of the bug. npx eslint src/gen-charts.ts reports the same one pre-existing warning (isMultiTypeChart unused), no new warnings introduced.

Checklist

• Style guidelines followed (tabs, single quotes, no semicolons)
• No new eslint warnings on modified file
• Self-review performed
• Comment added explaining why the font properties are emitted at this level (Scatter plot data label font size not working #1348)
• Verification harness confirms the fix and reproduces the bug on master
• Only src/*.ts modified — no dist / src/bld changes