A functional toolkit for authoring resource-leveling algorithms — compose constraint and scoring blocks, enumerate feasible schedules
feat(xlsx): alternating row-band shading in Gantt plot area
Paint alternating white / light-gray horizontal bands behind the Gantt
bars, one band per category, so task rows are visually separated in the
exported workbook. Implemented as a hard-step gradient fill on the plot
area (<c:spPr>) with duplicated stop positions per band and a 90deg
top-to-bottom angle aligned to the catAx maxMin orientation.
Russ T. Fugal
(Jun 4, 2026, 5:48 PM -0600)
bd07df1b
58216c9a
+36
+32
src/xlsx/XlsxWriter.ts
+32
src/xlsx/XlsxWriter.ts
···
288
288
return zip.generateAsync({ type: "arraybuffer", compression: "DEFLATE" });
289
289
}
290
290
291
+
/**
292
+
* Builds a gradient-fill `<c:spPr>` for the plot area that produces
293
+
* alternating horizontal row bands (white / light gray), one band per
294
+
* category. Each adjacent stop pair uses identical positions so the
295
+
* gradient becomes a hard step transition.
296
+
*/
297
+
function buildPlotShadingXml(n: number): string {
298
+
if (n <= 0) return "";
299
+
const EVEN = "FFFFFF";
300
+
const ODD = "F4F4F4";
301
+
const stops: string[] = [];
302
+
for (let i = 0; i < n; i += 1) {
303
+
const startPos = Math.round((i / n) * 100000);
304
+
const endPos = Math.round(((i + 1) / n) * 100000);
305
+
const color = i % 2 === 0 ? EVEN : ODD;
306
+
stops.push(`<a:gs pos="${startPos}"><a:srgbClr val="${color}"/></a:gs>`);
307
+
stops.push(`<a:gs pos="${endPos}"><a:srgbClr val="${color}"/></a:gs>`);
308
+
}
309
+
return (
310
+
"<c:spPr>" +
311
+
'<a:gradFill rotWithShape="1">' +
312
+
`<a:gsLst>${stops.join("")}</a:gsLst>` +
313
+
// 5400000 = 90° in 60000ths of a degree = top-to-bottom gradient.
314
+
// catAx uses orientation="maxMin", so band i=0 lands on the top row.
315
+
'<a:lin ang="5400000" scaled="0"/>' +
316
+
"</a:gradFill>" +
317
+
"<a:ln><a:noFill/></a:ln>" +
318
+
"</c:spPr>"
319
+
);
320
+
}
321
+
291
322
function buildChartXml({ items, origin, end, title, dataSheetName }: InjectArgs): string {
292
323
const n = items.length;
293
324
const lastRow = n + 1;
···
372
403
'<c:crossAx val="111111111"/>' +
373
404
'<c:majorUnit val="30"/>' +
374
405
"</c:valAx>" +
406
+
buildPlotShadingXml(n) +
375
407
"</c:plotArea>" +
376
408
'<c:plotVisOnly val="1"/><c:dispBlanksAs val="gap"/>' +
377
409
"</c:chart></c:chartSpace>"
+4
test/xlsx.test.ts
+4
test/xlsx.test.ts
···
148
148
expect(chartXml).toContain('val="4472C4"');
149
149
// Phase 2 color on the duration data points
150
150
expect(chartXml).toContain('val="ED7D31"');
151
+
// Plot area row shading: gradient with alternating white / light-gray bands.
152
+
expect(chartXml).toContain("<a:gradFill");
153
+
expect(chartXml).toContain('val="FFFFFF"');
154
+
expect(chartXml).toContain('val="F4F4F4"');
151
155
152
156
const drawingFile = zip.file("xl/drawings/drawing1.xml");
153
157
expect(drawingFile).not.toBeNull();