The chart that printed blank

A race between chart animation and a screenshot, diagnosed from both sides in one day.

Charts loaded through the incremental path rendered blank in the print PDF. On the page side, the placeholder chart had no type and the update path only updated, so a chart whose type changed was never recreated. On the print side, the screenshot fired while the animation was still drawing.

sequenceDiagram
  participant S as Print service
  participant P as Page
  participant C as Chart
  S->>P: open the page
  P->>C: update data (type changed, chart not recreated)
  C->>C: animation starts
  S->>P: screenshot before the animation ends
  Note over S,C: blank canvas in the PDF

Both were fixed the same day: recreate the chart when the type changes, and on the print side wait for a real type and draw the final frame with animation off.

Takeaway

The blank canvas was telling the truth. It had simply been photographed too early.

Client engagement, 2021 to 2026. Names, identifiers and internals are generalised.