Smooth X+Y interpolation on data change (HighCharts-like morph animation)

[dmitry-stakhov]

What I'm trying to achieve

When switching between time periods (e.g., 3 months → 6 months), I'd like the chart to smoothly morph all points to their new positions — both X and Y — similar to how HighCharts' redraw() works with its default plotOptions.series.animation.

HighCharts matches points by index, so when the series length stays constant but represents a different date range, points visually compress/expand horizontally while shifting vertically.

Current behavior in Vico

Vico's diff animation (animationSpec) only interpolates Y values. X positions jump instantly to their new layout. So when data changes with different X ranges, the chart "snaps" horizontally while smoothly animating vertically.

My current workaround

I'm passing Y-only values (no explicit X) and ensuring a fixed point count via upsampling/downsampling. This makes Vico distribute points evenly across indices 0..N, so the X positions never change and the Y morph gives an acceptable result.

However, this loses the proportional time spacing — gaps between data points are no longer proportional to actual time intervals.

Question

Is there a way to make CartesianChartHost's diff animation interpolate X positions as well? Or is there a recommended approach for achieving smooth horizontal + vertical morphing when the X range changes?

If not currently supported, would this be something worth considering as a feature — perhaps a CartesianLayerModel transition mode that interpolates both axes?

Environment

• Vico version: 3.1.0
• Compose Multiplatform 1.10.2
• Kotlin Multiplatform (Android + iOS)

[github-actions[bot]]

Hi! Thanks for the detailed write-up.

There is no built-in functionality for interpolating x values during diff animations at the moment — only y values are interpolated, as you noted. It’s something we’d like to look into for a future release.

In the meantime, subclassing the relevant components is, as usual, an option for achieving this on your end.

Since this is a feature request rather than a usage question, I’m moving the discussion to the “Ideas” category.