Coordinating chart animations

Animation carries a chart from one state to another through a sequence of intermediate values. Depending on what changes, those values may reshape plotted data, move the viewport, adjust a scale domain, or blend prepared representations. Although these changes appear as one transition, SwiftUI and Swift Charts consume them at different points in the update process.

A resolved SwiftUI layer can interpolate presentation properties without reconstructing the chart content. Viewport positions and scale domains are applied through modifiers that configure the chart, whereas plotted values are read when Swift Charts constructs marks and plots. Coordinating an animation requires each changing value to reach the part of the system that uses it.

Many transitions combine these paths. A change to the visible interval may require a new vertical domain, and a move from overview to detail may replace summary values with finer-grained observations. Their intermediate states must remain synchronized so the data, scales, and viewport describe the same moment throughout the animation, not only after it finishes.