stackOffsetSilhouette function Stack offsets Stacks
Shifts the baseline down such that the center of the streamgraph is always at zero.
final stack = Stack(…)..offset = stackOffsetSilhouette;
Implementation
void stackOffsetSilhouette(List<List<List<num>>> series, List<int> order) {
int n;
if (!((n = series.length) > 0)) return;
num y0, y;
for (var j = 0, s0 = series[order[0]], m = s0.length; j < m; ++j) {
y = 0;
for (var i = 0; i < n; ++i) {
y0 = series[i][j][1];
if (y0.isFinite) y += y0;
}
s0[j][1] += s0[j][0] = -y / 2;
}
stackOffsetNone(series, order);
}