Fix multielements (#987)

src/points.ts

@@ -0,0 +1,46 @@
+import { Point } from "./types";
+
+export function getSizeFromPoints(points: readonly Point[]) {
+  const xs = points.map(point => point[0]);
+  const ys = points.map(point => point[1]);
+  return {
+    width: Math.max(...xs) - Math.min(...xs),
+    height: Math.max(...ys) - Math.min(...ys),
+  };
+}
+export function rescalePoints(
+  dimension: 0 | 1,
+  nextDimensionSize: number,
+  prevPoints: readonly Point[],
+): readonly Point[] {
+  const prevDimValues = prevPoints.map(point => point[dimension]);
+  const prevMaxDimension = Math.max(...prevDimValues);
+  const prevMinDimension = Math.min(...prevDimValues);
+  const prevDimensionSize = prevMaxDimension - prevMinDimension;
+
+  const dimensionScaleFactor = nextDimensionSize / prevDimensionSize;
+
+  let nextMinDimension = Infinity;
+
+  const scaledPoints = prevPoints.map(prevPoint =>
+    prevPoint.map((value, currentDimension) => {
+      if (currentDimension !== dimension) {
+        return value;
+      }
+      const scaledValue = value * dimensionScaleFactor;
+      nextMinDimension = Math.min(scaledValue, nextMinDimension);
+      return scaledValue;
+    }),
+  );
+
+  const translation = prevMinDimension - nextMinDimension;
+
+  const nextPoints = scaledPoints.map(
+    scaledPoint =>
+      scaledPoint.map((value, currentDimension) => {
+        return currentDimension === dimension ? value + translation : value;
+      }) as [number, number],
+  );
+
+  return nextPoints;
+}