Tweak grid interval calculation to avoid fragments

oblador · Dec 2, 2019 · 29471a2 · 29471a2
1 parent 923b9a2
commit 29471a2
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Showing 2 changed files with 10 additions and 4 deletions.
diff --git a/src/lib/getGridIntervals.js b/src/lib/getGridIntervals.js
@@ -1,9 +1,13 @@
 export const getGridInterval = (maxValue, numberOfIntervals) => {
-  const granularity = Math.pow(10, Math.ceil(Math.log10(maxValue)) - 2) || 1;
-  const roundedMax = Math.round(
-    Math.ceil(maxValue / granularity) * granularity
+  const magnitude = Math.pow(10, Math.ceil(Math.log10(maxValue)) - 1);
+  const granularity = Math.max(
+    1,
+    magnitude * 3 > maxValue ? magnitude / 20 : magnitude / 10
+  );
+
+  return Math.round(
+    Math.ceil(maxValue / (numberOfIntervals - 1) / granularity) * granularity
   );
-  return roundedMax / (numberOfIntervals - 1);
 };
 
 export const getGridIntervals = (maxValue, numberOfIntervals) => {

diff --git a/src/lib/getGridIntervals.spec.js b/src/lib/getGridIntervals.spec.js
@@ -9,5 +9,7 @@ describe('getGridIntervals', () => {
   it('returns nicely rounded intervals', () => {
     expect(getGridIntervals(123, 3)).toEqual([0, 65, 130]);
     expect(getGridIntervals(2123, 5)).toEqual([0, 550, 1100, 1650, 2200]);
+    expect(getGridIntervals(8020, 5)).toEqual([0, 2100, 4200, 6300, 8400]);
+    expect(getGridIntervals(809, 5)).toEqual([0, 210, 420, 630, 840]);
   });
 });