Merge pull request #7935 from my-tien/7933-minor-ticklabel-format

fix: Format date tick labels with minor-tick precision when using `ticklabelindex`

Author: camdecoster

draftlogs/7935_fix.md

@@ -0,0 +1 @@
+- Fix tick label format sometimes being incompatible with the labeled tick when using `ticklabelindex` [[#7935](https://github.com/plotly/plotly.js/pull/7935)], with thanks to @my-tien for the contribution!

src/plots/cartesian/axes.js

@@ -716,6 +716,12 @@ axes.prepMinorTicks = function(mockAx, ax, opts) {
         // ensure identical tick0
         mockAx.tick0 = ax.tick0;
     }
+    if (ax._useTicklabelIndex) {
+        // this could always be done but the additional information on the minor
+        // axis is just necessary when using ticklabelindex.
+        autoTickRound(mockAx);
+        ax.minor._tickround = mockAx._tickround;
+    }
 };
 
 function isMultiple(bigger, smaller) {
@@ -1962,7 +1968,7 @@ function tickTextObj(ax, x, text) {
 }
 
 function formatDate(ax, out, hover, extraPrecision) {
-    var tr = ax._tickround;
+    var tr = ax._useTicklabelIndex ? ax.minor._tickround : ax._tickround;
     var fmt = (hover && ax.hoverformat) || axes.getTickFormat(ax);
 
     // Only apply extra precision if no explicit format was provided.

test/image/baselines/date_axes_period2_ticklabelindex.png

@@ -44,7 +44,7 @@
   "layout": {
     "showlegend": false,
     "width": 600,
-    "height": 500,
+    "height": 740,
     "yaxis": {
       "domain": [0, 0.04]
     },