revise dtick in respect to tickformat on period labels only when we could reduce ticks

 - revert changes of date_axes baseline
 - update date_axes2 baseline
 - fixup jasmine tests

Author: archmoj

src/plots/cartesian/axes.js

@@ -606,6 +606,7 @@ axes.calcTicks = function calcTicks(ax, opts) {
     }
 
     var isDLog = (ax.type === 'log') && !(isNumeric(ax.dtick) || ax.dtick.charAt(0) === 'L');
+    var isMDate = (ax.type === 'date') && !(isNumeric(ax.dtick) || ax.dtick.charAt(0) === 'M');
 
     var tickformat = axes.getTickFormat(ax);
     var isPeriod = ax.ticklabelmode === 'period';
@@ -628,12 +629,12 @@ axes.calcTicks = function calcTicks(ax, opts) {
                 // %I: hour (12-hour clock) as a decimal number [01,12]
             ) {
                 definedDelta = ONEHOUR;
-                if(noDtick) ax.dtick = ONEHOUR;
+                if(noDtick && !isMDate && ax.dtick < ONEHOUR) ax.dtick = ONEHOUR;
             } else if(
                 /%p/.test(tickformat) // %p: either AM or PM
             ) {
                 definedDelta = HALFDAY;
-                if(noDtick) ax.dtick = HALFDAY;
+                if(noDtick && !isMDate && ax.dtick < HALFDAY) ax.dtick = HALFDAY;
             } else if(
                 /%[Aadejuwx]/.test(tickformat)
                 // %A: full weekday name
@@ -646,36 +647,36 @@ axes.calcTicks = function calcTicks(ax, opts) {
                 // %x: the locale’s date, such as %-m/%-d/%Y
             ) {
                 definedDelta = ONEDAY;
-                if(noDtick) ax.dtick = ONEDAY;
+                if(noDtick && !isMDate && ax.dtick < ONEDAY) ax.dtick = ONEDAY;
             } else if(
                 /%[UVW]/.test(tickformat)
                 // %U: Sunday-based week of the year as a decimal number [00,53]
                 // %V: ISO 8601 week of the year as a decimal number [01, 53]
                 // %W: Monday-based week of the year as a decimal number [00,53]
             ) {
                 definedDelta = ONEWEEK;
-                if(noDtick) ax.dtick = ONEWEEK;
+                if(noDtick && !isMDate && ax.dtick < ONEWEEK) ax.dtick = ONEWEEK;
             } else if(
                 /%[Bbm]/.test(tickformat)
                 // %B: full month name
                 // %b: abbreviated month name
                 // %m: month as a decimal number [01,12]
             ) {
                 definedDelta = ONEAVGMONTH;
-                if(noDtick) ax.dtick = 'M1';
+                if(noDtick && ax.dtick < (isMDate ? 'M1' : ONEMINMONTH)) ax.dtick = 'M1';
             } else if(
                 /%[q]/.test(tickformat)
                 // %q: quarter of the year as a decimal number [1,4]
             ) {
                 definedDelta = ONEAVGQUARTER;
-                if(noDtick) ax.dtick = 'M3';
+                if(noDtick && ax.dtick < (isMDate ? 'M3' : ONEMINQUARTER)) ax.dtick = 'M3';
             } else if(
                 /%[Yy]/.test(tickformat)
                 // %Y: year with century as a decimal number, such as 1999
                 // %y: year without century as a decimal number [00,99]
             ) {
                 definedDelta = ONEAVGYEAR;
-                if(noDtick) ax.dtick = 'M12';
+                if(noDtick && ax.dtick < (isMDate ? 'M12' : ONEMINYEAR)) ax.dtick = 'M12';
             }
         }
     }

test/image/baselines/date_axes.png

@@ -5625,13 +5625,13 @@ describe('Test axes', function() {
         [
             {
                 formatter: '%H',
-                positions: ['2019-12-31 23:30', '2020-01-01 00:30', '2020-01-01 01:30', '2020-01-01 02:30', '2020-01-01 03:30', '2020-01-01 04:30', '2020-01-01 05:30', '2020-01-01 06:30', '2020-01-01 07:30', '2020-01-01 08:30', '2020-01-01 09:30', '2020-01-01 10:30', '2020-01-01 11:30', '2020-01-01 12:30', '2020-01-01 13:30', '2020-01-01 14:30', '2020-01-01 15:30', '2020-01-01 16:30', '2020-01-01 17:30', '2020-01-01 18:30', '2020-01-01 19:30', '2020-01-01 20:30', '2020-01-01 21:30', '2020-01-01 22:30', '2020-01-01 23:30', '2020-01-02 00:30', '2020-01-02 01:30'],
-                labels: ['Tue-23', 'Wed-00', 'Wed-01', 'Wed-02', 'Wed-03', 'Wed-04', 'Wed-05', 'Wed-06', 'Wed-07', 'Wed-08', 'Wed-09', 'Wed-10', 'Wed-11', 'Wed-12', 'Wed-13', 'Wed-14', 'Wed-15', 'Wed-16', 'Wed-17', 'Wed-18', 'Wed-19', 'Wed-20', 'Wed-21', 'Wed-22', 'Wed-23', 'Thu-00', ' ']
+                positions: ['2019-12-31 21:30', '2020-01-01 00:30', '2020-01-01 03:30', '2020-01-01 06:30', '2020-01-01 09:30', '2020-01-01 12:30', '2020-01-01 15:30', '2020-01-01 18:30', '2020-01-01 21:30', '2020-01-02 00:30'],
+                labels: [' ', 'Wed-00', 'Wed-03', 'Wed-06', 'Wed-09', 'Wed-12', 'Wed-15', 'Wed-18', 'Wed-21', 'Thu-00']
             },
             {
                 formatter: '%I',
-                positions: ['2019-12-31 23:30', '2020-01-01 00:30', '2020-01-01 01:30', '2020-01-01 02:30', '2020-01-01 03:30', '2020-01-01 04:30', '2020-01-01 05:30', '2020-01-01 06:30', '2020-01-01 07:30', '2020-01-01 08:30', '2020-01-01 09:30', '2020-01-01 10:30', '2020-01-01 11:30', '2020-01-01 12:30', '2020-01-01 13:30', '2020-01-01 14:30', '2020-01-01 15:30', '2020-01-01 16:30', '2020-01-01 17:30', '2020-01-01 18:30', '2020-01-01 19:30', '2020-01-01 20:30', '2020-01-01 21:30', '2020-01-01 22:30', '2020-01-01 23:30', '2020-01-02 00:30', '2020-01-02 01:30'],
-                labels: ['Tue-11', 'Wed-12', 'Wed-01', 'Wed-02', 'Wed-03', 'Wed-04', 'Wed-05', 'Wed-06', 'Wed-07', 'Wed-08', 'Wed-09', 'Wed-10', 'Wed-11', 'Wed-12', 'Wed-01', 'Wed-02', 'Wed-03', 'Wed-04', 'Wed-05', 'Wed-06', 'Wed-07', 'Wed-08', 'Wed-09', 'Wed-10', 'Wed-11', 'Thu-12', ' ']
+                positions: ['2019-12-31 21:30', '2020-01-01 00:30', '2020-01-01 03:30', '2020-01-01 06:30', '2020-01-01 09:30', '2020-01-01 12:30', '2020-01-01 15:30', '2020-01-01 18:30', '2020-01-01 21:30', '2020-01-02 00:30'],
+                labels: [' ', 'Wed-12', 'Wed-03', 'Wed-06', 'Wed-09', 'Wed-12', 'Wed-03', 'Wed-06', 'Wed-09', 'Thu-12']
             },
             {
                 formatter: '%p',