pull out tick0/dtick validation logic for reuse

Author: alexcjohnson

src/plots/cartesian/clean_ticks.js

@@ -0,0 +1,87 @@
+/**
+* Copyright 2012-2018, Plotly, Inc.
+* All rights reserved.
+*
+* This source code is licensed under the MIT license found in the
+* LICENSE file in the root directory of this source tree.
+*/
+
+
+'use strict';
+
+var isNumeric = require('fast-isnumeric');
+var Lib = require('../../lib');
+var ONEDAY = require('../../constants/numerical').ONEDAY;
+
+/**
+ * Return a validated dtick value for this axis
+ *
+ * @param {any} dtick: the candidate dtick. valid values are numbers and strings,
+ *     and further constrained depending on the axis type.
+ * @param {string} axType: the axis type
+ */
+exports.dtick = function(dtick, axType) {
+    var isLog = axType === 'log';
+    var isDate = axType === 'date';
+    var isCat = axType === 'category';
+    var dtickDflt = isDate ? ONEDAY : 1;
+
+    if(!dtick) return dtickDflt;
+
+    if(isNumeric(dtick)) {
+        dtick = Number(dtick);
+        if(dtick <= 0) return dtickDflt;
+        if(isCat) {
+            // category dtick must be positive integers
+            return Math.max(1, Math.round(dtick));
+        }
+        if(isDate) {
+            // date dtick must be at least 0.1ms (our current precision)
+            return Math.max(0.1, dtick);
+        }
+        return dtick;
+    }
+
+    if(typeof dtick !== 'string' || !(isDate || isLog)) {
+        return dtickDflt;
+    }
+
+    var prefix = dtick.charAt(0);
+    var dtickNum = dtick.substr(1);
+    dtickNum = isNumeric(dtickNum) ? Number(dtickNum) : 0;
+
+    if((dtickNum <= 0) || !(
+            // "M<n>" gives ticks every (integer) n months
+            (isDate && prefix === 'M' && dtickNum === Math.round(dtickNum)) ||
+            // "L<f>" gives ticks linearly spaced in data (not in position) every (float) f
+            (isLog && prefix === 'L') ||
+            // "D1" gives powers of 10 with all small digits between, "D2" gives only 2 and 5
+            (isLog && prefix === 'D' && (dtickNum === 1 || dtickNum === 2))
+        )) {
+        return dtickDflt;
+    }
+
+    return dtick;
+};
+
+/**
+ * Return a validated tick0 for this axis
+ *
+ * @param {any} tick0: the candidate tick0. Valid values are numbers and strings,
+ *     further constrained depending on the axis type
+ * @param {string} axType: the axis type
+ * @param {string} calendar: for date axes, the calendar to validate/convert with
+ * @param {any} dtick: an already valid dtick. Only used for D1 and D2 log dticks,
+ *     which do not support tick0 at all.
+ */
+exports.tick0 = function(tick0, axType, calendar, dtick) {
+    if(axType === 'date') {
+        return Lib.cleanDate(tick0, Lib.dateTick0(calendar));
+    }
+    if(dtick === 'D1' || dtick === 'D2') {
+        // D1 and D2 modes ignore tick0 entirely
+        return undefined;
+    }
+    // Aside from date axes, tick0 must be numeric
+    return isNumeric(tick0) ? Number(tick0) : 0;
+};

src/plots/cartesian/tick_value_defaults.js

@@ -9,9 +9,7 @@
 
 'use strict';
 
-var isNumeric = require('fast-isnumeric');
-var Lib = require('../../lib');
-var ONEDAY = require('../../constants/numerical').ONEDAY;
+var cleanTicks = require('./clean_ticks');
 
 
 module.exports = function handleTickValueDefaults(containerIn, containerOut, coerce, axType) {
@@ -33,47 +31,11 @@ module.exports = function handleTickValueDefaults(containerIn, containerOut, coe
     else if(tickmode === 'linear') {
         // dtick is usually a positive number, but there are some
         // special strings available for log or date axes
-        // default is 1 day for dates, otherwise 1
-        var dtickDflt = (axType === 'date') ? ONEDAY : 1;
-        var dtick = coerce('dtick', dtickDflt);
-        if(isNumeric(dtick)) {
-            containerOut.dtick = (dtick > 0) ? Number(dtick) : dtickDflt;
-        }
-        else if(typeof dtick !== 'string') {
-            containerOut.dtick = dtickDflt;
-        }
-        else {
-            // date and log special cases are all one character plus a number
-            var prefix = dtick.charAt(0),
-                dtickNum = dtick.substr(1);
-
-            dtickNum = isNumeric(dtickNum) ? Number(dtickNum) : 0;
-            if((dtickNum <= 0) || !(
-                    // "M<n>" gives ticks every (integer) n months
-                    (axType === 'date' && prefix === 'M' && dtickNum === Math.round(dtickNum)) ||
-                    // "L<f>" gives ticks linearly spaced in data (not in position) every (float) f
-                    (axType === 'log' && prefix === 'L') ||
-                    // "D1" gives powers of 10 with all small digits between, "D2" gives only 2 and 5
-                    (axType === 'log' && prefix === 'D' && (dtickNum === 1 || dtickNum === 2))
-                )) {
-                containerOut.dtick = dtickDflt;
-            }
-        }
-
-        // tick0 can have different valType for different axis types, so
-        // validate that now. Also for dates, change milliseconds to date strings
-        var tick0Dflt = (axType === 'date') ? Lib.dateTick0(containerOut.calendar) : 0;
-        var tick0 = coerce('tick0', tick0Dflt);
-        if(axType === 'date') {
-            containerOut.tick0 = Lib.cleanDate(tick0, tick0Dflt);
-        }
-        // Aside from date axes, dtick must be numeric; D1 and D2 modes ignore tick0 entirely
-        else if(isNumeric(tick0) && dtick !== 'D1' && dtick !== 'D2') {
-            containerOut.tick0 = Number(tick0);
-        }
-        else {
-            containerOut.tick0 = tick0Dflt;
-        }
+        // tick0 also has special logic
+        var dtick = containerOut.dtick = cleanTicks.dtick(
+            containerIn.dtick, axType);
+        containerOut.tick0 = cleanTicks.tick0(
+            containerIn.tick0, axType, containerOut.calendar, dtick);
     }
     else {
         var tickvals = coerce('tickvals');