[MD-Settings][Night Light] CL10: Add RTL languages support to the slider

chrome/browser/resources/settings/device_page/night_light_slider.js

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 (function() {
 
 /**
  * @fileoverview
  * night-light-slider is used to set the custom automatic schedule of the
  * Night Light feature, so that users can set their desired start and end
@@ skipping 38 matching lines @@
     'right': 'onRightKey_',
   },
 
   /**
    * The object currently being dragged. Either the start or end knobs.
    * @type {?Object}
    * @private
    */
   dragObject_: null,
 
+  /**
+   * The styles of slider legends determining their absolute left position in
+   * both LTR and RTL locales.
+   * @type {Array}
+   * @private
+   */
+  legendsStyles_: [
+    // The beginning 6:00 PM.
+    {ltr: 'left: 0%;', rtl: 'left: 100%'},
+    // 12:00 AM.
+    {ltr: 'left: 25%;', rtl: 'left: 75%'},
+    // 6:00 AM.
+    {ltr: 'left: 50%;', rtl: 'left: 50%'},
+    // 12:00 PM.
+    {ltr: 'left: 75%;', rtl: 'left: 25%'},
+    // The ending 6:00 PM.
+    {ltr: 'left: 100%;', rtl: 'left: 0%'},
+  ],
+
   /** @override */
   ready: function() {
     // Build the legend markers.
     var markersContainer = this.$.markersContainer;
     var width = markersContainer.offsetWidth;
     for (var i = 0; i <= HOURS_PER_DAY; ++i) {
       var marker = document.createElement('div');
       marker.className = 'markers';
       markersContainer.appendChild(marker);
       marker.style.left = (i * 100 / HOURS_PER_DAY) + '%';
     }
 
     this.async(function() {
       // Read the initial prefs values and refresh the slider.
       this.customTimesChanged_();
     });
   },
 
   /**
+   * @return {boolean} True if window is in a right-to-left locale.
+   * @private
+   */
+  isRTL_: function() {
+    return window.getComputedStyle(document.firstElementChild).direction ===
+        'rtl';
+  },
+
+  /**
+   * Gets the style of legend div determining its absolute left position.
+   * @param {number} index The index of the div in its parent #legendContainer.
+   * @return {string} the CSS style of the legend div.
+   * @private
+   */
+  getLegendStyle_: function(index) {
+    var style = this.legendsStyles_[index];
+    return this.isRTL_() ? style.rtl : style.ltr;

[stevenjb, 2017/06/22 20:23:42]

Any particular reason not to pass 0-100 to this and return 'left: ' + (rtl ? 100
- percent : percent) + '%' instead of using a table?

[afakhry, 2017/06/22 21:01:16]

No reason, other than I didn't want to do the calculation + string concatenation
every time this function is called.

Done.

+  },
+
+  /**
    * Expands or un-expands the knob being dragged along with its corresponding
    * label bubble.
    * @param {boolean} expand True to expand, and false to un-expand.
    * @private
    */
   setExpanded_: function(expand) {
     var knob = this.$.startKnob;
     var label = this.$.startLabel;
     if (this.dragObject_ == this.$.endKnob) {
       knob = this.$.endKnob;
@@ skipping 75 matching lines @@
   doKnobTracking_: function(event) {
     var deltaRatio = Math.abs(event.detail.ddx) / this.$.sliderBar.offsetWidth;
     var deltaMinutes = Math.floor(deltaRatio * TOTAL_MINUTES_PER_DAY);
     if (deltaMinutes <= 0)
       return;
 
     var knobPref = this.dragObject_ == this.$.startKnob ?
         'ash.night_light.custom_start_time' :
         'ash.night_light.custom_end_time';
 
-    if (event.detail.ddx > 0) {
+    var ddx = this.isRTL_() ? (-1 * event.detail.ddx) : event.detail.ddx;

[stevenjb, 2017/06/22 20:23:43]

nit: this.isRTL_() ? event.detail.ddx * -1 : event.detail.ddx;

[afakhry, 2017/06/22 21:01:16]

Done.

+    if (ddx > 0) {
       // Increment the knob's pref by the amount of deltaMinutes.
       this.incrementPref_(knobPref, deltaMinutes);
     } else {
       // Decrement the knob's pref by the amount of deltaMinutes.
       this.decrementPref_(knobPref, deltaMinutes);
     }
   },
 
   /**
    * Ends the dragging.
@@ skipping 80 matching lines @@
 
     if (ratio == 0) {
       // If the ratio is 0, then there are two possibilities:
       // - The knob time is 6:00 PM on the left side of the slider.
       // - The knob time is 6:00 PM on the right side of the slider.
       // We need to check the current knob offset ratio to determine which case
       // it is.
       var currentKnobRatio = this.getKnobRatio_(knob);
       ratio = currentKnobRatio > 0.5 ? 1.0 : 0.0;
     }
-
+    ratio = this.isRTL_() ? (1.0 - ratio) : ratio;
     knob.style.left = (ratio * this.$.sliderBar.offsetWidth) + 'px';
   },
 
   /**
    * Refreshes elements of the slider other than the knobs (the label bubbles,
    * and the progress bar).
    * @private
    */
   refresh_: function() {
     var endKnob = this.$.endKnob;
     var startKnob = this.$.startKnob;
     var startProgress = this.$.startProgress;
     var endProgress = this.$.endProgress;
     var startLabel = this.$.startLabel;
     var endLabel = this.$.endLabel;
 
     // The label bubbles have the same left coordinates as their corresponding
     // knobs.
     startLabel.style.left = startKnob.style.left;
     endLabel.style.left = endKnob.style.left;
 
+    if (this.isRTL_()) {
+      // In RTL locales, the relative positions of the knobs are flipped for the
+      // purpose of calculating the styles of the progress bars below.
+      startKnob = endKnob;
+      endKnob = this.$.startKnob;
+      startProgress = endProgress;
+      endProgress = this.$.startProgress;
+    }

[stevenjb, 2017/06/22 20:23:42]

nit: I think this would be more clear as:

var rtl = this.isRTL_();
var endKnob = rtl ? this.$.startKnob : this.$.endKnob;
etc

[afakhry, 2017/06/22 21:01:16]

Done.

+
     // The end progress bar starts from either the start knob or the start of
     // the slider (whichever is to its left) and ends at the end knob.
     var endProgressLeft = startKnob.offsetLeft >= endKnob.offsetLeft ?
         '0px' :
         startKnob.style.left;
     endProgress.style.left = endProgressLeft;
     endProgress.style.width =
         (parseFloat(endKnob.style.left) - parseFloat(endProgressLeft)) + 'px';
 
     // The start progress bar starts at the start knob, and ends at either the
@@ skipping 130 matching lines @@
   /**
    * Handles the 'left' key event.
    * @private
    */
   onLeftKey_: function(e) {
     e.preventDefault();
     var knobPref = this.getFocusedKnobPrefPathIfAny_();
     if (!knobPref)
       return;
 
-    this.decrementPref_(knobPref, 1);
+    if (this.isRTL_())
+      this.incrementPref_(knobPref, 1);
+    else
+      this.decrementPref_(knobPref, 1);
   },
 
   /**
    * Handles the 'right' key event.
    * @private
    */
   onRightKey_: function(e) {
     e.preventDefault();
     var knobPref = this.getFocusedKnobPrefPathIfAny_();
     if (!knobPref)
       return;
 
-    this.incrementPref_(knobPref, 1);
+    if (this.isRTL_())
+      this.decrementPref_(knobPref, 1);
+    else
+      this.incrementPref_(knobPref, 1);
   },
 
   /**
    * @return {boolean} Whether either of the two knobs is focused.
    * @private
    */
   isEitherKnobFocused_: function() {
     var activeElement = this.shadowRoot.activeElement;
     return activeElement == this.$.startKnob || activeElement == this.$.endKnob;
   },
@@ skipping 46 matching lines @@
   _focusedChanged: function(receivedFocusFromKeyboard) {
     // Overrides the _focusedChanged() from the PaperInkyFocusBehavior so that
     // it does nothing. This function is called only once for the entire
     // night-light-slider element even when focus is moved between the two
     // knobs. This doesn't allow us to decide on which knob the ripple will be
     // created. Hence we handle focus and blur explicitly above.
   }
 });
 
 })();