[Night Light] CL5: Schedule Settings

chrome/browser/resources/settings/controls/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.
+
+/**
+ * @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
+ * times.
+ */
+
+/** @const */ var TOTAL_MINUTES_PER_DAY = 24 * 60;
+/** @const */ var OFFSET_MINUTES_6PM = 18 * 60;
+/** @const */ var MIN_KNOBS_DISTANCE_MINUTES = 30;
+
+Polymer({
+  is: 'night-light-slider',
+
+  behaviors: [
+    I18nBehavior,
+    PrefsBehavior,
+    Polymer.IronA11yKeysBehavior,
+  ],
+
+  properties: {
+    /**
+     * The object currently being dragged. Either the start or end knobs.
+     * @type {?Object}
+     * @private
+     */
+    dragObject_: {
+      type: Object,
+      value: null,
+    },
+
+    /**
+     * The start knob time as a string to be shown on the start label bubble.
+     * @private
+     */
+    startTime_: {
+      type: String,
+    },
+
+    /**
+     * The end knob time as a string to be shown on the end label bubble.
+     * @private
+     */
+    endTime_: {
+      type: String,
+    },
+  },
+
+  observers: [
+    'customTimesChanged_(prefs.ash.night_light.custom_start_time.*, ' +
+                        'prefs.ash.night_light.custom_end_time.*)',
+  ],
+
+  keyBindings: {
+    'left': 'onLeftKey_',
+    'right': 'onRightKey_',
+  },
+
+  ready: function() {
+    // Build the legend markers.
+    var markersContainer = this.$.markersContainer;
+    var width = markersContainer.offsetWidth;
+    var num = 24;
+    for (var i = 0; i <= num; ++i) {
+      var marker = document.createElement('div');
+      marker.className = 'markers';
+      markersContainer.appendChild(marker);
+      marker.style.left = (i * 100 / num) + '%';
+    }
+    this.async(function() {
+      // Read the initial prefs values and refresh the slider.
+      this.customTimesChanged_();
+    });
+  },
+
+  /**
+   * Expands or un-expands the knob being dragged along with its corresponding
+   * label bubble.
+   * @param {boolean} expand True to expand, and false to un-expand.
+   * @private
+   */
+  setExpanded_: function(expand) {
+    var knob = this.$.startKnob;
+    var label = this.$.startLabel;
+    if (this.dragObject_ == this.$.endKnob) {
+      knob = this.$.endKnob;
+      label = this.$.endLabel;
+    }
+
+    if (expand) {
+      knob.classList.add('expanded-knob');
+      label.classList.add('expanded-knob');
+    } else {
+      knob.classList.remove('expanded-knob');
+      label.classList.remove('expanded-knob');
+    }
+  },
+
+  /**
+   * If one of the two knobs is focused, this function blurs it.
+   * @private
+   */
+  blurAnyFocusedKnob_: function() {
+    var activeElement = this.shadowRoot.activeElement;
+    if (activeElement == this.$.startKnob || activeElement == this.$.endKnob)
+      activeElement.blur();
+  },
+
+  /**
+   * Start dragging the target knob.
+   * @private
+   */
+  drag_: function(event) {
+    event.preventDefault();
+    this.dragObject_ = event.target;
+    this.setExpanded_(true);
+
+    // Focus is only given to the knobs by means of keyboard tab navigations.
+    // When we start dragging, we don't want to see any focus halos around any
+    // knob.
+    this.blurAnyFocusedKnob_();
+
+    // However, our night-light-slider element must get the focus.
+    this.focus();
+  },
+
+  /**
+   * Continues dragging the selected knob if any.
+   * @private
+   */
+  continueDrag_: function(event) {
+    if (!this.dragObject_)
+      return;
+
+    event.stopPropagation();
+    switch (event.detail.state) {
+      case 'start':
+        this.drag_(event);
+        break;
+      case 'track':
+        this.doKnobTracking_(event);
+        break;
+      case 'end':
+        this.drop_(event);
+        break;
+    }
+  },
+
+  /**
+   * Updates the knob's corresponding pref value in response to dragging, which
+   * will in turn update the location of the knob and its corresponding label
+   * bubble and its text contents.
+   * @private
+   */
+  doKnobTracking_: function(event) {
+    var deltaRatio = Math.abs(event.detail.ddx) / this.$.sliderBar.offsetWidth;
+    var deltaMinutes = Math.floor(deltaRatio * TOTAL_MINUTES_PER_DAY);
+    if (deltaMinutes <= 0)
+      return;
+
+    var knobPref = 'ash.night_light.custom_end_time';
+    if (this.dragObject_ == this.$.startKnob)
+      knobPref = 'ash.night_light.custom_start_time';
+
+    if (event.detail.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.
+   * @private
+   */
+  drop_: function(event) {
+    event.preventDefault();
+    this.setExpanded_(false);
+    this.dragObject_ = null;
+  },
+
+  /**
+   * Gets the given knob's offset ratio with respect to its parent element
+   * (which is the slider bar).
+   * @param {HTMLDivElement} knob Either one of the two knobs.
+   * @return {number}
+   * @private
+   */
+  getKnobRatio_: function(knob) {
+    return parseFloat(knob.style.left) / this.$.sliderBar.offsetWidth;
+  },
+
+  /**
+   * Pads the given number num with leading zeros such that its length as a
+   * string is 2.
+   * @param {number} num
+   * @return {string}
+   * @private
+   */
+  pad2_: function(num) {
+    var s = String(num);
+    if (s.length == 2)
+      return s;
+
+    return '0' + s;
+  },
+
+  /**
+   * Converts the offsetMinutes value (which the number of minutes since 00:00)
+   * to its string representation in the format 6:30 PM.
+   * @param {number} offsetMinutes The time of day represented as the number of
+   * minutes from 00:00.
+   * @return {string}
+   * @private
+   */
+  offsetMinutesToTimeString_: function(offsetMinutes) {
+    var hour = Math.floor(offsetMinutes / 60);
+    var amPm = hour >= 12 ? ' PM' : ' AM';
+    hour %= 12;
+    hour = hour == 0 ? 12 : hour;
+    var minute = Math.floor(offsetMinutes % 60);
+    return hour + ':' + this.pad2_(minute) + amPm;
+  },
+
+  /**
+   * Handles changes in the start and end times prefs.
+   * @private
+   */
+  customTimesChanged_: function() {
+    var startOffsetMinutes = /** @type {number} */(
+        this.getPref('ash.night_light.custom_start_time').value);
+    this.startTime_ = this.offsetMinutesToTimeString_(startOffsetMinutes);
+    this.updateKnobLeft_(this.$.startKnob, startOffsetMinutes);
+    var endOffsetMinutes = /** @type {number} */(
+        this.getPref('ash.night_light.custom_end_time').value);
+    this.endTime_ = this.offsetMinutesToTimeString_(endOffsetMinutes);
+    this.updateKnobLeft_(this.$.endKnob, endOffsetMinutes);
+    this.refresh_();
+  },
+
+  /**
+   * Updates the absolute left coordinate of the given knob based on the time it
+   * represents given as an offsetMinutes value.
+   * @param {HTMLDivElement} knob
+   * @param {number} offsetMinutes
+   * @private
+   */
+  updateKnobLeft_: function(knob, offsetMinutes) {
+    var offsetAfter6pm =
+        (offsetMinutes + TOTAL_MINUTES_PER_DAY - OFFSET_MINUTES_6PM) %
+            TOTAL_MINUTES_PER_DAY;
+    var ratio = offsetAfter6pm / TOTAL_MINUTES_PER_DAY;
+
+    if (ratio == 0) {
+      // If the ratio is 0, then there are two possibilities:
+      // - The knob time is 6:00 PM on the left side of the slider.
+      // - The knob time is 6:00 PM on the right side of the slider.
+      // We need to check the current knob offset ratio to determine which case
+      // it is.
+      var currentKnobRatio = this.getKnobRatio_(knob);
+      ratio = currentKnobRatio > 0.5 ? 1.0 : 0.0;
+    }
+
+    knob.style.left = (ratio * this.$.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;
+
+    // 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
+    // end knob or the end of the slider (whichever is to its right).
+    var startProgressRight = endKnob.offsetLeft < startKnob.offsetLeft
+                                ? this.$.sliderBar.offsetWidth
+                                : endKnob.style.left;
+    startProgress.style.left = startKnob.style.left;
+    startProgress.style.width =
+        (parseFloat(startProgressRight) - parseFloat(startKnob.style.left)) +
+        'px';
+
+    this.fixLabelsOverlapIfAny_();
+  },
+
+  /**
+   * If the label bubbles overlap, this function fixes them by moving the end
+   * label up a little.
+   * @private
+   */
+  fixLabelsOverlapIfAny_: function() {
+    var startLabel = this.$.startLabel;
+    var endLabel = this.$.endLabel;
+    var distance = Math.abs(parseFloat(startLabel.style.left) -
+        parseFloat(endLabel.style.left));
+    if (distance <= startLabel.offsetWidth) {
+      // Shift the end label up so that it doesn't overlap with the start label.
+      endLabel.classList.add('end-label-overlap');
+    } else {
+      endLabel.classList.remove('end-label-overlap');
+    }
+  },
+
+  /**
+   * Given the prefPath that corresponds to one knob time, it gets the value of
+   * the pref that corresponds to the other knob.
+   * @param {string} prefPath
+   * @return {number}
+   * @private
+   */
+  getOtherKnobPrefValue_: function(prefPath) {
+    if (prefPath == 'ash.night_light.custom_start_time')
+      return /** @type {number} */ (
+          this.getPref('ash.night_light.custom_end_time').value);
+
+    return /** @type {number} */ (
+        this.getPref('ash.night_light.custom_start_time').value);
+  },
+
+  /**
+   * Increments the value of the pref whose path is given by prefPath by the
+   * amount given in increment.
+   * @param {string} prefPath
+   * @param {number} increment
+   * @private
+   */
+  incrementPref_: function(prefPath, increment) {
+    var value = this.getPref(prefPath).value + increment;
+
+    var otherValue = this.getOtherKnobPrefValue_(prefPath);
+    if (otherValue > value &&
+        ((otherValue - value) < MIN_KNOBS_DISTANCE_MINUTES)) {
+      // We are incrementing the minutes offset moving towards the other knob.
+      // We have a minimum 30 minutes overlap threshold. Move this knob to the
+      // other side of the other knob.
+      //
+      // Was:
+      // ------ (+) --- 29 MIN --- + ------->>
+      //
+      // Now:
+      // ------ + --- 30 MIN --- (+) ------->>
+      //
+      // (+) ==> Knob being moved.
+      value = otherValue + MIN_KNOBS_DISTANCE_MINUTES;
+    }
+
+    // The knobs are allowed to wrap around.
+    this.setPrefValue(prefPath, (value % TOTAL_MINUTES_PER_DAY));
+  },
+
+  /**
+   * Decrements the value of the pref whose path is given by prefPath by the
+   * amount given in decrement.
+   * @param {string} prefPath
+   * @param {number} decrement
+   * @private
+   */
+  decrementPref_: function(prefPath, decrement) {
+    var value = /** @type {number} */(this.getPref(prefPath).value) - decrement;
+
+    var otherValue = this.getOtherKnobPrefValue_(prefPath);
+    if (value > otherValue &&
+        ((value - otherValue) < MIN_KNOBS_DISTANCE_MINUTES)) {
+      // We are decrementing the minutes offset moving towards the other knob.
+      // We have a minimum 30 minutes overlap threshold. Move this knob to the
+      // other side of the other knob.
+      //
+      // Was:
+      // <<------ + --- 29 MIN --- (+) -------
+      //
+      // Now:
+      // <<------ (+) --- 30 MIN --- + ------
+      //
+      // (+) ==> Knob being moved.
+      value = otherValue - MIN_KNOBS_DISTANCE_MINUTES;
+    }
+
+    // The knobs are allowed to wrap around.
+    if (value < 0)
+      value += TOTAL_MINUTES_PER_DAY;
+
+    this.setPrefValue(prefPath, Math.abs(value) % TOTAL_MINUTES_PER_DAY);
+  },
+
+  /**
+   * Gets the pref path of the currently focused knob. Returns null if no knob
+   * is currently focused.
+   * @return {?string}
+   * @private
+   */
+  getFocusedKnobPrefPathIfAny_: function() {
+    var focusedElement = this.shadowRoot.activeElement;
+    if (focusedElement == this.$.startKnob)
+      return 'ash.night_light.custom_start_time';
+
+    if (focusedElement == this.$.endKnob)
+      return 'ash.night_light.custom_end_time';
+
+    return null;
+  },
+
+  /**
+   * Handles the 'left' key event.
+   * @private
+   */
+  onLeftKey_: function(e) {
+    e.preventDefault();
+    var knobPref = this.getFocusedKnobPrefPathIfAny_();
+    if (!knobPref)
+      return;
+
+    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);
+  },
+});