/** @module delite/KeyNav */
define([
"dcl/dcl",
"dojo/dom-class",
"delite/keys", // keys.END keys.HOME, keys.LEFT_ARROW etc.
"./features",
"./Widget",
"dpointer/events", // so can just monitor for "pointerdown"
"./activationTracker" // delite-deactivated event when focus removed from KeyNav and logical descendants
], function (dcl, domClass, keys, has, Widget) {
/**
* Dispatched after the user has selected a different descendant, by clicking, arrow keys,
* or keyboard search.
* @example
* widget.on("keynav-child-navigated", function (evt) {
* console.log("old value: " + evt.oldValue);
* console.log("new value: " + evt.newValue);
* }
* @event module:delite/KeyNav#keynav-child-navigated
* @property {number} oldValue - The previously selected item.
* @property {number} newValue - The new selected item.
*/
// Generate map from keyCode to handler name
var keycodeToMethod = {};
for (var key in keys) {
keycodeToMethod[keys[key]] = key.replace(/[^_]+|_./g, function (c) {
return c.charAt(0) === "_" ? c.charAt(1) : c.toLowerCase();
}) + "KeyHandler";
}
/**
* Return true if node is an `<input>` or similar that responds to keyboard input.
* @param {Element} node
* @returns {boolean}
*/
function takesInput(node) {
var tag = node.nodeName.toLowerCase();
return !node.readOnly && (tag === "textarea" || (tag === "input" &&
/^(color|email|number|password|search|tel|text|url|range)$/.test(node.type)));
}
/**
* A mixin to allow arrow key and letter key navigation of child Elements.
* It can be used by delite/Container based widgets with a flat list of children,
* or more complex widgets like a Tree.
*
* To use this mixin, the subclass must:
*
* - Implement one method for each keystroke that subclass wants to handle, with names based on the keys
* defined in delite/keys. For example, `DOWN_ARROW` --> `downArrowKeyHandler()`.
* The method takes two parameters: the events, and the currently navigated node.
* For BIDI support, the left and right arrows are handled specially, mapped to the `previousArrowKeyHandler()`
* and `nextArrowKeyHandler()` methods in LTR mode, or reversed in RTL mode.
* Most subclasses will want to implement either `previousArrowKeyHandler()`
* and `nextArrowKeyHandler()`, or `downArrowKeyHandler()` and `upArrowKeyHandler()`.
* - Set all navigable descendants' initial tabIndex to "-1"; both initial descendants and any
* descendants added later, by for example `addChild()`. Exception: if `focusDescendants` is false then the
* descendants shouldn't have any tabIndex at all.
* - Define `descendantSelector` as a function or string that identifies navigable child Elements.
* - If the descendant elements contain text, they should have a label attribute. KeyNav uses the label
* attribute for letter key navigation.
*
* @mixin module:delite/KeyNav
* @augments module:delite/Widget
*/
return dcl(Widget, /** @lends module:delite/KeyNav# */ {
/*jshint -W101*/
/**
* When true, focus the descendant widgets as the user navigates to them via arrow keys or keyboard letter
* search. When false, rather than focusing the widgets, it merely sets `navigatedDescendant`,
* and sets the `d-active-descendant` class on the descendant widget the user has navigated to.
*
* False mode is intended for widgets like ComboBox where the focus is somewhere outside this widget
* (typically on an `<input>`) and keystrokes are merely being forwarded to the KeyNav widget.
*
* When set to false:
*
* - All navigable descendants must specify an id.
* - Navigable descendants shouldn't have any tabIndex (as opposed to having tabIndex=-1).
* - The focused element should specify `aria-owns` to point to this KeyNav Element.
* - The focused Element must be kept synced so that `aria-activedescendant` points to the currently
* navigated descendant. Do this responding to the `keynav-child-navigated` event emitted by this widget,
* or by calling `observe()` and monitoring changed to `navigatedDescendant`.
* - The focused Element must forward keystrokes by calling `emit("keydown", ...)` and/or
* `emit("keypress", ...)` on this widget.
* - You must somehow set the initial navigated descendant, typically by calling `navigateToFirst()` either
* when the the dropdown is opened, or on the first call to `downArrowKeyHandler()`.
* - You must have some CSS styling so that the currently navigated node is apparent.
*
* See http://www.w3.org/WAI/GL/wiki/Using_aria-activedescendant_to_allow_changes_in_focus_within_widgets_to_be_communicated_to_Assistive_Technology#Example_1:_Combobox
* for details.
* @member {boolean}
* @default true
* @protected
*/
focusDescendants: true,
/*jshint +W101*/
/**
* The currently navigated descendant, or null if there isn't one.
* @member {Element}
* @readonly
* @protected
*/
navigatedDescendant: null,
/**
* Selector to identify which descendant Elements are navigable via arrow keys or
* keyboard search. Note that for subclasses like a Tree, one navigable node could be a descendant of another.
*
* It's either a function that takes an Element parameter and returns true/false,
* or a CSS selector string, for example ".list-item".
*
* By default, the direct DOM children of this widget are considered the selectable descendants.
*
* Must be set in the prototype rather than on the instance.
*
* @member {string|Function}
* @protected
* @constant
*/
descendantSelector: null,
/**
* Figure out effective target of this event, either a navigable node, or this widget itself.
* Note that for subclasses like a Tree, one navigable node could be a descendant of another.
* @param {Event} evt
* @private
*/
_getTargetElement: function (evt) {
for (var child = evt.target; child !== this; child = child.parentNode) {
if (this._selectorFunc(child)) {
return child;
}
}
return this;
},
postRender: function () {
var self = this;
// Setup function to check which child nodes are navigable.
if (typeof this.descendantSelector === "string") {
var matchesFuncName = has("dom-matches");
this._selectorFunc = function (elem) {
return elem[matchesFuncName](this.descendantSelector);
};
} else if (this.descendantSelector) {
this._selectorFunc = this.descendantSelector;
} else {
this._selectorFunc = function (elem) { return elem.parentNode === self.containerNode; };
}
this.on("keypress", this._keynavKeyPressHandler.bind(this));
this.on("keydown", this._keynavKeyDownHandler.bind(this));
this.on("pointerdown", function (evt) {
var target = self._getTargetElement(evt);
if (target !== self) {
self._descendantNavigateHandler(target, evt);
}
});
if (this.focusDescendants) {
this.on("delite-deactivated", this._keynavDeactivatedHandler.bind(this));
this.on("focusin", function (evt) {
var target = self._getTargetElement(evt);
if (target === self) {
self._keynavFocusHandler(evt);
} else {
self._descendantNavigateHandler(target, evt);
}
});
}
},
attachedCallback: function () {
// If the user hasn't specified a tabindex declaratively, then set to default value.
if (this.focusDescendants && !this.hasAttribute("tabindex")) {
this.tabIndex = "0";
}
},
/**
* Called on home key.
* @param {Event} evt
* @param {Element} navigatedDescendant
* @protected
*/
homeKeyHandler: function () {
this.navigateToFirst();
},
/**
* Called on end key.
* @param {Event} evt
* @param {Element} navigatedDescendant
* @protected
*/
endKeyHandler: function () {
this.navigateToLast();
},
/**
/**
* Default focus() implementation: navigate to the first navigable descendant.
* Note that if `focusDescendants` is false, this will merely set the `d-active-descendant` class
* rather than actually focusing the descendant.
*/
focus: function () {
this.navigateToFirst();
},
/**
* Navigate to the first navigable descendant.
* Note that if `focusDescendants` is false, this will merely set the `d-active-descendant` class
* rather than actually focusing the descendant.
* @protected
*/
navigateToFirst: function () {
this.navigateTo(this.getNext(this, 1));
},
/**
* Navigate to the last navigable descendant.
* Note that if `focusDescendants` is false, this will merely set the `d-active-descendant` class
* rather than actually focusing the descendant.
* @protected
*/
navigateToLast: function () {
this.navigateTo(this.getNext(this, -1));
},
/**
* Navigate to the specified descendant.
* Note that if `focusDescendants` is false, this will merely set the `d-active-descendant` class
* rather than actually focusing the descendant.
* @param {Element} child - Reference to the descendant.
* @param {boolean} last - If true and if descendant has multiple focusable nodes, focus the
* last one instead of the first one. This assumes that the child's `focus()` method takes a boolean
* parameter where `true` means to focus the last child.
* @protected
*/
navigateTo: function (child, last) {
if (this.focusDescendants) {
// For IE focus outline to appear, must set tabIndex before focus.
// If this._savedTabIndex is set, use it instead of this.tabIndex, because it means
// the container's tabIndex has already been changed to -1.
child.tabIndex = "_savedTabIndex" in this ? this._savedTabIndex : this.tabIndex;
child.focus(last ? "end" : "start");
// _descendantNavigateHandler() will be called automatically from child's focus event.
} else {
this._descendantNavigateHandler(child);
}
},
/**
* Handler for when the container itself gets focus.
* Called only when `this.focusDescendants` is true.
* Initially the container itself has a tabIndex, but when it gets focus, switch focus to first child.
*
* @param {Event} evt
* @private
*/
_keynavFocusHandler: function () {
// Note that we can't use the delite-activated event because switching focus from that
// event handler confuses the activationTracker.js code (because it recursively triggers the
// delite-activated event). Also, delite-activated would fire when focus went
// directly to a child widget due to mouse click.
// Ignore spurious focus event:
// On IE, clicking the scrollbar of a select dropdown moves focus from the focused child item to me
if (this.navigatedDescendant) {
return;
}
// When the container gets focus by being tabbed into, or a descendant gets focus by being clicked,
// remove the container's tabIndex so that tab or shift-tab
// will go to the fields after/before the container, rather than the container itself
this._savedTabIndex = this.tabIndex;
this.removeAttribute("tabindex");
this.focus();
},
/**
* Handler for when focus is moved away the container, and its descendant (popup) widgets.
* Called only when `this.focusDescendants` is true.
* @private
*/
_keynavDeactivatedHandler: function () {
// then restore the container's tabIndex so that user can tab to it again.
// Note that using _onBlur() so that this doesn't happen when focus is shifted
// to one of my child widgets (typically a popup)
// TODO: for 2.0 consider changing this to blur whenever the container blurs, to be truthful that there is
// no focused child at that time.
this.setAttribute("tabindex", this._savedTabIndex);
delete this._savedTabIndex;
if (this.navigatedDescendant) {
this.navigatedDescendant.tabIndex = "-1";
this.navigatedDescendant = null;
}
},
/**
* Called when a child is navigated to, either by user clicking it, or programatically by arrow key handling
* code. It marks that the specified child is the navigated one.
* @param {Element} child
* @fires module:delite/KeyNav#keynav-child-navigated
* @private
*/
_descendantNavigateHandler: function (child) {
if (child && child !== this.navigatedDescendant) {
if (this.focusDescendants) {
if (this.navigatedDescendant && !this.navigatedDescendant._destroyed) {
// mark that the previously focusable node is no longer focusable
this.navigatedDescendant.tabIndex = "-1";
}
// If container still has tabIndex setting then remove it; instead we'll set tabIndex on child
if (!("_savedTabIndex" in this)) {
this._savedTabIndex = this.tabIndex;
this.removeAttribute("tabindex");
}
child.tabIndex = this._savedTabIndex;
}
if (this.navigatedDescendant) {
domClass.remove(this.navigatedDescendant, "d-active-descendant");
}
this.emit("keynav-child-navigated", {
oldValue: this.navigatedDescendant,
newValue: child
});
// mark that the new node is the currently navigated one
this.navigatedDescendant = child;
if (child) {
domClass.add(child, "d-active-descendant");
}
}
},
_searchString: "",
/**
* If multiple characters are typed where each keystroke happens within
* multiCharSearchDuration of the previous keystroke,
* search for nodes matching all the keystrokes.
*
* For example, typing "ab" will search for entries starting with
* "ab" unless the delay between "a" and "b" is greater than `multiCharSearchDuration`.
*
* @member {number} KeyNav#multiCharSearchDuration
* @default 1000
*/
multiCharSearchDuration: 1000,
/**
* When a key is pressed that matches a child item,
* this method is called so that a widget can take appropriate action if necessary.
*
* @param {Element} item
* @param {Event} evt
* @param {string} searchString
* @param {number} numMatches
* @private
*/
_keyboardSearchHandler: function (item, /*jshint unused: vars */ evt, searchString, numMatches) {
if (item) {
this.navigateTo(item);
}
},
/**
* Compares the searchString to the Element's text label, returning:
*
* - -1: a high priority match and stop searching
* - 0: not a match
* - 1: a match but keep looking for a higher priority match
*
* @param {Element} item
* @param {string} searchString
* @returns {number}
* @private
*/
_keyboardSearchCompare: function (item, searchString) {
var element = item,
text = item.label || (element.focusNode ? element.focusNode.label : "") || element.textContent || "",
currentString = text.replace(/^\s+/, "").substr(0, searchString.length).toLowerCase();
// stop searching after first match by default
return (!!searchString.length && currentString === searchString) ? -1 : 0;
},
/**
* When a key is pressed, if it's an arrow key etc. then it's handled here.
* @param {Event} evt
* @private
*/
_keynavKeyDownHandler: function (evt) {
// Ignore left, right, home, end, and space on <input> controls
if (takesInput(evt.target) &&
(evt.keyCode === keys.LEFT_ARROW || evt.keyCode === keys.RIGHT_ARROW ||
evt.keyCode === keys.HOME || evt.keyCode === keys.END || evt.keyCode === keys.SPACE)) {
return;
}
if (evt.keyCode === keys.SPACE && this._searchTimer && !(evt.ctrlKey || evt.altKey || evt.metaKey)) {
// If the user types some string like "new york", interpret the space as part of the search rather
// than to perform some action, even if there is a key handler method defined.
// Stop a11yclick from interpreting key as a click event.
// Also stop IE from scrolling, and most browsers (except FF) from emitting keypress event.
evt.preventDefault();
this._keyboardSearch(evt, " ");
} else {
// Otherwise call the handler specified in this.keyHandlers.
this._applyKeyHandler(evt);
}
},
/**
* If the class has defined a method to handle the specified key, then call it.
* See the description of `KeyNav` for details on how to define methods.
* @param {Event} evt
* @private
*/
_applyKeyHandler: function (evt) {
// Get name of method to call
var methodName;
switch (evt.keyCode) {
case keys.LEFT_ARROW:
methodName = this.isLeftToRight() ? "previousArrowKeyHandler" : "nextArrowKeyHandler";
break;
case keys.RIGHT_ARROW:
methodName = this.isLeftToRight() ? "nextArrowKeyHandler" : "previousArrowKeyHandler";
break;
default:
methodName = keycodeToMethod[evt.keyCode];
}
// Call it
var func = this[methodName];
if (func) {
func.call(this, evt, this.navigatedDescendant);
evt.stopPropagation();
evt.preventDefault();
this._searchString = ""; // so a DOWN_ARROW b doesn't search for ab
}
},
/**
* When a printable key is pressed, it's handled here, searching by letter.
* @param {Event} evt
* @private
*/
_keynavKeyPressHandler: function (evt) {
// Ignore:
// - keystrokes on <input> and <textarea>
// - duplicate events on firefox (ex: arrow key that will be handled by keydown handler)
// - control sequences like CMD-Q.
// - the SPACE key (only occurs on FF)
//
// Note: if there's no search in progress, then SPACE should be ignored. If there is a search
// in progress, then SPACE is handled in _keynavKeyDownHandler.
if (takesInput(evt.target) || evt.charCode <= keys.SPACE || evt.ctrlKey || evt.altKey || evt.metaKey) {
return;
}
evt.preventDefault();
evt.stopPropagation();
this._keyboardSearch(evt, String.fromCharCode(evt.charCode).toLowerCase());
},
/**
* Perform a search of the widget's options based on the user's keyboard activity.
*
* Called on keypress (and sometimes keydown), searches through this widget's children
* looking for items that match the user's typed search string. Multiple characters
* typed within `multiCharSearchDuration` of each other are combined for multi-character searching.
* @param {Event} evt
* @param {string} keyChar
* @private
*/
_keyboardSearch: function (evt, keyChar) {
var
matchedItem = null,
searchString,
numMatches = 0;
if (this._searchTimer) {
this._searchTimer.remove();
}
this._searchString += keyChar;
var allSameLetter = /^(.)\1*$/.test(this._searchString);
var searchLen = allSameLetter ? 1 : this._searchString.length;
searchString = this._searchString.substr(0, searchLen);
this._searchTimer = this.defer(function () { // this is the "success" timeout
this._searchTimer = null;
this._searchString = "";
}, this.multiCharSearchDuration);
var currentItem = this.navigatedDescendant || null;
if (searchLen === 1 || !currentItem) {
currentItem = this.getNext(currentItem, 1); // skip current
if (!currentItem) {
return;
} // no items
}
var stop = currentItem;
do {
var rc = this._keyboardSearchCompare(currentItem, searchString);
if (!!rc && numMatches++ === 0) {
matchedItem = currentItem;
}
if (rc === -1) { // priority match
numMatches = -1;
break;
}
currentItem = this.getNext(currentItem, 1);
} while (currentItem !== stop);
this._keyboardSearchHandler(matchedItem, evt, searchString, numMatches);
},
/**
* Returns the next or previous navigable descendant, relative to "child".
* If "child" is this, then it returns the first focusable descendant (when dir === 1)
* or last focusable descendant (when dir === -1).
* @param {Element} child - The current child Element.
* @param {number} dir - 1 = after, -1 = before
* @returns {Element}
* @protected
*/
getNext: function (child, dir) {
var root = this, origChild = child;
function dfsNext(node) {
if (node.firstElementChild) { return node.firstElementChild; }
while (node !== root) {
if (node.nextElementSibling) { return node.nextElementSibling; }
node = node.parentNode;
}
return root; // loop around, plus corner case when no children
}
function dfsLast(node) {
while (node.lastElementChild) { node = node.lastElementChild; }
return node;
}
function dfsPrev(node) {
return node === root ? dfsLast(root) : // loop around, plus corner case when no children
(node.previousElementSibling && dfsLast(node.previousElementSibling)) || node.parentNode;
}
while (true) {
child = dir > 0 ? dfsNext(child) : dfsPrev(child);
if (child === origChild) {
return null; // looped back to original child
} else if (this._selectorFunc(child)) {
return child; // this child matches
}
}
}
});
});