1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
8 * Orientation of a line.
17 * Map from keysetId to layout.
18 * @type {Map<String,KeysetLayout>}
24 * Container for storing a keyset's layout.
26 var KeysetLayout = function() {
30 KeysetLayout.prototype = {
32 * All keys in the keyset.
38 * Spacial partitioning of all keys in the keyset.
39 * @type {DecisionNode}
44 * Add a key to the keyset.
51 * Regenerates a decision tree using the keys in the keyset.
53 regenerateTree: function() {
54 // Split using horizontal lines first, as keyboards tend to be
56 var splits = findSplits(this.keys, Orientation.HORIZONTAL);
57 this.tree = createBinaryTree(0, splits.length - 1, splits);
59 this.tree.populate(this.keys);
63 * Searches the tree for the key closest to the point provided.
64 * @param {number} x The x-coordinate.
65 * @param {number} y The y-coordinate.
66 * @return {?kb-key} The key, or null if none found.
68 findClosestKey: function(x, y) {
69 var closestNode = this.tree.findClosestNode(x, y);
70 var key = closestNode.data;
73 // Ignore touches that aren't close.
74 return key.distanceTo(x, y) <= MAX_TOUCH_FUZZ_DISTANCE ?
79 * Returns the position data of all keys in this keyset.
80 * @return {Array<Map>}
82 getLayout: function() {
83 return this.keys.map(function(key) {
90 * Container for caching a key's data.
91 * @param {{style: {left: number, top: number, width: number,
92 * height: number}}} key The key to cache.
93 * left: The x-coordinate of the left edge of the key.
94 * top: The y-coordinate of the top edge of the key.
95 * width: The width of the key in px.
96 * height: The height of the key in px.
99 var Key = function(key) {
101 var style = key.style;
102 this.top = parseFloat(style.top) - KEY_PADDING_TOP;
103 this.left = parseFloat(style.left);
104 this.right = this.left + parseFloat(style.width);
105 this.bottom = this.top + parseFloat(style.height) + KEY_PADDING_TOP
106 + KEY_PADDING_BOTTOM;
111 * Manhattan distance from the the provided point to the key.
112 * @param {number} x The x-coordinate of the point.
113 * @param {number} y The y-coordinate of the point.
116 distanceTo: function(x, y) {
117 return Math.abs(this.intersect(new Line(x))) +
118 Math.abs(this.intersect(new Line(y, true)));
122 * Checks whether the key intersects with the line provided.
123 * @param {!Line} line The line.
124 * @return {number} Zero if it intersects, signed manhattan distance if it
127 intersect: function(line) {
128 var min = line.rotated ? this.top : this.left;
129 var max = line.rotated ? this.bottom : this.right;
130 return (line.c > max) ? line.c - max : Math.min(0, line.c - min);
134 * Returns the Key as a map.
135 * @return {Map<String,number>}
141 'width': this.right - this.left,
142 'height': this.bottom - this.bottom,
148 * Object representing the line y = c or x = c.
149 * @param {number} c The x or y coordinate of the intersection line depending
151 * @param {Orientation} orientation The orientation of the line.
154 var Line = function(c, orientation) {
156 this.rotated = orientation;
161 * The position of the provided point in relation to the line.
162 * @param {number} x The x-coordinate of the point.
163 * @param {number} y The y-coordinate of the point.
164 * @return {number} Zero if they intersect, negative if the point is before
165 * the line, positive if it's after.
167 testPoint: function(x, y) {
168 var c = this.rotated ? y : x;
169 return this.c == c ? 0 : c - this.c;
172 test: function(key) {
173 // Key already provides an intersect method. If the key is to the right of
174 // the line, then the line is to the left of the key.
175 return -1 * key.intersect(this);
180 * A node used to split 2D space.
181 * @param {Line} line The line to split the space with.
184 var DecisionNode = function(line) {
185 this.decision = line;
188 DecisionNode.prototype = {
190 * The test whether to proceed in the left or right branch.
196 * The branch for nodes that failed the decision test.
197 * @type {?DecisionNode}
202 * The branch for nodes that passed the decision test.
203 * @type {?DecisionNode}
208 * Finds the node closest to the point provided.
209 * @param {number} x The x-coordinate.
210 * @param {number} y The y-coordinate.
211 * @return {DecisionNode | LeafNode}
213 findClosestNode: function(x, y) {
214 return this.search(function(node) {
215 return node.decision.testPoint(x, y) >= 0;
220 * Populates the decision tree with elements.
221 * @param {Array{Key}} The child elements.
223 populate: function(data) {
228 for (var i = 0; i < data.length; i++) {
229 var result = this.decision.test(data[i]);
230 // Add to both branches if result == 0.
236 var currentRotation = this.decision.rotated;
238 * Splits the tree further such that each leaf has exactly one data point.
239 * @param {Array} array The data points.
240 * @return {DecisionNode | LeafNode} The new branch for the tree.
242 var updateBranch = function(array) {
243 if (array.length == 1) {
244 return new LeafNode(array[0]);
246 var splits = findSplits(array, !currentRotation);
247 var tree = createBinaryTree(0, splits.length - 1, splits);
248 tree.populate(array);
252 // All elements that passed the decision test.
253 if (pass.length > 0) {
255 this.pass.populate(pass);
257 this.pass = updateBranch(pass);
259 // All elements that failed the decision test.
260 if (fail.length > 0) {
262 this.fail.populate(fail);
264 this.fail = updateBranch(fail);
269 * Searches for the first leaf that matches the search function.
270 * @param {Function<DecisionNode>: Boolean} searchFn The function used to
271 * determine whether to search in the left or right subtree.
272 * @return {DecisionNode | LeafNode} The node that most closely matches the
275 search: function(searchFn) {
276 if (searchFn(this)) {
277 return this.pass ? this.pass.search(searchFn) : this;
279 return this.fail ? this.fail.search(searchFn) : this;
283 * Tests whether the key belongs in the left or right branch of this node.
284 * @param {Key} key The key being tested.
285 * @return {boolean} Whether it belongs in the right branch.
287 test: function(key) {
288 return this.decision.testKey(key);
293 * Structure representing a leaf in the decision tree. It contains a single
296 var LeafNode = function(data) {
300 LeafNode.prototype = {
307 * Converts the array to a binary tree.
308 * @param {number} start The start index.
309 * @param {number} end The end index.
310 * @param {Array} nodes The array to convert.
311 * @return {DecisionNode}
313 var createBinaryTree = function(start, end, nodes) {
316 var midpoint = Math.floor((end + start)/2);
317 var root = new DecisionNode(nodes[midpoint]);
318 root.fail = createBinaryTree(start, midpoint - 1, nodes);
319 root.pass = createBinaryTree(midpoint + 1, end, nodes);
324 * Calculates the optimum split points on the specified axis.
325 * @param {Array.<Keys>} allKeys All keys in the keyset.
326 * @param {Orientation} orientation Whether to split on the y-axis instead.
327 * @return {Array.<Line>} The optimum split points.
329 var findSplits = function(allKeys, orientation) {
331 * Returns the minimum edge on the key.
332 * @param {Key} key The key.
335 var getMin = function(key) {
336 return orientation == Orientation.HORIZONTAL ? key.top : key.left;
340 * Returns the maximum edge on the key.
341 * @param {Key} key The key.
343 var getMax = function(key) {
344 return orientation == Orientation.HORIZONTAL ? key.bottom : key.right;
348 * Returns a duplicate free version of array.
349 * @param {Array} array A sorted array.
350 * @return {Array} Sorted array without duplicates.
352 var unique = function(array) {
354 for (var i = 0; i< array.length; i++) {
355 if (i == 0 || result[result.length -1] != array[i])
356 result.push(array[i]);
362 * Creates an array of zeroes.
363 * @param {number} length The length of the array.
364 * @return {Array{number}}
366 var zeroes = function(length) {
367 var array = new Array(length);
368 for (var i = 0; i < length; i++) {
373 // All edges of keys.
375 for (var i = 0; i < allKeys.length; i++) {
376 var key = allKeys[i];
377 var min = getMin(key);
378 var max = getMax(key);
382 // Array.sort() sorts lexicographically by default.
383 edges.sort(function(a, b) {
386 edges = unique(edges);
387 // Container for projection sum from edge i to edge i + 1.
388 var intervalWeight = zeroes(edges.length);
390 for (var i = 0; i < allKeys.length; i++) {
391 var key = allKeys[i];
392 var min = getMin(key);
393 var max = getMax(key);
395 exports.binarySearch(edges, 0, edges.length - 1, function(index) {
396 var edge = edges[index];
397 return edge == min ? 0 : min - edge;
399 if (index < 0 || min != edges[index]) {
400 console.error("Unable to split keys.");
403 // Key can span multiple edges.
404 for (var j = index; j < edges.length && edges[j] < max; j++) {
405 intervalWeight[j] ++;
410 // Min and max are bad splits.
411 for (var i = 1; i < intervalWeight.length - 1; i++) {
412 if (intervalWeight[i] < intervalWeight[i - 1]) {
413 var mid = Math.abs((edges[i] + edges[i+1]) / 2)
414 splits.push(new Line(mid, orientation));
421 * Caches the layout of current keysets.
423 function recordKeysets_() {
425 var keysets = $('keyboard').querySelectorAll('kb-keyset').array();
426 for (var i = 0; i < keysets.length; i++) {
427 var keyset = keysets[i];
428 var layout = new KeysetLayout();
429 var rows = keyset.querySelectorAll('kb-row').array();
430 for (var j = 0; j < rows.length; j++) {
432 var nodes = row.children;
433 for (var k = 0 ; k < nodes.length; k++) {
434 layout.add(new Key(nodes[k]));
437 layout.regenerateTree();
438 layouts[keyset.id] = layout;
443 * Returns the layout of the keyset.
444 * @param{!String} id The id of the keyset.
447 var getKeysetLayout_ = function(id) {
451 exports.getKeysetLayout = getKeysetLayout_;
452 exports.recordKeysets = recordKeysets_;