1/*
2  Copyright (c) 2012 The Chromium Authors. All rights reserved.
3  Use of this source code is governed by a BSD-style license that can be
4  found in the LICENSE file.
5*/
6
7/**
8 * @fileoverview Class and functions to handle positioning of plot data points.
9 */
10
11/**
12 * Class that handles plot data positioning.
13 * @constructor
14 *
15 * @param {Array} plotData Data that will be plotted.  It is an array of lines,
16 *     where each line is an array of points, and each point is a length-2 array
17 *     representing an (x, y) pair.
18 */
19function Coordinates(plotData) {
20  this.plotData = plotData;
21
22  height = window.innerHeight - 16;
23  width = window.innerWidth - 16;
24
25  this.widthMax = width;
26  this.heightMax = Math.min(400, height - 85);
27
28  this.processValues_('x');
29  this.processValues_('y');
30}
31
32/**
33 * Determines the min/max x or y values in the plot, accounting for some extra
34 * buffer space.
35 *
36 * @param {string} type The type of value to process, either 'x' or 'y'.
37 */
38Coordinates.prototype.processValues_ = function (type) {
39  var merged = [];
40  for (var i = 0; i < this.plotData.length; i++)
41    for (var j = 0; j < this.plotData[i].length; j++) {
42      if (type == 'x')
43        merged.push(parseFloat(this.plotData[i][j][0]));  // Index 0 is x value.
44      else
45        merged.push(parseFloat(this.plotData[i][j][1]));  // Index 1 is y value.
46    }
47
48  min = merged[0];
49  max = merged[0];
50  for (var i = 1; i < merged.length; ++i) {
51    if (isNaN(min) || merged[i] < min)
52      min = merged[i];
53    if (isNaN(max) || merged[i] > max)
54      max = merged[i];
55  }
56
57  var bufferSpace = 0.02 * (max - min);
58
59  if (type == 'x') {
60    this.xBufferSpace_ = bufferSpace;
61    this.xMinValue_ = min;
62    this.xMaxValue_ = max;
63  } else {
64    this.yBufferSpace_ = bufferSpace;
65    this.yMinValue_ = min;
66    this.yMaxValue_ = max;
67  }
68};
69
70/**
71 * Difference between horizontal upper and lower limit values.
72 *
73 * @return {number} The x value range.
74 */
75Coordinates.prototype.xValueRange = function() {
76  return this.xUpperLimitValue() - this.xLowerLimitValue();
77};
78
79/**
80 * Difference between vertical upper and lower limit values.
81 *
82 * @return {number} The y value range.
83 */
84Coordinates.prototype.yValueRange = function() {
85  return this.yUpperLimitValue() - this.yLowerLimitValue();
86};
87
88/**
89 * Converts horizontal data value to pixel value on canvas.
90 *
91 * @param {number} value The x data value.
92 * @return {number} The corresponding x pixel value on the canvas.
93 */
94Coordinates.prototype.xPixel = function(value) {
95  return this.widthMax *
96      ((value - this.xLowerLimitValue()) / this.xValueRange());
97};
98
99/**
100 * Converts vertical data value to pixel value on canvas.
101 *
102 * @param {number} value The y data value.
103 * @return {number} The corresponding y pixel value on the canvas.
104 */
105Coordinates.prototype.yPixel = function(value) {
106  if (this.yValueRange() == 0) {
107    // Completely horizontal lines should be centered horizontally.
108    return this.heightMax / 2;
109  } else {
110    return this.heightMax -
111        (this.heightMax *
112         (value - this.yLowerLimitValue()) / this.yValueRange());
113  }
114};
115
116/**
117 * Converts x point on canvas to data value it represents.
118 *
119 * @param {number} position The x pixel value on the canvas.
120 * @return {number} The corresponding x data value.
121 */
122Coordinates.prototype.xValue = function(position) {
123  return this.xLowerLimitValue() +
124      (position / this.widthMax * this.xValueRange());
125};
126
127/**
128 * Converts y point on canvas to data value it represents.
129 *
130 * @param {number} position The y pixel value on the canvas.
131 * @return {number} The corresponding y data value.
132 */
133Coordinates.prototype.yValue = function(position) {
134  var ratio = this.heightMax / (this.heightMax - position);
135  return this.yLowerLimitValue() + (this.yValueRange() / ratio);
136};
137
138/**
139 * Returns the minimum x value of all the data points.
140 *
141 * @return {number} The minimum x value of all the data points.
142 */
143Coordinates.prototype.xMinValue = function() {
144  return this.xMinValue_;
145};
146
147/**
148 * Returns the maximum x value of all the data points.
149 *
150 * @return {number} The maximum x value of all the data points.
151 */
152Coordinates.prototype.xMaxValue = function() {
153  return this.xMaxValue_;
154};
155
156/**
157 * Returns the minimum y value of all the data points.
158 *
159 * @return {number} The minimum y value of all the data points.
160 */
161Coordinates.prototype.yMinValue = function() {
162  return this.yMinValue_;
163};
164
165/**
166 * Returns the maximum y value of all the data points.
167 *
168 * @return {number} The maximum y value of all the data points.
169 */
170Coordinates.prototype.yMaxValue = function() {
171  return this.yMaxValue_;
172};
173
174/**
175 * Returns the x value at the lower limit of the bounding box of the canvas.
176 *
177 * @return {number} The x value at the lower limit of the bounding box of
178 *     the canvas.
179 */
180Coordinates.prototype.xLowerLimitValue = function() {
181  return this.xMinValue_ - this.xBufferSpace_;
182};
183
184/**
185 * Returns the x value at the upper limit of the bounding box of the canvas.
186 *
187 * @return {number} The x value at the upper limit of the bounding box of
188 *     the canvas.
189 */
190Coordinates.prototype.xUpperLimitValue = function() {
191  return this.xMaxValue_ + this.xBufferSpace_;
192};
193
194/**
195 * Returns the y value at the lower limit of the bounding box of the canvas.
196 *
197 * @return {number} The y value at the lower limit of the bounding box of
198 *     the canvas.
199 */
200Coordinates.prototype.yLowerLimitValue = function() {
201  return this.yMinValue_ - this.yBufferSpace_;
202};
203
204/**
205 * Returns the y value at the upper limit of the bounding box of the canvas.
206 *
207 * @return {number} The y value at the upper limit of the bounding box of
208 *     the canvas.
209 */
210Coordinates.prototype.yUpperLimitValue = function() {
211  return this.yMaxValue_ + this.yBufferSpace_;
212};
213