1 package org.opentrafficsim.graphs;
2
3 import java.awt.Color;
4 import java.awt.Paint;
5
6 import org.jfree.chart.renderer.PaintScale;
7
8 /**
9 * Create a continuous color paint scale. <br>
10 * Primarily intended for the contour plots, but sufficiently abstract for more general use. <br>
11 * A continuous color paint scale creates paints (actually simple Colors) by linearly interpolating between a limited set of RGB
12 * Color values that correspond to given input values.
13 * <p>
14 * Copyright (c) 2013-2015 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
15 * BSD-style license. See <a href="http://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
16 * <p>
17 * $LastChangedDate: 2015-07-26 01:01:13 +0200 (Sun, 26 Jul 2015) $, @version $Revision: 1155 $, by $Author: averbraeck $,
18 * initial version Jul 30, 2014 <br>
19 * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
20 */
21 public class ContinuousColorPaintScale implements PaintScale
22 {
23 /** Boundary values for this ColorPaintScale. */
24 private double[] bounds;
25
26 /** Color values to use at the boundary values. */
27 private Color[] boundColors;
28
29 /** Format string to render values in a human readable format (used in tool tip texts). */
30 private final String format;
31
32 /**
33 * Create a new ContinuousColorPaintScale.
34 * @param format Format string to render the value under the mouse in a human readable format
35 * @param bounds Double[] array of boundary values (all values must be distinct and the number of values must be >= 2)
36 * @param boundColors Color[] array of the colors to use at the boundary values (must have same size as bounds)
37 */
38 ContinuousColorPaintScale(final String format, final double[] bounds, final Color[] boundColors)
39 {
40 this.format = format;
41 if (bounds.length < 2)
42 {
43 throw new Error("bounds must have >= 2 entries");
44 }
45 if (bounds.length != boundColors.length)
46 {
47 throw new Error("bounds must have same length as boundColors");
48 }
49 this.bounds = new double[bounds.length];
50 this.boundColors = new Color[bounds.length];
51 // Store the bounds and boundColors in order of increasing bound value.
52 // This is as inefficient as bubble sorting, but we're dealing with only a few values here.
53 for (int nextBound = 0; nextBound < bounds.length; nextBound++)
54 {
55 // Find the lowest not-yet used bound
56 double currentLowest = Double.POSITIVE_INFINITY;
57 int bestIndex = -1;
58 int index;
59 for (index = 0; index < bounds.length; index++)
60 {
61 if (bounds[index] < currentLowest && (nextBound == 0 || bounds[index] > this.bounds[nextBound - 1]))
62 {
63 bestIndex = index;
64 currentLowest = bounds[index];
65 }
66 }
67 if (bestIndex < 0)
68 {
69 throw new Error("duplicate value in bounds");
70 }
71 this.bounds[nextBound] = bounds[bestIndex];
72 this.boundColors[nextBound] = boundColors[bestIndex];
73 }
74 }
75
76 /** {@inheritDoc} */
77 @Override
78 public final double getLowerBound()
79 {
80 return this.bounds[0];
81 }
82
83 /**
84 * Create a mixed color component. When ratio varies from 0.0 to 1.0, the result varies from <i>low</i> to <i>high</i>. If
85 * ratio is outside the range 0.0 to 1.0, the result value can be outside the <i>range</i> <i>low</i> to <i>high</i>.
86 * However, the result is always limited to the range 0..255.
87 * @param ratio Double; value (normally) between 0.0 and 1.0.
88 * @param low Integer; this value is returned when ratio equals 0.0
89 * @param high Integer; this value is returned when ratio equals 1.0
90 * @return Integer; the ratio-weighted average of <i>low</i> and <i>high</i>
91 */
92 private static int mixComponent(final double ratio, final int low, final int high)
93 {
94 final double mix = low * (1 - ratio) + high * ratio;
95 int result = (int) mix;
96 if (result < 0)
97 {
98 result = 0;
99 }
100 if (result > 255)
101 {
102 result = 255;
103 }
104 return result;
105 }
106
107 /** {@inheritDoc} */
108 @Override
109 public final Paint getPaint(final double value)
110 {
111 int bucket;
112 for (bucket = 0; bucket < this.bounds.length - 1; bucket++)
113 {
114 if (value < this.bounds[bucket + 1])
115 {
116 break;
117 }
118 }
119 if (bucket >= this.bounds.length - 1)
120 {
121 bucket = this.bounds.length - 2;
122 }
123 final double ratio = (value - this.bounds[bucket]) / (this.bounds[bucket + 1] - this.bounds[bucket]);
124 Color mix =
125 new Color(mixComponent(ratio, this.boundColors[bucket].getRed(), this.boundColors[bucket + 1].getRed()),
126 mixComponent(ratio, this.boundColors[bucket].getGreen(), this.boundColors[bucket + 1].getGreen()),
127 mixComponent(ratio, this.boundColors[bucket].getBlue(), this.boundColors[bucket + 1].getBlue()));
128 return mix;
129 }
130
131 /** {@inheritDoc} */
132 @Override
133 public final double getUpperBound()
134 {
135 return this.bounds[this.bounds.length - 1];
136 }
137
138 /**
139 * Retrieve the format string.
140 * @return format string
141 */
142 public final String getFormat()
143 {
144 return this.format;
145 }
146
147 }