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) 2013-2014 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/node/13">OpenTrafficSim License</a>.
16 * <p>
17 * @version Jul 30, 2014 <br>
18 * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
19 */
20 public class ContinuousColorPaintScale implements PaintScale
21 {
22 /** Boundary values for this ColorPaintScale. */
23 private double[] bounds;
24
25 /** Color values to use at the boundary values. */
26 private Color[] boundColors;
27
28 /** Format string to render values in a human readable format (used in tool tip texts). */
29 private final String format;
30
31 /**
32 * Create a new ContinuousColorPaintScale.
33 * @param format Format string to render the value under the mouse in a human readable format
34 * @param bounds Double[] array of boundary values (all values must be distinct and the number of values must be >= 2)
35 * @param boundColors Color[] array of the colors to use at the boundary values (must have same size as bounds)
36 */
37 ContinuousColorPaintScale(final String format, final double[] bounds, final Color[] boundColors)
38 {
39 this.format = format;
40 if (bounds.length < 2)
41 {
42 throw new Error("bounds must have >= 2 entries");
43 }
44 if (bounds.length != boundColors.length)
45 {
46 throw new Error("bounds must have same length as boundColors");
47 }
48 this.bounds = new double[bounds.length];
49 this.boundColors = new Color[bounds.length];
50 // Store the bounds and boundColors in order of increasing bound value.
51 // This is as inefficient as bubble sorting, but we're dealing with only a few values here.
52 for (int nextBound = 0; nextBound < bounds.length; nextBound++)
53 {
54 // Find the lowest not-yet used bound
55 double currentLowest = Double.POSITIVE_INFINITY;
56 int bestIndex = -1;
57 int index;
58 for (index = 0; index < bounds.length; index++)
59 {
60 if (bounds[index] < currentLowest && (nextBound == 0 || bounds[index] > this.bounds[nextBound - 1]))
61 {
62 bestIndex = index;
63 currentLowest = bounds[index];
64 }
65 }
66 if (bestIndex < 0)
67 {
68 throw new Error("duplicate value in bounds");
69 }
70 this.bounds[nextBound] = bounds[bestIndex];
71 this.boundColors[nextBound] = boundColors[bestIndex];
72 }
73 }
74
75 /** {@inheritDoc} */
76 @Override
77 public final double getLowerBound()
78 {
79 return this.bounds[0];
80 }
81
82 /**
83 * 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
84 * 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>.
85 * However, the result is always limited to the range 0..255.
86 * @param ratio Double; value (normally) between 0.0 and 1.0.
87 * @param low Integer; this value is returned when ratio equals 0.0
88 * @param high Integer; this value is returned when ratio equals 1.0
89 * @return Integer; the ratio-weighted average of <i>low</i> and <i>high</i>
90 */
91 private static int mixComponent(final double ratio, final int low, final int high)
92 {
93 final double mix = low * (1 - ratio) + high * ratio;
94 int result = (int) mix;
95 if (result < 0)
96 {
97 result = 0;
98 }
99 if (result > 255)
100 {
101 result = 255;
102 }
103 return result;
104 }
105
106 /** {@inheritDoc} */
107 @Override
108 public final Paint getPaint(final double value)
109 {
110 int bucket;
111 for (bucket = 0; bucket < this.bounds.length - 1; bucket++)
112 {
113 if (value < this.bounds[bucket + 1])
114 {
115 break;
116 }
117 }
118 if (bucket >= this.bounds.length - 1)
119 {
120 bucket = this.bounds.length - 2;
121 }
122 final double ratio = (value - this.bounds[bucket]) / (this.bounds[bucket + 1] - this.bounds[bucket]);
123 Color mix =
124 new Color(mixComponent(ratio, this.boundColors[bucket].getRed(), this.boundColors[bucket + 1].getRed()),
125 mixComponent(ratio, this.boundColors[bucket].getGreen(), this.boundColors[bucket + 1].getGreen()),
126 mixComponent(ratio, this.boundColors[bucket].getBlue(), this.boundColors[bucket + 1].getBlue()));
127 return mix;
128 }
129
130 /** {@inheritDoc} */
131 @Override
132 public final double getUpperBound()
133 {
134 return this.bounds[this.bounds.length - 1];
135 }
136
137 /**
138 * Retrieve the format string.
139 * @return format string
140 */
141 public final String getFormat()
142 {
143 return this.format;
144 }
145
146 }