001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.tools;
003
004import java.awt.Color;
005import java.awt.FontMetrics;
006import java.awt.Graphics2D;
007
008/**
009 * Utility class that helps to work with color scale for coloring GPX tracks etc.
010 * @since 7319
011 */
012public final class ColorScale {
013    private double min, max;
014    private Color noDataColor;
015    private Color belowMinColor;
016    private Color aboveMaxColor;
017
018    private Color[] colors;
019    private String title = "";
020    private int intervalCount = 5;
021
022    private ColorScale() {
023
024    }
025
026    public static ColorScale createHSBScale(int count) {
027        ColorScale sc = new ColorScale();
028        sc.colors = new Color[count];
029        for (int i = 0; i < count; i++) {
030            sc.colors[i] = Color.getHSBColor(i / 300.0f, 1, 1);
031        }
032        sc.setRange(0, 255);
033        sc.addBounds();
034        return sc;
035    }
036
037    public static ColorScale createCyclicScale(int count) {
038        ColorScale sc = new ColorScale();
039        // CHECKSTYLE.OFF: SingleSpaceSeparator
040        //                   red  yellow  green   blue    red
041        int[] h = new int[] {0,    59,     127,    244,   360};
042        int[] s = new int[] {100,  84,     99,     100};
043        int[] b = new int[] {90,   93,     74,     83};
044        // CHECKSTYLE.ON: SingleSpaceSeparator
045
046        sc.colors = new Color[count];
047        for (int i = 0; i < sc.colors.length; i++) {
048
049            float angle = i / 256f * 4;
050            int quadrant = (int) angle;
051            angle -= quadrant;
052            quadrant = Utils.mod(quadrant+1, 4);
053
054            float vh = h[quadrant] * w(angle) + h[quadrant+1] * (1 - w(angle));
055            float vs = s[quadrant] * w(angle) + s[Utils.mod(quadrant+1, 4)] * (1 - w(angle));
056            float vb = b[quadrant] * w(angle) + b[Utils.mod(quadrant+1, 4)] * (1 - w(angle));
057
058            sc.colors[i] = Color.getHSBColor(vh/360f, vs/100f, vb/100f);
059        }
060        sc.setRange(0, 2*Math.PI);
061        sc.addBounds();
062        return sc;
063    }
064
065    /**
066     * transition function:
067     *  w(0)=1, w(1)=0, 0&lt;=w(x)&lt;=1
068     * @param x number: 0&lt;=x&lt;=1
069     * @return the weighted value
070     */
071    private static float w(float x) {
072        if (x < 0.5)
073            return 1 - 2*x*x;
074        else
075            return 2*(1-x)*(1-x);
076    }
077
078    public void setRange(double min, double max) {
079        this.min = min;
080        this.max = max;
081    }
082
083    /**
084     * Add standard colors for values below min or above max value
085     */
086    public void addBounds() {
087        aboveMaxColor = colors[colors.length-1];
088        belowMinColor = colors[0];
089    }
090
091    public Color getColor(double value) {
092        if (value < min) return belowMinColor;
093        if (value > max) return aboveMaxColor;
094        if (Double.isNaN(value)) return noDataColor;
095        final int n = colors.length;
096        int idx = (int) ((value-min)*colors.length / (max-min));
097        if (idx < colors.length) {
098            return colors[idx];
099        } else {
100            return colors[n-1]; // this happens when value==max
101        }
102    }
103
104    public Color getColor(Number value) {
105        return (value == null) ? noDataColor : getColor(value.doubleValue());
106    }
107
108    public Color getNoDataColor() {
109        return noDataColor;
110    }
111
112    public void setNoDataColor(Color noDataColor) {
113        this.noDataColor = noDataColor;
114    }
115
116    public ColorScale makeTransparent(int alpha) {
117        for (int i = 0; i < colors.length; i++) {
118            colors[i] = new Color((colors[i].getRGB() & 0xFFFFFF) | ((alpha & 0xFF) << 24), true);
119        }
120        return this;
121    }
122
123    public ColorScale addTitle(String title) {
124        this.title = title;
125        return this;
126    }
127
128    public ColorScale setIntervalCount(int intervalCount) {
129        this.intervalCount = intervalCount;
130        return this;
131    }
132
133    public ColorScale makeReversed() {
134        int n = colors.length;
135        Color tmp;
136        for (int i = 0; i < n/2; i++) {
137            tmp = colors[i];
138            colors[i] = colors[n-1-i];
139            colors[n-1-i] = tmp;
140        }
141        tmp = belowMinColor;
142        belowMinColor = aboveMaxColor;
143        aboveMaxColor = tmp;
144        return this;
145    }
146
147    public void drawColorBar(Graphics2D g, int x, int y, int w, int h, double valueScale) {
148        int n = colors.length;
149
150        for (int i = 0; i < n; i++) {
151            g.setColor(colors[i]);
152            if (w < h) {
153                g.fillRect(x, y+i*h/n, w, h/n+1);
154            } else {
155                g.fillRect(x+i*w/n, y, w/n+1, h);
156            }
157        }
158
159        int fw, fh;
160        FontMetrics fm = g.getFontMetrics();
161        fh = fm.getHeight()/2;
162        fw = fm.stringWidth(String.valueOf(Math.max((int) Math.abs(max*valueScale),
163                (int) Math.abs(min*valueScale)))) + fm.stringWidth("0.123");
164        g.setColor(noDataColor);
165        if (title != null) {
166            g.drawString(title, x-fw-3, y-fh*3/2);
167        }
168        for (int i = 0; i <= intervalCount; i++) {
169            g.setColor(colors[(int) (1.0*i*n/intervalCount-1e-10)]);
170            final double val = min+i*(max-min)/intervalCount;
171            final String txt = String.format("%.3f", val*valueScale);
172            if (w < h) {
173                g.drawString(txt, x-fw-3, y+i*h/intervalCount+fh/2);
174            } else {
175                g.drawString(txt, x+i*w/intervalCount-fw/2, y+fh-3);
176            }
177        }
178    }
179}