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 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        //                    red   yellow  green   blue    red
040        int[] h = new int[] { 0,    59,     127,    244,    360};
041        int[] s = new int[] { 100,  84,     99,     100 };
042        int[] b = new int[] { 90,   93,     74,     83 };
043
044        sc.colors = new Color[count];
045        for (int i = 0; i < sc.colors.length; i++) {
046
047            float angle = 4 - i / 256f * 4;
048            int quadrant = (int) angle;
049            angle -= quadrant;
050            quadrant = Utils.mod(quadrant+1, 4);
051
052            float vh = h[quadrant] * w(angle) + h[quadrant+1] * (1 - w(angle));
053            float vs = s[quadrant] * w(angle) + s[Utils.mod(quadrant+1, 4)] * (1 - w(angle));
054            float vb = b[quadrant] * w(angle) + b[Utils.mod(quadrant+1, 4)] * (1 - w(angle));
055
056            sc.colors[i] = Color.getHSBColor(vh/360f, vs/100f, vb/100f);
057        }
058        sc.setRange(0, 2*Math.PI);
059        sc.addBounds();
060        return sc;
061    }
062
063    /**
064     * transition function:
065     *  w(0)=1, w(1)=0, 0&lt;=w(x)&lt;=1
066     * @param x number: 0&lt;=x&lt;=1
067     * @return the weighted value
068     */
069    private static float w(float x) {
070        if (x < 0.5)
071            return 1 - 2*x*x;
072        else
073            return 2*(1-x)*(1-x);
074    }
075
076    public void setRange(double min, double max) {
077        this.min = min;
078        this.max = max;
079    }
080
081    /**
082     * Add standard colors for values below min or above max value
083     */
084    public void addBounds() {
085        aboveMaxColor = colors[colors.length-1];
086        belowMinColor = colors[0];
087    }
088
089    public final Color getColor(double value) {
090        if (value<min) return belowMinColor;
091        if (value>max) return aboveMaxColor;
092        if (Double.isNaN(value)) return noDataColor;
093        final int n = colors.length;
094        int idx = (int) ((value-min)*colors.length / (max-min));
095        if (idx<colors.length) {
096            return colors[idx];
097        } else {
098            return colors[n-1]; // this happens when value==max
099        }
100    }
101
102    public final Color getColor(Number value) {
103        return (value==null)? noDataColor : getColor(value.doubleValue());
104    }
105
106    public Color getNoDataColor() {
107        return noDataColor;
108    }
109
110    public void setNoDataColor(Color noDataColor) {
111        this.noDataColor = noDataColor;
112    }
113
114    public ColorScale makeTransparent(int alpha) {
115        for (int i = 0; i < colors.length; i++) {
116            colors[i] = new Color((colors[i].getRGB() & 0xFFFFFF) | ((alpha & 0xFF) << 24), true);
117        }
118        return this;
119    }
120
121    public ColorScale addTitle(String title) {
122        this.title = title;
123        return this;
124    }
125
126    public ColorScale setIntervalCount(int intervalCount) {
127        this.intervalCount = intervalCount;
128        return this;
129    }
130
131    public ColorScale makeReversed() {
132        int n = colors.length;
133        Color tmp;
134        for (int i=0; i<n/2; i++) {
135            tmp = colors[i];
136            colors[i] = colors[n-1-i];
137            colors[n-1-i] = tmp;
138        }
139        tmp = belowMinColor;
140        belowMinColor = aboveMaxColor;
141        aboveMaxColor = tmp;
142        return this;
143    }
144
145    public void drawColorBar(Graphics2D g, int x, int y, int w, int h, double valueScale) {
146        int n=colors.length;
147
148        for (int i=0; i<n; i++) {
149            g.setColor(colors[i]);
150            if (w<h) {
151                g.fillRect(x, y+i*h/n, w, h/n+1);
152            } else {
153                g.fillRect(x+i*w/n, y, w/n+1, h);
154            }
155        }
156
157        int fw, fh;
158        FontMetrics fm = g.getFontMetrics();
159        fh = fm.getHeight()/2;
160        fw = fm.stringWidth(String.valueOf(Math.max((int)Math.abs(max*valueScale), (int)Math.abs(min*valueScale)))) + fm.stringWidth("0.123");
161        g.setColor(noDataColor);
162        if (title != null) {
163            g.drawString(title, x-fw-3, y-fh*3/2);
164        }
165        for (int i=0; i<=intervalCount; i++) {
166            g.setColor(colors[(int)(1.0*i*n/intervalCount-1e-10)]);
167            final double val =  min+i*(max-min)/intervalCount;
168            final String txt = String.format("%.3f", val*valueScale);
169            if (w<h) {
170                g.drawString(txt, x-fw-3, y+i*h/intervalCount+fh/2);
171            } else {
172                g.drawString(txt, x+i*w/intervalCount-fw/2, y+fh-3);
173            }
174        }
175    }
176}