Mercurial > projects > dwt-addons

comparison dwtx/jface/internal/text/revisions/Colors.d @ 129:eb30df5ca28b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Added JFace Text sources
author Frank Benoit <benoit@tionex.de>
date Sat, 23 Aug 2008 19:10:48 +0200
parents
children c4fb132a086c
comparison
equal deleted inserted replaced
128:8df1d4193877 129:eb30df5ca28b
1 /*******************************************************************************
2 * Copyright (c) 2006, 2007 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 * Port to the D programming language:
11 * Frank Benoit <benoit@tionex.de>
12 *******************************************************************************/
13 module dwtx.jface.internal.text.revisions.Colors;
14
15 import dwt.dwthelper.utils;
16
17
18 import dwt.DWT;
19 import dwt.graphics.RGB;
20 import dwtx.core.runtime.Assert;
21
22 /**
23 * Utility for color operations.
24 *
25 * @since 3.3
26 */
27 public final class Colors {
28 /*
29 * Implementation note: Color computation assumes sRGB, which is probably not true, and does not
30 * always give good results. CIE based algorithms would be better, see
31 * http://www.w3.org/TR/PNG-ColorAppendix.html and http://en.wikipedia.org/wiki/Lab_color_space
32 */
33
34 /**
35 * Returns the human-perceived brightness of a color as float in [0.0, 1.0]. The used RGB
36 * weights come from http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9.
37 *
38 * @param rgb the color
39 * @return the gray-scale value
40 */
41 public static float brightness(RGB rgb) {
42 return Math.min(1f, (0.2126f * rgb.red + 0.7152f * rgb.green + 0.0722f * rgb.blue + 0.5f) / 255f);
43 }
44
45 /**
46 * Normalizes a color in its perceived brightness. Yellows are darkened, while blues and reds
47 * are lightened. Depending on the hue, the brightness range within the RGB gamut may be
48 * different, outside values are clipped. Note that this is an approximation; the returned RGB
49 * is not guaranteed to have the requested {@link #brightness(RGB) brightness}.
50 *
51 * @param color the color to normalize
52 * @param brightness the requested brightness, in [0,&nbsp;1]
53 * @return a normalized version of <code>color</code>
54 * @see #brightness(RGB)
55 */
56 public static RGB adjustBrightness(RGB color, float brightness) {
57 float[] hsi= toHSI(color);
58 float psychoFactor= brightness - brightness(color);
59 float weight= 0.5f; // found by trial and error
60 hsi[2]= Math.max(0, Math.min(1.0f, hsi[2] + psychoFactor * weight));
61 color= fromHSI(hsi);
62 return color;
63 }
64
65 /**
66 * Converts an {@link RGB} to an <a href="http://en.wikipedia.org/wiki/HSL_color_space">HSI</a>
67 * triplet.
68 *
69 * @param color the color to convert
70 * @return the HSI float array of length 3
71 */
72 private static float[] toHSI(RGB color) {
73 float r = color.red / 255f;
74 float g = color.green / 255f;
75 float b = color.blue / 255f;
76 float max = Math.max(Math.max(r, g), b);
77 float min = Math.min(Math.min(r, g), b);
78 float delta = max - min;
79 float maxPlusMin= max + min;
80 float intensity = maxPlusMin / 2;
81 float saturation= intensity < 0.5 ? delta / maxPlusMin : delta / (2 - maxPlusMin);
82
83 float hue = 0;
84 if (delta !is 0) {
85 if (r is max) {
86 hue = (g - b) / delta;
87 } else {
88 if (g is max) {
89 hue = 2 + (b - r) / delta;
90 } else {
91 hue = 4 + (r - g) / delta;
92 }
93 }
94 hue *= 60;
95 if (hue < 0) hue += 360;
96 }
97 return new float[] {hue, saturation, intensity};
98 }
99
100 /**
101 * Converts a <a href="http://en.wikipedia.org/wiki/HSL_color_space">HSI</a> triplet to an RGB.
102 *
103 * @param hsi the HSI values
104 * @return the RGB corresponding to the HSI spec
105 */
106 private static RGB fromHSI(float[] hsi) {
107 float r, g, b;
108 float hue= hsi[0];
109 float saturation= hsi[1];
110 float intensity= hsi[2];
111 if (saturation is 0) {
112 r = g = b = intensity;
113 } else {
114 float temp2= intensity < 0.5f ? intensity * (1.0f + saturation) : (intensity + saturation) - (intensity * saturation);
115 float temp1= 2f * intensity - temp2;
116 if (hue is 360) hue = 0;
117 hue /= 360;
118
119 r= hue2RGB(temp1, temp2, hue + 1f/3f);
120 g= hue2RGB(temp1, temp2, hue);
121 b= hue2RGB(temp1, temp2, hue - 1f/3f);
122 }
123
124 int red = (int)(r * 255 + 0.5);
125 int green = (int)(g * 255 + 0.5);
126 int blue = (int)(b * 255 + 0.5);
127 return new RGB(red, green, blue);
128 }
129
130 private static float hue2RGB(float t1, float t2, float hue) {
131 if (hue < 0)
132 hue += 1;
133 else if (hue > 1)
134 hue -= 1;
135 if (6f * hue < 1)
136 return t1 +(t2 - t1) * 6f * hue;
137 if (2f * hue < 1)
138 return t2;
139 if (3f * hue < 2)
140 return t1 + (t2 - t1) * (2f/3f - hue) * 6f;
141 return t1;
142 }
143
144 /**
145 * Returns an RGB that lies between the given foreground and background
146 * colors using the given mixing factor. A <code>factor</code> of 1.0 will produce a
147 * color equal to <code>fg</code>, while a <code>factor</code> of 0.0 will produce one
148 * equal to <code>bg</code>.
149 * @param bg the background color
150 * @param fg the foreground color
151 * @param factor the mixing factor, must be in [0,&nbsp;1]
152 *
153 * @return the interpolated color
154 */
155 public static RGB blend(RGB bg, RGB fg, float factor) {
156 Assert.isLegal(bg !is null);
157 Assert.isLegal(fg !is null);
158 Assert.isLegal(factor >= 0f && factor <= 1f);
159
160 float complement= 1f - factor;
161 return new RGB(
162 (int) (complement * bg.red + factor * fg.red),
163 (int) (complement * bg.green + factor * fg.green),
164 (int) (complement * bg.blue + factor * fg.blue)
165 );
166 }
167
168 /**
169 * Returns an array of colors in a smooth palette from <code>start</code> to <code>end</code>.
170 * <p>
171 * The returned array has size <code>steps</code>, and the color at index 0 is <code>start</code>, the color
172 * at index <code>steps&nbsp;-&nbsp;1</code> is <code>end</code>.
173 *
174 * @param start the start color of the palette
175 * @param end the end color of the palette
176 * @param steps the requested size, must be &gt; 0
177 * @return an array of <code>steps</code> colors in the palette from <code>start</code> to <code>end</code>
178 */
179 public static RGB[] palette(RGB start, RGB end, int steps) {
180 Assert.isLegal(start !is null);
181 Assert.isLegal(end !is null);
182 Assert.isLegal(steps > 0);
183
184 if (steps is 1)
185 return new RGB[] { start };
186
187 float step= 1.0f / (steps - 1);
188 RGB[] gradient= new RGB[steps];
189 for (int i= 0; i < steps; i++)
190 gradient[i]= blend(start, end, step * i);
191
192 return gradient;
193 }
194
195 /**
196 * Returns an array of colors with hues evenly distributed on the hue wheel defined by the <a
197 * href="http://en.wikipedia.org/wiki/HSV_color_space">HSB color space</a>. The returned array
198 * has size <code>steps</code>. The distance <var>d</var> between two successive colors is
199 * in [120&#176;,&nbsp;180&#176;].
200 * <p>
201 * The color at a given <code>index</code> has the hue returned by
202 * {@linkplain #computeHue(int) computeHue(index)}; i.e. the computed hues are not equidistant,
203 * but adaptively distributed on the color wheel.
204 * </p>
205 * <p>
206 * The first six colors returned correspond to the following {@link DWT} color constants:
207 * {@link DWT#COLOR_RED red}, {@link DWT#COLOR_GREEN green}, {@link DWT#COLOR_BLUE blue},
208 * {@link DWT#COLOR_YELLOW yellow}, {@link DWT#COLOR_CYAN cyan},
209 * {@link DWT#COLOR_MAGENTA magenta}.
210 * </p>
211 *
212 * @param steps the requested size, must be &gt;= 2
213 * @return an array of <code>steps</code> colors evenly distributed on the color wheel
214 */
215 public static RGB[] rainbow(int steps) {
216 Assert.isLegal(steps >= 2);
217
218 RGB[] rainbow= new RGB[steps];
219 for (int i= 0; i < steps; i++)
220 rainbow[i]= new RGB(computeHue(i), 1f, 1f);
221
222 return rainbow;
223 }
224
225 /**
226 * Returns an indexed hue in [0&#176;,&nbsp;360&#176;), distributing the hues evenly on the hue wheel
227 * defined by the <a href="http://en.wikipedia.org/wiki/HSV_color_space">HSB (or HSV) color
228 * space</a>. The distance <var>d</var> between two successive colors is in [120&#176;,&nbsp;180&#176;].
229 * <p>
230 * The first six colors returned correspond to the following {@link DWT} color constants:
231 * {@link DWT#COLOR_RED red}, {@link DWT#COLOR_GREEN green}, {@link DWT#COLOR_BLUE blue},
232 * {@link DWT#COLOR_YELLOW yellow}, {@link DWT#COLOR_CYAN cyan},
233 * {@link DWT#COLOR_MAGENTA magenta}.
234 * </p>
235 *
236 * @param index the index of the color, must be &gt;= 0
237 * @return a color hue in [0&#176;,&nbsp;360&#176;)
238 * @see RGB#RGB(float, float, float)
239 */
240 public static float computeHue(final int index) {
241 Assert.isLegal(index >= 0);
242 /*
243 * Base 3 gives a nice partitioning for RGB colors with red, green, blue being the colors
244 * 0,1,2, and yellow, cyan, magenta colors 3,4,5.
245 */
246 final int base= 3;
247 final float range= 360f;
248
249 // partition the baseRange by using the least significant bit to select one half of the
250 // partitioning
251 int baseIndex= index / base;
252 float baseRange= range / base;
253 float baseOffset= 0f;
254 while (baseIndex > 0) {
255 baseRange /= 2;
256 int lsb= baseIndex % 2;
257 baseOffset += lsb * baseRange;
258 baseIndex >>= 1;
259 }
260
261 final int baseMod= index % base;
262 final float hue= baseOffset + baseMod * range / base;
263 Assert.isTrue(hue >= 0 && hue < 360);
264 return hue;
265 }
266
267 private Colors() {
268 // not instantiatable
269 }
270
271 }