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| 1 | /* | ||
| 2 | * Copyright (c) 2006, 2011, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.awt; | ||
| 27 | |||
| 28 | import java.awt.geom.AffineTransform; | ||
| 29 | import java.awt.geom.Point2D; | ||
| 30 | import java.awt.geom.Rectangle2D; | ||
| 31 | import java.awt.image.ColorModel; | ||
| 32 | import java.beans.ConstructorProperties; | ||
| 33 | |||
| 34 | /** | ||
| 35 | * The {@code LinearGradientPaint} class provides a way to fill | ||
| 36 | * a {@link java.awt.Shape} with a linear color gradient pattern. The user | ||
| 37 | * may specify two or more gradient colors, and this paint will provide an | ||
| 38 | * interpolation between each color. The user also specifies start and end | ||
| 39 | * points which define where in user space the color gradient should begin | ||
| 40 | * and end. | ||
| 41 | * <p> | ||
| 42 | * The user must provide an array of floats specifying how to distribute the | ||
| 43 | * colors along the gradient. These values should range from 0.0 to 1.0 and | ||
| 44 | * act like keyframes along the gradient (they mark where the gradient should | ||
| 45 | * be exactly a particular color). | ||
| 46 | * <p> | ||
| 47 | * In the event that the user does not set the first keyframe value equal | ||
| 48 | * to 0 and/or the last keyframe value equal to 1, keyframes will be created | ||
| 49 | * at these positions and the first and last colors will be replicated there. | ||
| 50 | * So, if a user specifies the following arrays to construct a gradient:<br> | ||
| 51 | * <pre> | ||
| 52 | * {Color.BLUE, Color.RED}, {.3f, .7f} | ||
| 53 | * </pre> | ||
| 54 | * this will be converted to a gradient with the following keyframes:<br> | ||
| 55 | * <pre> | ||
| 56 | * {Color.BLUE, Color.BLUE, Color.RED, Color.RED}, {0f, .3f, .7f, 1f} | ||
| 57 | * </pre> | ||
| 58 | * | ||
| 59 | * <p> | ||
| 60 | * The user may also select what action the {@code LinearGradientPaint} object | ||
| 61 | * takes when it is filling the space outside the start and end points by | ||
| 62 | * setting {@code CycleMethod} to either {@code REFLECTION} or {@code REPEAT}. | ||
| 63 | * The distances between any two colors in any of the reflected or repeated | ||
| 64 | * copies of the gradient are the same as the distance between those same two | ||
| 65 | * colors between the start and end points. | ||
| 66 | * Note that some minor variations in distances may occur due to sampling at | ||
| 67 | * the granularity of a pixel. | ||
| 68 | * If no cycle method is specified, {@code NO_CYCLE} will be chosen by | ||
| 69 | * default, which means the endpoint colors will be used to fill the | ||
| 70 | * remaining area. | ||
| 71 | * <p> | ||
| 72 | * The colorSpace parameter allows the user to specify in which colorspace | ||
| 73 | * the interpolation should be performed, default sRGB or linearized RGB. | ||
| 74 | * | ||
| 75 | * <p> | ||
| 76 | * The following code demonstrates typical usage of | ||
| 77 | * {@code LinearGradientPaint}: | ||
| 78 | * <p> | ||
| 79 | * <pre> | ||
| 80 | * Point2D start = new Point2D.Float(0, 0); | ||
| 81 | * Point2D end = new Point2D.Float(50, 50); | ||
| 82 | * float[] dist = {0.0f, 0.2f, 1.0f}; | ||
| 83 | * Color[] colors = {Color.RED, Color.WHITE, Color.BLUE}; | ||
| 84 | * LinearGradientPaint p = | ||
| 85 | * new LinearGradientPaint(start, end, dist, colors); | ||
| 86 | * </pre> | ||
| 87 | * <p> | ||
| 88 | * This code will create a {@code LinearGradientPaint} which interpolates | ||
| 89 | * between red and white for the first 20% of the gradient and between white | ||
| 90 | * and blue for the remaining 80%. | ||
| 91 | * | ||
| 92 | * <p> | ||
| 93 | * This image demonstrates the example code above for each | ||
| 94 | * of the three cycle methods: | ||
| 95 | * <p> | ||
| 96 | * <center> | ||
| 97 | * <img src = "doc-files/LinearGradientPaint.png"> | ||
| 98 | * </center> | ||
| 99 | * | ||
| 100 | * @see java.awt.Paint | ||
| 101 | * @see java.awt.Graphics2D#setPaint | ||
| 102 | * @author Nicholas Talian, Vincent Hardy, Jim Graham, Jerry Evans | ||
| 103 | * @since 1.6 | ||
| 104 | */ | ||
| 105 | public final class LinearGradientPaint extends MultipleGradientPaint { | ||
| 106 | |||
| 107 | /** Gradient start and end points. */ | ||
| 108 | private final Point2D start, end; | ||
| 109 | |||
| 110 | /** | ||
| 111 | * Constructs a {@code LinearGradientPaint} with a default | ||
| 112 | * {@code NO_CYCLE} repeating method and {@code SRGB} color space. | ||
| 113 | * | ||
| 114 | * @param startX the X coordinate of the gradient axis start point | ||
| 115 | * in user space | ||
| 116 | * @param startY the Y coordinate of the gradient axis start point | ||
| 117 | * in user space | ||
| 118 | * @param endX the X coordinate of the gradient axis end point | ||
| 119 | * in user space | ||
| 120 | * @param endY the Y coordinate of the gradient axis end point | ||
| 121 | * in user space | ||
| 122 | * @param fractions numbers ranging from 0.0 to 1.0 specifying the | ||
| 123 | * distribution of colors along the gradient | ||
| 124 | * @param colors array of colors corresponding to each fractional value | ||
| 125 | * | ||
| 126 | * @throws NullPointerException | ||
| 127 | * if {@code fractions} array is null, | ||
| 128 | * or {@code colors} array is null, | ||
| 129 | * @throws IllegalArgumentException | ||
| 130 | * if start and end points are the same points, | ||
| 131 | * or {@code fractions.length != colors.length}, | ||
| 132 | * or {@code colors} is less than 2 in size, | ||
| 133 | * or a {@code fractions} value is less than 0.0 or greater than 1.0, | ||
| 134 | * or the {@code fractions} are not provided in strictly increasing order | ||
| 135 | */ | ||
| 136 | public LinearGradientPaint(float startX, float startY, | ||
| 137 | float endX, float endY, | ||
| 138 | float[] fractions, Color[] colors) | ||
| 139 | { | ||
| 140 | this(new Point2D.Float(startX, startY), | ||
| 141 | new Point2D.Float(endX, endY), | ||
| 142 | fractions, | ||
| 143 | colors, | ||
| 144 | CycleMethod.NO_CYCLE); | ||
| 145 | } | ||
| 146 | |||
| 147 | /** | ||
| 148 | * Constructs a {@code LinearGradientPaint} with a default {@code SRGB} | ||
| 149 | * color space. | ||
| 150 | * | ||
| 151 | * @param startX the X coordinate of the gradient axis start point | ||
| 152 | * in user space | ||
| 153 | * @param startY the Y coordinate of the gradient axis start point | ||
| 154 | * in user space | ||
| 155 | * @param endX the X coordinate of the gradient axis end point | ||
| 156 | * in user space | ||
| 157 | * @param endY the Y coordinate of the gradient axis end point | ||
| 158 | * in user space | ||
| 159 | * @param fractions numbers ranging from 0.0 to 1.0 specifying the | ||
| 160 | * distribution of colors along the gradient | ||
| 161 | * @param colors array of colors corresponding to each fractional value | ||
| 162 | * @param cycleMethod either {@code NO_CYCLE}, {@code REFLECT}, | ||
| 163 | * or {@code REPEAT} | ||
| 164 | * | ||
| 165 | * @throws NullPointerException | ||
| 166 | * if {@code fractions} array is null, | ||
| 167 | * or {@code colors} array is null, | ||
| 168 | * or {@code cycleMethod} is null | ||
| 169 | * @throws IllegalArgumentException | ||
| 170 | * if start and end points are the same points, | ||
| 171 | * or {@code fractions.length != colors.length}, | ||
| 172 | * or {@code colors} is less than 2 in size, | ||
| 173 | * or a {@code fractions} value is less than 0.0 or greater than 1.0, | ||
| 174 | * or the {@code fractions} are not provided in strictly increasing order | ||
| 175 | */ | ||
| 176 | public LinearGradientPaint(float startX, float startY, | ||
| 177 | float endX, float endY, | ||
| 178 | float[] fractions, Color[] colors, | ||
| 179 | CycleMethod cycleMethod) | ||
| 180 | { | ||
| 181 | this(new Point2D.Float(startX, startY), | ||
| 182 | new Point2D.Float(endX, endY), | ||
| 183 | fractions, | ||
| 184 | colors, | ||
| 185 | cycleMethod); | ||
| 186 | } | ||
| 187 | |||
| 188 | /** | ||
| 189 | * Constructs a {@code LinearGradientPaint} with a default | ||
| 190 | * {@code NO_CYCLE} repeating method and {@code SRGB} color space. | ||
| 191 | * | ||
| 192 | * @param start the gradient axis start {@code Point2D} in user space | ||
| 193 | * @param end the gradient axis end {@code Point2D} in user space | ||
| 194 | * @param fractions numbers ranging from 0.0 to 1.0 specifying the | ||
| 195 | * distribution of colors along the gradient | ||
| 196 | * @param colors array of colors corresponding to each fractional value | ||
| 197 | * | ||
| 198 | * @throws NullPointerException | ||
| 199 | * if one of the points is null, | ||
| 200 | * or {@code fractions} array is null, | ||
| 201 | * or {@code colors} array is null | ||
| 202 | * @throws IllegalArgumentException | ||
| 203 | * if start and end points are the same points, | ||
| 204 | * or {@code fractions.length != colors.length}, | ||
| 205 | * or {@code colors} is less than 2 in size, | ||
| 206 | * or a {@code fractions} value is less than 0.0 or greater than 1.0, | ||
| 207 | * or the {@code fractions} are not provided in strictly increasing order | ||
| 208 | */ | ||
| 209 | public LinearGradientPaint(Point2D start, Point2D end, | ||
| 210 | float[] fractions, Color[] colors) | ||
| 211 | { | ||
| 212 | this(start, end, | ||
| 213 | fractions, colors, | ||
| 214 | CycleMethod.NO_CYCLE); | ||
| 215 | } | ||
| 216 | |||
| 217 | /** | ||
| 218 | * Constructs a {@code LinearGradientPaint} with a default {@code SRGB} | ||
| 219 | * color space. | ||
| 220 | * | ||
| 221 | * @param start the gradient axis start {@code Point2D} in user space | ||
| 222 | * @param end the gradient axis end {@code Point2D} in user space | ||
| 223 | * @param fractions numbers ranging from 0.0 to 1.0 specifying the | ||
| 224 | * distribution of colors along the gradient | ||
| 225 | * @param colors array of colors corresponding to each fractional value | ||
| 226 | * @param cycleMethod either {@code NO_CYCLE}, {@code REFLECT}, | ||
| 227 | * or {@code REPEAT} | ||
| 228 | * | ||
| 229 | * @throws NullPointerException | ||
| 230 | * if one of the points is null, | ||
| 231 | * or {@code fractions} array is null, | ||
| 232 | * or {@code colors} array is null, | ||
| 233 | * or {@code cycleMethod} is null | ||
| 234 | * @throws IllegalArgumentException | ||
| 235 | * if start and end points are the same points, | ||
| 236 | * or {@code fractions.length != colors.length}, | ||
| 237 | * or {@code colors} is less than 2 in size, | ||
| 238 | * or a {@code fractions} value is less than 0.0 or greater than 1.0, | ||
| 239 | * or the {@code fractions} are not provided in strictly increasing order | ||
| 240 | */ | ||
| 241 | public LinearGradientPaint(Point2D start, Point2D end, | ||
| 242 | float[] fractions, Color[] colors, | ||
| 243 | CycleMethod cycleMethod) | ||
| 244 | { | ||
| 245 | this(start, end, | ||
| 246 | fractions, colors, | ||
| 247 | cycleMethod, | ||
| 248 | ColorSpaceType.SRGB, | ||
| 249 | new AffineTransform()); | ||
| 250 | } | ||
| 251 | |||
| 252 | /** | ||
| 253 | * Constructs a {@code LinearGradientPaint}. | ||
| 254 | * | ||
| 255 | * @param start the gradient axis start {@code Point2D} in user space | ||
| 256 | * @param end the gradient axis end {@code Point2D} in user space | ||
| 257 | * @param fractions numbers ranging from 0.0 to 1.0 specifying the | ||
| 258 | * distribution of colors along the gradient | ||
| 259 | * @param colors array of colors corresponding to each fractional value | ||
| 260 | * @param cycleMethod either {@code NO_CYCLE}, {@code REFLECT}, | ||
| 261 | * or {@code REPEAT} | ||
| 262 | * @param colorSpace which color space to use for interpolation, | ||
| 263 | * either {@code SRGB} or {@code LINEAR_RGB} | ||
| 264 | * @param gradientTransform transform to apply to the gradient | ||
| 265 | * | ||
| 266 | * @throws NullPointerException | ||
| 267 | * if one of the points is null, | ||
| 268 | * or {@code fractions} array is null, | ||
| 269 | * or {@code colors} array is null, | ||
| 270 | * or {@code cycleMethod} is null, | ||
| 271 | * or {@code colorSpace} is null, | ||
| 272 | * or {@code gradientTransform} is null | ||
| 273 | * @throws IllegalArgumentException | ||
| 274 | * if start and end points are the same points, | ||
| 275 | * or {@code fractions.length != colors.length}, | ||
| 276 | * or {@code colors} is less than 2 in size, | ||
| 277 | * or a {@code fractions} value is less than 0.0 or greater than 1.0, | ||
| 278 | * or the {@code fractions} are not provided in strictly increasing order | ||
| 279 | */ | ||
| 280 | @ConstructorProperties({ "startPoint", "endPoint", "fractions", "colors", "cycleMethod", "colorSpace", "transform" }) | ||
| 281 | public LinearGradientPaint(Point2D start, Point2D end, | ||
| 282 | float[] fractions, Color[] colors, | ||
| 283 | CycleMethod cycleMethod, | ||
| 284 | ColorSpaceType colorSpace, | ||
| 285 | AffineTransform gradientTransform) | ||
| 286 | { | ||
| 287 | super(fractions, colors, cycleMethod, colorSpace, gradientTransform); | ||
| 288 | |||
| 289 | // check input parameters | ||
| 290 | if (start == null || end == null) { | ||
| 291 | throw new NullPointerException("Start and end points must be" + | ||
| 292 | "non-null"); | ||
| 293 | } | ||
| 294 | |||
| 295 | if (start.equals(end)) { | ||
| 296 | throw new IllegalArgumentException("Start point cannot equal" + | ||
| 297 | "endpoint"); | ||
| 298 | } | ||
| 299 | |||
| 300 | // copy the points... | ||
| 301 | this.start = new Point2D.Double(start.getX(), start.getY()); | ||
| 302 | this.end = new Point2D.Double(end.getX(), end.getY()); | ||
| 303 | } | ||
| 304 | |||
| 305 | /** | ||
| 306 | * Creates and returns a {@link PaintContext} used to | ||
| 307 | * generate a linear color gradient pattern. | ||
| 308 | * See the {@link Paint#createContext specification} of the | ||
| 309 | * method in the {@link Paint} interface for information | ||
| 310 | * on null parameter handling. | ||
| 311 | * | ||
| 312 | * @param cm the preferred {@link ColorModel} which represents the most convenient | ||
| 313 | * format for the caller to receive the pixel data, or {@code null} | ||
| 314 | * if there is no preference. | ||
| 315 | * @param deviceBounds the device space bounding box | ||
| 316 | * of the graphics primitive being rendered. | ||
| 317 | * @param userBounds the user space bounding box | ||
| 318 | * of the graphics primitive being rendered. | ||
| 319 | * @param transform the {@link AffineTransform} from user | ||
| 320 | * space into device space. | ||
| 321 | * @param hints the set of hints that the context object can use to | ||
| 322 | * choose between rendering alternatives. | ||
| 323 | * @return the {@code PaintContext} for | ||
| 324 | * generating color patterns. | ||
| 325 | * @see Paint | ||
| 326 | * @see PaintContext | ||
| 327 | * @see ColorModel | ||
| 328 | * @see Rectangle | ||
| 329 | * @see Rectangle2D | ||
| 330 | * @see AffineTransform | ||
| 331 | * @see RenderingHints | ||
| 332 | */ | ||
| 333 | public PaintContext createContext(ColorModel cm, | ||
| 334 | Rectangle deviceBounds, | ||
| 335 | Rectangle2D userBounds, | ||
| 336 | AffineTransform transform, | ||
| 337 | RenderingHints hints) | ||
| 338 | { | ||
| 339 | // avoid modifying the user's transform... | ||
| 340 | transform = new AffineTransform(transform); | ||
| 341 | // incorporate the gradient transform | ||
| 342 | transform.concatenate(gradientTransform); | ||
| 343 | |||
| 344 | if ((fractions.length == 2) && | ||
| 345 | (cycleMethod != CycleMethod.REPEAT) && | ||
| 346 | (colorSpace == ColorSpaceType.SRGB)) | ||
| 347 | { | ||
| 348 | // faster to use the basic GradientPaintContext for this | ||
| 349 | // common case | ||
| 350 | boolean cyclic = (cycleMethod != CycleMethod.NO_CYCLE); | ||
| 351 | return new GradientPaintContext(cm, start, end, | ||
| 352 | transform, | ||
| 353 | colors[0], colors[1], | ||
| 354 | cyclic); | ||
| 355 | } else { | ||
| 356 | return new LinearGradientPaintContext(this, cm, | ||
| 357 | deviceBounds, userBounds, | ||
| 358 | transform, hints, | ||
| 359 | start, end, | ||
| 360 | fractions, colors, | ||
| 361 | cycleMethod, colorSpace); | ||
| 362 | } | ||
| 363 | } | ||
| 364 | |||
| 365 | /** | ||
| 366 | * Returns a copy of the start point of the gradient axis. | ||
| 367 | * | ||
| 368 | * @return a {@code Point2D} object that is a copy of the point | ||
| 369 | * that anchors the first color of this {@code LinearGradientPaint} | ||
| 370 | */ | ||
| 371 | public Point2D getStartPoint() { | ||
| 372 | return new Point2D.Double(start.getX(), start.getY()); | ||
| 373 | } | ||
| 374 | |||
| 375 | /** | ||
| 376 | * Returns a copy of the end point of the gradient axis. | ||
| 377 | * | ||
| 378 | * @return a {@code Point2D} object that is a copy of the point | ||
| 379 | * that anchors the last color of this {@code LinearGradientPaint} | ||
| 380 | */ | ||
| 381 | public Point2D getEndPoint() { | ||
| 382 | return new Point2D.Double(end.getX(), end.getY()); | ||
| 383 | } | ||
| 384 | } | ||