RadialGradientPaint.java revision 3724
4301N/A * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved. 4301N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4301N/A * This code is free software; you can redistribute it and/or modify it 4301N/A * under the terms of the GNU General Public License version 2 only, as 4301N/A * published by the Free Software Foundation. Oracle designates this 4301N/A * particular file as subject to the "Classpath" exception as provided 4301N/A * by Oracle in the LICENSE file that accompanied this code. 4301N/A * This code is distributed in the hope that it will be useful, but WITHOUT 4301N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 4301N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 4301N/A * version 2 for more details (a copy is included in the LICENSE file that 4301N/A * You should have received a copy of the GNU General Public License version 4301N/A * 2 along with this work; if not, write to the Free Software Foundation, 4301N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 4301N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 4301N/A * or visit www.oracle.com if you need additional information or have any 4301N/A * The {@code RadialGradientPaint} class provides a way to fill a shape with 4301N/A * a circular radial color gradient pattern. The user may specify 2 or more 4301N/A * gradient colors, and this paint will provide an interpolation between 4301N/A * The user must specify the circle controlling the gradient pattern, 4301N/A * which is described by a center point and a radius. The user can also 4301N/A * specify a separate focus point within that circle, which controls the 4301N/A * location of the first color of the gradient. By default the focus is 4301N/A * set to be the center of the circle. 4301N/A * This paint will map the first color of the gradient to the focus point, 4301N/A * and the last color to the perimeter of the circle, interpolating 4301N/A * smoothly for any in-between colors specified by the user. Any line drawn 4301N/A * from the focus point to the circumference will thus span all the gradient 4301N/A * Specifying a focus point outside of the circle's radius will result in the 4301N/A * focus being set to the intersection point of the focus-center line and the 4301N/A * The user must provide an array of floats specifying how to distribute the 4301N/A * colors along the gradient. These values should range from 0.0 to 1.0 and 4301N/A * act like keyframes along the gradient (they mark where the gradient should 4301N/A * be exactly a particular color). 4301N/A * In the event that the user does not set the first keyframe value equal 4301N/A * to 0 and/or the last keyframe value equal to 1, keyframes will be created 4301N/A * at these positions and the first and last colors will be replicated there. 4301N/A * So, if a user specifies the following arrays to construct a gradient:<br> 4301N/A * {Color.BLUE, Color.RED}, {.3f, .7f} 4301N/A * this will be converted to a gradient with the following keyframes:<br> * {Color.BLUE, Color.BLUE, Color.RED, Color.RED}, {0f, .3f, .7f, 1f} * The user may also select what action the {@code RadialGradientPaint} object * takes when it is filling the space outside the circle's radius by * setting {@code CycleMethod} to either {@code REFLECTION} or {@code REPEAT}. * The gradient color proportions are equal for any particular line drawn * from the focus point. The following figure shows that the distance AB * is equal to the distance BC, and the distance AD is equal to the distance DE. * If the gradient and graphics rendering transforms are uniformly scaled and * the user sets the focus so that it coincides with the center of the circle, * the gradient color proportions are equal for any line drawn from the center. * The following figure shows the distances AB, BC, AD, and DE. They are all equal. * Note that some minor variations in distances may occur due to sampling at * the granularity of a pixel. * If no cycle method is specified, {@code NO_CYCLE} will be chosen by * default, which means the the last keyframe color will be used to fill the * The colorSpace parameter allows the user to specify in which colorspace * the interpolation should be performed, default sRGB or linearized RGB. * The following code demonstrates typical usage of * {@code RadialGradientPaint}, where the center and focus points are * Point2D center = new Point2D.Float(50, 50); * float[] dist = {0.0f, 0.2f, 1.0f}; * Color[] colors = {Color.RED, Color.WHITE, Color.BLUE}; * RadialGradientPaint p = * new RadialGradientPaint(center, radius, dist, colors); * This image demonstrates the example code above, with default * (centered) focus for each of the three cycle methods: * It is also possible to specify a non-centered focus point, as * Point2D center = new Point2D.Float(50, 50); * Point2D focus = new Point2D.Float(40, 40); * float[] dist = {0.0f, 0.2f, 1.0f}; * Color[] colors = {Color.RED, Color.WHITE, Color.BLUE}; * RadialGradientPaint p = * new RadialGradientPaint(center, radius, focus, * This image demonstrates the previous example code, with non-centered * focus for each of the three cycle methods: * @see java.awt.Graphics2D#setPaint * @author Nicholas Talian, Vincent Hardy, Jim Graham, Jerry Evans /** Focus point which defines the 0% gradient stop X coordinate. */ /** Center of the circle defining the 100% gradient stop X coordinate. */ /** Radius of the outermost circle defining the 100% gradient stop. */ * Constructs a {@code RadialGradientPaint} with a default * {@code NO_CYCLE} repeating method and {@code SRGB} color space, * using the center as the focus point. * @param cx the X coordinate in user space of the center point of the * circle defining the gradient. The last color of the * gradient is mapped to the perimeter of this circle. * @param cy the Y coordinate in user space of the center point of the * circle defining the gradient. The last color of the * gradient is mapped to the perimeter of this circle. * @param radius the radius of the circle defining the extents of the * @param fractions numbers ranging from 0.0 to 1.0 specifying the * distribution of colors along the gradient * @param colors array of colors to use in the gradient. The first color * is used at the focus point, the last color around the * perimeter of the circle. * @throws NullPointerException * if {@code fractions} array is null, * or {@code colors} array is null * @throws IllegalArgumentException * if {@code radius} is non-positive, * or {@code fractions.length != colors.length}, * or {@code colors} is less than 2 in size, * or a {@code fractions} value is less than 0.0 or greater than 1.0, * or the {@code fractions} are not provided in strictly increasing order * Constructs a {@code RadialGradientPaint} with a default * {@code NO_CYCLE} repeating method and {@code SRGB} color space, * using the center as the focus point. * @param center the center point, in user space, of the circle defining * @param radius the radius of the circle defining the extents of the * @param fractions numbers ranging from 0.0 to 1.0 specifying the * distribution of colors along the gradient * @param colors array of colors to use in the gradient. The first color * is used at the focus point, the last color around the * perimeter of the circle. * @throws NullPointerException * if {@code center} point is null, * or {@code fractions} array is null, * or {@code colors} array is null * @throws IllegalArgumentException * if {@code radius} is non-positive, * or {@code fractions.length != colors.length}, * or {@code colors} is less than 2 in size, * or a {@code fractions} value is less than 0.0 or greater than 1.0, * or the {@code fractions} are not provided in strictly increasing order * Constructs a {@code RadialGradientPaint} with a default * {@code SRGB} color space, using the center as the focus point. * @param cx the X coordinate in user space of the center point of the * circle defining the gradient. The last color of the * gradient is mapped to the perimeter of this circle. * @param cy the Y coordinate in user space of the center point of the * circle defining the gradient. The last color of the * gradient is mapped to the perimeter of this circle. * @param radius the radius of the circle defining the extents of the * @param fractions numbers ranging from 0.0 to 1.0 specifying the * distribution of colors along the gradient * @param colors array of colors to use in the gradient. The first color * is used at the focus point, the last color around the * perimeter of the circle. * @param cycleMethod either {@code NO_CYCLE}, {@code REFLECT}, * @throws NullPointerException * if {@code fractions} array is null, * or {@code colors} array is null, * or {@code cycleMethod} is null * @throws IllegalArgumentException * if {@code radius} is non-positive, * or {@code fractions.length != colors.length}, * or {@code colors} is less than 2 in size, * or a {@code fractions} value is less than 0.0 or greater than 1.0, * or the {@code fractions} are not provided in strictly increasing order * Constructs a {@code RadialGradientPaint} with a default * {@code SRGB} color space, using the center as the focus point. * @param center the center point, in user space, of the circle defining * @param radius the radius of the circle defining the extents of the * @param fractions numbers ranging from 0.0 to 1.0 specifying the * distribution of colors along the gradient * @param colors array of colors to use in the gradient. The first color * is used at the focus point, the last color around the * perimeter of the circle. * @param cycleMethod either {@code NO_CYCLE}, {@code REFLECT}, * @throws NullPointerException * if {@code center} point is null, * or {@code fractions} array is null, * or {@code colors} array is null, * or {@code cycleMethod} is null * @throws IllegalArgumentException * if {@code radius} is non-positive, * or {@code fractions.length != colors.length}, * or {@code colors} is less than 2 in size, * or a {@code fractions} value is less than 0.0 or greater than 1.0, * or the {@code fractions} are not provided in strictly increasing order * Constructs a {@code RadialGradientPaint} with a default * {@code SRGB} color space. * @param cx the X coordinate in user space of the center point of the * circle defining the gradient. The last color of the * gradient is mapped to the perimeter of this circle. * @param cy the Y coordinate in user space of the center point of the * circle defining the gradient. The last color of the * gradient is mapped to the perimeter of this circle. * @param radius the radius of the circle defining the extents of the * @param fx the X coordinate of the point in user space to which the * @param fy the Y coordinate of the point in user space to which the * @param fractions numbers ranging from 0.0 to 1.0 specifying the * distribution of colors along the gradient * @param colors array of colors to use in the gradient. The first color * is used at the focus point, the last color around the * perimeter of the circle. * @param cycleMethod either {@code NO_CYCLE}, {@code REFLECT}, * @throws NullPointerException * if {@code fractions} array is null, * or {@code colors} array is null, * or {@code cycleMethod} is null * @throws IllegalArgumentException * if {@code radius} is non-positive, * or {@code fractions.length != colors.length}, * or {@code colors} is less than 2 in size, * or a {@code fractions} value is less than 0.0 or greater than 1.0, * or the {@code fractions} are not provided in strictly increasing order * Constructs a {@code RadialGradientPaint} with a default * {@code SRGB} color space. * @param center the center point, in user space, of the circle defining * the gradient. The last color of the gradient is mapped * to the perimeter of this circle. * @param radius the radius of the circle defining the extents of the color * @param focus the point in user space to which the first color is mapped * @param fractions numbers ranging from 0.0 to 1.0 specifying the * distribution of colors along the gradient * @param colors array of colors to use in the gradient. The first color * is used at the focus point, the last color around the * perimeter of the circle. * @param cycleMethod either {@code NO_CYCLE}, {@code REFLECT}, * @throws NullPointerException * if one of the points is null, * or {@code fractions} array is null, * or {@code colors} array is null, * or {@code cycleMethod} is null * @throws IllegalArgumentException * if {@code radius} is non-positive, * or {@code fractions.length != colors.length}, * or {@code colors} is less than 2 in size, * or a {@code fractions} value is less than 0.0 or greater than 1.0, * or the {@code fractions} are not provided in strictly increasing order * Constructs a {@code RadialGradientPaint}. * @param center the center point in user space of the circle defining the * gradient. The last color of the gradient is mapped to * the perimeter of this circle. * @param radius the radius of the circle defining the extents of the * @param focus the point in user space to which the first color is mapped * @param fractions numbers ranging from 0.0 to 1.0 specifying the * distribution of colors along the gradient * @param colors array of colors to use in the gradient. The first color * is used at the focus point, the last color around the * perimeter of the circle. * @param cycleMethod either {@code NO_CYCLE}, {@code REFLECT}, * @param colorSpace which color space to use for interpolation, * either {@code SRGB} or {@code LINEAR_RGB} * @param gradientTransform transform to apply to the gradient * @throws NullPointerException * if one of the points is null, * or {@code fractions} array is null, * or {@code colors} array is null, * or {@code cycleMethod} is null, * or {@code colorSpace} is null, * or {@code gradientTransform} is null * @throws IllegalArgumentException * if {@code radius} is non-positive, * or {@code fractions.length != colors.length}, * or {@code colors} is less than 2 in size, * or a {@code fractions} value is less than 0.0 or greater than 1.0, * or the {@code fractions} are not provided in strictly increasing order @
ConstructorProperties({
"centerPoint",
"radius",
"focusPoint",
"fractions",
"colors",
"cycleMethod",
"colorSpace",
"transform" })
* Constructs a {@code RadialGradientPaint} with a default * {@code SRGB} color space. * The gradient circle of the {@code RadialGradientPaint} is defined * by the given bounding box. * This constructor is a more convenient way to express the * following (equivalent) code:<br> * double gw = gradientBounds.getWidth(); * double gh = gradientBounds.getHeight(); * double cx = gradientBounds.getCenterX(); * double cy = gradientBounds.getCenterY(); * Point2D center = new Point2D.Double(cx, cy); * AffineTransform gradientTransform = new AffineTransform(); * gradientTransform.translate(cx, cy); * gradientTransform.scale(gw / 2, gh / 2); * gradientTransform.translate(-cx, -cy); * RadialGradientPaint gp = * new RadialGradientPaint(center, 1.0f, center, * @param gradientBounds the bounding box, in user space, of the circle * defining the outermost extent of the gradient * @param fractions numbers ranging from 0.0 to 1.0 specifying the * distribution of colors along the gradient * @param colors array of colors to use in the gradient. The first color * is used at the focus point, the last color around the * perimeter of the circle. * @param cycleMethod either {@code NO_CYCLE}, {@code REFLECT}, * @throws NullPointerException * if {@code gradientBounds} is null, * or {@code fractions} array is null, * or {@code colors} array is null, * or {@code cycleMethod} is null * @throws IllegalArgumentException * if {@code gradientBounds} is empty, * or {@code fractions.length != colors.length}, * or {@code colors} is less than 2 in size, * or a {@code fractions} value is less than 0.0 or greater than 1.0, * or the {@code fractions} are not provided in strictly increasing order // gradient center/focal point is the center of the bounding box, // radius is set to 1.0, and then we set a scale transform // to achieve an elliptical gradient defined by the bounding box * Creates and returns a {@link PaintContext} used to * generate a circular radial color gradient pattern. * See the description of the {@link Paint#createContext createContext} method * for information on null parameter handling. * @param cm the preferred {@link ColorModel} which represents the most convenient * format for the caller to receive the pixel data, or {@code null} * if there is no preference. * @param deviceBounds the device space bounding box * of the graphics primitive being rendered. * @param userBounds the user space bounding box * of the graphics primitive being rendered. * @param transform the {@link AffineTransform} from user * space into device space. * @param hints the set of hints that the context object can use to * choose between rendering alternatives. * @return the {@code PaintContext} for * generating color patterns. // avoid modifying the user's transform... // incorporate the gradient transform * Returns a copy of the center point of the radial gradient. * @return a {@code Point2D} object that is a copy of the center point * Returns a copy of the focus point of the radial gradient. * @return a {@code Point2D} object that is a copy of the focus point * Returns the radius of the circle defining the radial gradient. * @return the radius of the circle defining the radial gradient