1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.graphics; 18 19 public class SweepGradient extends GradientShader { 20 21 private SweepGradientPaint mPaint; 22 23 /** 24 * A subclass of Shader that draws a sweep gradient around a center point. 25 * 26 * @param cx The x-coordinate of the center 27 * @param cy The y-coordinate of the center 28 * @param colors The colors to be distributed between around the center. 29 * There must be at least 2 colors in the array. 30 * @param positions May be NULL. The relative position of 31 * each corresponding color in the colors array, beginning 32 * with 0 and ending with 1.0. If the values are not 33 * monotonic, the drawing may produce unexpected results. 34 * If positions is NULL, then the colors are automatically 35 * spaced evenly. 36 */ 37 public SweepGradient(float cx, float cy, 38 int colors[], float positions[]) { 39 super(colors, positions); 40 41 mPaint = new SweepGradientPaint(cx, cy, mColors, mPositions); 42 } 43 44 /** 45 * A subclass of Shader that draws a sweep gradient around a center point. 46 * 47 * @param cx The x-coordinate of the center 48 * @param cy The y-coordinate of the center 49 * @param color0 The color to use at the start of the sweep 50 * @param color1 The color to use at the end of the sweep 51 */ 52 public SweepGradient(float cx, float cy, int color0, int color1) { 53 this(cx, cy, new int[] { color0, color1}, null /*positions*/); 54 } 55 56 @Override 57 java.awt.Paint getJavaPaint() { 58 return mPaint; 59 } 60 61 private static class SweepGradientPaint extends GradientPaint { 62 63 private final float mCx; 64 private final float mCy; 65 66 public SweepGradientPaint(float cx, float cy, int[] colors, float[] positions) { 67 super(colors, positions, null /*tileMode*/); 68 mCx = cx; 69 mCy = cy; 70 } 71 72 public java.awt.PaintContext createContext( 73 java.awt.image.ColorModel colorModel, 74 java.awt.Rectangle deviceBounds, 75 java.awt.geom.Rectangle2D userBounds, 76 java.awt.geom.AffineTransform xform, 77 java.awt.RenderingHints hints) { 78 precomputeGradientColors(); 79 return new SweepGradientPaintContext(colorModel); 80 } 81 82 private class SweepGradientPaintContext implements java.awt.PaintContext { 83 84 private final java.awt.image.ColorModel mColorModel; 85 86 public SweepGradientPaintContext(java.awt.image.ColorModel colorModel) { 87 mColorModel = colorModel; 88 } 89 90 public void dispose() { 91 } 92 93 public java.awt.image.ColorModel getColorModel() { 94 return mColorModel; 95 } 96 97 public java.awt.image.Raster getRaster(int x, int y, int w, int h) { 98 java.awt.image.BufferedImage image = new java.awt.image.BufferedImage(w, h, 99 java.awt.image.BufferedImage.TYPE_INT_ARGB); 100 101 int[] data = new int[w*h]; 102 103 // compute angle from each point to the center, and figure out the distance from 104 // it. 105 int index = 0; 106 for (int iy = 0 ; iy < h ; iy++) { 107 for (int ix = 0 ; ix < w ; ix++) { 108 float dx = x + ix - mCx; 109 float dy = y + iy - mCy; 110 float angle; 111 if (dx == 0) { 112 angle = (float) (dy < 0 ? 3 * Math.PI / 2 : Math.PI / 2); 113 } else if (dy == 0) { 114 angle = (float) (dx < 0 ? Math.PI : 0); 115 } else { 116 angle = (float) Math.atan(dy / dx); 117 if (dx > 0) { 118 if (dy < 0) { 119 angle += Math.PI * 2; 120 } 121 } else { 122 angle += Math.PI; 123 } 124 } 125 126 // convert to 0-1. value and get color 127 data[index++] = getGradientColor((float) (angle / (2 * Math.PI))); 128 } 129 } 130 131 image.setRGB(0 /*startX*/, 0 /*startY*/, w, h, data, 0 /*offset*/, w /*scansize*/); 132 133 return image.getRaster(); 134 } 135 136 } 137 } 138 139 } 140 141
