1 /*
   2  * Copyright (c) 2009, 2013, 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 com.sun.scenario.effect.impl.state;
  27 
  28 import java.nio.FloatBuffer;
  29 import com.sun.scenario.effect.impl.BufferUtil;
  30 
  31 /**
  32  * The state and implementation class for calculating 1 dimensional
  33  * linear convolution kernels for performing gaussian blurs.
  34  */
  35 public class GaussianBlurState extends HVSeparableKernel {
  36     private float hradius;
  37     private float vradius;
  38     private FloatBuffer weights;
  39 
  40     void checkRadius(float radius) {
  41         if (radius < 0f || radius > 63f) {
  42             throw new IllegalArgumentException("Radius must be in the range [1,63]");
  43         }
  44     }
  45 
  46     public float getRadius() {
  47         return (hradius + vradius) / 2.0f;
  48     }
  49 
  50     public void setRadius(float radius) {
  51         checkRadius(radius);
  52         this.hradius = radius;
  53         this.vradius = radius;
  54     }
  55 
  56     public float getHRadius() {
  57         return hradius;
  58     }
  59 
  60     public void setHRadius(float hradius) {
  61         checkRadius(hradius);
  62         this.hradius = hradius;
  63     }
  64 
  65     public float getVRadius() {
  66         return vradius;
  67     }
  68 
  69     public void setVRadius(float vradius) {
  70         checkRadius(vradius);
  71         this.vradius = vradius;
  72     }
  73 
  74     float getRadius(int pass) {
  75         return (pass == 0 ? hradius : vradius);
  76     }
  77 
  78     @Override
  79     public boolean isNop() {
  80         return hradius == 0 && vradius == 0;
  81     }
  82 
  83     @Override
  84     public boolean isNop(int pass) {
  85         return getRadius(pass) == 0;
  86     }
  87 
  88     public int getPad(int pass) {
  89         return (int) Math.ceil(getRadius(pass));
  90     }
  91 
  92     public int getScaledPad(int pass) {
  93         return getPad(pass);
  94     }
  95 
  96     public float getScaledRadius(int pass) {
  97         return getRadius(pass);
  98     }
  99 
 100     @Override
 101     public int getKernelSize(int pass) {
 102         return getPad(pass) * 2 + 1;
 103     }
 104 
 105     public float getSpread() {
 106         return 0f;
 107     }
 108 
 109     @Override
 110     public FloatBuffer getWeights(int pass) {
 111         float r0 = getScaledRadius(0);
 112         float r1 = getScaledRadius(1);
 113         // We need to apply the spread on only one pass
 114         // Prefer pass1 if r1 is not tiny (or at least bigger than r0)
 115         // Otherwise use pass 0 so that it doesn't disappear
 116         int spreadpass = (r1 > 1f || r1 >= r0) ? 1 : 0;
 117 
 118         float r = (pass == 0) ? r0 : r1;
 119         float s = (pass == spreadpass) ? getSpread() : 0f;
 120         weights = getGaussianWeights(weights, getScaledPad(pass), r, s);
 121         return weights;
 122     }
 123 
 124     static FloatBuffer getGaussianWeights(FloatBuffer weights,
 125                                           int pad,
 126                                           float radius,
 127                                           float spread)
 128     {
 129         int r = pad;
 130         int klen = (r * 2) + 1;
 131         if (weights == null) {
 132             weights = BufferUtil.newFloatBuffer(128);
 133         }
 134         weights.clear();
 135         float sigma = radius / 3;
 136         float sigma22 = 2 * sigma * sigma;
 137         if (sigma22 < Float.MIN_VALUE) {
 138             // Avoid divide by 0 below (it can generate NaN values).
 139             sigma22 = Float.MIN_VALUE;
 140         }
 141         float total = 0.0F;
 142         for (int row = -r; row <= r; row++) {
 143             float kval = (float) Math.exp(-(row * row) / sigma22);
 144             weights.put(kval);
 145             total += kval;
 146         }
 147         total += (weights.get(0) - total) * spread;
 148         for (int i = 0; i < klen; i++) {
 149             weights.put(i, weights.get(i) / total);
 150         }
 151         int limit = getPeerSize(klen);
 152         while (weights.position() < limit) {
 153             weights.put(0.0F);
 154         }
 155         weights.limit(limit);
 156         weights.rewind();
 157         return weights;
 158     }
 159 }