1 /*
   2  * Copyright (c) 2015, 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 sun.java2d.marlin;
  27 
  28 import sun.awt.geom.PathConsumer2D;
  29 
  30 final class CollinearSimplifier implements PathConsumer2D {
  31 
  32     enum SimplifierState {
  33 
  34         Empty, PreviousPoint, PreviousLine
  35     };
  36     // slope precision threshold
  37     static final float EPS = 1e-4f; // aaime proposed 1e-3f
  38 
  39     PathConsumer2D delegate;
  40     SimplifierState state;
  41     float px1, py1, px2, py2;
  42     float pslope;
  43 
  44     CollinearSimplifier() {
  45     }
  46 
  47     public CollinearSimplifier init(PathConsumer2D delegate) {
  48         this.delegate = delegate;
  49         this.state = SimplifierState.Empty;
  50 
  51         return this; // fluent API
  52     }
  53 
  54     @Override
  55     public void pathDone() {
  56         emitStashedLine();
  57         state = SimplifierState.Empty;
  58         delegate.pathDone();
  59     }
  60 
  61     @Override
  62     public void closePath() {
  63         emitStashedLine();
  64         state = SimplifierState.Empty;
  65         delegate.closePath();
  66     }
  67 
  68     @Override
  69     public long getNativeConsumer() {
  70         return 0;
  71     }
  72 
  73     @Override
  74     public void quadTo(float x1, float y1, float x2, float y2) {
  75         emitStashedLine();
  76         delegate.quadTo(x1, y1, x2, y2);
  77         // final end point:
  78         state = SimplifierState.PreviousPoint;
  79         px1 = x2;
  80         py1 = y2;
  81     }
  82 
  83     @Override
  84     public void curveTo(float x1, float y1, float x2, float y2,
  85                         float x3, float y3) {
  86         emitStashedLine();
  87         delegate.curveTo(x1, y1, x2, y2, x3, y3);
  88         // final end point:
  89         state = SimplifierState.PreviousPoint;
  90         px1 = x3;
  91         py1 = y3;
  92     }
  93 
  94     @Override
  95     public void moveTo(float x, float y) {
  96         emitStashedLine();
  97         delegate.moveTo(x, y);
  98         state = SimplifierState.PreviousPoint;
  99         px1 = x;
 100         py1 = y;
 101     }
 102 
 103     @Override
 104     public void lineTo(final float x, final float y) {
 105         switch (state) {
 106             case Empty:
 107                 delegate.lineTo(x, y);
 108                 state = SimplifierState.PreviousPoint;
 109                 px1 = x;
 110                 py1 = y;
 111                 return;
 112 
 113             case PreviousPoint:
 114                 state = SimplifierState.PreviousLine;
 115                 px2 = x;
 116                 py2 = y;
 117                 pslope = getSlope(px1, py1, x, y);
 118                 return;
 119 
 120             case PreviousLine:
 121                 final float slope = getSlope(px2, py2, x, y);
 122                 // test for collinearity
 123                 if ((slope == pslope) || (Math.abs(pslope - slope) < EPS)) {
 124                     // merge segments
 125                     px2 = x;
 126                     py2 = y;
 127                     return;
 128                 }
 129                 // emit previous segment
 130                 delegate.lineTo(px2, py2);
 131                 px1 = px2;
 132                 py1 = py2;
 133                 px2 = x;
 134                 py2 = y;
 135                 pslope = slope;
 136                 return;
 137             default:
 138         }
 139     }
 140 
 141     private void emitStashedLine() {
 142         if (state == SimplifierState.PreviousLine) {
 143             delegate.lineTo(px2, py2);
 144         }
 145     }
 146 
 147     private static float getSlope(float x1, float y1, float x2, float y2) {
 148         float dy = y2 - y1;
 149         if (dy == 0f) {
 150             return (x2 > x1) ? Float.POSITIVE_INFINITY
 151                    : Float.NEGATIVE_INFINITY;
 152         }
 153         return (x2 - x1) / dy;
 154     }
 155 }