1 /*
   2  * Copyright (c) 2015, 2017, 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 
  29 final class DCollinearSimplifier implements DPathConsumer2D {
  30 
  31     enum SimplifierState {
  32 
  33         Empty, PreviousPoint, PreviousLine
  34     };
  35     // slope precision threshold
  36     static final double EPS = 1e-4d; // aaime proposed 1e-3d
  37 
  38     DPathConsumer2D delegate;
  39     SimplifierState state;
  40     double px1, py1, px2, py2;
  41     double pslope;
  42 
  43     DCollinearSimplifier() {
  44     }
  45 
  46     public DCollinearSimplifier init(DPathConsumer2D delegate) {
  47         this.delegate = delegate;
  48         this.state = SimplifierState.Empty;
  49 
  50         return this; // fluent API
  51     }
  52 
  53     @Override
  54     public void pathDone() {
  55         emitStashedLine();
  56         state = SimplifierState.Empty;
  57         delegate.pathDone();
  58     }
  59 
  60     @Override
  61     public void closePath() {
  62         emitStashedLine();
  63         state = SimplifierState.Empty;
  64         delegate.closePath();
  65     }
  66 
  67     @Override
  68     public long getNativeConsumer() {
  69         return 0;
  70     }
  71 
  72     @Override
  73     public void quadTo(double x1, double y1, double x2, double y2) {
  74         emitStashedLine();
  75         delegate.quadTo(x1, y1, x2, y2);
  76         // final end point:
  77         state = SimplifierState.PreviousPoint;
  78         px1 = x2;
  79         py1 = y2;
  80     }
  81 
  82     @Override
  83     public void curveTo(double x1, double y1, double x2, double y2,
  84                         double x3, double y3) {
  85         emitStashedLine();
  86         delegate.curveTo(x1, y1, x2, y2, x3, y3);
  87         // final end point:
  88         state = SimplifierState.PreviousPoint;
  89         px1 = x3;
  90         py1 = y3;
  91     }
  92 
  93     @Override
  94     public void moveTo(double x, double y) {
  95         emitStashedLine();
  96         delegate.moveTo(x, y);
  97         state = SimplifierState.PreviousPoint;
  98         px1 = x;
  99         py1 = y;
 100     }
 101 
 102     @Override
 103     public void lineTo(final double x, final double y) {
 104         switch (state) {
 105             case Empty:
 106                 delegate.lineTo(x, y);
 107                 state = SimplifierState.PreviousPoint;
 108                 px1 = x;
 109                 py1 = y;
 110                 return;
 111 
 112             case PreviousPoint:
 113                 state = SimplifierState.PreviousLine;
 114                 px2 = x;
 115                 py2 = y;
 116                 pslope = getSlope(px1, py1, x, y);
 117                 return;
 118 
 119             case PreviousLine:
 120                 final double slope = getSlope(px2, py2, x, y);
 121                 // test for collinearity
 122                 if ((slope == pslope) || (Math.abs(pslope - slope) < EPS)) {
 123                     // merge segments
 124                     px2 = x;
 125                     py2 = y;
 126                     return;
 127                 }
 128                 // emit previous segment
 129                 delegate.lineTo(px2, py2);
 130                 px1 = px2;
 131                 py1 = py2;
 132                 px2 = x;
 133                 py2 = y;
 134                 pslope = slope;
 135                 return;
 136             default:
 137         }
 138     }
 139 
 140     private void emitStashedLine() {
 141         if (state == SimplifierState.PreviousLine) {
 142             delegate.lineTo(px2, py2);
 143         }
 144     }
 145 
 146     private static double getSlope(double x1, double y1, double x2, double y2) {
 147         double dy = y2 - y1;
 148         if (dy == 0.0d) {
 149             return (x2 > x1) ? Double.POSITIVE_INFINITY
 150                    : Double.NEGATIVE_INFINITY;
 151         }
 152         return (x2 - x1) / dy;
 153     }
 154 }