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      1 
      2 //----------------------------------------------------------------------------
      3 // Anti-Grain Geometry - Version 2.3
      4 // Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
      5 //
      6 // Permission to copy, use, modify, sell and distribute this software
      7 // is granted provided this copyright notice appears in all copies.
      8 // This software is provided "as is" without express or implied
      9 // warranty, and with no claim as to its suitability for any purpose.
     10 //
     11 //----------------------------------------------------------------------------
     12 // Contact: mcseem (at) antigrain.com
     13 //          mcseemagg (at) yahoo.com
     14 //          http://www.antigrain.com
     15 //----------------------------------------------------------------------------
     16 //
     17 // Liang-Barsky clipping
     18 //
     19 //----------------------------------------------------------------------------
     20 #ifndef AGG_CLIP_LIANG_BARSKY_INCLUDED
     21 #define AGG_CLIP_LIANG_BARSKY_INCLUDED
     22 #include "agg_basics.h"
     23 #include "third_party/base/numerics/safe_math.h"
     24 namespace agg
     25 {
     26 template<class T>
     27 inline unsigned clipping_flags(T x, T y, const rect_base<T>& clip_box)
     28 {
     29     return  (x > clip_box.x2) |
     30             ((y > clip_box.y2) << 1) |
     31             ((x < clip_box.x1) << 2) |
     32             ((y < clip_box.y1) << 3);
     33 }
     34 template<class T>
     35 inline unsigned clip_liang_barsky(T x1, T y1, T x2, T y2,
     36                                   const rect_base<T>& clip_box,
     37                                   T* x, T* y)
     38 {
     39     const float nearzero = 1e-30f;
     40 
     41     pdfium::base::CheckedNumeric<float> width = x2;
     42     width -= x1;
     43     if (!width.IsValid())
     44         return 0;
     45     pdfium::base::CheckedNumeric<float> height = y2;
     46     height -= y1;
     47     if (!height.IsValid())
     48         return 0;
     49 
     50     float deltax = width.ValueOrDefault(0);
     51     float deltay = height.ValueOrDefault(0);
     52     unsigned np = 0;
     53     if(deltax == 0) {
     54         deltax = (x1 > clip_box.x1) ? -nearzero : nearzero;
     55     }
     56     float xin, xout;
     57     if(deltax > 0) {
     58         xin  = (float)clip_box.x1;
     59         xout = (float)clip_box.x2;
     60     } else {
     61         xin  = (float)clip_box.x2;
     62         xout = (float)clip_box.x1;
     63     }
     64     float tinx = (xin - x1) / deltax;
     65     if(deltay == 0) {
     66         deltay = (y1 > clip_box.y1) ? -nearzero : nearzero;
     67     }
     68     float yin, yout;
     69     if(deltay > 0) {
     70         yin  = (float)clip_box.y1;
     71         yout = (float)clip_box.y2;
     72     } else {
     73         yin  = (float)clip_box.y2;
     74         yout = (float)clip_box.y1;
     75     }
     76     float tiny = (yin - y1) / deltay;
     77     float tin1, tin2;
     78     if (tinx < tiny) {
     79         tin1 = tinx;
     80         tin2 = tiny;
     81     } else {
     82         tin1 = tiny;
     83         tin2 = tinx;
     84     }
     85     if(tin1 <= 1.0f) {
     86         if(0 < tin1) {
     87             *x++ = (T)xin;
     88             *y++ = (T)yin;
     89             ++np;
     90         }
     91         if(tin2 <= 1.0f) {
     92           float toutx = (xout - x1) / deltax;
     93           float touty = (yout - y1) / deltay;
     94           float tout1 = (toutx < touty) ? toutx : touty;
     95           if (tin2 > 0 || tout1 > 0) {
     96                 if(tin2 <= tout1) {
     97                     if(tin2 > 0) {
     98                         if(tinx > tiny) {
     99                           *x++ = (T)xin;
    100                           *y++ = (T)(y1 + (deltay * tinx));
    101                         } else {
    102                           *x++ = (T)(x1 + (deltax * tiny));
    103                           *y++ = (T)yin;
    104                         }
    105                         ++np;
    106                     }
    107                     if(tout1 < 1.0f) {
    108                         if(toutx < touty) {
    109                           *x++ = (T)xout;
    110                           *y++ = (T)(y1 + (deltay * toutx));
    111                         } else {
    112                           *x++ = (T)(x1 + (deltax * touty));
    113                           *y++ = (T)yout;
    114                         }
    115                     } else {
    116                         *x++ = x2;
    117                         *y++ = y2;
    118                     }
    119                     ++np;
    120                 } else {
    121                     if(tinx > tiny) {
    122                         *x++ = (T)xin;
    123                         *y++ = (T)yout;
    124                     } else {
    125                         *x++ = (T)xout;
    126                         *y++ = (T)yin;
    127                     }
    128                     ++np;
    129                 }
    130           }
    131         }
    132     }
    133     return np;
    134 }
    135 }
    136 #endif
    137