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Member "reportlab-3.5.32/src/rl_addons/renderPM/libart_lgpl/art_rgb_affine_private.c" (1 Oct 2019, 3363 Bytes) of package /linux/privat/reportlab-3.5.32.tar.gz:


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    1 /* Libart_LGPL - library of basic graphic primitives
    2  * Copyright (C) 1998 Raph Levien
    3  *
    4  * This library is free software; you can redistribute it and/or
    5  * modify it under the terms of the GNU Library General Public
    6  * License as published by the Free Software Foundation; either
    7  * version 2 of the License, or (at your option) any later version.
    8  *
    9  * This library is distributed in the hope that it will be useful,
   10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   12  * Library General Public License for more details.
   13  *
   14  * You should have received a copy of the GNU Library General Public
   15  * License along with this library; if not, write to the
   16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   17  * Boston, MA 02111-1307, USA.
   18  */
   19 
   20 #include "config.h"
   21 #include "art_rgb_affine_private.h"
   22 
   23 #include <math.h>
   24 #include "art_misc.h"
   25 #include "art_point.h"
   26 #include "art_affine.h"
   27 
   28 /* Private functions for the rgb affine image compositors - primarily,
   29    the determination of runs, eliminating the need for source image
   30    bbox calculation in the inner loop. */
   31 
   32 /* Determine a "run", such that the inverse affine of all pixels from
   33    (x0, y) inclusive to (x1, y) exclusive fit within the bounds
   34    of the source image.
   35 
   36    Initial values of x0, x1, and result values stored in first two
   37    pointer arguments.
   38 */
   39 
   40 #define EPSILON 1e-6
   41 
   42 void
   43 art_rgb_affine_run (int *p_x0, int *p_x1, int y,
   44             int src_width, int src_height,
   45             const double affine[6])
   46 {
   47   int x0, x1;
   48   double z;
   49   double x_intercept;
   50   int xi;
   51 
   52   x0 = *p_x0;
   53   x1 = *p_x1;
   54 
   55   /* do left and right edges */
   56   if (affine[0] > EPSILON)
   57     {
   58       z = affine[2] * (y + 0.5) + affine[4];
   59       x_intercept = -z / affine[0];
   60       xi = (int) ceil (x_intercept + EPSILON - 0.5);
   61       if (xi > x0)
   62     x0 = xi;
   63       x_intercept = (-z + src_width) / affine[0];
   64       xi = (int) ceil (x_intercept - EPSILON - 0.5);
   65       if (xi < x1)
   66     x1 = xi;
   67     }
   68   else if (affine[0] < -EPSILON)
   69     {
   70       z = affine[2] * (y + 0.5) + affine[4];
   71       x_intercept = (-z + src_width) / affine[0];
   72       xi = (int) ceil (x_intercept + EPSILON - 0.5);
   73       if (xi > x0)
   74     x0 = xi;
   75       x_intercept = -z / affine[0];
   76       xi = (int) ceil (x_intercept - EPSILON - 0.5);
   77       if (xi < x1)
   78     x1 = xi;
   79     }
   80   else
   81     {
   82       z = affine[2] * (y + 0.5) + affine[4];
   83       if (z < 0 || z >= src_width)
   84     {
   85       *p_x1 = *p_x0;
   86       return;
   87     }
   88     }
   89 
   90   /* do top and bottom edges */
   91   if (affine[1] > EPSILON)
   92     {
   93       z = affine[3] * (y + 0.5) + affine[5];
   94       x_intercept = -z / affine[1];
   95       xi = (int) ceil (x_intercept + EPSILON - 0.5);
   96       if (xi > x0)
   97     x0 = xi;
   98       x_intercept = (-z + src_height) / affine[1];
   99       xi = (int) ceil (x_intercept - EPSILON - 0.5);
  100       if (xi < x1)
  101     x1 = xi;
  102     }
  103   else if (affine[1] < -EPSILON)
  104     {
  105       z = affine[3] * (y + 0.5) + affine[5];
  106       x_intercept = (-z + src_height) / affine[1];
  107       xi = (int) ceil (x_intercept + EPSILON - 0.5);
  108       if (xi > x0)
  109     x0 = xi;
  110       x_intercept = -z / affine[1];
  111       xi = (int) ceil (x_intercept - EPSILON - 0.5);
  112       if (xi < x1)
  113     x1 = xi;
  114     }
  115   else
  116     {
  117       z = affine[3] * (y + 0.5) + affine[5];
  118       if (z < 0 || z >= src_height)
  119     {
  120       *p_x1 = *p_x0;
  121       return;
  122     }
  123     }
  124 
  125   *p_x0 = x0;
  126   *p_x1 = x1;
  127 }