src/libnr/nr-pixblock-line.cpp

   1 #define __NR_PIXBLOCK_LINE_C__
   2
   3 /*
   4  * Pixel buffer rendering library
   5  *
   6  * Authors:
   7  *   Lauris Kaplinski <lauris@kaplinski.com>
   8  *
   9  * This code is in public domain
  10  */
  11
  12 #include <libnr/nr-pixops.h>
  13 #include <libnr/nr-pixblock-pixel.h>
  14
  15 void
  16 nr_pixblock_draw_line_rgba32 (NRPixBlock *d, long x0, long y0, long x1, long y1, short /*first*/, unsigned long rgba)
  17 {
  18         long deltax, deltay, xinc1, xinc2, yinc1, yinc2;
  19         long den, num, numadd, numpixels;
  20         long x, y, curpixel;
  21         /* Pixblock */
  22         int dbpp;
  23         NRPixBlock spb;
  24         unsigned char *spx;
  25
  26         if (x1 >= x0) {
  27                 deltax = x1 - x0;
  28                 xinc1 = 1;
  29                 xinc2 = 1;
  30         } else {
  31                 deltax = x0 - x1;
  32                 xinc1 = -1;
  33                 xinc2 = -1;
  34         }
  35
  36         if (y1 >= y0) {
  37                 deltay = y1 - y0;
  38                 yinc1 = 1;
  39                 yinc2 = 1;
  40         } else {
  41                 deltay = y0 - y1;
  42                 yinc1 = -1;
  43                 yinc2 = -1;
  44         }
  45
  46         if (deltax >= deltay) {
  47                 xinc1 = 0;
  48                 yinc2 = 0;
  49                 den = deltax;
  50                 num = deltax / 2;
  51                 numadd = deltay;
  52                 numpixels = deltax;
  53         } else {
  54                 xinc2 = 0;
  55                 yinc1 = 0;
  56                 den = deltay;
  57                 num = deltay / 2;
  58                 numadd = deltax;
  59                 numpixels = deltay;
  60         }
  61
  62         /* We can be quite sure 1x1 pixblock is TINY */
  63         nr_pixblock_setup_fast (&spb, NR_PIXBLOCK_MODE_R8G8B8A8N, 0, 0, 1, 1, 0);
  64         spb.empty = 0;
  65         spx = NR_PIXBLOCK_PX (&spb);
  66         spx[0] = NR_RGBA32_R (rgba);
  67         spx[1] = NR_RGBA32_G (rgba);
  68         spx[2] = NR_RGBA32_B (rgba);
  69         spx[3] = NR_RGBA32_A (rgba);
  70
  71         dbpp = NR_PIXBLOCK_BPP (d);
  72
  73         x = x0;
  74         y = y0;
  75
  76         for (curpixel = 0; curpixel <= numpixels; curpixel++) {
  77                 if ((x >= d->area.x0) && (y >= d->area.y0) && (x < d->area.x1) && (y < d->area.y1)) {
  78                         nr_compose_pixblock_pixblock_pixel (d, NR_PIXBLOCK_PX (d) + (y - d->area.y0) * d->rs + (x - d->area.x0) * dbpp, &spb, spx);
  79                 }
  80                 num += numadd;
  81                 if (num >= den) {
  82                         num -= den;
  83                         x += xinc1;
  84                         y += yinc1;
  85                 }
  86                 x += xinc2;
  87                 y += yinc2;
  88         }
  89
  90         nr_pixblock_release (&spb);
  91 }
  92