vp8/common/textblit.c

   1 /*
   2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11 #include <stdlib.h>
  12
  13
  14 void vp8_blit_text(const char *msg, unsigned char *address, const int pitch)
  15 {
  16     int letter_bitmap;
  17     unsigned char *output_pos = address;
  18     int colpos;
  19     const int font[] =
  20     {
  21         0x0, 0x5C00, 0x8020, 0xAFABEA, 0xD7EC0, 0x1111111, 0x1855740, 0x18000,
  22         0x45C0, 0x74400, 0x51140, 0x23880, 0xC4000, 0x21080, 0x80000, 0x111110,
  23         0xE9D72E, 0x87E40, 0x12AD732, 0xAAD62A, 0x4F94C4, 0x4D6B7, 0x456AA,
  24         0x3E8423, 0xAAD6AA, 0xAAD6A2, 0x2800, 0x2A00, 0x8A880, 0x52940, 0x22A20,
  25         0x15422, 0x6AD62E, 0x1E4A53E, 0xAAD6BF, 0x8C62E, 0xE8C63F, 0x118D6BF,
  26         0x1094BF, 0xCAC62E, 0x1F2109F, 0x118FE31, 0xF8C628, 0x8A89F, 0x108421F,
  27         0x1F1105F, 0x1F4105F, 0xE8C62E, 0x2294BF, 0x164C62E, 0x12694BF, 0x8AD6A2,
  28         0x10FC21, 0x1F8421F, 0x744107, 0xF8220F, 0x1151151, 0x117041, 0x119D731,
  29         0x47E0, 0x1041041, 0xFC400, 0x10440, 0x1084210, 0x820
  30     };
  31     colpos = 0;
  32
  33     while (msg[colpos] != 0)
  34     {
  35         char letter = msg[colpos];
  36         int fontcol, fontrow;
  37
  38         if (letter <= 'Z' && letter >= ' ')
  39             letter_bitmap = font[letter-' '];
  40         else if (letter <= 'z' && letter >= 'a')
  41             letter_bitmap = font[letter-'a'+'A' - ' '];
  42         else
  43             letter_bitmap = font[0];
  44
  45         for (fontcol = 6; fontcol >= 0 ; fontcol--)
  46             for (fontrow = 0; fontrow < 5; fontrow++)
  47                 output_pos[fontrow *pitch + fontcol] =
  48                     ((letter_bitmap >> (fontcol * 5)) & (1 << fontrow) ? 255 : 0);
  49
  50         output_pos += 7;
  51         colpos++;
  52     }
  53 }
  54
  55 static void plot (const int x, const int y, unsigned char *image, const int pitch)
  56 {
  57     image [x+y*pitch] ^= 255;
  58 }
  59
  60 /* Bresenham line algorithm */
  61 void vp8_blit_line(int x0, int x1, int y0, int y1, unsigned char *image, const int pitch)
  62 {
  63     int steep = abs(y1 - y0) > abs(x1 - x0);
  64     int deltax, deltay;
  65     int error, ystep, y, x;
  66
  67     if (steep)
  68     {
  69         int t;
  70         t = x0;
  71         x0 = y0;
  72         y0 = t;
  73
  74         t = x1;
  75         x1 = y1;
  76         y1 = t;
  77     }
  78
  79     if (x0 > x1)
  80     {
  81         int t;
  82         t = x0;
  83         x0 = x1;
  84         x1 = t;
  85
  86         t = y0;
  87         y0 = y1;
  88         y1 = t;
  89     }
  90
  91     deltax = x1 - x0;
  92     deltay = abs(y1 - y0);
  93     error  = deltax / 2;
  94
  95     y = y0;
  96
  97     if (y0 < y1)
  98         ystep = 1;
  99     else
 100         ystep = -1;
 101
 102     if (steep)
 103     {
 104         for (x = x0; x <= x1; x++)
 105         {
 106             plot(y,x, image, pitch);
 107
 108             error = error - deltay;
 109             if (error < 0)
 110             {
 111                 y = y + ystep;
 112                 error = error + deltax;
 113             }
 114         }
 115     }
 116     else
 117     {
 118         for (x = x0; x <= x1; x++)
 119         {
 120             plot(x,y, image, pitch);
 121
 122             error = error - deltay;
 123             if (error < 0)
 124             {
 125                 y = y + ystep;
 126                 error = error + deltax;
 127             }
 128         }
 129     }
 130 }