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      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 #include "vp9/common/vp9_textblit.h"
     14 
     15 static const int font[] = {
     16   0x0, 0x5C00, 0x8020, 0xAFABEA, 0xD7EC0, 0x1111111, 0x1855740, 0x18000,
     17   0x45C0, 0x74400, 0x51140, 0x23880, 0xC4000, 0x21080, 0x80000, 0x111110,
     18   0xE9D72E, 0x87E40, 0x12AD732, 0xAAD62A, 0x4F94C4, 0x4D6B7, 0x456AA,
     19   0x3E8423, 0xAAD6AA, 0xAAD6A2, 0x2800, 0x2A00, 0x8A880, 0x52940, 0x22A20,
     20   0x15422, 0x6AD62E, 0x1E4A53E, 0xAAD6BF, 0x8C62E, 0xE8C63F, 0x118D6BF,
     21   0x1094BF, 0xCAC62E, 0x1F2109F, 0x118FE31, 0xF8C628, 0x8A89F, 0x108421F,
     22   0x1F1105F, 0x1F4105F, 0xE8C62E, 0x2294BF, 0x164C62E, 0x12694BF, 0x8AD6A2,
     23   0x10FC21, 0x1F8421F, 0x744107, 0xF8220F, 0x1151151, 0x117041, 0x119D731,
     24   0x47E0, 0x1041041, 0xFC400, 0x10440, 0x1084210, 0x820
     25 };
     26 
     27 static void plot(int x, int y, unsigned char *image, int pitch) {
     28   image[x + y * pitch] ^= 255;
     29 }
     30 
     31 void vp9_blit_text(const char *msg, unsigned char *address, const int pitch) {
     32   int letter_bitmap;
     33   unsigned char *output_pos = address;
     34   int colpos = 0;
     35 
     36   while (msg[colpos] != 0) {
     37     char letter = msg[colpos];
     38     int fontcol, fontrow;
     39 
     40     if (letter <= 'Z' && letter >= ' ')
     41       letter_bitmap = font[letter - ' '];
     42     else if (letter <= 'z' && letter >= 'a')
     43       letter_bitmap = font[letter - 'a' + 'A' - ' '];
     44     else
     45       letter_bitmap = font[0];
     46 
     47     for (fontcol = 6; fontcol >= 0; fontcol--)
     48       for (fontrow = 0; fontrow < 5; fontrow++)
     49         output_pos[fontrow * pitch + fontcol] =
     50           ((letter_bitmap >> (fontcol * 5)) & (1 << fontrow) ? 255 : 0);
     51 
     52     output_pos += 7;
     53     colpos++;
     54   }
     55 }
     56 
     57 
     58 
     59 /* Bresenham line algorithm */
     60 void vp9_blit_line(int x0, int x1, int y0, int y1, unsigned char *image,
     61                    int pitch) {
     62   int steep = abs(y1 - y0) > abs(x1 - x0);
     63   int deltax, deltay;
     64   int error, ystep, y, x;
     65 
     66   if (steep) {
     67     int t;
     68     t = x0;
     69     x0 = y0;
     70     y0 = t;
     71 
     72     t = x1;
     73     x1 = y1;
     74     y1 = t;
     75   }
     76 
     77   if (x0 > x1) {
     78     int t;
     79     t = x0;
     80     x0 = x1;
     81     x1 = t;
     82 
     83     t = y0;
     84     y0 = y1;
     85     y1 = t;
     86   }
     87 
     88   deltax = x1 - x0;
     89   deltay = abs(y1 - y0);
     90   error  = deltax / 2;
     91 
     92   y = y0;
     93 
     94   if (y0 < y1)
     95     ystep = 1;
     96   else
     97     ystep = -1;
     98 
     99   if (steep) {
    100     for (x = x0; x <= x1; x++) {
    101       plot(y, x, image, pitch);
    102 
    103       error = error - deltay;
    104       if (error < 0) {
    105         y = y + ystep;
    106         error = error + deltax;
    107       }
    108     }
    109   } else {
    110     for (x = x0; x <= x1; x++) {
    111       plot(x, y, image, pitch);
    112 
    113       error = error - deltay;
    114       if (error < 0) {
    115         y = y + ystep;
    116         error = error + deltax;
    117       }
    118     }
    119   }
    120 }
    121