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      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <stdio.h>
     18 #include <stdlib.h>
     19 #include <unistd.h>
     20 #include <string.h>
     21 
     22 #define to565(r,g,b)                                            \
     23     ((((r) >> 3) << 11) | (((g) >> 2) << 5) | ((b) >> 3))
     24 
     25 #define from565_r(x) ((((x) >> 11) & 0x1f) * 255 / 31)
     26 #define from565_g(x) ((((x) >> 5) & 0x3f) * 255 / 63)
     27 #define from565_b(x) (((x) & 0x1f) * 255 / 31)
     28 
     29 void to_565_raw(void)
     30 {
     31     unsigned char in[3];
     32     unsigned short out;
     33 
     34     while(read(0, in, 3) == 3) {
     35         out = to565(in[0],in[1],in[2]);
     36         write(1, &out, 2);
     37     }
     38     return;
     39 }
     40 
     41 void to_565_raw_dither(int width)
     42 {
     43     unsigned char in[3];
     44     unsigned short out;
     45     int i = 0;
     46     int e;
     47 
     48     int* error = malloc((width+2) * 3 * sizeof(int));
     49     int* next_error = malloc((width+2) * 3 * sizeof(int));
     50     memset(error, 0, (width+2) * 3 * sizeof(int));
     51     memset(next_error, 0, (width+2) * 3 * sizeof(int));
     52     error += 3;        // array goes from [-3..((width+1)*3+2)]
     53     next_error += 3;
     54 
     55     while(read(0, in, 3) == 3) {
     56         int r = in[0] + error[i*3+0];
     57         int rb = (r < 0) ? 0 : ((r > 255) ? 255 : r);
     58 
     59         int g = in[1] + error[i*3+1];
     60         int gb = (g < 0) ? 0 : ((g > 255) ? 255 : g);
     61 
     62         int b = in[2] + error[i*3+2];
     63         int bb = (b < 0) ? 0 : ((b > 255) ? 255 : b);
     64 
     65         out = to565(rb, gb, bb);
     66         write(1, &out, 2);
     67 
     68 #define apply_error(ch) {                                               \
     69             next_error[(i-1)*3+ch] += e * 3 / 16;                       \
     70             next_error[(i)*3+ch] += e * 5 / 16;                         \
     71             next_error[(i+1)*3+ch] += e * 1 / 16;                       \
     72             error[(i+1)*3+ch] += e - ((e*1/16) + (e*3/16) + (e*5/16));  \
     73         }
     74 
     75         e = r - from565_r(out);
     76         apply_error(0);
     77 
     78         e = g - from565_g(out);
     79         apply_error(1);
     80 
     81         e = b - from565_b(out);
     82         apply_error(2);
     83 
     84 #undef apply_error
     85 
     86         ++i;
     87         if (i == width) {
     88             // error <- next_error; next_error <- 0
     89             int* temp = error; error = next_error; next_error = temp;
     90             memset(next_error, 0, (width+1) * 3 * sizeof(int));
     91             i = 0;
     92         }
     93     }
     94 
     95     free(error-3);
     96     free(next_error-3);
     97 
     98     return;
     99 }
    100 
    101 void to_565_rle(void)
    102 {
    103     unsigned char in[3];
    104     unsigned short last, color, count;
    105     unsigned total = 0;
    106     count = 0;
    107 
    108     while(read(0, in, 3) == 3) {
    109         color = to565(in[0],in[1],in[2]);
    110         if (count) {
    111             if ((color == last) && (count != 65535)) {
    112                 count++;
    113                 continue;
    114             } else {
    115                 write(1, &count, 2);
    116                 write(1, &last, 2);
    117                 total += count;
    118             }
    119         }
    120         last = color;
    121         count = 1;
    122     }
    123     if (count) {
    124         write(1, &count, 2);
    125         write(1, &last, 2);
    126         total += count;
    127     }
    128     fprintf(stderr,"%d pixels\n",total);
    129 }
    130 
    131 int main(int argc, char **argv)
    132 {
    133     if ((argc == 2) && (!strcmp(argv[1],"-rle"))) {
    134         to_565_rle();
    135     } else {
    136         if (argc > 2 && (!strcmp(argv[1], "-w"))) {
    137             to_565_raw_dither(atoi(argv[2]));
    138         } else {
    139             to_565_raw();
    140         }
    141     }
    142     return 0;
    143 }
    144