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 
to_565_raw(void)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 
to_565_raw_dither(int width)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 
to_565_rle(void)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 
main(int argc,char ** argv)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