blind-set-alpha.c - blind - suckless command-line video editing utility
 (HTM) git clone git://git.suckless.org/blind
 (DIR) Log
 (DIR) Files
 (DIR) Refs
 (DIR) README
 (DIR) LICENSE
       ---
       blind-set-alpha.c (1645B)
       ---
            1 /* See LICENSE file for copyright and license details. */
            2 #include "common.h"
            3 
            4 USAGE("[-i] alpha-stream")
            5 
            6 #define PROCESS(TYPE, INV)\
            7         do {\
            8                 size_t i;\
            9                 TYPE *luma = (TYPE *)(alpha->buf) + alpha->luma_chan;\
           10                 TYPE *alph = (TYPE *)(alpha->buf) + alpha->alpha_chan;\
           11                 TYPE *out  = (TYPE *)(colour->buf) + colour->alpha_chan;\
           12                 n /= colour->chan_size;\
           13                 for (i = 0; i < n; i += colour->n_chan)\
           14                         out[i] *= (INV luma[i]) * alph[i];\
           15         } while (0)
           16 
           17 static void process_lf  (struct stream *colour, struct stream *alpha, size_t n) {PROCESS(double,);}
           18 static void process_lf_i(struct stream *colour, struct stream *alpha, size_t n) {PROCESS(double, 1 -);}
           19 static void process_f   (struct stream *colour, struct stream *alpha, size_t n) {PROCESS(float,);}
           20 static void process_f_i (struct stream *colour, struct stream *alpha, size_t n) {PROCESS(float, 1 -);}
           21 
           22 int
           23 main(int argc, char *argv[])
           24 {
           25         int invert = 0;
           26         struct stream colour, alpha;
           27         void (*process)(struct stream *colour, struct stream *alpha, size_t n);
           28 
           29         ARGBEGIN {
           30         case 'i':
           31                 invert = 1;
           32                 break;
           33         default:
           34                 usage();
           35         } ARGEND;
           36 
           37         if (argc != 1)
           38                 usage();
           39 
           40         eopen_stream(&colour, NULL);
           41         eopen_stream(&alpha, argv[0]);
           42 
           43         CHECK_CHANS(&colour, != -1, != -1);
           44         CHECK_ALPHA(&colour);
           45         if (colour.encoding == DOUBLE)
           46                 process = invert ? process_lf_i : process_lf;
           47         else if (colour.encoding == FLOAT)
           48                 process = invert ? process_f_i : process_f;
           49         else
           50                 eprintf("pixel format %s is not supported, try xyza\n", colour.pixfmt);
           51 
           52         fprint_stream_head(stdout, &colour);
           53         efflush(stdout, "<stdout>");
           54         process_two_streams(&colour, &alpha, STDOUT_FILENO, "<stdout>", process);
           55         return 0;
           56 }