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	blind-find-rectangle.c - blind - suckless command-line video editing utility
	git clone git://git.suckless.org/blind
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	blind-find-rectangle.c (3127B)
	---
	1 /* See LICENSE file for copyright and license details. */
	2 #include "common.h"
	3
	4 USAGE("[-a min-area] [-h min-height] [-w min-width] X Y Z [alpha]")
	5
	6 struct pair {
	7 size_t x;
	8 size_t w;
	9 };
	10
	11 static struct stream stream;
	12 static size_t min_width = 1;
	13 static size_t min_height = 1;
	14 static size_t min_area = 1;
	15 static struct pair *stack = NULL;
	16 static size_t *cache = NULL;
	17 static char *buf = NULL;
	18
	19 static void
	20 process(const void *colour)
	21 {
	22 size_t y, x, x0, w, w0, h, top, area;
	23 size_t best_area, x1, x2, y1, y2;
	24 for (;;) {
	25 top = x1 = x2 = y1 = y2 = best_area = 0;
	26 memset(cache, 0, (stream.width + 1) * sizeof(*cache));
	27 for (y = 0; eread_row(&stream, buf); y++) {
	28 w = 0;
	29 for (x = 0; x <= stream.width; x++) {
	30 if (x != stream.width) {
	31 if (!memcmp(buf + x * stream.pix…
	32 cache[x] += 1;
	33 else
	34 cache[x] = 0;
	35 }
	36 if (cache[x] > w) {
	37 stack[top].x = x;
	38 stack[top++].w = w;
	39 w = cache[x];
	40 } else if (cache[x] < w) {
	41 do {
	42 x0 = stack[--top].x;
	43 w0 = stack[top].w;
	44 area = w * (x - x0);
	45 if (area > best_area) {
	46 best_area = area;
	47 x1 = x0;
	48 x2 = x - 1;
	49 y1 = y - w + 1;
	50 y2 = y;
	51 }
	52 w = w0;
	53 } while (cache[x] < w);
	54 if ((w = cache[x])) {
	55 stack[top].x = x0;
	56 stack[top++].w = w0;
	57 }
	58 }
	59 }
	60 fprintf(stderr, "%zu\n", y);
	61 }
	62 if (!y)
	63 break;
	64 w = x2 - x1 + 1;
	65 h = y2 - y1 + 1;
	66 if (best_area < min_area \|\| w < min_width \|\| h < min_hei…
	67 printf("0 0 0 0\n");
	68 else
	69 printf("%zu %zu %zu %zu\n", x1, y1, w, h);
	70 }
	71 }
	72
	73 int
	74 main(int argc, char *argv[])
	75 {
	76 double colour_lf[4];
	77 float colour_f[4];
	78 double X, Y, Z, alpha = 1;
	79
	80 ARGBEGIN {
	81 case 'a':
	82 min_area = etozu_flag('a', UARGF(), 1, SIZE_MAX);
	83 break;
	84 case 'h':
	85 min_height = etozu_flag('h', UARGF(), 1, SIZE_MAX);
	86 break;
	87 case 'w':
	88 min_width = etozu_flag('w', UARGF(), 1, SIZE_MAX);
	89 break;
	90 default:
	91 usage();
	92 } ARGEND;
	93
	94 if (argc != 3 && argc != 4)
	95 usage();
	96
	97 X = etolf_arg("the X value", argv[0]);
	98 Y = etolf_arg("the Y value", argv[1]);
	99 Z = etolf_arg("the Z value", argv[2]);
	100 if (argc > 3)
	101 alpha = etolf_arg("the alpha value", argv[3]);
	102
	103 eopen_stream(&stream, NULL);
	104 echeck_dimensions(&stream, WIDTH, NULL);
	105 if (stream.width == SIZE_MAX)
	106 eprintf("video is too wide\n");
	107 if (stream.width > SIZE_MAX / stream.height)
	108 eprintf("video is too large\n");
	109
	110 stack = emalloc2(stream.width + 1, sizeof(*stack));
	111 cache = emalloc2(stream.width + 1, sizeof(*cache));
	112 buf = emalloc(stream.row_size);
	113
	114 if (argc > 3)
	115 CHECK_ALPHA(&stream);
	116 CHECK_N_CHAN(&stream, 1, 3 + !!stream.alpha);
	117 if (stream.encoding == DOUBLE) {
	118 colour_lf[0] = X;
	119 colour_lf[1] = Y;
	120 colour_lf[2] = Z;
	121 colour_lf[3] = alpha;
	122 process(colour_lf);
	123 } else if (stream.encoding == FLOAT) {
	124 colour_f[0] = (float)X;
	125 colour_f[1] = (float)Y;
	126 colour_f[2] = (float)Z;
	127 colour_f[3] = (float)alpha;
	128 process(colour_f);
	129 } else {
	130 eprintf("pixel format %s is not supported, try xyza\n", …
	131 }
	132
	133 fshut(stdout, "<stdout>");
	134 free(stack);
	135 free(cache);
	136 free(buf);
	137 return 0;
	138 }