1 files changed, 135 insertions, 0 deletions
diff --git a/src/blind-find-rectangle.c b/src/blind-find-rectangle.c
new file mode 100644
index 0000000..87d2734
--- /dev/null
+++ b/src/blind-find-rectangle.c
@@ -0,0 +1,135 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+USAGE("[-a min-area] [-h min-height] [-w min-width] X Y Z [alpha]")
+
+struct pair {
+	size_t x;
+	size_t w;
+};
+
+static struct stream stream;
+static double X, Y, Z, alpha = 1;
+static size_t min_width = 1;
+static size_t min_height = 1;
+static size_t min_area = 1;
+static struct pair *stack = NULL;
+static size_t *cache = NULL;
+static char *buf = NULL;
+
+static void
+process(const void *colour)
+{
+	size_t y, x, x0, w, w0, h, top, area;
+	size_t best_area, x1, x2, y1, y2;
+	for (;;) {
+		top = x1 = x2 = y1 = y2 = best_area = 0;
+		memset(cache, 0, (stream.width + 1) * sizeof(*cache));
+		for (y = 0; eread_row(&stream, buf); y++) {
+			w = 0;
+			for (x = 0; x <= stream.width; x++) {
+				if (x != stream.width) {
+					if (!memcmp(buf + x * stream.pixel_size, colour, stream.pixel_size))
+						cache[x] += 1;
+					else
+						cache[x] = 0;
+				}
+				if (cache[x] > w) {
+					stack[top].x = x;
+					stack[top++].w = w;
+					w = cache[x];
+				} else if (cache[x] < w) {
+					do {
+						x0 = stack[--top].x;
+						w0 = stack[top].w;
+						area = w * (x - x0);
+						if (area > best_area) {
+							best_area = area;
+							x1 = x0;
+							x2 = x - 1;
+							y1 = y - w + 1;
+							y2 = y;
+						}
+						w = w0;
+					}  while (cache[x] < w);
+					if ((w = cache[x])) {
+						stack[top].x = x0;
+						stack[top++].w = w0;
+					}
+				}
+			}
+			fprintf(stderr, "%zu\n", y);
+		}
+		if (!y)
+			break;
+		w = x2 - x1 + 1;
+		h = y2 - y1 + 1;
+		if (best_area < min_area || w < min_width || h < min_height)
+			printf("0 0 0 0\n");
+		else
+			printf("%zu %zu %zu %zu\n", x1, y1, w, h);
+	}
+}
+
+int
+main(int argc, char *argv[])
+{
+	double colour_lf[4];
+	double colour_f[4];
+
+	ARGBEGIN {
+	case 'a':
+		min_area = etozu_flag('a', UARGF(), 1, SIZE_MAX);
+		break;
+	case 'h':
+		min_height = etozu_flag('h', UARGF(), 1, SIZE_MAX);
+		break;
+	case 'w':
+		min_width = etozu_flag('w', UARGF(), 1, SIZE_MAX);
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc != 3 && argc != 4)
+		usage();
+
+	X = etolf_arg("the X value", argv[0]);
+	Y = etolf_arg("the Y value", argv[1]);
+	Z = etolf_arg("the Z value", argv[2]);
+	if (argc > 3)
+		alpha = etolf_arg("the alpha value", argv[3]);
+
+	eopen_stream(&stream, NULL);
+	echeck_dimensions(&stream, WIDTH, NULL);
+	if (stream.width == SIZE_MAX)
+		eprintf("video is too wide\n");
+	if (stream.width > SIZE_MAX / stream.height)
+		eprintf("video is too large\n");
+
+	stack = emalloc2(stream.width + 1, sizeof(*stack));
+	cache = emalloc2(stream.width + 1, sizeof(*cache));
+	buf   = emalloc(stream.row_size);
+
+	if (!strcmp(stream.pixfmt, "xyza")) {
+		colour_lf[0] = X;
+		colour_lf[1] = Y;
+		colour_lf[2] = Z;
+		colour_lf[3] = alpha;
+		process(colour_lf);
+	} else if (!strcmp(stream.pixfmt, "xyza f")) {
+		colour_f[0] = (float)X;
+		colour_f[1] = (float)Y;
+		colour_f[2] = (float)Z;
+		colour_f[3] = (float)alpha;
+		process(colour_f);
+	} else {
+		eprintf("pixel format %s is not supported, try xyza\n", stream.pixfmt);
+	}
+
+	fshut(stdout, "<stdout>");
+	free(stack);
+	free(cache);
+	free(buf);
+	return 0;
+}