aboutsummaryrefslogtreecommitdiff
path: root/svg-flatten/src/nopencv.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'svg-flatten/src/nopencv.cpp')
-rw-r--r--svg-flatten/src/nopencv.cpp157
1 files changed, 157 insertions, 0 deletions
diff --git a/svg-flatten/src/nopencv.cpp b/svg-flatten/src/nopencv.cpp
new file mode 100644
index 0000000..77c6cc6
--- /dev/null
+++ b/svg-flatten/src/nopencv.cpp
@@ -0,0 +1,157 @@
+
+#include <iostream>
+
+#include "nopencv.hpp"
+
+using namespace gerbolyze;
+using namespace gerbolyze::nopencv;
+
+/* directions:
+ * 0
+ * 7 1
+ * ^
+ * |
+ * 6 <--- X ---> 2
+ * |
+ * v
+ * 5 3
+ * 4
+ *
+ */
+enum Direction {
+ D_N,
+ D_NE,
+ D_E,
+ D_SE,
+ D_S,
+ D_SW,
+ D_W,
+ D_NW
+};
+
+//const char * const dir_str[8] = { "N", "NE", "E", "SE", "S", "SW", "W", "NW" };
+
+static struct {
+ int x;
+ int y;
+} dir_to_coords[8] = {{0, -1}, {1, -1}, {1, 0}, {1, 1}, {0, 1}, {-1, 1}, {-1, 0}, {-1, -1}};
+
+static Direction flip_direction[8] = {
+ D_S,
+ D_SW,
+ D_W,
+ D_NW,
+ D_N,
+ D_NE,
+ D_E,
+ D_SE
+};
+
+static void follow(gerbolyze::nopencv::Image32 img, int start_x, int start_y, Direction initial_direction, int nbd, int connectivity, Polygon &poly) {
+
+ //cerr << "follow " << start_x << " " << start_y << " | dir=" << dir_str[initial_direction] << " nbd=" << nbd << " conn=" << connectivity << endl;
+ int dir_inc = (connectivity == 4) ? 2 : 1;
+
+ int probe_x, probe_y;
+
+ /* homing run: find starting point for algorithm steps below. */
+ bool found = false;
+ int k;
+ for (k=initial_direction; k<initial_direction+8; k += dir_inc) {
+ probe_x = start_x + dir_to_coords[k % 8].x;
+ probe_y = start_y + dir_to_coords[k % 8].y;
+
+ if (img.at_default(probe_x, probe_y) != 0) {
+ found = true;
+ break;
+ }
+ }
+
+ if (!found) { /* No nonzero pixels found. This is a single-pixel contour */
+ img.at(start_x, start_y) = nbd;
+ poly.emplace_back(d2p{(double)start_x, (double)start_y});
+ poly.emplace_back(d2p{(double)start_x+1, (double)start_y});
+ poly.emplace_back(d2p{(double)start_x+1, (double)start_y+1});
+ poly.emplace_back(d2p{(double)start_x, (double)start_y+1});
+ return;
+ }
+
+ /* starting point found. */
+ int current_direction = k % 8;
+ int start_direction = current_direction;
+ int center_x = start_x, center_y = start_y;
+ //cerr << " init: " << center_x << " " << center_y << " / " << dir_str[current_direction] << endl;
+
+ do {
+ bool flag = false;
+ for (k = current_direction + 8 - dir_inc; k >= current_direction; k -= dir_inc) {
+ probe_x = center_x + dir_to_coords[k % 8].x;
+ probe_y = center_y + dir_to_coords[k % 8].y;
+ if (k%8 == D_E)
+ flag = true;
+
+ if (img.at_default(probe_x, probe_y) != 0) {
+ break;
+ }
+ }
+
+ int set_val = 0;
+ if (flag && img.at_default(center_x+1, center_y) == 0) {
+ img.at(center_x, center_y) = -nbd;
+ set_val = -nbd;
+ } else if (img.at(center_x, center_y) == 1) {
+ img.at(center_x, center_y) = nbd;
+ set_val = nbd;
+ }
+
+ for (int l = (current_direction + 8 - 2 + 1) / 2 * 2; l > k; l -= dir_inc) {
+ switch (l%8) {
+ case 0: poly.emplace_back(d2p{(double)center_x, (double)center_y}); break;
+ case 2: poly.emplace_back(d2p{(double)center_x+1, (double)center_y}); break;
+ case 4: poly.emplace_back(d2p{(double)center_x+1, (double)center_y+1}); break;
+ case 6: poly.emplace_back(d2p{(double)center_x, (double)center_y+1}); break;
+ }
+ }
+
+ center_x = probe_x;
+ center_y = probe_y;
+ current_direction = flip_direction[k % 8];
+
+ //cerr << " " << center_x << " " << center_y << " / " << dir_str[current_direction] << " -> " << set_val << endl;
+ } while (center_x != start_x || center_y != start_y || current_direction != start_direction);
+}
+
+
+void gerbolyze::nopencv::find_blobs(gerbolyze::nopencv::Image32 img, gerbolyze::nopencv::ContourCallback cb) {
+ int nbd = 1;
+ Polygon poly;
+ for (int y=0; y<img.rows(); y++) {
+ for (int x=0; x<img.cols(); x++) {
+ int val_xy = img.at(x, y);
+ /* Note: outer borders are followed with 8-connectivity, hole borders with 4-connectivity. This prevents
+ * incorrect results in this case:
+ *
+ * 1 1 1 | 0 0 0
+ * |
+ * 1 1 1 | 0 0 0
+ * ----------+---------- <== Here
+ * 0 0 0 | 1 1 1
+ * |
+ * 0 0 0 | 1 1 1
+ */
+ if (img.at_default(x-1, y) == 0 && val_xy == 1) { /* outer border starting point */
+ nbd += 1;
+ follow(img, x, y, D_W, nbd, 8, poly);
+ cb(poly, CP_CONTOUR);
+ poly.clear();
+
+ } else if (val_xy >= 1 && img.at_default(x+1, y) == 0) { /* hole border starting point */
+ nbd += 1;
+ follow(img, x, y, D_E, nbd, 4, poly);
+ cb(poly, CP_HOLE);
+ poly.clear();
+ }
+ }
+ }
+}
+