+/* while, for a scanline, we need both starting as well as ending segments in order
+ to *reconstruct* horizontal lines, we only need one or the other to *process*
+ horizontal lines from the input data.
+
+ So horizontal lines are processed twice: first they create hotpixels by intersecting
+ all segments on the scanline (EVENT_HORIZTONAL). Secondly, they are processed for
+ their actual content. The second also happens for all segments that received more than
+ one point in this scanline.
+*/
+void horiz_reset(horizdata_t*horiz)
+{
+ horiz->num = 0;
+}
+
+void horiz_destroy(horizdata_t*horiz)
+{
+ if(horiz->data) rfx_free(horiz->data);
+ horiz->data = 0;
+}
+
+static int compare_horizontals(const void *_h1, const void *_h2)
+{
+ horizontal_t*h1 = (horizontal_t*)_h1;
+ horizontal_t*h2 = (horizontal_t*)_h2;
+ return h1->x1 - h2->x1;
+}
+
+static void process_horizontals(status_t*status)
+{
+ horizdata_t*horiz = &status->horiz;
+ qsort(horiz->data, horiz->num, sizeof(horizontal_t), compare_horizontals);
+ int t;
+ int xstart = 0;
+ for(t=0;t<horiz->num;t++) {
+ horizontal_t*h = &horiz->data[t];
+#ifdef DEBUG
+ fprintf(stderr, "horizontal (y=%.2f): %.2f -> %.2f dir=%s fs=%p\n",
+ h->y * status->gridsize,
+ h->x1 * status->gridsize,
+ h->x2 * status->gridsize,
+ h->dir==DIR_UP?"up":"down", h->fs);
+#endif
+ assert(h->y == status->y);
+ assert(xrow_contains(status->xrow, h->x1));
+ assert(xrow_contains(status->xrow, h->x2));
+
+ int pos = xrow_find(status->xrow, h->x1);
+ int x = h->x1;
+ assert(pos <= status->xrow->num);
+ assert(pos == status->xrow->num || status->xrow->x[pos] > x);
+
+ while(x < h->x2) {
+ int next_x = pos < status->xrow->num ? status->xrow->x[pos] : h->x2;
+ pos++;
+
+ assert(next_x > x);
+
+ point_t p1 = {x,h->y};
+ point_t p2 = {next_x,h->y};
+ segment_t* left = actlist_find(status->actlist, p1, p2);
+ assert(!left || left->fs_out_ok);
+#ifdef DEBUG
+ fprintf(stderr, " fragment %.2f..%.2f edge=%08x\n",
+ x * status->gridsize,
+ next_x * status->gridsize,
+ h->fs);
+ if(left) {
+ fprintf(stderr, " segment [%d] (%.2f,%.2f -> %.2f,%2f, at %.2f,%.2f) is to the left\n",
+ SEGNR(left),
+ left->a.x * status->gridsize,
+ left->a.y * status->gridsize,
+ left->b.x * status->gridsize,
+ left->b.y * status->gridsize,
+ left->pos.x * status->gridsize,
+ left->pos.y * status->gridsize
+ );
+ /* this segment might be a distance away from the left point
+ of the horizontal line if the horizontal line belongs to a stroke
+ with segments that just ended (so this horizontal line appears to
+ be "floating in space" from our current point of view)
+ assert(left->pos.y == h->y && left->pos.x == h->x1);
+ */
+ }
+#endif
+ windstate_t below = left?left->wind:status->windrule->start(status->context);
+ windstate_t above = status->windrule->add(status->context, below, h->fs, h->dir, h->polygon_nr);
+ edgestyle_t*fs = status->windrule->diff(&above, &below);
+ if(fs) {
+#ifdef DEBUG
+ fprintf(stderr, " ...storing\n");
+#endif
+ append_stroke(status, p1, p2, DIR_INVERT(h->dir), fs);
+ } else {
+#ifdef DEBUG
+ fprintf(stderr, " ...ignoring (below: (wind_nr=%d, filled=%d), above: (wind_nr=%d, filled=%d) %s\n",
+ below.wind_nr, below.is_filled,
+ above.wind_nr, above.is_filled,
+ h->dir==DIR_UP?"up":"down"
+ );
+#endif
+ }
+ x = next_x;
+ }
+ }
+}
+
+static void store_horizontal(status_t*status, point_t p1, point_t p2, edgestyle_t*fs, segment_dir_t dir, int polygon_nr)
+{
+ assert(p1.y == p2.y);
+ assert(p1.x != p2.x); // TODO: can this happen?
+
+ if(p1.x > p2.x) {
+ dir = DIR_INVERT(dir);
+ point_t p_1 = p1;
+ point_t p_2 = p2;
+ p1 = p_2;
+ p2 = p_1;
+ }
+
+ if(status->horiz.size == status->horiz.num) {
+ if(!status->horiz.size)
+ status->horiz.size = 16;
+ status->horiz.size *= 2;
+ status->horiz.data = rfx_realloc(status->horiz.data, sizeof(status->horiz.data[0])*status->horiz.size);
+ }
+ horizontal_t*h = &status->horiz.data[status->horiz.num++];
+ h->y = p1.y;
+ h->x1 = p1.x;
+ h->x2 = p2.x;
+ h->fs = fs;
+ h->dir = dir;
+ h->polygon_nr = polygon_nr;
+}
+
+