small polygon refinement

diff --git a/lib/gfxpoly/convert.c b/lib/gfxpoly/convert.c
index dae58b6..39517d7 100644 (file)
--- a/lib/gfxpoly/convert.c
+++ b/lib/gfxpoly/convert.c
@@ -175,9 +175,8 @@ static void compactlineto(polywriter_t*w, int32_t x, int32_t y)
     if(p.x == data->last.x && p.y == data->last.y)
        return;
 
-    if(p.y < data->last.y && data->dir != DIR_UP ||
-       p.y > data->last.y && data->dir != DIR_DOWN || 
-       data->new) {
+    if((p.y < data->last.y && data->dir != DIR_UP) ||
+       (p.y > data->last.y && data->dir != DIR_DOWN) || data->new) {
        finish_segment(data);
        data->dir = p.y > data->last.y ? DIR_DOWN : DIR_UP;
        data->points[0] = data->last;
@@ -407,7 +406,7 @@ gfxline_t*gfxline_from_gfxpoly(gfxpoly_t*poly)
 }
 #endif
 
-gfxline_t*gfxline_from_gfxpoly(gfxpoly_t*poly)
+static gfxline_t*mkgfxline(gfxpoly_t*poly, char preserve_direction)
 {
     gfxpolystroke_t*stroke;
     int count = 0;
@@ -416,6 +415,7 @@ gfxline_t*gfxline_from_gfxpoly(gfxpoly_t*poly)
     dict_t*d = dict_new2(&point_type);
     dict_t*todo = dict_new2(&ptr_type);
     gfxpolystroke_t*stroke_min= poly->strokes;
+    int32_t x_min=stroke_min->points[0].x;
     int32_t y_min=stroke_min->points[0].y;
     for(stroke=poly->strokes;stroke;stroke=stroke->next) {
        dict_put(todo, stroke, stroke);
@@ -423,10 +423,15 @@ gfxline_t*gfxline_from_gfxpoly(gfxpoly_t*poly)
        count += stroke->num_points;
        if(stroke->dir == DIR_UP) {
            dict_put(d, &stroke->points[stroke->num_points-1], stroke);
+           if(!preserve_direction)
+               dict_put(d, &stroke->points[0], stroke);
        } else {
            dict_put(d, &stroke->points[0], stroke);
+           if(!preserve_direction)
+               dict_put(d, &stroke->points[stroke->num_points-1], stroke);
        }
-       if(stroke->points[0].y < y_min) {
+       if(stroke->points[0].y < y_min ||
+          (stroke->points[0].y == y_min && stroke->points[0].x < x_min)) {
            y_min = stroke->points[0].y;
            stroke_min = stroke;
        }
@@ -439,17 +444,29 @@ gfxline_t*gfxline_from_gfxpoly(gfxpoly_t*poly)
     point_t last = {INVALID_COORD, INVALID_COORD};
     char should_connect = 0;
     while(stroke) {
+       if(stroke && !preserve_direction) {
+           char del1 = dict_del2(d, &stroke->points[0], stroke);
+           char del2 = dict_del2(d, &stroke->points[stroke->num_points-1], stroke);
+           assert(del1 && del2);
+       }
        assert(dict_contains(todo, stroke));
        int t;
        int pos = 0;
        int incr = 1;
-       if(stroke->dir == DIR_UP) {
-           pos = stroke->num_points-1;
-           incr = -1;
+       if(preserve_direction) {
+           if(stroke->dir == DIR_UP) {
+               pos = stroke->num_points-1;
+               incr = -1;
+           }
+       } else {
+           // try to find matching point on either end.
+           // Prefer downward.
+           if(last.x == stroke->points[stroke->num_points-1].x &&
+              last.y == stroke->points[stroke->num_points-1].y) {
+               pos = stroke->num_points-1;
+               incr = -1;
+           }
        }
-       /* TODO: keeping the up/down order intact increases the polygon size
-                considerably. If this is going to be an even/odd polygon,
-                we could ignore it and save some space */
        if(last.x != stroke->points[pos].x || last.y != stroke->points[pos].y) {
            l[count].x = stroke->points[pos].x * poly->gridsize;
            l[count].y = stroke->points[pos].y * poly->gridsize;
@@ -491,6 +508,16 @@ gfxline_t*gfxline_from_gfxpoly(gfxpoly_t*poly)
     return l;
 }
 
+gfxline_t*gfxline_from_gfxpoly(gfxpoly_t*poly)
+{
+    return mkgfxline(poly, 0);
+}
+
+gfxline_t*gfxline_from_gfxpoly_updown(gfxpoly_t*poly)
+{
+    return mkgfxline(poly, 1);
+}
+
 static windcontext_t onepolygon = {1};
 gfxline_t* gfxpoly_circular_to_evenodd(gfxline_t*line, double gridsize)
 {

diff --git a/lib/gfxpoly/convert.h b/lib/gfxpoly/convert.h
index f0a8fb9..7c18958 100644 (file)
--- a/lib/gfxpoly/convert.h
+++ b/lib/gfxpoly/convert.h
@@ -22,6 +22,7 @@ gfxpoly_t* gfxpoly_from_file(const char*filename, double gridsize);
 void gfxpoly_destroy(gfxpoly_t*poly);
 
 gfxline_t*gfxline_from_gfxpoly(gfxpoly_t*poly);
+gfxline_t*gfxline_from_gfxpoly_updown(gfxpoly_t*poly); // preserves up/down
 
 gfxline_t* gfxpoly_circular_to_evenodd(gfxline_t*line, double gridsize);
 gfxpoly_t* gfxpoly_createbox(double x1, double y1,double x2, double y2, double gridsize);