drop use of bounding box to determine whether an item covers a point; add Item::cover...

[ardour.git] / libs / canvas / polygon.cc

diff --git a/libs/canvas/polygon.cc b/libs/canvas/polygon.cc
index 1103cedbeea045861cb16ef3e5fa03c09efffd65..37046f4d4a6f7ac7a83a24a4b1a9767a76d6c559 100644 (file)
--- a/libs/canvas/polygon.cc
+++ b/libs/canvas/polygon.cc
@@ -25,10 +25,19 @@ Polygon::Polygon (Group* parent)
        : Item (parent)
        , PolyItem (parent)
        , Fill (parent)
+       , multiple (0)
+       , constant (0)
+       , cached_size (0)
 {
 
 }
 
+Polygon::~Polygon ()
+{
+       delete [] multiple;
+       delete [] constant;
+}
+
 void
 Polygon::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 {
@@ -51,3 +60,72 @@ Polygon::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
        }
 }
 
+void 
+Polygon::cache_shape_computation () const
+{
+       Points::size_type npoints = _points.size();
+
+       if (npoints == 0) {
+               return;
+       }
+
+       Points::size_type i;
+       Points::size_type j = npoints -1;
+
+       if (cached_size < npoints) {
+               cached_size = npoints;
+               delete [] multiple;
+               multiple = new float[cached_size];
+               delete [] constant;
+               constant = new float[cached_size];
+       }
+
+       for (i = 0; i < npoints; i++) {
+               if (_points[j].y == _points[i].y) {
+                       constant[i] = _points[i].x;
+                       multiple[i] = 0; 
+               } else {
+                       constant[i] = _points[i].x-(_points[i].y*_points[j].x)/(_points[j].y-_points[i].y)+(_points[i].y*_points[i].x)/(_points[j].y-_points[i].y);
+                       multiple[i] = (_points[j].x-_points[i].x)/(_points[j].y-_points[i].y); 
+               }
+
+               j = i; 
+       }
+}
+
+bool 
+Polygon::covers (Duple const & point) const
+{
+       Duple p = canvas_to_item (point);
+
+       Points::size_type npoints = _points.size();
+
+       if (npoints == 0) {
+               return false;
+       }
+
+       Points::size_type i;
+       Points::size_type j = npoints -1;
+       bool oddNodes = false;
+       
+       if (_bounding_box_dirty) {
+               compute_bounding_box ();
+       }
+       
+       for (i = 0; i < npoints; i++) {
+               if (((_points[i].y < p.y && _points[j].y >= p.y) || (_points[j].y < p.y && _points[i].y >= p.y))) {
+                       oddNodes ^= (p.y * multiple[i] + constant[i] < p.x); 
+               }
+               j = i; 
+       }
+       
+       return oddNodes; 
+} 
+
+void
+Polygon::compute_bounding_box () const
+{
+       PolyItem::compute_bounding_box ();
+       cache_shape_computation ();
+}
+