| /* |
| * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer. |
| * 2. Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials |
| * provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
| * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
| * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
| * OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "platform/geometry/FloatPolygon.h" |
| #include "platform/geometry/FloatShapeHelpers.h" |
| |
| #include <memory> |
| #include "platform/wtf/MathExtras.h" |
| |
| namespace blink { |
| |
| static inline bool AreCollinearPoints(const FloatPoint& p0, |
| const FloatPoint& p1, |
| const FloatPoint& p2) { |
| return !Determinant(p1 - p0, p2 - p0); |
| } |
| |
| static inline bool AreCoincidentPoints(const FloatPoint& p0, |
| const FloatPoint& p1) { |
| return p0.X() == p1.X() && p0.Y() == p1.Y(); |
| } |
| |
| static inline bool IsPointOnLineSegment(const FloatPoint& vertex1, |
| const FloatPoint& vertex2, |
| const FloatPoint& point) { |
| return point.X() >= std::min(vertex1.X(), vertex2.X()) && |
| point.X() <= std::max(vertex1.X(), vertex2.X()) && |
| AreCollinearPoints(vertex1, vertex2, point); |
| } |
| |
| static inline unsigned NextVertexIndex(unsigned vertex_index, |
| unsigned n_vertices, |
| bool clockwise) { |
| return ((clockwise) ? vertex_index + 1 : vertex_index - 1 + n_vertices) % |
| n_vertices; |
| } |
| |
| static unsigned FindNextEdgeVertexIndex(const FloatPolygon& polygon, |
| unsigned vertex_index1, |
| bool clockwise) { |
| unsigned n_vertices = polygon.NumberOfVertices(); |
| unsigned vertex_index2 = |
| NextVertexIndex(vertex_index1, n_vertices, clockwise); |
| |
| while (vertex_index2 && AreCoincidentPoints(polygon.VertexAt(vertex_index1), |
| polygon.VertexAt(vertex_index2))) |
| vertex_index2 = NextVertexIndex(vertex_index2, n_vertices, clockwise); |
| |
| while (vertex_index2) { |
| unsigned vertex_index3 = |
| NextVertexIndex(vertex_index2, n_vertices, clockwise); |
| if (!AreCollinearPoints(polygon.VertexAt(vertex_index1), |
| polygon.VertexAt(vertex_index2), |
| polygon.VertexAt(vertex_index3))) |
| break; |
| vertex_index2 = vertex_index3; |
| } |
| |
| return vertex_index2; |
| } |
| |
| FloatPolygon::FloatPolygon(std::unique_ptr<Vector<FloatPoint>> vertices, |
| WindRule fill_rule) |
| : vertices_(std::move(vertices)), fill_rule_(fill_rule) { |
| unsigned n_vertices = NumberOfVertices(); |
| edges_.resize(n_vertices); |
| empty_ = n_vertices < 3; |
| |
| if (n_vertices) |
| bounding_box_.SetLocation(VertexAt(0)); |
| |
| if (empty_) |
| return; |
| |
| unsigned min_vertex_index = 0; |
| for (unsigned i = 1; i < n_vertices; ++i) { |
| const FloatPoint& vertex = VertexAt(i); |
| if (vertex.Y() < VertexAt(min_vertex_index).Y() || |
| (vertex.Y() == VertexAt(min_vertex_index).Y() && |
| vertex.X() < VertexAt(min_vertex_index).X())) |
| min_vertex_index = i; |
| } |
| FloatPoint next_vertex = VertexAt((min_vertex_index + 1) % n_vertices); |
| FloatPoint prev_vertex = |
| VertexAt((min_vertex_index + n_vertices - 1) % n_vertices); |
| bool clockwise = Determinant(VertexAt(min_vertex_index) - prev_vertex, |
| next_vertex - prev_vertex) > 0; |
| |
| unsigned edge_index = 0; |
| unsigned vertex_index1 = 0; |
| do { |
| bounding_box_.Extend(VertexAt(vertex_index1)); |
| unsigned vertex_index2 = |
| FindNextEdgeVertexIndex(*this, vertex_index1, clockwise); |
| edges_[edge_index].polygon_ = this; |
| edges_[edge_index].vertex_index1_ = vertex_index1; |
| edges_[edge_index].vertex_index2_ = vertex_index2; |
| edges_[edge_index].edge_index_ = edge_index; |
| ++edge_index; |
| vertex_index1 = vertex_index2; |
| } while (vertex_index1); |
| |
| if (edge_index > 3) { |
| const FloatPolygonEdge& first_edge = edges_[0]; |
| const FloatPolygonEdge& last_edge = edges_[edge_index - 1]; |
| if (AreCollinearPoints(last_edge.Vertex1(), last_edge.Vertex2(), |
| first_edge.Vertex2())) { |
| edges_[0].vertex_index1_ = last_edge.vertex_index1_; |
| edge_index--; |
| } |
| } |
| |
| edges_.resize(edge_index); |
| empty_ = edges_.size() < 3; |
| |
| if (empty_) |
| return; |
| |
| for (unsigned i = 0; i < edges_.size(); ++i) { |
| FloatPolygonEdge* edge = &edges_[i]; |
| edge_tree_.Add(EdgeInterval(edge->MinY(), edge->MaxY(), edge)); |
| } |
| } |
| |
| bool FloatPolygon::OverlappingEdges( |
| float min_y, |
| float max_y, |
| Vector<const FloatPolygonEdge*>& result) const { |
| Vector<FloatPolygon::EdgeInterval> overlapping_edge_intervals; |
| edge_tree_.AllOverlaps(FloatPolygon::EdgeInterval(min_y, max_y, 0), |
| overlapping_edge_intervals); |
| unsigned overlapping_edge_intervals_size = overlapping_edge_intervals.size(); |
| result.resize(overlapping_edge_intervals_size); |
| for (unsigned i = 0; i < overlapping_edge_intervals_size; ++i) { |
| const FloatPolygonEdge* edge = static_cast<const FloatPolygonEdge*>( |
| overlapping_edge_intervals[i].Data()); |
| DCHECK(edge); |
| result[i] = edge; |
| } |
| return overlapping_edge_intervals_size > 0; |
| } |
| |
| static inline float LeftSide(const FloatPoint& vertex1, |
| const FloatPoint& vertex2, |
| const FloatPoint& point) { |
| return ((point.X() - vertex1.X()) * (vertex2.Y() - vertex1.Y())) - |
| ((vertex2.X() - vertex1.X()) * (point.Y() - vertex1.Y())); |
| } |
| |
| bool FloatPolygon::ContainsEvenOdd(const FloatPoint& point) const { |
| unsigned crossing_count = 0; |
| for (unsigned i = 0; i < NumberOfEdges(); ++i) { |
| const FloatPoint& vertex1 = EdgeAt(i).Vertex1(); |
| const FloatPoint& vertex2 = EdgeAt(i).Vertex2(); |
| if (IsPointOnLineSegment(vertex1, vertex2, point)) |
| return true; |
| if ((vertex1.Y() <= point.Y() && vertex2.Y() > point.Y()) || |
| (vertex1.Y() > point.Y() && vertex2.Y() <= point.Y())) { |
| float vt = (point.Y() - vertex1.Y()) / (vertex2.Y() - vertex1.Y()); |
| if (point.X() < vertex1.X() + vt * (vertex2.X() - vertex1.X())) |
| ++crossing_count; |
| } |
| } |
| return crossing_count & 1; |
| } |
| |
| bool FloatPolygon::ContainsNonZero(const FloatPoint& point) const { |
| int winding_number = 0; |
| for (unsigned i = 0; i < NumberOfEdges(); ++i) { |
| const FloatPoint& vertex1 = EdgeAt(i).Vertex1(); |
| const FloatPoint& vertex2 = EdgeAt(i).Vertex2(); |
| if (IsPointOnLineSegment(vertex1, vertex2, point)) |
| return true; |
| if (vertex2.Y() <= point.Y()) { |
| if ((vertex1.Y() > point.Y()) && (LeftSide(vertex1, vertex2, point) > 0)) |
| ++winding_number; |
| } else if (vertex2.Y() >= point.Y()) { |
| if ((vertex1.Y() <= point.Y()) && (LeftSide(vertex1, vertex2, point) < 0)) |
| --winding_number; |
| } |
| } |
| return winding_number; |
| } |
| |
| bool FloatPolygon::Contains(const FloatPoint& point) const { |
| if (!bounding_box_.Contains(point)) |
| return false; |
| return (FillRule() == RULE_NONZERO) ? ContainsNonZero(point) |
| : ContainsEvenOdd(point); |
| } |
| |
| bool VertexPair::Intersection(const VertexPair& other, |
| FloatPoint& point) const { |
| // See: http://paulbourke.net/geometry/pointlineplane/, |
| // "Intersection point of two lines in 2 dimensions" |
| |
| const FloatSize& this_delta = Vertex2() - Vertex1(); |
| const FloatSize& other_delta = other.Vertex2() - other.Vertex1(); |
| float denominator = Determinant(this_delta, other_delta); |
| if (!denominator) |
| return false; |
| |
| // The two line segments: "this" vertex1,vertex2 and "other" vertex1,vertex2, |
| // have been defined in parametric form. Each point on the line segment is: |
| // vertex1 + u * (vertex2 - vertex1), when 0 <= u <= 1. We're computing the |
| // values of u for each line at their intersection point. |
| |
| const FloatSize& vertex1_delta = Vertex1() - other.Vertex1(); |
| float u_this_line = Determinant(other_delta, vertex1_delta) / denominator; |
| float u_other_line = Determinant(this_delta, vertex1_delta) / denominator; |
| |
| if (u_this_line < 0 || u_other_line < 0 || u_this_line > 1 || |
| u_other_line > 1) |
| return false; |
| |
| point = Vertex1() + u_this_line * this_delta; |
| return true; |
| } |
| |
| } // namespace blink |
