/*
polyspan.h
Polyspan Header
Copyright (c) 2002-2005 Robert B. Quattlebaum Jr., Adrian Bentley
Copyright (c) 2007, 2008 Chris Moore
Copyright (c) 2012-2013 Carlos López
......... ... 2015 Ivan Mahonin
This package is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.
This package is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
*/
#ifndef _POLYSPAN_H_
#define _POLYSPAN_H_
#include <vector>
#include "geometry.h"
class Polyspan {
public:
struct PenMark {
int y, x;
Real cover, area;
PenMark(): y(), x(), cover(), area() { }
PenMark(int xin, int yin, Real c, Real a):
y(yin), x(xin), cover(c), area(a) { }
void set(int xin, int yin, Real c, Real a)
{ y = yin; x = xin; cover = c; area = a; }
void setcoord(int xin, int yin)
{ y = yin; x = xin; }
void setcover(Real c, Real a)
{ cover = c; area = a; }
void addcover(Real c, Real a)
{ cover += c; area += a; }
bool operator < (const PenMark &rhs) const
{ return y == rhs.y ? x < rhs.x : y < rhs.y; }
};
typedef std::vector<PenMark> cover_array;
//for assignment to flags value
enum PolySpanFlags {
NotSorted = 0x8000,
NotClosed = 0x4000
};
enum {
MAX_SUBDIVISION_SIZE = 64,
MIN_SUBDIVISION_DRAW_LEVELS = 4
};
private:
Vector arc[3*MAX_SUBDIVISION_SIZE + 1];
cover_array covers;
PenMark current;
int open_index;
//ending position of last primitive
Real cur_x;
Real cur_y;
//starting position of current primitive list
Real close_x;
Real close_y;
//flags for the current segment
int flags;
//the window that will be drawn (used for clipping)
ContextRect window;
//add the current cell, but only if there is information to add
void addcurrent();
//move to the next cell (cover values 0 initially), keeping the current if necessary
void move_pen(int x, int y);
static bool clip_conic(const Vector *p, const ContextRect &r);
static Real max_edges_conic(const Vector *p);
static void subd_conic_stack(Vector *arc);
static bool clip_cubic(const Vector *p, const ContextRect &r);
static Real max_edges_cubic(const Vector *p);
static void subd_cubic_stack(Vector *arc);
public:
Polyspan();
const ContextRect& get_window() const { return window; }
const cover_array& get_covers() const { return covers; }
bool notclosed() const
{ return (flags & NotClosed) || (cur_x != close_x) || (cur_y != close_y); }
//0 out all the variables involved in processing
void clear();
void init(const ContextRect &window)
{ clear(); this->window = window; }
void init(int minx, int miny, int maxx, int maxy)
{
clear();
window.minx = minx;
window.miny = miny;
window.maxx = maxx;
window.maxy = maxy;
}
//close the primitives with a line (or rendering will not work as expected)
void close();
// Not recommended - destroys any separation of spans currently held
void merge_all();
//will sort the marks if they are not sorted
void sort_marks();
//encapsulate the current sublist of marks (used for drawing)
void encapsulate_current();
//move to start a new primitive list (enclose the last primitive if need be)
void move_to(Real x, Real y);
//primitive_to functions
void line_to(Real x, Real y);
void conic_to(Real x1, Real y1, Real x, Real y);
void cubic_to(Real x1, Real y1, Real x2, Real y2, Real x, Real y);
void draw_scanline(int y, Real x1, Real y1, Real x2, Real y2);
void draw_line(Real x1, Real y1, Real x2, Real y2);
Real extract_alpha(Real area, bool evenodd) const;
};
#endif