mapnik/include/scanline_aa.hh
2005-04-10 20:39:53 +00:00

843 lines
21 KiB
C++

/* This file is part of Mapnik (c++ mapping toolkit)
* Copyright (C) 2005 Artem Pavlenko
*
* Mapnik 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 any later version.
*
* This program 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
// Credits:
// I gratefully acknowledge the inspiring work of Maxim Shemanarev (McSeem),
// author of Anti-Grain Geometry (http://www.antigrain.com), and also the developers
// of the FreeType library (http://www.freetype.org). I have slightly modified the polygon
// rasterizing algorithm to work with my library, but render_line and
// render_hline remain intact.
//$Id$
#ifndef SCANLINE_AA_HH
#define SCANLINE_AA_HH
#include "envelope.hh"
#include "geometry.hh"
#include "graphics.hh"
#include "style.hh"
namespace mapnik
{
enum path_commands_e
{
path_cmd_stop = 0, //----path_cmd_stop
path_cmd_move_to = 1, //----path_cmd_move_to
path_cmd_line_to = 2, //----path_cmd_line_to
path_cmd_curve3 = 3, //----path_cmd_curve3
path_cmd_curve4 = 4, //----path_cmd_curve4
path_cmd_end_poly = 6, //----path_cmd_end_poly
path_cmd_mask = 0x0F //----path_cmd_mask
};
//------------------------------------------------------------path_flags_e
enum path_flags_e
{
path_flags_none = 0, //----path_flags_none
path_flags_ccw = 0x10, //----path_flags_ccw
path_flags_cw = 0x20, //----path_flags_cw
path_flags_close = 0x40, //----path_flags_close
path_flags_mask = 0xF0 //----path_flags_mask
};
inline bool is_vertex(unsigned c)
{
return c >= path_cmd_move_to && c < path_cmd_end_poly;
}
inline bool is_move_to(unsigned c)
{
return c == path_cmd_move_to;
}
inline bool is_close(unsigned c)
{
return (c & ~(path_flags_cw | path_flags_ccw)) ==
(path_cmd_end_poly | path_flags_close);
}
inline unsigned clipping_flags(int x, int y, const Envelope<int>& clip_box)
{
return (x > clip_box.maxx()) |
((y > clip_box.maxy()) << 1) |
((x < clip_box.minx()) << 2) |
((y < clip_box.miny()) << 3);
}
template<class T>
inline unsigned clip_liang_barsky(T x1, T y1, T x2, T y2,
const Envelope<T>& clip_box,
T* x, T* y)
{
const double nearzero = 1e-30;
double deltax = x2 - x1;
double deltay = y2 - y1;
double xin;
double xout;
double yin;
double yout;
double tinx;
double tiny;
double toutx;
double touty;
double tin1;
double tin2;
double tout1;
unsigned np = 0;
if(deltax == 0.0)
{
// bump off of the vertical
deltax = (x1 > clip_box.minx()) ? -nearzero : nearzero;
}
if(deltay == 0.0)
{
// bump off of the horizontal
deltay = (y1 > clip_box.miny()) ? -nearzero : nearzero;
}
if(deltax > 0.0)
{
// points to right
xin = clip_box.minx();
xout = clip_box.maxx();
}
else
{
xin = clip_box.maxx();
xout = clip_box.minx();
}
if(deltay > 0.0)
{
// points up
yin = clip_box.miny();
yout = clip_box.maxy();
}
else
{
yin = clip_box.maxy();
yout = clip_box.miny();
}
tinx = (xin - x1) / deltax;
tiny = (yin - y1) / deltay;
if (tinx < tiny)
{
// hits x first
tin1 = tinx;
tin2 = tiny;
}
else
{
// hits y first
tin1 = tiny;
tin2 = tinx;
}
if(tin1 <= 1.0)
{
if(0.0 < tin1)
{
*x++ = (T)xin;
*y++ = (T)yin;
++np;
}
if(tin2 <= 1.0)
{
toutx = (xout - x1) / deltax;
touty = (yout - y1) / deltay;
tout1 = (toutx < touty) ? toutx : touty;
if(tin2 > 0.0 || tout1 > 0.0)
{
if(tin2 <= tout1)
{
if(tin2 > 0.0)
{
if(tinx > tiny)
{
*x++ = (T)xin;
*y++ = (T)(y1 + tinx * deltay);
}
else
{
*x++ = (T)(x1 + tiny * deltax);
*y++ = (T)yin;
}
++np;
}
if(tout1 < 1.0)
{
if(toutx < touty)
{
*x++ = (T)xout;
*y++ = (T)(y1 + toutx * deltay);
}
else
{
*x++ = (T)(x1 + touty * deltax);
*y++ = (T)yout;
}
}
else
{
*x++ = x2;
*y++ = y2;
}
++np;
}
else
{
if(tinx > tiny)
{
*x++ = (T)xin;
*y++ = (T)yout;
}
else
{
*x++ = (T)xout;
*y++ = (T)yin;
}
++np;
}
}
}
}
return np;
}
enum
{
poly_base_shift = 8,
poly_base_size = 1 << poly_base_shift,
poly_base_mask = poly_base_size - 1
};
inline int poly_coord(double c)
{
return int(c * poly_base_size);
}
struct cell_aa
{
short x;
short y;
int packed_coord;
int cover;
int area;
void set(int x, int y, int c, int a);
void set_coord(int x, int y);
void set_cover(int c, int a);
void add_cover(int c, int a);
};
class outline_aa
{
enum {
cell_block_shift = 12,
cell_block_size = 1 << cell_block_shift,
cell_block_mask = cell_block_size - 1,
cell_block_pool = 256,
cell_block_limit = 1024
};
public:
~outline_aa();
outline_aa();
void reset();
void move_to(int x, int y);
void line_to(int x, int y);
int min_x() const { return m_min_x; }
int min_y() const { return m_min_y; }
int max_x() const { return m_max_x; }
int max_y() const { return m_max_y; }
const cell_aa* const* cells();
unsigned num_cells() { cells(); return m_num_cells; }
bool sorted() const { return m_sorted; }
private:
outline_aa(const outline_aa&);
const outline_aa& operator = (const outline_aa&);
void set_cur_cell(int x, int y);
void add_cur_cell();
void sort_cells();
void render_hline(int ey, int x1, int y1, int x2, int y2);
void render_line(int x1, int y1, int x2, int y2);
void allocate_block();
static void qsort_cells(cell_aa** start, unsigned num);
private:
unsigned m_num_blocks;
unsigned m_max_blocks;
unsigned m_cur_block;
unsigned m_num_cells;
cell_aa** m_cells;
cell_aa* m_cur_cell_ptr;
cell_aa** m_sorted_cells;
unsigned m_sorted_size;
cell_aa m_cur_cell;
int m_cur_x;
int m_cur_y;
int m_min_x;
int m_min_y;
int m_max_x;
int m_max_y;
bool m_sorted;
};
enum filling_rule_e
{
fill_non_zero,
fill_even_odd
};
template <typename PixBuffer> class ScanlineRasterizerAA
{
enum status
{
status_initial,
status_line_to,
status_closed
};
struct iterator
{
const cell_aa* const* cells;
int cover;
int last_y;
};
enum
{
aa_shift = 8,
aa_num = 1 << aa_shift,
aa_mask = aa_num - 1,
aa_2num = aa_num * 2,
aa_2mask = aa_2num - 1
};
private:
PixBuffer* pixbuf_;
outline_aa m_outline;
int m_gamma[aa_num];
filling_rule_e m_filling_rule;
int m_clipped_start_x;
int m_clipped_start_y;
int m_start_x;
int m_start_y;
int m_prev_x;
int m_prev_y;
unsigned m_prev_flags;
unsigned m_status;
Envelope<int> m_clip_box;
bool m_clipping;
iterator m_iterator;
public:
ScanlineRasterizerAA(PixBuffer& pixbuf)
:pixbuf_(&pixbuf),
m_filling_rule(fill_non_zero),
m_clipped_start_x(0),
m_clipped_start_y(0),
m_start_x(0),
m_start_y(0),
m_prev_x(0),
m_prev_y(0),
m_prev_flags(0),
m_status(status_initial),
m_clipping(false)
{
for(int i = 0; i < aa_num; i++) m_gamma[i] = i;
}
template <typename Transform>
void render(const geometry_type& geom,const Color& c);
private:
ScanlineRasterizerAA(const ScanlineRasterizerAA&);
ScanlineRasterizerAA& operator=(const ScanlineRasterizerAA&);
void render_hline(int x0,int x1,int y,unsigned rgba);
void blend_hline(int x0,int x1,int y,const unsigned char* cover,
unsigned rgba);
int min_x() const { return m_outline.min_x(); }
int min_y() const { return m_outline.min_y(); }
int max_x() const { return m_outline.max_x(); }
int max_y() const { return m_outline.max_y(); }
void reset();
void filling_rule(filling_rule_e filling_rule);
void clip_box(double x1, double y1, double x2, double y2);
void reset_clipping();
template<class GammaF> void gamma(const GammaF& gamma_function)
{
int i;
for(i = 0; i < aa_num; i++)
{
m_gamma[i] = int(floor(gamma_function(double(i) / aa_mask) * aa_mask + 0.5));
}
}
unsigned apply_gamma(unsigned cover) const
{
return m_gamma[cover];
}
void add_vertex(double x, double y, unsigned cmd);
void move_to(int x, int y);
void line_to(int x, int y);
void close_polygon();
void move_to_no_clip(int x, int y);
void line_to_no_clip(int x, int y);
void close_polygon_no_clip();
void clip_segment(int x, int y);
unsigned calculate_alpha(int area) const
{
int cover = area >> (poly_base_shift*2 + 1 - aa_shift);
if(cover < 0) cover = -cover;
if(m_filling_rule == fill_even_odd)
{
cover &= aa_2mask;
if(cover > aa_num)
{
cover = aa_2num - cover;
}
}
if(cover > aa_mask) cover = aa_mask;
return m_gamma[cover];
}
void sort()
{
m_outline.cells();
}
bool rewind_scanlines()
{
close_polygon();
m_iterator.cells = m_outline.cells();
if(m_outline.num_cells() == 0)
{
return false;
}
m_iterator.cover = 0;
m_iterator.last_y = (*m_iterator.cells)->y;
return true;
}
template<class Scanline> bool sweep_scanline(Scanline& sl)
{
sl.reset_spans();
for(;;)
{
const cell_aa* cur_cell = *m_iterator.cells;
if(cur_cell == 0) return false;
++m_iterator.cells;
m_iterator.last_y = cur_cell->y;
for(;;)
{
int coord = cur_cell->packed_coord;
int area = cur_cell->area;
int last_x = cur_cell->x;
m_iterator.cover += cur_cell->cover;
//accumulate all cells with the same coordinates
for(; (cur_cell = *m_iterator.cells) != 0; ++m_iterator.cells)
{
if(cur_cell->packed_coord != coord) break;
area += cur_cell->area;
m_iterator.cover += cur_cell->cover;
}
int alpha;
if(cur_cell == 0 || cur_cell->y != m_iterator.last_y)
{
if(area)
{
alpha = calculate_alpha((m_iterator.cover << (poly_base_shift + 1)) - area);
if(alpha)
{
sl.add_cell(last_x, alpha);
}
++last_x;
}
break;
}
++m_iterator.cells;
if(area)
{
alpha = calculate_alpha((m_iterator.cover << (poly_base_shift + 1)) - area);
if(alpha)
{
sl.add_cell(last_x, alpha);
}
++last_x;
}
if(cur_cell->x > last_x)
{
alpha = calculate_alpha(m_iterator.cover << (poly_base_shift + 1));
if(alpha)
{
sl.add_span(last_x, cur_cell->x - last_x, alpha);
}
}
}
if(sl.num_spans())
{
sl.finalize(m_iterator.last_y);
break;
}
}
return true;
}
};
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::reset()
{
m_outline.reset();
m_status = status_initial;
}
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::clip_box(double x1, double y1, double x2, double y2)
{
//reset();
m_clip_box = Envelope<int>(poly_coord(x1), poly_coord(y1),
poly_coord(x2), poly_coord(y2));
//m_clip_box.normalize();
m_clipping = true;
}
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::move_to_no_clip(int x, int y)
{
if(m_status == status_line_to)
{
close_polygon_no_clip();
}
m_outline.move_to(x,y);
m_clipped_start_x = x;
m_clipped_start_y = y;
m_status = status_line_to;
}
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::line_to_no_clip(int x, int y)
{
if(m_status != status_initial)
{
m_outline.line_to(x , y);
m_status = status_line_to;
}
}
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::close_polygon_no_clip()
{
if(m_status == status_line_to)
{
m_outline.line_to(m_clipped_start_x, m_clipped_start_y);
m_status = status_closed;
}
}
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::clip_segment(int x, int y)
{
unsigned flags = clipping_flags(x, y, m_clip_box);
if(m_prev_flags == flags)
{
if(flags == 0)
{
if(m_status == status_initial)
{
move_to_no_clip(x, y);
}
else
{
line_to_no_clip(x, y);
}
}
}
else
{
int cx[4];
int cy[4];
unsigned n = clip_liang_barsky<int>(m_prev_x, m_prev_y,
x, y,
m_clip_box,
cx, cy);
const int* px = cx;
const int* py = cy;
while(n--)
{
if(m_status == status_initial)
{
move_to_no_clip(*px++, *py++);
}
else
{
line_to_no_clip(*px++, *py++);
}
}
}
m_prev_flags = flags;
m_prev_x = x;
m_prev_y = y;
}
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::add_vertex(double x, double y, unsigned cmd)
{
if(is_close(cmd))
{
close_polygon();
}
else
{
if(is_move_to(cmd))
{
move_to(poly_coord(x), poly_coord(y));
}
else
{
if(is_vertex(cmd))
{
line_to(poly_coord(x), poly_coord(y));
}
}
}
}
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::move_to(int x, int y)
{
if(m_clipping)
{
if(m_outline.sorted())
{
reset();
}
if(m_status == status_line_to)
{
close_polygon();
}
m_prev_x = m_start_x = x;
m_prev_y = m_start_y = y;
m_status = status_initial;
m_prev_flags = clipping_flags(x, y, m_clip_box);
if(m_prev_flags == 0)
{
move_to_no_clip(x, y);
}
}
else
{
move_to_no_clip(x, y);
}
}
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::line_to(int x, int y)
{
if(m_clipping)
{
clip_segment(x, y);
}
else
{
line_to_no_clip(x, y);
}
}
template<typename PixBuffer>
void ScanlineRasterizerAA<PixBuffer>::close_polygon()
{
if(m_clipping)
{
clip_segment(m_start_x, m_start_y);
}
close_polygon_no_clip();
}
template<class T> class scanline_u
{
public:
typedef T cover_type;
struct span
{
short x;
short len;
cover_type* covers;
};
typedef span* iterator;
typedef const span* const_iterator;
~scanline_u();
scanline_u();
void reset(int min_x, int max_x);
void add_cell(int x, unsigned cover);
void add_cells(int x, unsigned len, const T* covers);
void add_span(int x, unsigned len, unsigned cover);
void finalize(int y) { m_y = y; }
void reset_spans();
int y() const { return m_y; }
unsigned num_spans() const { return unsigned(m_cur_span - m_spans); }
const_iterator begin() const { return m_spans + 1; }
iterator begin() { return m_spans + 1; }
private:
scanline_u<T>(const scanline_u<T>&);
const scanline_u<T>& operator = (const scanline_u<T>&);
private:
int m_min_x;
unsigned m_max_len;
int m_last_x;
int m_y;
cover_type* m_covers;
span* m_spans;
span* m_cur_span;
};
template<class T> scanline_u<T>::~scanline_u()
{
delete [] m_spans;
delete [] m_covers;
}
template<class T> scanline_u<T>::scanline_u() :
m_min_x(0),
m_max_len(0),
m_last_x(0x7FFFFFF0),
m_covers(0),
m_spans(0),
m_cur_span(0)
{
}
template<class T> void scanline_u<T>::reset(int min_x, int max_x)
{
unsigned max_len = max_x - min_x + 2;
if(max_len > m_max_len)
{
delete [] m_spans;
delete [] m_covers;
m_covers = new cover_type [max_len];
m_spans = new span [max_len];
m_max_len = max_len;
}
m_last_x = 0x7FFFFFF0;
m_min_x = min_x;
m_cur_span = m_spans;
}
template<class T> inline void scanline_u<T>::reset_spans()
{
m_last_x = 0x7FFFFFF0;
m_cur_span = m_spans;
}
template<class T> inline void scanline_u<T>::add_cell(int x, unsigned cover)
{
x -= m_min_x;
m_covers[x] = (unsigned char)cover;
if(x == m_last_x+1)
{
m_cur_span->len++;
}
else
{
m_cur_span++;
m_cur_span->x = (short)(x + m_min_x);
m_cur_span->len = 1;
m_cur_span->covers = m_covers + x;
}
m_last_x = x;
}
template<class T> void scanline_u<T>::add_cells(int x, unsigned len, const T* covers)
{
x -= m_min_x;
memcpy(m_covers + x, covers, len * sizeof(T));
if(x == m_last_x+1)
{
m_cur_span->len += (short)len;
}
else
{
m_cur_span++;
m_cur_span->x = (short)(x + m_min_x);
m_cur_span->len = (short)len;
m_cur_span->covers = m_covers + x;
}
m_last_x = x + len - 1;
}
template<class T> void scanline_u<T>::add_span(int x, unsigned len, unsigned cover)
{
x -= m_min_x;
memset(m_covers + x, cover, len);
if(x == m_last_x+1)
{
m_cur_span->len += (short)len;
}
else
{
m_cur_span++;
m_cur_span->x = (short)(x + m_min_x);
m_cur_span->len = (short)len;
m_cur_span->covers = m_covers + x;
}
m_last_x = x + len - 1;
}
typedef scanline_u<unsigned char> scanline_u8;
typedef scanline_u<unsigned short> scanline_u16;
typedef scanline_u<unsigned int> scanline_u32;
}
#endif //SCANLINE_AA_HH