processing4/agg/agg_path_storage.cpp

//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.3
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Permission to copy, use, modify, sell and distribute this software 
// is granted provided this copyright notice appears in all copies. 
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
//          mcseemagg@yahoo.com
//          http://www.antigrain.com
//----------------------------------------------------------------------------
//
// Class path_storage
//
//----------------------------------------------------------------------------
#include <string.h>
#include <math.h>
#include "agg_path_storage.h"
#include "agg_math.h"
#include "agg_bezier_arc.h"


namespace agg
{

    //------------------------------------------------------------------------
    path_storage::~path_storage()
    {
        if(m_total_blocks)
        {
            double** coord_blk = m_coord_blocks + m_total_blocks - 1;
            while(m_total_blocks--)
            {
                delete [] *coord_blk;
                --coord_blk;
            }
            delete [] m_coord_blocks;
        }
    }


    //------------------------------------------------------------------------
    path_storage::path_storage() :
        m_total_vertices(0),
        m_total_blocks(0),
        m_max_blocks(0),
        m_coord_blocks(0),
        m_cmd_blocks(0),
        m_iterator(0)
    {
    }


    //------------------------------------------------------------------------
    path_storage::path_storage(const path_storage& ps) : 
        m_total_vertices(0),
        m_total_blocks(0),
        m_max_blocks(0),
        m_coord_blocks(0),
        m_cmd_blocks(0),
        m_iterator(0)
    {
        copy_from(ps);
    }


    //------------------------------------------------------------------------
    void path_storage::remove_all()
    {
        m_total_vertices = 0;
        m_iterator = 0;
    }


    //------------------------------------------------------------------------
    void path_storage::copy_from(const path_storage& ps)
    {
        remove_all();
        unsigned i;
        for(i = 0; i < ps.total_vertices(); i++)
        {
            double x, y;
            unsigned cmd = ps.vertex(i, &x, &y);
            add_vertex(x, y, cmd);
        }
    }


    //------------------------------------------------------------------------
    void path_storage::allocate_block(unsigned nb)
    {
        if(nb >= m_max_blocks) 
        {
            double** new_coords = 
                new double* [(m_max_blocks + block_pool) * 2];

            unsigned char** new_cmds = 
                (unsigned char**)(new_coords + m_max_blocks + block_pool);

            if(m_coord_blocks)
            {
                memcpy(new_coords, 
                       m_coord_blocks, 
                       m_max_blocks * sizeof(double*));

                memcpy(new_cmds, 
                       m_cmd_blocks, 
                       m_max_blocks * sizeof(unsigned char*));

                delete [] m_coord_blocks;
            }
            m_coord_blocks = new_coords;
            m_cmd_blocks = new_cmds;
            m_max_blocks += block_pool;
        }
        m_coord_blocks[nb] = 
            new double [block_size * 2 + 
                        block_size / 
                        (sizeof(double) / sizeof(unsigned char))];

        m_cmd_blocks[nb]  = 
            (unsigned char*)(m_coord_blocks[nb] + block_size * 2);

        m_total_blocks++;
    }


    //------------------------------------------------------------------------
    void path_storage::rewind(unsigned path_id)
    {
        m_iterator = path_id; 
    }



    //------------------------------------------------------------------------
    void path_storage::arc_to(double rx, double ry,
                              double angle,
                              bool large_arc_flag,
                              bool sweep_flag,
                              double x, double y)
    {
        if(m_total_vertices && is_vertex(command(m_total_vertices - 1)))
        {
            const double epsilon = 1e-30;
            double x0 = 0.0;
            double y0 = 0.0;
            last_vertex(&x0, &y0);

            rx = fabs(rx);
            ry = fabs(ry);

            // Ensure radii are valid
            //-------------------------
            if(rx < epsilon || ry < epsilon) 
            {
                line_to(x, y);
                return;
            }

            if(calc_distance(x0, y0, x, y) < epsilon)
            {
                // If the endpoints (x, y) and (x0, y0) are identical, then this
                // is equivalent to omitting the elliptical arc segment entirely.
                return;
            }
            bezier_arc_svg a(x0, y0, rx, ry, angle, large_arc_flag, sweep_flag, x, y);
            if(a.radii_ok())
            {
                add_path(a, 0, true);
            }
            else
            {
                line_to(x, y);
            }
        }
        else
        {
            move_to(x, y);
        }
    }


    //------------------------------------------------------------------------
    void path_storage::arc_rel(double rx, double ry,
                               double angle,
                               bool large_arc_flag,
                               bool sweep_flag,
                               double dx, double dy)
    {
        rel_to_abs(&dx, &dy);
        arc_to(rx, ry, angle, large_arc_flag, sweep_flag, dx, dy);
    }


    //------------------------------------------------------------------------
    void path_storage::curve3(double x_ctrl, double y_ctrl, 
                              double x_to,   double y_to)
    {
        add_vertex(x_ctrl, y_ctrl, path_cmd_curve3);
        add_vertex(x_to,   y_to,   path_cmd_curve3);
    }

    //------------------------------------------------------------------------
    void path_storage::curve3_rel(double dx_ctrl, double dy_ctrl, 
                                  double dx_to,   double dy_to)
    {
        rel_to_abs(&dx_ctrl, &dy_ctrl);
        rel_to_abs(&dx_to,   &dy_to);
        add_vertex(dx_ctrl, dy_ctrl, path_cmd_curve3);
        add_vertex(dx_to,   dy_to,   path_cmd_curve3);
    }

    //------------------------------------------------------------------------
    void path_storage::curve3(double x_to, double y_to)
    {
        double x0;
        double y0;
        if(is_vertex(last_vertex(&x0, &y0)))
        {
            double x_ctrl;
            double y_ctrl; 
            unsigned cmd = prev_vertex(&x_ctrl, &y_ctrl);
            if(is_curve(cmd))
            {
                x_ctrl = x0 + x0 - x_ctrl;
                y_ctrl = y0 + y0 - y_ctrl;
            }
            else
            {
                x_ctrl = x0;
                y_ctrl = y0;
            }
            curve3(x_ctrl, y_ctrl, x_to, y_to);
        }
    }


    //------------------------------------------------------------------------
    void path_storage::curve3_rel(double dx_to, double dy_to)
    {
        rel_to_abs(&dx_to, &dy_to);
        curve3(dx_to, dy_to);
    }


    //------------------------------------------------------------------------
    void path_storage::curve4(double x_ctrl1, double y_ctrl1, 
                              double x_ctrl2, double y_ctrl2, 
                              double x_to,    double y_to)
    {
        add_vertex(x_ctrl1, y_ctrl1, path_cmd_curve4);
        add_vertex(x_ctrl2, y_ctrl2, path_cmd_curve4);
        add_vertex(x_to,    y_to,    path_cmd_curve4);
    }

    //------------------------------------------------------------------------
    void path_storage::curve4_rel(double dx_ctrl1, double dy_ctrl1, 
                                  double dx_ctrl2, double dy_ctrl2, 
                                  double dx_to,    double dy_to)
    {
        rel_to_abs(&dx_ctrl1, &dy_ctrl1);
        rel_to_abs(&dx_ctrl2, &dy_ctrl2);
        rel_to_abs(&dx_to,    &dy_to);
        add_vertex(dx_ctrl1, dy_ctrl1, path_cmd_curve4);
        add_vertex(dx_ctrl2, dy_ctrl2, path_cmd_curve4);
        add_vertex(dx_to,    dy_to,    path_cmd_curve4);
    }


    //------------------------------------------------------------------------
    void path_storage::curve4(double x_ctrl2, double y_ctrl2, 
                              double x_to,    double y_to)
    {
        double x0;
        double y0;
        if(is_vertex(last_vertex(&x0, &y0)))
        {
            double x_ctrl1;
            double y_ctrl1; 
            unsigned cmd = prev_vertex(&x_ctrl1, &y_ctrl1);
            if(is_curve(cmd))
            {
                x_ctrl1 = x0 + x0 - x_ctrl1;
                y_ctrl1 = y0 + y0 - y_ctrl1;
            }
            else
            {
                x_ctrl1 = x0;
                y_ctrl1 = y0;
            }
            curve4(x_ctrl1, y_ctrl1, x_ctrl2, y_ctrl2, x_to, y_to);
        }
    }


    //------------------------------------------------------------------------
    void path_storage::curve4_rel(double dx_ctrl2, double dy_ctrl2, 
                                  double dx_to,    double dy_to)
    {
        rel_to_abs(&dx_ctrl2, &dy_ctrl2);
        rel_to_abs(&dx_to,    &dy_to);
        curve4(dx_ctrl2, dy_ctrl2, dx_to, dy_to);
    }


    //------------------------------------------------------------------------
    void path_storage::end_poly(unsigned flags)
    {
        if(m_total_vertices)
        {
            if(is_vertex(command(m_total_vertices - 1)))
            {
                add_vertex(0.0, 0.0, path_cmd_end_poly | flags);
            }
        }
    }


    //------------------------------------------------------------------------
    unsigned path_storage::start_new_path()
    {
        if(m_total_vertices)
        {
            if(!is_stop(command(m_total_vertices - 1)))
            {
                add_vertex(0.0, 0.0, path_cmd_stop);
            }
        }
        return m_total_vertices;
    }


    //------------------------------------------------------------------------
    void path_storage::add_poly(const double* vertices, unsigned num,
                                bool solid_path, unsigned end_flags)
    {
        if(num)
        {
            if(!solid_path)
            {
                move_to(vertices[0], vertices[1]);
                vertices += 2;
                --num;
            }
            while(num--)
            {
                line_to(vertices[0], vertices[1]);
                vertices += 2;
            }
            if(end_flags) end_poly(end_flags);
        }
    }


    //------------------------------------------------------------------------
    unsigned path_storage::perceive_polygon_orientation(unsigned start, unsigned end)
    {
        // Calculate signed area (double area to be exact)
        //---------------------
        unsigned np = end - start;
        double area = 0.0;
        unsigned i;
        for(i = 0; i < np; i++)
        {
            double x1, y1, x2, y2;
            vertex(start + i,            &x1, &y1);
            vertex(start + (i + 1) % np, &x2, &y2);
            area += x1 * y2 - y1 * x2;
        }
        return (area < 0.0) ? path_flags_cw : path_flags_ccw;
    }


    //------------------------------------------------------------------------
    void path_storage::invert_polygon(unsigned start, unsigned end)
    {
        unsigned i;
        unsigned tmp_cmd = command(start);
        
        --end; // Make "end" inclusive

        // Shift all commands to one position
        for(i = start; i < end; i++)
        {
            modify_command(i, command(i + 1));
        }

        // Assign starting command to the ending command
        modify_command(end, tmp_cmd);

        // Reverse the polygon
        while(end > start)
        {
            unsigned start_nb = start >> block_shift;
            unsigned end_nb   = end   >> block_shift;
            double* start_ptr = m_coord_blocks[start_nb] + ((start & block_mask) << 1);
            double* end_ptr   = m_coord_blocks[end_nb]   + ((end   & block_mask) << 1);
            double tmp_xy;

            tmp_xy       = *start_ptr;
            *start_ptr++ = *end_ptr;
            *end_ptr++   = tmp_xy;

            tmp_xy       = *start_ptr;
            *start_ptr   = *end_ptr;
            *end_ptr     = tmp_xy;

            tmp_cmd = m_cmd_blocks[start_nb][start & block_mask];
            m_cmd_blocks[start_nb][start & block_mask] = m_cmd_blocks[end_nb][end & block_mask];
            m_cmd_blocks[end_nb][end & block_mask] = (unsigned char)tmp_cmd;

            ++start;
            --end;
        }
    }


    //------------------------------------------------------------------------
    unsigned path_storage::arrange_polygon_orientation(unsigned start, 
                                                       path_flags_e orientation)
    {
        if(orientation == path_flags_none) return start;
        
        // Skip all non-vertices at the beginning
        while(start < m_total_vertices && !is_vertex(command(start))) ++start;

        // Skip all insignificant move_to
        while(start+1 < m_total_vertices && 
              is_move_to(command(start)) &&
              is_move_to(command(start+1))) ++start;

        // Find the last vertex
        unsigned end = start + 1;
        while(end < m_total_vertices && !is_next_poly(command(end))) ++end;

        if(end - start > 2)
        {
            if(perceive_polygon_orientation(start, end) != unsigned(orientation))
            {
                // Invert polygon, set orientation flag, and skip all end_poly
                invert_polygon(start, end);
                unsigned cmd;
                while(end < m_total_vertices && is_end_poly(cmd = command(end)))
                {
                    modify_command(end++, set_orientation(cmd, orientation));
                }
            }
        }
        return end;
    }


    //------------------------------------------------------------------------
    unsigned path_storage::arrange_orientations(unsigned start, 
                                                path_flags_e orientation)
    {
        if(orientation != path_flags_none)
        {
            while(start < m_total_vertices)
            {
                start = arrange_polygon_orientation(start, orientation);
                if(is_stop(command(start)))
                {
                    ++start;
                    break;
                }
            }
        }
        return start;
    }


    //------------------------------------------------------------------------
    void path_storage::arrange_orientations_all_paths(path_flags_e orientation)
    {
        if(orientation != path_flags_none)
        {
            unsigned start = 0;
            while(start < m_total_vertices)
            {
                start = arrange_orientations(start, orientation);
            }
        }
    }


    //------------------------------------------------------------------------
    void path_storage::flip_x(double x1, double x2)
    {
        unsigned i;
        double x, y;
        for(i = 0; i < m_total_vertices; i++)
        {
            unsigned cmd = vertex(i, &x, &y);
            if(is_vertex(cmd))
            {
                modify_vertex(i, x2 - x + x1, y);
            }
        }
    }


    //------------------------------------------------------------------------
    void path_storage::flip_y(double y1, double y2)
    {
        unsigned i;
        double x, y;
        for(i = 0; i < m_total_vertices; i++)
        {
            unsigned cmd = vertex(i, &x, &y);
            if(is_vertex(cmd))
            {
                modify_vertex(i, x, y2 - y + y1);
            }
        }
    }


}