mapnik/deps/agg/src/agg_line_profile_aa.cpp

//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.4
// 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
//----------------------------------------------------------------------------

#include "agg_renderer_outline_aa.h"

namespace agg
{

//---------------------------------------------------------------------
void line_profile_aa::width(double w)
{
    if(w < 0.0) w = 0.0;

    if(w < m_smoother_width) w += w;
    else                     w += m_smoother_width;

    w *= 0.5;

    w -= m_smoother_width;
    double s = m_smoother_width;
    if(w < 0.0)
    {
        s += w;
        w = 0.0;
    }
    set(w, s);
}


//---------------------------------------------------------------------
line_profile_aa::value_type* line_profile_aa::profile(double w)
{
    m_subpixel_width = uround(w * subpixel_scale);
    unsigned size = m_subpixel_width + subpixel_scale * 6;
    if(size > m_profile.size())
    {
        m_profile.resize(size);
    }
    return &m_profile[0];
}


//---------------------------------------------------------------------
void line_profile_aa::set(double center_width, double smoother_width)
{
    double base_val = 1.0;
    if(center_width == 0.0)   center_width = 1.0 / subpixel_scale;
    if(smoother_width == 0.0) smoother_width = 1.0 / subpixel_scale;

    double width = center_width + smoother_width;
    if(width < m_min_width)
    {
        double k = width / m_min_width;
        base_val *= k;
        center_width /= k;
        smoother_width /= k;
    }

    value_type* ch = profile(center_width + smoother_width);

    unsigned subpixel_center_width = unsigned(center_width * subpixel_scale);
    unsigned subpixel_smoother_width = unsigned(smoother_width * subpixel_scale);

    value_type* ch_center   = ch + subpixel_scale*2;
    value_type* ch_smoother = ch_center + subpixel_center_width;

    unsigned i;

    unsigned val = m_gamma[unsigned(base_val * aa_mask)];
    ch = ch_center;
    for(i = 0; i < subpixel_center_width; i++)
    {
        *ch++ = (value_type)val;
    }

    for(i = 0; i < subpixel_smoother_width; i++)
    {
        *ch_smoother++ =
            m_gamma[unsigned((base_val -
                              base_val *
                              (double(i) / subpixel_smoother_width)) * aa_mask)];
    }

    unsigned n_smoother = profile_size() -
        subpixel_smoother_width -
        subpixel_center_width -
        subpixel_scale*2;

    val = m_gamma[0];
    for(i = 0; i < n_smoother; i++)
    {
        *ch_smoother++ = (value_type)val;
    }

    ch = ch_center;
    for(i = 0; i < subpixel_scale*2; i++)
    {
        *--ch = *ch_center++;
    }
}


}