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//----------------------------------------------------------------------------
// 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
//----------------------------------------------------------------------------
//
// Filtering class image_filter_lut implemantation
//
//----------------------------------------------------------------------------
#include "agg_image_filters.h"
namespace agg
{
//--------------------------------------------------------------------
image_filter_lut::~image_filter_lut()
{
delete [] m_weight_array;
}
//--------------------------------------------------------------------
image_filter_lut::image_filter_lut() :
m_weight_array(0),
m_max_size(0)
{}
//--------------------------------------------------------------------
void image_filter_lut::realloc(double _radius)
{
m_radius = _radius;
m_diameter = unsigned(ceil(_radius)) * 2;
m_start = -int(m_diameter / 2 - 1);
unsigned size = m_diameter << image_subpixel_shift;
if(size > m_max_size)
{
delete [] m_weight_array;
m_weight_array = new int16 [size];
m_max_size = size;
}
}
//--------------------------------------------------------------------
// This function normalizes integer values and corrects the rounding
// errors. It doesn't do anything with the source floating point values
// (m_weight_array_dbl), it corrects only integers according to the rule
// of 1.0 which means that any sum of pixel weights must be equal to 1.0.
// So, the filter function must produce a graph of the proper shape.
//--------------------------------------------------------------------
void image_filter_lut::normalize()
{
unsigned i;
int flip = 1;
for(i = 0; i < image_subpixel_size; i++)
{
for(;;)
{
int sum = 0;
unsigned j;
for(j = 0; j < m_diameter; j++)
{
sum += m_weight_array[j * image_subpixel_size + i];
}
if(sum == image_filter_size) break;
double k = double(image_filter_size) / double(sum);
sum = 0;
for(j = 0; j < m_diameter; j++)
{
sum += m_weight_array[j * image_subpixel_size + i] =
int16(m_weight_array[j * image_subpixel_size + i] * k);
}
sum -= image_filter_size;
int16 inc = (sum > 0) ? -1 : 1;
for(j = 0; j < m_diameter && sum; j++)
{
flip ^= 1;
unsigned idx = flip ? m_diameter/2 + j/2 : m_diameter/2 - j/2;
int v = m_weight_array[idx * image_subpixel_size + i];
if(v < image_filter_size)
{
m_weight_array[idx * image_subpixel_size + i] =
m_weight_array[idx * image_subpixel_size + i] + inc;
sum += inc;
}
}
}
}
unsigned pivot = m_diameter << (image_subpixel_shift - 1);
for(i = 0; i < pivot; i++)
{
m_weight_array[pivot + i] = m_weight_array[pivot - i];
}
unsigned end = (diameter() << image_subpixel_shift) - 1;
m_weight_array[0] = m_weight_array[end];
}
}
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