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agg_image_filters.cpp
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105 lines (88 loc) · 3.53 KB
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//----------------------------------------------------------------------------
// 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: [email protected]
// http://www.antigrain.com
//----------------------------------------------------------------------------
//
// Filtering class image_filter_lut implemantation
//
//----------------------------------------------------------------------------
#include "agg_image_filters.h"
namespace agg
{
//--------------------------------------------------------------------
void image_filter_lut::realloc_lut(double radius)
{
m_radius = radius;
m_diameter = uceil(radius) * 2;
m_start = -int(m_diameter / 2 - 1);
unsigned size = m_diameter << image_subpixel_shift;
if(size > m_weight_array.size())
{
m_weight_array.resize(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_scale; i++)
{
for(;;)
{
int sum = 0;
unsigned j;
for(j = 0; j < m_diameter; j++)
{
sum += m_weight_array[j * image_subpixel_scale + i];
}
if(sum == image_filter_scale) break;
double k = double(image_filter_scale) / double(sum);
sum = 0;
for(j = 0; j < m_diameter; j++)
{
sum += m_weight_array[j * image_subpixel_scale + i] =
iround(m_weight_array[j * image_subpixel_scale + i] * k);
}
sum -= image_filter_scale;
int 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_scale + i];
if(v < image_filter_scale)
{
m_weight_array[idx * image_subpixel_scale + i] += inc;
sum += inc;
}
}
}
}
#ifndef MPL_FIX_AGG_IMAGE_FILTER_LUT_BUGS
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];
#endif
}
}