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#ifndef __AGG_WORKAROUND_H__
#define __AGG_WORKAROUND_H__
#include "agg_pixfmt_rgba.h"
/**********************************************************************
WORKAROUND: This class is to workaround a bug in Agg SVN where the
blending of RGBA32 pixels does not preserve enough precision
*/
template<class ColorT, class Order>
struct fixed_blender_rgba_pre : agg::conv_rgba_pre<ColorT, Order>
{
typedef ColorT color_type;
typedef Order order_type;
typedef typename color_type::value_type value_type;
typedef typename color_type::calc_type calc_type;
typedef typename color_type::long_type long_type;
enum base_scale_e
{
base_shift = color_type::base_shift,
base_mask = color_type::base_mask
};
//--------------------------------------------------------------------
static AGG_INLINE void blend_pix(value_type* p,
value_type cr, value_type cg, value_type cb,
value_type alpha, agg::cover_type cover)
{
blend_pix(p,
color_type::mult_cover(cr, cover),
color_type::mult_cover(cg, cover),
color_type::mult_cover(cb, cover),
color_type::mult_cover(alpha, cover));
}
//--------------------------------------------------------------------
static AGG_INLINE void blend_pix(value_type* p,
value_type cr, value_type cg, value_type cb,
value_type alpha)
{
alpha = base_mask - alpha;
p[Order::R] = (value_type)(((p[Order::R] * alpha) >> base_shift) + cr);
p[Order::G] = (value_type)(((p[Order::G] * alpha) >> base_shift) + cg);
p[Order::B] = (value_type)(((p[Order::B] * alpha) >> base_shift) + cb);
p[Order::A] = (value_type)(base_mask - ((alpha * (base_mask - p[Order::A])) >> base_shift));
}
};
template<class ColorT, class Order>
struct fixed_blender_rgba_plain : agg::conv_rgba_plain<ColorT, Order>
{
typedef ColorT color_type;
typedef Order order_type;
typedef typename color_type::value_type value_type;
typedef typename color_type::calc_type calc_type;
typedef typename color_type::long_type long_type;
enum base_scale_e { base_shift = color_type::base_shift };
//--------------------------------------------------------------------
static AGG_INLINE void blend_pix(value_type* p,
value_type cr, value_type cg, value_type cb, value_type alpha, agg::cover_type cover)
{
blend_pix(p, cr, cg, cb, color_type::mult_cover(alpha, cover));
}
//--------------------------------------------------------------------
static AGG_INLINE void blend_pix(value_type* p,
value_type cr, value_type cg, value_type cb, value_type alpha)
{
if(alpha == 0) return;
calc_type a = p[Order::A];
calc_type r = p[Order::R] * a;
calc_type g = p[Order::G] * a;
calc_type b = p[Order::B] * a;
a = ((alpha + a) << base_shift) - alpha * a;
p[Order::A] = (value_type)(a >> base_shift);
p[Order::R] = (value_type)((((cr << base_shift) - r) * alpha + (r << base_shift)) / a);
p[Order::G] = (value_type)((((cg << base_shift) - g) * alpha + (g << base_shift)) / a);
p[Order::B] = (value_type)((((cb << base_shift) - b) * alpha + (b << base_shift)) / a);
}
};
#endif
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