127 lines
4.8 KiB
C++
127 lines
4.8 KiB
C++
//----------------------------------------------------------------------------
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// Anti-Grain Geometry - Version 2.4
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// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
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//
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// Permission to copy, use, modify, sell and distribute this software
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// is granted provided this copyright notice appears in all copies.
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// This software is provided "as is" without express or implied
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// warranty, and with no claim as to its suitability for any purpose.
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//
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//----------------------------------------------------------------------------
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// Contact: mcseem@antigrain.com
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// mcseemagg@yahoo.com
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// http://www.antigrain.com
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//----------------------------------------------------------------------------
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#ifndef AGG_SPAN_GRADIENT_ALPHA_INCLUDED
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#define AGG_SPAN_GRADIENT_ALPHA_INCLUDED
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#include "agg_span_gradient.h"
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namespace agg
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{
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//======================================================span_gradient_alpha
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template<class ColorT,
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class Interpolator,
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class GradientF,
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class AlphaF>
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class span_gradient_alpha
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{
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public:
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typedef Interpolator interpolator_type;
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typedef ColorT color_type;
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typedef typename color_type::value_type alpha_type;
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enum downscale_shift_e
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{
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downscale_shift = interpolator_type::subpixel_shift - gradient_subpixel_shift
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};
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//--------------------------------------------------------------------
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span_gradient_alpha() {}
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//--------------------------------------------------------------------
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span_gradient_alpha(interpolator_type& inter,
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GradientF& gradient_function,
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AlphaF& alpha_function,
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double d1, double d2) :
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m_interpolator(&inter),
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m_gradient_function(&gradient_function),
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m_alpha_function(&alpha_function),
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m_d1(iround(d1 * gradient_subpixel_scale)),
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m_d2(iround(d2 * gradient_subpixel_scale))
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{}
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//--------------------------------------------------------------------
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interpolator_type& interpolator() { return *m_interpolator; }
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const GradientF& gradient_function() const { return *m_gradient_function; }
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const AlphaF& alpha_function() const { return *m_alpha_function; }
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double d1() const { return double(m_d1) / gradient_subpixel_scale; }
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double d2() const { return double(m_d2) / gradient_subpixel_scale; }
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//--------------------------------------------------------------------
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void interpolator(interpolator_type& i) { m_interpolator = &i; }
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void gradient_function(const GradientF& gf) { m_gradient_function = &gf; }
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void alpha_function(const AlphaF& af) { m_alpha_function = ⁡ }
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void d1(double v) { m_d1 = iround(v * gradient_subpixel_scale); }
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void d2(double v) { m_d2 = iround(v * gradient_subpixel_scale); }
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//--------------------------------------------------------------------
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void prepare() {}
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//--------------------------------------------------------------------
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void generate(color_type* span, int x, int y, unsigned len)
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{
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int dd = m_d2 - m_d1;
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if(dd < 1) dd = 1;
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m_interpolator->begin(x+0.5, y+0.5, len);
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do
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{
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m_interpolator->coordinates(&x, &y);
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int d = m_gradient_function->calculate(x >> downscale_shift,
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y >> downscale_shift, m_d2);
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d = ((d - m_d1) * (int)m_alpha_function->size()) / dd;
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if(d < 0) d = 0;
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if(d >= (int)m_alpha_function->size()) d = m_alpha_function->size() - 1;
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span->a = (*m_alpha_function)[d];
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++span;
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++(*m_interpolator);
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}
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while(--len);
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}
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private:
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interpolator_type* m_interpolator;
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GradientF* m_gradient_function;
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AlphaF* m_alpha_function;
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int m_d1;
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int m_d2;
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};
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//=======================================================gradient_alpha_x
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template<class ColorT> struct gradient_alpha_x
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{
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typedef typename ColorT::value_type alpha_type;
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alpha_type operator [] (alpha_type x) const { return x; }
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};
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//====================================================gradient_alpha_x_u8
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struct gradient_alpha_x_u8
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{
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typedef int8u alpha_type;
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alpha_type operator [] (alpha_type x) const { return x; }
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};
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//==========================================gradient_alpha_one_munus_x_u8
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struct gradient_alpha_one_munus_x_u8
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{
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typedef int8u alpha_type;
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alpha_type operator [] (alpha_type x) const { return 255-x; }
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};
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}
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#endif
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