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Diffstat (limited to 'src/agg/agg_color_gray.h')
| -rw-r--r-- | src/agg/agg_color_gray.h | 1047 |
1 files changed, 1047 insertions, 0 deletions
diff --git a/src/agg/agg_color_gray.h b/src/agg/agg_color_gray.h new file mode 100644 index 000000000..f66588c11 --- /dev/null +++ b/src/agg/agg_color_gray.h @@ -0,0 +1,1047 @@ +//---------------------------------------------------------------------------- +// 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 +//---------------------------------------------------------------------------- +// +// Adaptation for high precision colors has been sponsored by +// Liberty Technology Systems, Inc., visit http://lib-sys.com +// +// Liberty Technology Systems, Inc. is the provider of +// PostScript and PDF technology for software developers. +// +//---------------------------------------------------------------------------- +// +// color types gray8, gray16 +// +//---------------------------------------------------------------------------- + +#ifndef AGG_COLOR_GRAY_INCLUDED +#define AGG_COLOR_GRAY_INCLUDED + +#include "agg_basics.h" +#include "agg_color_rgba.h" + +namespace agg +{ + + //===================================================================gray8 + template<class Colorspace> + struct gray8T + { + typedef int8u value_type; + typedef int32u calc_type; + typedef int32 long_type; + enum base_scale_e + { + base_shift = 8, + base_scale = 1 << base_shift, + base_mask = base_scale - 1, + base_MSB = 1 << (base_shift - 1) + }; + typedef gray8T self_type; + + value_type v; + value_type a; + + static value_type luminance(const rgba& c) + { + // Calculate grayscale value as per ITU-R BT.709. + return value_type(uround((0.2126 * c.r + 0.7152 * c.g + 0.0722 * c.b) * base_mask)); + } + + static value_type luminance(const rgba8& c) + { + // Calculate grayscale value as per ITU-R BT.709. + return value_type((55u * c.r + 184u * c.g + 18u * c.b) >> 8); + } + + static void convert(gray8T<linear>& dst, const gray8T<sRGB>& src) + { + dst.v = sRGB_conv<value_type>::rgb_from_sRGB(src.v); + dst.a = src.a; + } + + static void convert(gray8T<sRGB>& dst, const gray8T<linear>& src) + { + dst.v = sRGB_conv<value_type>::rgb_to_sRGB(src.v); + dst.a = src.a; + } + + static void convert(gray8T<linear>& dst, const rgba8& src) + { + dst.v = luminance(src); + dst.a = src.a; + } + + static void convert(gray8T<linear>& dst, const srgba8& src) + { + // The RGB weights are only valid for linear values. + convert(dst, rgba8(src)); + } + + static void convert(gray8T<sRGB>& dst, const rgba8& src) + { + dst.v = sRGB_conv<value_type>::rgb_to_sRGB(luminance(src)); + dst.a = src.a; + } + + static void convert(gray8T<sRGB>& dst, const srgba8& src) + { + // The RGB weights are only valid for linear values. + convert(dst, rgba8(src)); + } + + //-------------------------------------------------------------------- + gray8T() {} + + //-------------------------------------------------------------------- + explicit gray8T(unsigned v_, unsigned a_ = base_mask) : + v(int8u(v_)), a(int8u(a_)) {} + + //-------------------------------------------------------------------- + gray8T(const self_type& c, unsigned a_) : + v(c.v), a(value_type(a_)) {} + + //-------------------------------------------------------------------- + gray8T(const rgba& c) : + v(luminance(c)), + a(value_type(uround(c.a * base_mask))) {} + + //-------------------------------------------------------------------- + template<class T> + gray8T(const gray8T<T>& c) + { + convert(*this, c); + } + + //-------------------------------------------------------------------- + template<class T> + gray8T(const rgba8T<T>& c) + { + convert(*this, c); + } + + //-------------------------------------------------------------------- + template<class T> + T convert_from_sRGB() const + { + typename T::value_type y = sRGB_conv<typename T::value_type>::rgb_from_sRGB(v); + return T(y, y, y, sRGB_conv<typename T::value_type>::alpha_from_sRGB(a)); + } + + template<class T> + T convert_to_sRGB() const + { + typename T::value_type y = sRGB_conv<typename T::value_type>::rgb_to_sRGB(v); + return T(y, y, y, sRGB_conv<typename T::value_type>::alpha_to_sRGB(a)); + } + + //-------------------------------------------------------------------- + rgba8 make_rgba8(const linear&) const + { + return rgba8(v, v, v, a); + } + + rgba8 make_rgba8(const sRGB&) const + { + return convert_from_sRGB<srgba8>(); + } + + operator rgba8() const + { + return make_rgba8(Colorspace()); + } + + //-------------------------------------------------------------------- + srgba8 make_srgba8(const linear&) const + { + return convert_to_sRGB<rgba8>(); + } + + srgba8 make_srgba8(const sRGB&) const + { + return srgba8(v, v, v, a); + } + + operator srgba8() const + { + return make_rgba8(Colorspace()); + } + + //-------------------------------------------------------------------- + rgba16 make_rgba16(const linear&) const + { + rgba16::value_type rgb = (v << 8) | v; + return rgba16(rgb, rgb, rgb, (a << 8) | a); + } + + rgba16 make_rgba16(const sRGB&) const + { + return convert_from_sRGB<rgba16>(); + } + + operator rgba16() const + { + return make_rgba16(Colorspace()); + } + + //-------------------------------------------------------------------- + rgba32 make_rgba32(const linear&) const + { + rgba32::value_type v32 = v / 255.0f; + return rgba32(v32, v32, v32, a / 255.0f); + } + + rgba32 make_rgba32(const sRGB&) const + { + return convert_from_sRGB<rgba32>(); + } + + operator rgba32() const + { + return make_rgba32(Colorspace()); + } + + //-------------------------------------------------------------------- + static AGG_INLINE double to_double(value_type a) + { + return double(a) / base_mask; + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type from_double(double a) + { + return value_type(uround(a * base_mask)); + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type empty_value() + { + return 0; + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type full_value() + { + return base_mask; + } + + //-------------------------------------------------------------------- + AGG_INLINE bool is_transparent() const + { + return a == 0; + } + + //-------------------------------------------------------------------- + AGG_INLINE bool is_opaque() const + { + return a == base_mask; + } + + //-------------------------------------------------------------------- + // Fixed-point multiply, exact over int8u. + static AGG_INLINE value_type multiply(value_type a, value_type b) + { + calc_type t = a * b + base_MSB; + return value_type(((t >> base_shift) + t) >> base_shift); + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type demultiply(value_type a, value_type b) + { + if (a * b == 0) + { + return 0; + } + else if (a >= b) + { + return base_mask; + } + else return value_type((a * base_mask + (b >> 1)) / b); + } + + //-------------------------------------------------------------------- + template<typename T> + static AGG_INLINE T downscale(T a) + { + return a >> base_shift; + } + + //-------------------------------------------------------------------- + template<typename T> + static AGG_INLINE T downshift(T a, unsigned n) + { + return a >> n; + } + + //-------------------------------------------------------------------- + // Fixed-point multiply, exact over int8u. + // Specifically for multiplying a color component by a cover. + static AGG_INLINE value_type mult_cover(value_type a, value_type b) + { + return multiply(a, b); + } + + //-------------------------------------------------------------------- + static AGG_INLINE cover_type scale_cover(cover_type a, value_type b) + { + return multiply(b, a); + } + + //-------------------------------------------------------------------- + // Interpolate p to q by a, assuming q is premultiplied by a. + static AGG_INLINE value_type prelerp(value_type p, value_type q, value_type a) + { + return p + q - multiply(p, a); + } + + //-------------------------------------------------------------------- + // Interpolate p to q by a. + static AGG_INLINE value_type lerp(value_type p, value_type q, value_type a) + { + int t = (q - p) * a + base_MSB - (p > q); + return value_type(p + (((t >> base_shift) + t) >> base_shift)); + } + + //-------------------------------------------------------------------- + self_type& clear() + { + v = a = 0; + return *this; + } + + //-------------------------------------------------------------------- + self_type& transparent() + { + a = 0; + return *this; + } + + //-------------------------------------------------------------------- + self_type& opacity(double a_) + { + if (a_ < 0) a = 0; + else if (a_ > 1) a = 1; + else a = (value_type)uround(a_ * double(base_mask)); + return *this; + } + + //-------------------------------------------------------------------- + double opacity() const + { + return double(a) / double(base_mask); + } + + //-------------------------------------------------------------------- + self_type& premultiply() + { + if (a < base_mask) + { + if (a == 0) v = 0; + else v = multiply(v, a); + } + return *this; + } + + //-------------------------------------------------------------------- + self_type& demultiply() + { + if (a < base_mask) + { + if (a == 0) + { + v = 0; + } + else + { + calc_type v_ = (calc_type(v) * base_mask) / a; + v = value_type((v_ > base_mask) ? (value_type)base_mask : v_); + } + } + return *this; + } + + //-------------------------------------------------------------------- + self_type gradient(self_type c, double k) const + { + self_type ret; + calc_type ik = uround(k * base_scale); + ret.v = lerp(v, c.v, ik); + ret.a = lerp(a, c.a, ik); + return ret; + } + + //-------------------------------------------------------------------- + AGG_INLINE void add(const self_type& c, unsigned cover) + { + calc_type cv, ca; + if (cover == cover_mask) + { + if (c.a == base_mask) + { + *this = c; + return; + } + else + { + cv = v + c.v; + ca = a + c.a; + } + } + else + { + cv = v + mult_cover(c.v, cover); + ca = a + mult_cover(c.a, cover); + } + v = (value_type)((cv > calc_type(base_mask)) ? calc_type(base_mask) : cv); + a = (value_type)((ca > calc_type(base_mask)) ? calc_type(base_mask) : ca); + } + + //-------------------------------------------------------------------- + static self_type no_color() { return self_type(0,0); } + }; + + typedef gray8T<linear> gray8; + typedef gray8T<sRGB> sgray8; + + + //==================================================================gray16 + struct gray16 + { + typedef int16u value_type; + typedef int32u calc_type; + typedef int64 long_type; + enum base_scale_e + { + base_shift = 16, + base_scale = 1 << base_shift, + base_mask = base_scale - 1, + base_MSB = 1 << (base_shift - 1) + }; + typedef gray16 self_type; + + value_type v; + value_type a; + + static value_type luminance(const rgba& c) + { + // Calculate grayscale value as per ITU-R BT.709. + return value_type(uround((0.2126 * c.r + 0.7152 * c.g + 0.0722 * c.b) * base_mask)); + } + + static value_type luminance(const rgba16& c) + { + // Calculate grayscale value as per ITU-R BT.709. + return value_type((13933u * c.r + 46872u * c.g + 4732u * c.b) >> 16); + } + + static value_type luminance(const rgba8& c) + { + return luminance(rgba16(c)); + } + + static value_type luminance(const srgba8& c) + { + return luminance(rgba16(c)); + } + + static value_type luminance(const rgba32& c) + { + return luminance(rgba(c)); + } + + //-------------------------------------------------------------------- + gray16() {} + + //-------------------------------------------------------------------- + explicit gray16(unsigned v_, unsigned a_ = base_mask) : + v(int16u(v_)), a(int16u(a_)) {} + + //-------------------------------------------------------------------- + gray16(const self_type& c, unsigned a_) : + v(c.v), a(value_type(a_)) {} + + //-------------------------------------------------------------------- + gray16(const rgba& c) : + v(luminance(c)), + a((value_type)uround(c.a * double(base_mask))) {} + + //-------------------------------------------------------------------- + gray16(const rgba8& c) : + v(luminance(c)), + a((value_type(c.a) << 8) | c.a) {} + + //-------------------------------------------------------------------- + gray16(const srgba8& c) : + v(luminance(c)), + a((value_type(c.a) << 8) | c.a) {} + + //-------------------------------------------------------------------- + gray16(const rgba16& c) : + v(luminance(c)), + a(c.a) {} + + //-------------------------------------------------------------------- + gray16(const gray8& c) : + v((value_type(c.v) << 8) | c.v), + a((value_type(c.a) << 8) | c.a) {} + + //-------------------------------------------------------------------- + gray16(const sgray8& c) : + v(sRGB_conv<value_type>::rgb_from_sRGB(c.v)), + a(sRGB_conv<value_type>::alpha_from_sRGB(c.a)) {} + + //-------------------------------------------------------------------- + operator rgba8() const + { + return rgba8(v >> 8, v >> 8, v >> 8, a >> 8); + } + + //-------------------------------------------------------------------- + operator srgba8() const + { + value_type y = sRGB_conv<value_type>::rgb_to_sRGB(v); + return srgba8(y, y, y, sRGB_conv<value_type>::alpha_to_sRGB(a)); + } + + //-------------------------------------------------------------------- + operator rgba16() const + { + return rgba16(v, v, v, a); + } + + //-------------------------------------------------------------------- + operator rgba32() const + { + rgba32::value_type v32 = v / 65535.0f; + return rgba32(v32, v32, v32, a / 65535.0f); + } + + //-------------------------------------------------------------------- + operator gray8() const + { + return gray8(v >> 8, a >> 8); + } + + //-------------------------------------------------------------------- + operator sgray8() const + { + return sgray8( + sRGB_conv<value_type>::rgb_to_sRGB(v), + sRGB_conv<value_type>::alpha_to_sRGB(a)); + } + + //-------------------------------------------------------------------- + static AGG_INLINE double to_double(value_type a) + { + return double(a) / base_mask; + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type from_double(double a) + { + return value_type(uround(a * base_mask)); + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type empty_value() + { + return 0; + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type full_value() + { + return base_mask; + } + + //-------------------------------------------------------------------- + AGG_INLINE bool is_transparent() const + { + return a == 0; + } + + //-------------------------------------------------------------------- + AGG_INLINE bool is_opaque() const + { + return a == base_mask; + } + + //-------------------------------------------------------------------- + // Fixed-point multiply, exact over int16u. + static AGG_INLINE value_type multiply(value_type a, value_type b) + { + calc_type t = a * b + base_MSB; + return value_type(((t >> base_shift) + t) >> base_shift); + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type demultiply(value_type a, value_type b) + { + if (a * b == 0) + { + return 0; + } + else if (a >= b) + { + return base_mask; + } + else return value_type((a * base_mask + (b >> 1)) / b); + } + + //-------------------------------------------------------------------- + template<typename T> + static AGG_INLINE T downscale(T a) + { + return a >> base_shift; + } + + //-------------------------------------------------------------------- + template<typename T> + static AGG_INLINE T downshift(T a, unsigned n) + { + return a >> n; + } + + //-------------------------------------------------------------------- + // Fixed-point multiply, almost exact over int16u. + // Specifically for multiplying a color component by a cover. + static AGG_INLINE value_type mult_cover(value_type a, cover_type b) + { + return multiply(a, b << 8 | b); + } + + //-------------------------------------------------------------------- + static AGG_INLINE cover_type scale_cover(cover_type a, value_type b) + { + return mult_cover(b, a) >> 8; + } + + //-------------------------------------------------------------------- + // Interpolate p to q by a, assuming q is premultiplied by a. + static AGG_INLINE value_type prelerp(value_type p, value_type q, value_type a) + { + return p + q - multiply(p, a); + } + + //-------------------------------------------------------------------- + // Interpolate p to q by a. + static AGG_INLINE value_type lerp(value_type p, value_type q, value_type a) + { + int t = (q - p) * a + base_MSB - (p > q); + return value_type(p + (((t >> base_shift) + t) >> base_shift)); + } + + //-------------------------------------------------------------------- + self_type& clear() + { + v = a = 0; + return *this; + } + + //-------------------------------------------------------------------- + self_type& transparent() + { + a = 0; + return *this; + } + + //-------------------------------------------------------------------- + self_type& opacity(double a_) + { + if (a_ < 0) a = 0; + else if(a_ > 1) a = 1; + else a = (value_type)uround(a_ * double(base_mask)); + return *this; + } + + //-------------------------------------------------------------------- + double opacity() const + { + return double(a) / double(base_mask); + } + + + //-------------------------------------------------------------------- + self_type& premultiply() + { + if (a < base_mask) + { + if(a == 0) v = 0; + else v = multiply(v, a); + } + return *this; + } + + //-------------------------------------------------------------------- + self_type& demultiply() + { + if (a < base_mask) + { + if (a == 0) + { + v = 0; + } + else + { + calc_type v_ = (calc_type(v) * base_mask) / a; + v = (v_ > base_mask) ? value_type(base_mask) : value_type(v_); + } + } + return *this; + } + + //-------------------------------------------------------------------- + self_type gradient(self_type c, double k) const + { + self_type ret; + calc_type ik = uround(k * base_scale); + ret.v = lerp(v, c.v, ik); + ret.a = lerp(a, c.a, ik); + return ret; + } + + //-------------------------------------------------------------------- + AGG_INLINE void add(const self_type& c, unsigned cover) + { + calc_type cv, ca; + if (cover == cover_mask) + { + if (c.a == base_mask) + { + *this = c; + return; + } + else + { + cv = v + c.v; + ca = a + c.a; + } + } + else + { + cv = v + mult_cover(c.v, cover); + ca = a + mult_cover(c.a, cover); + } + v = (value_type)((cv > calc_type(base_mask)) ? calc_type(base_mask) : cv); + a = (value_type)((ca > calc_type(base_mask)) ? calc_type(base_mask) : ca); + } + + //-------------------------------------------------------------------- + static self_type no_color() { return self_type(0,0); } + }; + + + //===================================================================gray32 + struct gray32 + { + typedef float value_type; + typedef double calc_type; + typedef double long_type; + typedef gray32 self_type; + + value_type v; + value_type a; + + // Calculate grayscale value as per ITU-R BT.709. + static value_type luminance(double r, double g, double b) + { + return value_type(0.2126 * r + 0.7152 * g + 0.0722 * b); + } + + static value_type luminance(const rgba& c) + { + return luminance(c.r, c.g, c.b); + } + + static value_type luminance(const rgba32& c) + { + return luminance(c.r, c.g, c.b); + } + + static value_type luminance(const rgba8& c) + { + return luminance(c.r / 255.0, c.g / 255.0, c.g / 255.0); + } + + static value_type luminance(const rgba16& c) + { + return luminance(c.r / 65535.0, c.g / 65535.0, c.g / 65535.0); + } + + //-------------------------------------------------------------------- + gray32() {} + + //-------------------------------------------------------------------- + explicit gray32(value_type v_, value_type a_ = 1) : + v(v_), a(a_) {} + + //-------------------------------------------------------------------- + gray32(const self_type& c, value_type a_) : + v(c.v), a(a_) {} + + //-------------------------------------------------------------------- + gray32(const rgba& c) : + v(luminance(c)), + a(value_type(c.a)) {} + + //-------------------------------------------------------------------- + gray32(const rgba8& c) : + v(luminance(c)), + a(value_type(c.a / 255.0)) {} + + //-------------------------------------------------------------------- + gray32(const srgba8& c) : + v(luminance(rgba32(c))), + a(value_type(c.a / 255.0)) {} + + //-------------------------------------------------------------------- + gray32(const rgba16& c) : + v(luminance(c)), + a(value_type(c.a / 65535.0)) {} + + //-------------------------------------------------------------------- + gray32(const rgba32& c) : + v(luminance(c)), + a(value_type(c.a)) {} + + //-------------------------------------------------------------------- + gray32(const gray8& c) : + v(value_type(c.v / 255.0)), + a(value_type(c.a / 255.0)) {} + + //-------------------------------------------------------------------- + gray32(const sgray8& c) : + v(sRGB_conv<value_type>::rgb_from_sRGB(c.v)), + a(sRGB_conv<value_type>::alpha_from_sRGB(c.a)) {} + + //-------------------------------------------------------------------- + gray32(const gray16& c) : + v(value_type(c.v / 65535.0)), + a(value_type(c.a / 65535.0)) {} + + //-------------------------------------------------------------------- + operator rgba() const + { + return rgba(v, v, v, a); + } + + //-------------------------------------------------------------------- + operator gray8() const + { + return gray8(uround(v * 255.0), uround(a * 255.0)); + } + + //-------------------------------------------------------------------- + operator sgray8() const + { + // Return (non-premultiplied) sRGB values. + return sgray8( + sRGB_conv<value_type>::rgb_to_sRGB(v), + sRGB_conv<value_type>::alpha_to_sRGB(a)); + } + + //-------------------------------------------------------------------- + operator gray16() const + { + return gray16(uround(v * 65535.0), uround(a * 65535.0)); + } + + //-------------------------------------------------------------------- + operator rgba8() const + { + rgba8::value_type y = uround(v * 255.0); + return rgba8(y, y, y, uround(a * 255.0)); + } + + //-------------------------------------------------------------------- + operator srgba8() const + { + srgba8::value_type y = sRGB_conv<value_type>::rgb_to_sRGB(v); + return srgba8(y, y, y, sRGB_conv<value_type>::alpha_to_sRGB(a)); + } + + //-------------------------------------------------------------------- + operator rgba16() const + { + rgba16::value_type y = uround(v * 65535.0); + return rgba16(y, y, y, uround(a * 65535.0)); + } + + //-------------------------------------------------------------------- + operator rgba32() const + { + return rgba32(v, v, v, a); + } + + //-------------------------------------------------------------------- + static AGG_INLINE double to_double(value_type a) + { + return a; + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type from_double(double a) + { + return value_type(a); + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type empty_value() + { + return 0; + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type full_value() + { + return 1; + } + + //-------------------------------------------------------------------- + AGG_INLINE bool is_transparent() const + { + return a <= 0; + } + + //-------------------------------------------------------------------- + AGG_INLINE bool is_opaque() const + { + return a >= 1; + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type invert(value_type x) + { + return 1 - x; + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type multiply(value_type a, value_type b) + { + return value_type(a * b); + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type demultiply(value_type a, value_type b) + { + return (b == 0) ? 0 : value_type(a / b); + } + + //-------------------------------------------------------------------- + template<typename T> + static AGG_INLINE T downscale(T a) + { + return a; + } + + //-------------------------------------------------------------------- + template<typename T> + static AGG_INLINE T downshift(T a, unsigned n) + { + return n > 0 ? a / (1 << n) : a; + } + + //-------------------------------------------------------------------- + static AGG_INLINE value_type mult_cover(value_type a, cover_type b) + { + return value_type(a * b / cover_mask); + } + + //-------------------------------------------------------------------- + static AGG_INLINE cover_type scale_cover(cover_type a, value_type b) + { + return cover_type(uround(a * b)); + } + + //-------------------------------------------------------------------- + // Interpolate p to q by a, assuming q is premultiplied by a. + static AGG_INLINE value_type prelerp(value_type p, value_type q, value_type a) + { + return (1 - a) * p + q; // more accurate than "p + q - p * a" + } + + //-------------------------------------------------------------------- + // Interpolate p to q by a. + static AGG_INLINE value_type lerp(value_type p, value_type q, value_type a) + { + // The form "p + a * (q - p)" avoids a multiplication, but may produce an + // inaccurate result. For example, "p + (q - p)" may not be exactly equal + // to q. Therefore, stick to the basic expression, which at least produces + // the correct result at either extreme. + return (1 - a) * p + a * q; + } + + //-------------------------------------------------------------------- + self_type& clear() + { + v = a = 0; + return *this; + } + + //-------------------------------------------------------------------- + self_type& transparent() + { + a = 0; + return *this; + } + + //-------------------------------------------------------------------- + self_type& opacity(double a_) + { + if (a_ < 0) a = 0; + else if (a_ > 1) a = 1; + else a = value_type(a_); + return *this; + } + + //-------------------------------------------------------------------- + double opacity() const + { + return a; + } + + + //-------------------------------------------------------------------- + self_type& premultiply() + { + if (a < 0) v = 0; + else if(a < 1) v *= a; + return *this; + } + + //-------------------------------------------------------------------- + self_type& demultiply() + { + if (a < 0) v = 0; + else if (a < 1) v /= a; + return *this; + } + + //-------------------------------------------------------------------- + self_type gradient(self_type c, double k) const + { + return self_type( + value_type(v + (c.v - v) * k), + value_type(a + (c.a - a) * k)); + } + + //-------------------------------------------------------------------- + static self_type no_color() { return self_type(0,0); } + }; +} + + + + +#endif |