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+ impl colorize-alpha image filter

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NOTE:currently linear interpolation between two colours only
  TODO:support multiple colour stops : https://developer.mozilla.org/en-US/docs/CSS/linear-gradient
This commit is contained in:
artemp 2013-03-20 15:17:41 +00:00
parent feaf757c07
commit 4b713f6ed0
2 changed files with 78 additions and 1 deletions
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72
include/mapnik/image_filter.hpp
View file

@ -404,6 +404,78 @@ void apply_filter(Src & src, agg_stack_blur const& op)
agg::stack_blur_rgba32(pixf,op.rx,op.ry);
}
template <typename Src>
void apply_filter(Src & src, colorize_alpha const& op)
{
using namespace boost::gil;
mapnik::color const& c0 = op.c0_;
mapnik::color const& c1 = op.c1_;
uint8_t reds[256];
uint8_t greens[256];
uint8_t blues[256];
for (unsigned a=0; a < 256;++a)
{
reds[a] = (c0.red() + (c1.red() - c0.red()) * a) >> 8;
greens[a] = (c0.green() + (c1.green() - c0.green()) * a) >> 8;
blues[a] = (c0.blue() + (c1.blue() - c0.blue()) * a) >> 8;
}
rgba8_view_t src_view = rgba8_view(src);
for (int y=0; y<src_view.height(); ++y)
{
rgba8_view_t::x_iterator src_it = src_view.row_begin(y);
for (int x=0; x<src_view.width(); ++x)
{
uint8_t & r = get_color(src_it[x], red_t());
uint8_t & g = get_color(src_it[x], green_t());
uint8_t & b = get_color(src_it[x], blue_t());
uint8_t & a = get_color(src_it[x], alpha_t());
if ( a > 0)
{
//r = (c0.red() + (c1.red() - c0.red()) * a) >> 8;
//g = (c0.green() + (c1.green() - c0.green()) * a) >> 8;
//b = (c0.blue() + (c1.blue() - c0.blue()) * a) >> 8;
r = (reds[a] * a + 255) >> 8;
g = (greens[a] * a + 255) >> 8;
b = (blues[a] * a + 255) >> 8;
#if 0
// rainbow
r = 0;
g = 0;
b = 0;
if (a < 64)
{
g = a * 4;
b = 255;
}
else if (a >= 64 && a < 128)
{
g = 255;
b = 255 - ((a - 64) * 4);
}
else if (a >= 128 && a < 192)
{
r = (a - 128) * 4;
g = 255;
}
else // >= 192
{
r = 255;
g = 255 - ((a - 192) * 4);
}
r = (r * a + 255) >> 8;
g = (g * a + 255) >> 8;
b = (b * a + 255) >> 8;
#endif
}
}
}
}
template <typename Src>
void apply_filter(Src & src, hsla const& transform)
{

7
include/mapnik/image_filter_types.hpp
View file

@ -101,9 +101,14 @@ struct hsla
struct colorize_alpha
{
colorize_alpha(mapnik::color const& c0, mapnik::color const& c1)
: c0_(c0),
c1_(c1)
{
// TODO: implement me!
// TODO: support multiple color-stops
// https://developer.mozilla.org/en-US/docs/CSS/linear-gradient
}
mapnik::color c0_;
mapnik::color c1_;
};
typedef boost::variant<filter::blur,