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Add specialisation for nodata->rgba8 conversion for mapnik::image_gray8

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( fixes gdal-overview-gray8 visual test)
This commit is contained in:
Artem Pavlenko 2024-03-28 15:33:41 +00:00
parent e394db6c8f
commit 6479059c7e
1 changed files with 19 additions and 2 deletions
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21
src/raster_colorizer.cpp
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@ -100,6 +100,23 @@ bool raster_colorizer::add_stop(colorizer_stop const& stop)
return true; return true;
} }
namespace {
template <typename PixelType>
float get_nodata_color()
{
return 0; // rgba(0,0,0,0)
}
template<>
float get_nodata_color<std::uint8_t>()
{
// GDAL specific interpretation of nodata
// for GDT_Byte single band -> rgba(0,0,0,255)
return static_cast<float>(0xff000000);
}
}
template<typename T> template<typename T>
void raster_colorizer::colorize(image_rgba8& out, void raster_colorizer::colorize(image_rgba8& out,
T const& in, T const& in,
@ -121,11 +138,11 @@ void raster_colorizer::colorize(image_rgba8& out,
pixel_type val = in_row[x]; pixel_type val = in_row[x];
if (nodata && (std::fabs(val - *nodata) < epsilon_)) if (nodata && (std::fabs(val - *nodata) < epsilon_))
{ {
out_row[x] = 0; // rgba(0,0,0,0) out_row[x] = get_nodata_color<pixel_type>();
} }
else else
{ {
out_row[x] = get_color(val); out_row[x] = get_color(static_cast<float>(val));
} }
} }
} }