From 86785a5923c93224fed90bd78c4d6568577962f5 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Wed, 23 Sep 2020 20:46:03 +0300
Subject: [PATCH] Improve color blur implementation

---
 libs/pcg/include/psemek/pcg/blur.hpp | 18 +++++++++++++++---
 libs/pcg/source/blur.cpp             | 16 ++++++++++------
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/libs/pcg/include/psemek/pcg/blur.hpp b/libs/pcg/include/psemek/pcg/blur.hpp
index f27bc494..47fde7c6 100644
--- a/libs/pcg/include/psemek/pcg/blur.hpp
+++ b/libs/pcg/include/psemek/pcg/blur.hpp
@@ -2,8 +2,10 @@
 
 #include <psemek/gfx/pixmap.hpp>
 #include <psemek/pcg/seamless.hpp>
+#include <psemek/util/functional.hpp>
 
 #include <vector>
+#include <type_traits>
 
 namespace psemek::pcg
 {
@@ -15,17 +17,20 @@ namespace psemek::pcg
 
 	}
 
-	template <typename T>
-	gfx::basic_pixmap<T> blur(gfx::basic_pixmap<T> const & p, int size, float sigma, seamless_tag)
+	template <typename T, typename To, typename From>
+	gfx::basic_pixmap<T> blur(gfx::basic_pixmap<T> const & p, To && to, From && from, int size, float sigma, seamless_tag)
 	{
 		gfx::basic_pixmap<T> res({p.width(), p.height()}, T{});
 
+		using R = std::decay_t<decltype(to(*p.begin()))>;
+
 		auto c = detail::gauss_coeffs(size, sigma);
 
 		for (std::size_t y = 0; y < p.height(); ++y)
 		{
 			for (std::size_t x = 0; x < p.width(); ++x)
 			{
+				auto v = R{};
 				for (int j = - size; j <= size; ++j)
 				{
 					for (int i = - size; i <= size; ++i)
@@ -38,15 +43,22 @@ namespace psemek::pcg
 						while (iy < 0) iy += p.height();
 						if (static_cast<std::size_t>(iy) >= p.height()) iy = iy % p.height();
 
-						res(x, y) += p(ix, iy) * c[i + size] * c[j + size];
+						v += to(p(ix, iy)) * c[i + size] * c[j + size];
 					}
 				}
+				res(x, y) = from(v);
 			}
 		}
 
 		return res;
 	}
 
+	template <typename T, typename To, typename From>
+	gfx::basic_pixmap<T> blur(gfx::basic_pixmap<T> const & p, int size, float sigma, seamless_tag)
+	{
+		return blur(p, util::id, util::id, size, sigma, seamless);
+	}
+
 	gfx::pixmap_rgb blur(gfx::pixmap_rgb const & p, int size, float sigma, seamless_tag);
 	gfx::pixmap_rgba blur(gfx::pixmap_rgba const & p, int size, float sigma, seamless_tag);
 
diff --git a/libs/pcg/source/blur.cpp b/libs/pcg/source/blur.cpp
index 56f59ca5..68858944 100644
--- a/libs/pcg/source/blur.cpp
+++ b/libs/pcg/source/blur.cpp
@@ -27,18 +27,22 @@ namespace psemek::pcg
 
 	}
 
+	template <typename Pixel>
+	auto color_blur_impl(gfx::basic_pixmap<Pixel> const & p, int size, float sigma, seamless_tag)
+	{
+		auto to = [](auto const & c){ return gfx::to_colorf(c); };
+		auto from = [](auto const & c){ return gfx::to_coloru8(c); };
+		return blur(p, to, from, size, sigma, seamless);
+	}
+
 	gfx::pixmap_rgb blur(gfx::pixmap_rgb const & p, int size, float sigma, seamless_tag)
 	{
-		auto converted = util::map([](gfx::color_rgb const & c){ return gfx::to_colorf(c); }, p);
-		converted = blur(converted, size, sigma, seamless);
-		return util::map([](geom::vector<float, 3> const & c){ return gfx::to_coloru8(c); }, converted);
+		return color_blur_impl(p, size, sigma, seamless);
 	}
 
 	gfx::pixmap_rgba blur(gfx::pixmap_rgba const & p, int size, float sigma, seamless_tag)
 	{
-		auto converted = util::map([](gfx::color_rgba const & c){ return gfx::to_colorf(c); }, p);
-		converted = blur(converted, size, sigma, seamless);
-		return util::map([](geom::vector<float, 4> const & c){ return gfx::to_coloru8(c); }, converted);
+		return color_blur_impl(p, size, sigma, seamless);
 	}
 
 }