Window blur

libraries/libgraphics/Color.h

@@ -46,6 +46,15 @@ typedef union Color {
 		return *this = *this * other;
 	}
 
+	[[nodiscard]] constexpr Color operator+(Color other) const {
+		return {
+				(uint8_t)(r + other.r),
+				(uint8_t)(g + other.g),
+				(uint8_t)(b + other.b),
+				(uint8_t)(a + other.a)
+		};
+	}
+
 	[[nodiscard]] constexpr Color lightened(float amount = 0.25) const {
 		return darkened(1 + amount);
 	}

libraries/libgraphics/Framebuffer.cpp

@@ -151,6 +151,80 @@ void Framebuffer::copy_blitting_flipped(const Framebuffer& other, Rect other_are
 	}
 }
 
+void Framebuffer::blur(Gfx::Rect area, int radius) const {
+	int window_size = radius * 2 + 1;
+	area = area.overlapping_area(Rect {0, 0, width, height});
+
+	auto do_pass = [&]() {
+		// First, apply blur horizontally.
+		for(int y = area.y; y < area.y + area.height; y++) {
+			int window[3] = {0, 0, 0};
+			Color window_preblur[window_size];
+			int preblur_index = 0;
+
+			// Populate window
+			for(int i = -radius; i <= radius; i++) {
+				auto color = data[(std::min(std::max(area.x + i, 0), width - 1)) + y * width];
+				window_preblur[i + radius] = color;
+				window[0] += color.r;
+				window[1] += color.g;
+				window[2] += color.b;
+			}
+
+			for(int x = area.x; x < area.x + area.width; x++) {
+				data[x + y * width] = {
+						(uint8_t) (window[0] / window_size),
+						(uint8_t) (window[1] / window_size),
+						(uint8_t) (window[2] / window_size),
+				};
+				auto window_add = data[(std::min(x + radius + 1, width - 1)) + y * width];
+				auto window_sub = window_preblur[preblur_index];
+				window_preblur[preblur_index] = window_add;
+				preblur_index++;
+				preblur_index %= window_size;
+				window[0] += (int) window_add.r - (int) window_sub.r;
+				window[1] += (int) window_add.g - (int) window_sub.g;
+				window[2] += (int) window_add.b - (int) window_sub.b;
+			}
+		}
+
+		// Then, apply blur vertically.
+		for(int x = area.x; x < area.x + area.width; x++) {
+			int window[3] = {0, 0, 0};
+			Color window_preblur[window_size];
+			int preblur_index = 0;
+
+			// Populate window
+			for(int i = -radius; i <= radius; i++) {
+				auto color = data[x + (std::min(std::max(area.y + i, 0), height - 1)) * width];
+				window_preblur[i + radius] = color;
+				window[0] += color.r;
+				window[1] += color.g;
+				window[2] += color.b;
+			}
+
+			for(int y = area.y; y < area.y + area.height; y++) {
+				data[x + y * width] = {
+						(uint8_t) (window[0] / window_size),
+						(uint8_t) (window[1] / window_size),
+						(uint8_t) (window[2] / window_size),
+				};
+				auto window_add = data[x + (std::min(y + radius + 1, height - 1)) * width];
+				auto window_sub = window_preblur[preblur_index];
+				window_preblur[preblur_index] = window_add;
+				preblur_index++;
+				preblur_index %= window_size;
+				window[0] += (int) window_add.r - (int) window_sub.r;
+				window[1] += (int) window_add.g - (int) window_sub.g;
+				window[2] += (int) window_add.b - (int) window_sub.b;
+			}
+		}
+	};
+
+	for(int i = 0; i < 3; i++)
+		do_pass();
+}
+
 void Framebuffer::copy_tiled(const Framebuffer& other, Rect other_area, const Point& pos) const {
 	//Make sure self_area is in bounds of the framebuffer
 	Rect self_area = {pos.x, pos.y, other_area.width, other_area.height};