From 30a0ed66780250edcb7cb4f2b6bd35a3b08af749 Mon Sep 17 00:00:00 2001
From: MacDue <macdue@dueutil.tech>
Date: Mon, 20 Jun 2022 12:23:57 +0100
Subject: [PATCH] LibGfx: Avoid AK::Function indirection in FastBoxBlurFilter +
 flatten it

This dropped a few percent when profiling Lubrsi's test.
---
 .../LibGfx/Filters/FastBoxBlurFilter.cpp      | 49 ++++++++++---------
 1 file changed, 26 insertions(+), 23 deletions(-)

diff --git a/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.cpp b/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.cpp
index 7cbec6ea7c..66f18136ff 100644
--- a/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.cpp
+++ b/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.cpp
@@ -33,30 +33,9 @@ void FastBoxBlurFilter::apply_single_pass(size_t radius)
     apply_single_pass(radius, radius);
 }
 
-// Based on the super fast blur algorithm by Quasimondo, explored here: https://stackoverflow.com/questions/21418892/understanding-super-fast-blur-algorithm
-void FastBoxBlurFilter::apply_single_pass(size_t radius_x, size_t radius_y)
+template<typename GetPixelFunction, typename SetPixelFunction>
+static void do_single_pass(int width, int height, size_t radius_x, size_t radius_y, GetPixelFunction get_pixel_function, SetPixelFunction set_pixel_function)
 {
-    auto format = m_bitmap.format();
-    VERIFY(format == BitmapFormat::BGRA8888 || format == BitmapFormat::BGRx8888);
-
-    Function<Color(int, int)> get_pixel_function;
-    Function<void(int, int, Color)> set_pixel_function;
-    switch (format) {
-    case BitmapFormat::BGRx8888:
-        get_pixel_function = [&](int x, int y) { return m_bitmap.get_pixel<StorageFormat::BGRx8888>(x, y); };
-        set_pixel_function = [&](int x, int y, Color color) { return m_bitmap.set_pixel<StorageFormat::BGRx8888>(x, y, color); };
-        break;
-    case BitmapFormat::BGRA8888:
-        get_pixel_function = [&](int x, int y) { return m_bitmap.get_pixel<StorageFormat::BGRA8888>(x, y); };
-        set_pixel_function = [&](int x, int y, Color color) { return m_bitmap.set_pixel<StorageFormat::BGRA8888>(x, y, color); };
-        break;
-    default:
-        VERIFY_NOT_REACHED();
-    }
-
-    int height = m_bitmap.height();
-    int width = m_bitmap.width();
-
     int div_x = 2 * radius_x + 1;
     int div_y = 2 * radius_y + 1;
 
@@ -149,6 +128,30 @@ void FastBoxBlurFilter::apply_single_pass(size_t radius_x, size_t radius_y)
     }
 }
 
+// Based on the super fast blur algorithm by Quasimondo, explored here: https://stackoverflow.com/questions/21418892/understanding-super-fast-blur-algorithm
+FLATTEN void FastBoxBlurFilter::apply_single_pass(size_t radius_x, size_t radius_y)
+{
+    auto format = m_bitmap.format();
+    VERIFY(format == BitmapFormat::BGRA8888 || format == BitmapFormat::BGRx8888);
+
+    switch (format) {
+    case BitmapFormat::BGRx8888:
+        do_single_pass(
+            m_bitmap.width(), m_bitmap.height(), radius_x, radius_y,
+            [&](int x, int y) { return m_bitmap.get_pixel<StorageFormat::BGRx8888>(x, y); },
+            [&](int x, int y, Color color) { return m_bitmap.set_pixel<StorageFormat::BGRx8888>(x, y, color); });
+        break;
+    case BitmapFormat::BGRA8888:
+        do_single_pass(
+            m_bitmap.width(), m_bitmap.height(), radius_x, radius_y,
+            [&](int x, int y) { return m_bitmap.get_pixel<StorageFormat::BGRA8888>(x, y); },
+            [&](int x, int y, Color color) { return m_bitmap.set_pixel<StorageFormat::BGRA8888>(x, y, color); });
+        break;
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
 // Math from here: http://blog.ivank.net/fastest-gaussian-blur.html
 void FastBoxBlurFilter::apply_three_passes(size_t radius)
 {