LibGfx: Allow for different {x,y}-radii in FastBoxBlurFilter

Use different specified radii for the two seperate passes.

The gaussian approximation is not changed to accept two parameters since
the math is not exactly straight forward and therefore something for a
later patch. For now, let's progress!

2 files changed, 24 insertions, 16 deletions

diff --git a/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.cpp b/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.cpp
index 57c632521e..7cbec6ea7c 100644
--- a/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.cpp
+++ b/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.cpp
@@ -28,9 +28,14 @@ FastBoxBlurFilter::FastBoxBlurFilter(Bitmap& bitmap)
 {
 }
 
-// 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)
 {
+    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)
+{
     auto format = m_bitmap.format();
     VERIFY(format == BitmapFormat::BGRA8888 || format == BitmapFormat::BGRx8888);
 
@@ -52,7 +57,8 @@ void FastBoxBlurFilter::apply_single_pass(size_t radius)
     int height = m_bitmap.height();
     int width = m_bitmap.width();
 
-    int div = 2 * radius + 1;
+    int div_x = 2 * radius_x + 1;
+    int div_y = 2 * radius_y + 1;
 
     Vector<u8, 1024> intermediate_red;
     Vector<u8, 1024> intermediate_green;
@@ -72,7 +78,7 @@ void FastBoxBlurFilter::apply_single_pass(size_t radius)
         size_t sum_alpha = 0;
 
         // Setup sliding window
-        for (int i = -(int)radius; i <= (int)radius; ++i) {
+        for (int i = -(int)radius_x; i <= (int)radius_x; ++i) {
             auto color_at_px = get_pixel_function(clamp(i, 0, width - 1), y);
             sum_red += red_value(color_at_px);
             sum_green += green_value(color_at_px);
@@ -81,13 +87,13 @@ void FastBoxBlurFilter::apply_single_pass(size_t radius)
         }
         // Slide horizontally
         for (int x = 0; x < width; ++x) {
-            intermediate_red[y * width + x] = (sum_red / div);
-            intermediate_green[y * width + x] = (sum_green / div);
-            intermediate_blue[y * width + x] = (sum_blue / div);
-            intermediate_alpha[y * width + x] = (sum_alpha / div);
+            intermediate_red[y * width + x] = (sum_red / div_x);
+            intermediate_green[y * width + x] = (sum_green / div_x);
+            intermediate_blue[y * width + x] = (sum_blue / div_x);
+            intermediate_alpha[y * width + x] = (sum_alpha / div_x);
 
-            auto leftmost_x_coord = max(x - (int)radius, 0);
-            auto rightmost_x_coord = min(x + (int)radius + 1, width - 1);
+            auto leftmost_x_coord = max(x - (int)radius_x, 0);
+            auto rightmost_x_coord = min(x + (int)radius_x + 1, width - 1);
 
             auto leftmost_x_color = get_pixel_function(leftmost_x_coord, y);
             auto rightmost_x_color = get_pixel_function(rightmost_x_coord, y);
@@ -111,7 +117,7 @@ void FastBoxBlurFilter::apply_single_pass(size_t radius)
         size_t sum_alpha = 0;
 
         // Setup sliding window
-        for (int i = -(int)radius; i <= (int)radius; ++i) {
+        for (int i = -(int)radius_y; i <= (int)radius_y; ++i) {
             int offset = clamp(i, 0, height - 1) * width + x;
             sum_red += intermediate_red[offset];
             sum_green += intermediate_green[offset];
@@ -121,15 +127,15 @@ void FastBoxBlurFilter::apply_single_pass(size_t radius)
 
         for (int y = 0; y < height; ++y) {
             auto color = Color(
-                sum_red / div,
-                sum_green / div,
-                sum_blue / div,
-                sum_alpha / div);
+                sum_red / div_y,
+                sum_green / div_y,
+                sum_blue / div_y,
+                sum_alpha / div_y);
 
             set_pixel_function(x, y, color);
 
-            auto topmost_y_coord = max(y - (int)radius, 0);
-            auto bottommost_y_coord = min(y + (int)radius + 1, height - 1);
+            auto topmost_y_coord = max(y - (int)radius_y, 0);
+            auto bottommost_y_coord = min(y + (int)radius_y + 1, height - 1);
 
             sum_red += intermediate_red[x + bottommost_y_coord * width];
             sum_red -= intermediate_red[x + topmost_y_coord * width];
diff --git a/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.h b/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.h
index 57a6fd9c78..3536776298 100644
--- a/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.h
+++ b/Userland/Libraries/LibGfx/Filters/FastBoxBlurFilter.h
@@ -15,6 +15,8 @@ public:
     FastBoxBlurFilter(Bitmap&);
 
     void apply_single_pass(size_t radius);
+    void apply_single_pass(size_t radius_x, size_t radius_y);
+
     void apply_three_passes(size_t radius);
 
 private: