feat: Add 'Average image colour' background fill mode

src/config/ui_preferences_display_background.cpp

@@ -40,6 +40,7 @@ static const cfg_auto_combo_option<BackgroundFillType> g_background_fill_options
     { _T("Default"), BackgroundFillType::Default },
     { _T("Solid colour"), BackgroundFillType::SolidColour },
     { _T("Gradient"), BackgroundFillType::Gradient },
+    { _T("Average image colour"), BackgroundFillType::AverageImageColor },
 };
 
 static const cfg_auto_combo_option<BackgroundImageType> g_background_image_options[] = {
@@ -48,7 +49,7 @@ static const cfg_auto_combo_option<BackgroundImageType> g_background_image_optio
     { _T("Custom image"), BackgroundImageType::CustomImage },
 };
 
-static cfg_auto_combo<BackgroundFillType, 3> cfg_background_fill_type(GUID_CFG_BACKGROUND_MODE,
+static cfg_auto_combo<BackgroundFillType, 4> cfg_background_fill_type(GUID_CFG_BACKGROUND_MODE,
                                                                       IDC_BACKGROUND_FILL_TYPE,
                                                                       BackgroundFillType::Default,
                                                                       g_background_fill_options);

src/img_processing.cpp

@@ -370,6 +370,41 @@ void transpose_image_noalloc(int width, int height, const uint8_t* in_pixels, ui
             }
         }
     }
+
+RGBAColour compute_average_colour(const Image& img)
+{
+    if(!img.valid())
+    {
+        return {};
+    }
+
+    uint64_t total_r = 0;
+    uint64_t total_g = 0;
+    uint64_t total_b = 0;
+
+    for(int y=0; y<img.height; y++)
+    {
+        for(int x=0; x<img.width; x++)
+        {
+            uint8_t* px = img.pixels + (y * img.width + x) * 4;
+            total_r += px[0];
+            total_g += px[1];
+            total_b += px[2];
+        }
+    }
+
+    const uint64_t num_pixels = img.width * img.height;
+    if(num_pixels == 0)
+    {
+        return {};
+    }
+
+    uint8_t avg_r = (uint8_t)(total_r / num_pixels);
+    uint8_t avg_g = (uint8_t)(total_g / num_pixels);
+    uint8_t avg_b = (uint8_t)(total_b / num_pixels);
+
+    return {avg_r, avg_g, avg_b, 255};
+}
 }
 Image transpose_image(const Image& img)
 {
@@ -526,6 +561,37 @@ static void boxblur_horizontal_noalloc(int width, int height, const uint8_t* in_
         }
     }
 }
+
+RGBAColour compute_average_colour(const Image& img)
+{
+    if(!img.valid())
+    {
+        return {};
+    }
+
+    uint64_t total_r = 0;
+    uint64_t total_g = 0;
+    uint64_t total_b = 0;
+
+    for(int y=0; y<img.height; y++)
+    {
+        for(int x=0; x<img.width; x++)
+        {
+            uint8_t* px = img.pixels + (y * img.width + x) * 4;
+            total_r += px[0];
+            total_g += px[1];
+            total_b += px[2];
+        }
+    }
+
+    const uint64_t num_pixels = img.width * img.height;
+    uint8_t avg_r = (uint8_t)(total_r / num_pixels);
+    uint8_t avg_g = (uint8_t)(total_g / num_pixels);
+    uint8_t avg_b = (uint8_t)(total_b / num_pixels);
+
+    return {avg_r, avg_g, avg_b, 255};
+}
+
 static Image image_boxblur_linear_horizontal(const Image& img, int radius)
 {
     uint8_t* pixels = (uint8_t*)malloc(img.width * img.height * 4);

src/img_processing.h

@@ -43,6 +43,7 @@ Image lerp_image(const Image& lhs, const Image& rhs, double t);
 Image lerp_offset_image(const Image& full_img, const Image& offset_img, CPoint offset, double t);
 Image resize_image(const Image& input, int out_width, int out_height);
 Image transpose_image(const Image& input);
+RGBAColour compute_average_colour(const Image& img);
 Image blur_image(const Image& input, int radius);
 
 void toggle_image_rgba_bgra_inplace(Image& img);

src/preferences.h

@@ -57,6 +57,7 @@ enum class BackgroundFillType : int
     Default = 0,
     SolidColour = 1,
     Gradient = 2,
+    AverageImageColor = 3,
 };
 
 enum class BackgroundImageType : int

src/ui_lyrics_panel.cpp

@@ -143,6 +143,7 @@ void LyricPanel::compute_background_image()
     }
 
     Image bg_colour = {};
+    const BackgroundImageType img_type = preferences::background::image_type();
     switch(preferences::background::fill_type())
     {
         case BackgroundFillType::Default:
@@ -173,10 +174,24 @@ void LyricPanel::compute_background_image()
                                                    botleft,
                                                    botright);
         }
+        break;
+
+        case BackgroundFillType::AverageImageColor:
+        {
+            RGBAColour colour = from_colorref(defaultui::background_colour());
+            if(img_type == BackgroundImageType::AlbumArt)
+            {
+                colour = compute_average_colour(m_albumart_original);
+            }
+            else if(img_type == BackgroundImageType::CustomImage)
+            {
+                colour = compute_average_colour(m_custom_img_original);
+            }
+            bg_colour = generate_background_colour(client_rect.Width(), client_rect.Height(), colour);
+        }
         break;
     }
 
-    const BackgroundImageType img_type = preferences::background::image_type();
     if(img_type == BackgroundImageType::None)
     {
         m_background_img = std::move(bg_colour);