Blur game covers properly

data/gtk/style.css

@@ -9,4 +9,9 @@
     color: @light_1;
     background-color: @dark_5;
     opacity: 0.8;
+}
+
+/* This is to hide a weird GdkPixbuf upscaling glitch */
+#details_view_blurred_cover {
+    transform: scale(1.2);
 }

data/gtk/window.blp

@@ -35,6 +35,7 @@ template CartridgesWindow : Adw.ApplicationWindow {
 
       Overlay details_view {
         name: "details_view";
+        overflow: hidden;
 
         [overlay]
         Box details_view_box {
@@ -219,6 +220,7 @@ template CartridgesWindow : Adw.ApplicationWindow {
         }
 
         Picture details_view_blurred_cover {
+          name: "details_view_blurred_cover";
           keep-aspect-ratio: false;
         }
       }

src/game_cover.py

@@ -18,10 +18,13 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 from gi.repository import GdkPixbuf, Gio, GLib
+from PIL import Image, ImageFilter, ImageStat
 
 
 class GameCover:
     pixbuf = None
+    blurred = None
+    luminance = None
     path = None
     animation = None
     anim_iter = None
@@ -47,6 +50,8 @@ class GameCover:
     def new_cover(self, path=None):
         self.animation = None
         self.pixbuf = None
+        self.blurred = None
+        self.luminance = None
         self.path = path
 
         if path:
@@ -62,6 +67,36 @@ class GameCover:
     def get_pixbuf(self):
         return self.animation.get_static_image() if self.animation else self.pixbuf
 
+    def get_blurred(self):
+        if not self.blurred:
+            if self.path:
+                with Image.open(self.path) as image:
+                    image = (
+                        image.convert("RGB")
+                        .resize((8, 12))
+                        .filter(ImageFilter.GaussianBlur(3))
+                    )
+
+                    tmp_path = Gio.File.new_tmp(None)[0].get_path()
+                    image.save(tmp_path, "tiff", compression=None)
+
+                    self.blurred = GdkPixbuf.Pixbuf.new_from_file(tmp_path)
+
+                    stat = ImageStat.Stat(image.convert("L"))
+
+                    self.luminance = (
+                        (stat.mean[0] + stat.extrema[0][0]) / 510,
+                        (stat.mean[0] + stat.extrema[0][1]) / 510,
+                    )
+            else:
+                self.blurred = GdkPixbuf.Pixbuf.new_from_resource_at_scale(
+                    "/hu/kramo/Cartridges/library_placeholder.svg", 2, 3, False
+                )
+
+                self.luminance = (0.5, 0.5)
+
+        return self.blurred
+
     def add_picture(self, picture):
         self.pictures.add(picture)
         if not self.animation:

src/window.py

@@ -21,9 +21,8 @@ import json
 import os
 from datetime import datetime
 from pathlib import Path
-from struct import unpack_from
 
-from gi.repository import Adw, Gdk, GdkPixbuf, Gio, GLib, Gtk
+from gi.repository import Adw, Gdk, Gio, GLib, Gtk
 
 from .game import Game
 
@@ -71,7 +70,6 @@ class CartridgesWindow(Adw.ApplicationWindow):
     game_covers = {}
     toasts = {}
     active_game = None
-    scaled_pixbuf = None
     details_view_game_cover = None
     sort_state = "a-z"
 
@@ -236,11 +234,9 @@ class CartridgesWindow(Adw.ApplicationWindow):
         self.details_view_game_cover = game.game_cover
         self.details_view_game_cover.add_picture(self.details_view_cover)
 
-        self.scaled_pixbuf = (
-            self.details_view_game_cover.get_pixbuf()
-            or self.details_view_game_cover.placeholder_pixbuf
-        ).scale_simple(2, 3, GdkPixbuf.InterpType.BILINEAR)
-        self.details_view_blurred_cover.set_pixbuf(self.scaled_pixbuf)
+        self.details_view_blurred_cover.set_pixbuf(
+            self.details_view_game_cover.get_blurred()
+        )
 
         self.details_view_title.set_label(game.name)
         self.details_view_header_bar_title.set_title(game.name)
@@ -274,33 +270,12 @@ class CartridgesWindow(Adw.ApplicationWindow):
                 self.details_view_blurred_cover.set_opacity(0.3)
                 return
 
-            colors = {
-                unpack_from(
-                    "BBBB",
-                    self.scaled_pixbuf.get_pixels(),
-                    offset=index * self.scaled_pixbuf.get_n_channels(),
-                )
-                for index in range(6)
-            }
-
             dark_theme = style_manager.get_dark()
 
-            luminances = []
-
-            for red, green, blue, alpha in colors:
-                # https://en.wikipedia.org/wiki/Relative_luminance
-                luminance = red * 0.2126 + green * 0.7152 + blue * 0.0722
-
-                luminances.append(
-                    (luminance * alpha) / 255**2
-                    if dark_theme
-                    else (alpha * (luminance - 255)) / 255**2 + 1
-                )
-
             self.details_view_blurred_cover.set_opacity(
-                1.3 - (sum(luminances) / len(luminances) + max(luminances)) / 2
+                1.2 - self.details_view_game_cover.luminance[0]
                 if dark_theme
-                else 0.2 + (sum(luminances) / len(luminances) + min(luminances)) / 2
+                else 0.2 + self.details_view_game_cover.luminance[1]
             )
 
     def sort_func(self, child1, child2):