homescreens/folio: Use MultiEffect for blur and blur behind task switcher

components/mobileshell/qml/homescreen/HomeScreen.qml

@@ -59,6 +59,11 @@ Item {
     property real leftMargin
     property real rightMargin
 
+    /**
+     * The opacity value that the homescreen content gets.
+     */
+    readonly property real contentOpacity: itemContainer.opacity
+
     function evaluateMargins() {
         topMargin = plasmoidItem.availableScreenRect.y
         bottomMargin = root.height - (plasmoidItem.availableScreenRect.y + plasmoidItem.availableScreenRect.height)

containments/homescreens/folio/package/contents/ui/main.qml

@@ -1,9 +1,10 @@
 // SPDX-FileCopyrightText: 2023 Devin Lin <devin@kde.org>
 // SPDX-License-Identifier: LGPL-2.0-or-later
 
-import QtQuick 2.15
-import QtQuick.Window 2.15
-import QtQuick.Layouts 1.1
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Effects
 
 import org.kde.kirigami 2.20 as Kirigami
 
@@ -15,8 +16,6 @@ import org.kde.plasma.private.mobileshell.state as MobileShellState
 import org.kde.private.mobile.homescreen.folio 1.0 as Folio
 import org.kde.plasma.private.mobileshell.windowplugin as WindowPlugin
 
-import Qt5Compat.GraphicalEffects
-
 ContainmentItem {
     id: root
 
@@ -31,11 +30,14 @@ ContainmentItem {
     }
 
     // wallpaper blur
-    FastBlur {
-        radius: 50
+    MultiEffect {
+        blurEnabled: true
+        blur: 1.0
+        blurMax: 50
         source: Plasmoid.wallpaperGraphicsObject
         anchors.fill: parent
         opacity: Math.max(
+            1 - homeScreen.contentOpacity,
             Folio.HomeScreenState.appDrawerOpenProgress, 
             Folio.HomeScreenState.searchWidgetOpenProgress, 
             Folio.HomeScreenState.folderOpenProgress