[effects/desktopgrid] Enable blur behind windows

Summary: Use the blur effect even when the desktop grid is used.

Test Plan: {F5828458}

Reviewers: davidedmundson, fredrik, #vdg, #kwin, graesslin, ngraham

Reviewed By: #vdg, #kwin, graesslin, ngraham

Subscribers: graesslin, kwin, #kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D12620

effects/desktopgrid/desktopgrid.cpp

@@ -162,6 +162,12 @@ void DesktopGridEffect::prePaintScreen(ScreenPrePaintData& data, int time)
         if (!activated && timeline.currentValue() == 0 && !(isUsingPresentWindows() && isMotionManagerMovingWindows()))
             finish();
     }
+
+    for (auto const &w : effects->stackingOrder()) {
+        m_windowForceBlurRoleState[w] = w->data(WindowForceBlurRole).toBool();
+        w->setData(WindowForceBlurRole, QVariant(true));
+    }
+
     effects->prePaintScreen(data, time);
 }
 
@@ -249,6 +255,11 @@ void DesktopGridEffect::postPaintScreen()
             }
         }
     }
+
+    for (auto &w : effects->stackingOrder()) {
+        w->setData(WindowForceBlurRole, m_windowForceBlurRoleState.value(w, false));
+    }
+
     effects->postPaintScreen();
 }
 

effects/desktopgrid/desktopgrid.h

@@ -175,6 +175,9 @@ private:
     // Shortcut - needed to toggle the effect
     QList<QKeySequence> shortcut;
 
+    // State of WindowForceBlurRole before this effect
+    QMap <EffectWindow*, bool> m_windowForceBlurRoleState;
+
     PresentWindowsEffectProxy* m_proxy;
     QList<WindowMotionManager> m_managers;
     bool m_usePresentWindows;