Add OnScreenDisplayLayer which is placed even ontop of the active fullscreen window

It is to be used for volume change feedback and similar confirmation popups

REVIEW: 121300

client.cpp

@@ -625,6 +625,7 @@ void Client::detectNoBorder()
     case NET::TopMenu :
     case NET::Splash :
     case NET::Notification :
+    case NET::OnScreenDisplay :
         noborder = true;
         app_noborder = true;
         break;

layers.cpp

@@ -39,11 +39,13 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
  the clients were created.
 
  Every window has one layer assigned in which it is. There are 7 layers,
- from bottom : DesktopLayer, BelowLayer, NormalLayer, DockLayer, AboveLayer, NotificationLayer
- and ActiveLayer (see also NETWM sect.7.10.). The layer a window is in depends
+ from bottom : DesktopLayer, BelowLayer, NormalLayer, DockLayer, AboveLayer, NotificationLayer,
+ ActiveLayer and OnScreenDisplayLayer (see also NETWM sect.7.10.). The layer a window is in depends
  on the window type, and on other things like whether the window is active. We extend the layers
- provided in NETWM by the NotificationLayer, which contains notification windows. Those are kept
- above all windows except the active fullscreen window.
+ provided in NETWM by the NotificationLayer and OnScreenDisplayLayer.
+ The NoficationLayer contains notification windows which are kept above all windows except the active
+ fullscreen window. The OnScreenDisplayLayer is used for eg. volume and brightness change feedback and
+ is kept above all windows since it provides immediate response to a user action.
 
  NET::Splash clients belong to the Normal layer. NET::TopMenu clients
  belong to Dock layer. Clients that are both NET::Dock and NET::KeepBelow
@@ -826,6 +828,8 @@ Layer Client::belongsToLayer() const
             return AboveLayer;
         return DockLayer;
     }
+    if (isOnScreenDisplay())
+        return OnScreenDisplayLayer;
     if (isNotification())
         return NotificationLayer;
     if (keepBelow())
@@ -834,6 +838,7 @@ Layer Client::belongsToLayer() const
         return ActiveLayer;
     if (keepAbove())
         return AboveLayer;
+
     return NormalLayer;
 }
 

placement.cpp

@@ -70,8 +70,8 @@ void Placement::place(Client* c, QRect& area)
         placeDialog(c, area, options->placement());
     else if (c->isSplash())
         placeOnMainWindow(c, area);   // on mainwindow, if any, otherwise centered
-    else if (c->isNotification())
-        placeNotification(c, area);
+    else if (c->isOnScreenDisplay() || c->isNotification())
+        placeOnScreenDisplay(c, area);
     else
         place(c, area, options->placement());
 }
@@ -483,7 +483,7 @@ void Placement::placeUtility(Client* c, QRect& area, Policy /*next*/)
     place(c, area, Default);
 }
 
-void Placement::placeNotification(Client* c, QRect& area)
+void Placement::placeOnScreenDisplay(Client* c, QRect& area)
 {
     // place at lower 1/3 of the screen
     const int x = area.left() + (area.width() -  c->width())  / 2;

placement.h

@@ -71,7 +71,7 @@ public:
     void placeZeroCornered(Client* c, const QRect& area, Policy next = Unknown);
     void placeDialog(Client* c, QRect& area, Policy next = Unknown);
     void placeUtility(Client* c, QRect& area, Policy next = Unknown);
-    void placeNotification(Client* c, QRect& area);
+    void placeOnScreenDisplay(Client* c, QRect& area);
 
     void reinitCascading(int desktop);
 

toplevel.h

@@ -148,6 +148,10 @@ class Toplevel
      * See _NET_WM_WINDOW_TYPE_NOTIFICATION at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
     Q_PROPERTY(bool notification READ isNotification)
+    /**
+     * Returns whether the window is an On Screen Display.
+     */
+    Q_PROPERTY(bool onScreenDisplay READ isOnScreenDisplay)
     /**
      * Returns whether the window is a combobox popup.
      * See _NET_WM_WINDOW_TYPE_COMBO at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
@@ -222,6 +226,7 @@ public:
     bool isPopupMenu() const; // a context popup, not dropdown, not torn-off
     bool isTooltip() const;
     bool isNotification() const;
+    bool isOnScreenDisplay() const;
     bool isComboBox() const;
     bool isDNDIcon() const;
 
@@ -583,6 +588,11 @@ inline bool Toplevel::isNotification() const
     return windowType() == NET::Notification;
 }
 
+inline bool Toplevel::isOnScreenDisplay() const
+{
+    return windowType() == NET::OnScreenDisplay;
+}
+
 inline bool Toplevel::isComboBox() const
 {
     return windowType() == NET::ComboBox;

utils.h

@@ -44,12 +44,12 @@ namespace KWin
 // window types that are supported as normal windows (i.e. KWin actually manages them)
 const NET::WindowTypes SUPPORTED_MANAGED_WINDOW_TYPES_MASK = NET::NormalMask | NET::DesktopMask | NET::DockMask
         | NET::ToolbarMask | NET::MenuMask | NET::DialogMask /*| NET::OverrideMask*/ | NET::TopMenuMask
-        | NET::UtilityMask | NET::SplashMask | NET::NotificationMask;
+        | NET::UtilityMask | NET::SplashMask | NET::NotificationMask | NET::OnScreenDisplayMask;
 // window types that are supported as unmanaged (mainly for compositing)
 const NET::WindowTypes SUPPORTED_UNMANAGED_WINDOW_TYPES_MASK = NET::NormalMask | NET::DesktopMask | NET::DockMask
         | NET::ToolbarMask | NET::MenuMask | NET::DialogMask /*| NET::OverrideMask*/ | NET::TopMenuMask
         | NET::UtilityMask | NET::SplashMask | NET::DropdownMenuMask | NET::PopupMenuMask
-        | NET::TooltipMask | NET::NotificationMask | NET::ComboBoxMask | NET::DNDIconMask;
+        | NET::TooltipMask | NET::NotificationMask | NET::ComboBoxMask | NET::DNDIconMask | NET::OnScreenDisplayMask;
 
 const QPoint invalidPoint(INT_MIN, INT_MIN);
 
@@ -80,6 +80,7 @@ enum Layer {
     AboveLayer,
     NotificationLayer, // layer for windows of type notification
     ActiveLayer, // active fullscreen, or active dialog
+    OnScreenDisplayLayer, // layer for On Screen Display windows such as volume feedback
     UnmanagedLayer, // layer for override redirect windows.
     NumLayers // number of layers, must be last
 };