KWin does not require a decoration plugin any more

With config option "NoPlugin" in group "Style" it is possible to
no request that KWin should be run without a decoration plugin.
This is a change for Plasma Active to properly support no decorations.

As well if a decoration plugin cannot be loaded, KWin will no longer
exit, but continue to run just without a decoration. As a nice
side-effect changes in Oxygen no longer destroy my kwin build ;-)

BUG: 224440
FIXED-IN: 4.7.0
CCMAIL: sebas@kde.org

client.cpp

@@ -695,7 +695,7 @@ void Client::resizeDecoration(const QSize& s)
 
 bool Client::noBorder() const
 {
-    return noborder || isFullScreen();
+    return !workspace()->hasDecorationPlugin() || noborder || isFullScreen();
 }
 
 bool Client::userCanSetNoBorder() const

composite.cpp

@@ -319,8 +319,10 @@ void Workspace::suspendCompositing(bool suspend)
     finishCompositing();
     setupCompositing(); // will do nothing if suspended
     // notify decorations that composition state has changed
-    KDecorationFactory* factory = mgr->factory();
-    factory->reset(SettingCompositing);
+    if (hasDecorationPlugin()) {
+        KDecorationFactory* factory = mgr->factory();
+        factory->reset(SettingCompositing);
+    }
     emit compositingToggled(!compositingSuspended);
 }
 

libkdecorations/kdecoration_plugins_p.cpp

@@ -101,10 +101,14 @@ KDecoration* KDecorationPlugins::createDecoration(KDecorationBridge* bridge)
 // returns true if plugin was loaded successfully
 bool KDecorationPlugins::loadPlugin(QString nameStr)
 {
+    KConfigGroup group(config, QString("Style"));
     if (nameStr.isEmpty()) {
-        KConfigGroup group(config, QString("Style"));
         nameStr = group.readEntry("PluginLib", defaultPlugin);
     }
+    if (group.readEntry<bool>("NoPlugin", false)) {
+        error(i18n("Loading of window decoration plugin library disabled in configuration."));
+        return false;
+    }
 
     KLibrary *oldLibrary = library;
     KDecorationFactory* oldFactory = fact;

plugins.cpp

@@ -31,6 +31,7 @@ namespace KWin
 
 PluginMgr::PluginMgr()
     : KDecorationPlugins(KGlobal::config())
+    , m_noDecoration(false)
 {
     defaultPlugin = (QPixmap::defaultDepth() > 8) ?
                     "kwin3_oxygen" : "kwin3_plastik";
@@ -39,9 +40,9 @@ PluginMgr::PluginMgr()
 
 void PluginMgr::error(const QString &error_msg)
 {
-    qWarning("%s", (i18n("KWin: ") + error_msg +
-                    i18n("\nKWin will now exit...")).toLocal8Bit().data());
-    exit(1);
+    qWarning("%s", (i18n("KWin: ") + error_msg).toLocal8Bit().data());
+
+    setNoDecoration(true);
 }
 
 bool PluginMgr::provides(Requirement)
@@ -49,4 +50,14 @@ bool PluginMgr::provides(Requirement)
     return false;
 }
 
+void PluginMgr::setNoDecoration(bool noDecoration)
+{
+    m_noDecoration = noDecoration;
+}
+
+bool PluginMgr::hasNoDecoration() const
+{
+    return m_noDecoration;
+}
+
 } // namespace

plugins.h

@@ -33,8 +33,15 @@ class PluginMgr
 public:
     PluginMgr();
     virtual bool provides(Requirement);
+    /**
+     * @returns @c true if there is no decoration plugin.
+     **/
+    bool hasNoDecoration() const;
 protected:
     virtual void error(const QString& error_msg);
+private:
+    void setNoDecoration(bool noDecoration);
+    bool m_noDecoration;
 };
 
 } // namespace

workspace.cpp

@@ -355,7 +355,7 @@ void Workspace::init()
         ,
     };
 
-    if (mgr->factory()->supports(AbilityExtendIntoClientArea))
+    if (hasDecorationPlugin() && mgr->factory()->supports(AbilityExtendIntoClientArea))
         protocols[ NETRootInfo::PROTOCOLS2 ] |= NET::WM2FrameOverlap;
 
     QX11Info info;
@@ -1058,7 +1058,7 @@ void Workspace::slotReconfigure()
     forEachClient(CheckIgnoreFocusStealingProcedure());
     updateToolWindows(true);
 
-    if (mgr->reset(changed)) {
+    if (hasDecorationPlugin() && mgr->reset(changed)) {
         // Decorations need to be recreated
 
         // This actually seems to make things worse now
@@ -1140,7 +1140,11 @@ void Workspace::slotReconfigure()
     }
     // just so that we reset windows in the right manner, 'activate' the current active window
     notifyTilingWindowActivated(activeClient());
-    rootInfo->setSupported(NET::WM2FrameOverlap, mgr->factory()->supports(AbilityExtendIntoClientArea));
+    if (hasDecorationPlugin()) {
+        rootInfo->setSupported(NET::WM2FrameOverlap, mgr->factory()->supports(AbilityExtendIntoClientArea));
+    } else {
+        rootInfo->setSupported(NET::WM2FrameOverlap, false);
+    }
 }
 
 void Workspace::slotReinitCompositing()
@@ -1158,8 +1162,10 @@ void Workspace::slotReinitCompositing()
     compositingSuspended = false;
     options->compositingInitialized = false;
     setupCompositing();
-    KDecorationFactory* factory = mgr->factory();
-    factory->reset(SettingCompositing);
+    if (hasDecorationPlugin()) {
+        KDecorationFactory* factory = mgr->factory();
+        factory->reset(SettingCompositing);
+    }
 
     if (effects) { // setupCompositing() may fail
         effects->reconfigure();
@@ -2539,6 +2545,9 @@ int Workspace::topMenuHeight() const
 
 KDecoration* Workspace::createDecoration(KDecorationBridge* bridge)
 {
+    if (!hasDecorationPlugin()) {
+        return NULL;
+    }
     return mgr->createDecoration(bridge);
 }
 
@@ -2548,8 +2557,11 @@ KDecoration* Workspace::createDecoration(KDecorationBridge* bridge)
  */
 QList<int> Workspace::decorationSupportedColors() const
 {
-    KDecorationFactory* factory = mgr->factory();
     QList<int> ret;
+    if (!hasDecorationPlugin()) {
+        return ret;
+    }
+    KDecorationFactory* factory = mgr->factory();
     for (Ability ab = ABILITYCOLOR_FIRST;
             ab < ABILITYCOLOR_END;
             ab = static_cast<Ability>(ab + 1))

workspace.h

@@ -90,6 +90,7 @@ public:
     bool workspaceEvent(QEvent*);
 
     KDecoration* createDecoration(KDecorationBridge* bridge);
+    bool hasDecorationPlugin() const;
 
     bool hasClient(const Client*);
 
@@ -1307,28 +1308,51 @@ inline void Workspace::checkCompositeTimer()
         setCompositeTimer();
 }
 
+inline bool Workspace::hasDecorationPlugin() const
+{
+    if (!mgr) {
+        return false;
+    }
+    return !mgr->hasNoDecoration();
+}
+
 inline bool Workspace::hasDecorationShadows() const
 {
+    if (!hasDecorationPlugin()) {
+        return false;
+    }
     return mgr->factory()->supports(AbilityProvidesShadow);
 }
 
 inline bool Workspace::decorationHasAlpha() const
 {
+    if (!hasDecorationPlugin()) {
+        return false;
+    }
     return mgr->factory()->supports(AbilityUsesAlphaChannel);
 }
 
 inline bool Workspace::decorationSupportsClientGrouping() const
 {
+    if (!hasDecorationPlugin()) {
+        return false;
+    }
     return mgr->factory()->supports(AbilityClientGrouping);
 }
 
 inline bool Workspace::decorationSupportsFrameOverlap() const
 {
+    if (!hasDecorationPlugin()) {
+        return false;
+    }
     return mgr->factory()->supports(AbilityExtendIntoClientArea);
 }
 
 inline bool Workspace::decorationSupportsBlurBehind() const
 {
+    if (!hasDecorationPlugin()) {
+        return false;
+    }
     return mgr->factory()->supports(AbilityUsesBlurBehind);
 }