add support for graphicssystem selection

REVIEW: 103430
CCBUG: 289904
(cherry picked from commit ded4ed4e9dc32316c41a43b6e906bece4b92338f)

composite.cpp

@@ -232,8 +232,17 @@ void Workspace::finishCompositing()
 void Workspace::fallbackToXRenderCompositing()
 {
     finishCompositing();
-    options->compositingMode = XRenderCompositing;
-    setupCompositing();
+    KConfigGroup config(KSharedConfig::openConfig("kwinrc"), "Compositing");
+    config.writeEntry("Backend", "XRender");
+    config.writeEntry("GraphicsSystem", "native");
+    config.sync();
+    if (Extensions::nonNativePixmaps()) { // must restart to change the graphicssystem
+        restartKWin("automatic graphicssystem change for XRender backend");
+        return;
+    } else {
+        options->compositingMode = XRenderCompositing;
+        setupCompositing();
+    }
 }
 
 void Workspace::lostCMSelection()

libkwineffects/kwinglobals.cpp

@@ -134,7 +134,8 @@ void Extensions::init()
     kDebug(1212) << "Extensions: shape: 0x" << QString::number(shape_version, 16)
                  << " composite: 0x" << QString::number(composite_version, 16)
                  << " render: 0x" << QString::number(render_version, 16)
-                 << " fixes: 0x" << QString::number(fixes_version, 16) << endl;
+                 << " fixes: 0x" << QString::number(fixes_version, 16)
+                 << " non_native_pixmaps: " << non_native_pixmaps << endl;
 }
 
 void Extensions::fillExtensionsData(const char**& extensions, int& nextensions, int*&opcodes, int*& error_bases)

main.cpp

@@ -409,6 +409,22 @@ KDE_EXPORT int kdemain(int argc, char * argv[])
 
     KWorkSpace::trimMalloc();
 
+    // the raster graphicssystem has a quite terrible performance on the XRender backend or when not
+    // compositing at all while some to many decorations suffer from bad performance of the native
+    // graphicssystem (lack of implementation, QGradient internally uses the raster system and
+    // XPutImage's the result because some graphics drivers have insufficient or bad performing
+    // implementations of XRenderCreate*Gradient)
+    //
+    // Therefore we allow configurationa and do some automagic selection to discourage
+    // ""known to be stupid" ideas ;-P
+    // The invalid system parameter "" will use the systems default graphicssystem
+    // "!= XRender" is intended since eg. pot. SW backends likely would profit from raster as well
+    KConfigGroup config(KSharedConfig::openConfig("kwinrc"), "Compositing");
+    QString preferredSystem("native");
+    if (config.readEntry("Enabled", true) && config.readEntry("Backend", "OpenGL") != "XRender")
+        preferredSystem = "";
+    QApplication::setGraphicsSystem(config.readEntry("GraphicsSystem", preferredSystem));
+
     Display* dpy = XOpenDisplay(NULL);
     if (!dpy) {
         fprintf(stderr, "%s: FATAL ERROR while trying to open display %s\n",

workspace.cpp

@@ -1044,10 +1044,24 @@ void Workspace::slotReconfigure()
     }
 }
 
+void Workspace::restartKWin(const QString &reason)
+{
+    kDebug(1212) << "restarting kwin for:" << reason;
+    char cmd[1024]; // copied from crashhandler - maybe not the best way to do?
+    sprintf(cmd, "%s --replace &", QFile::encodeName(QCoreApplication::applicationFilePath()).constData());
+    system(cmd);
+}
+
 void Workspace::slotReinitCompositing()
 {
     // Reparse config. Config options will be reloaded by setupCompositing()
     KGlobal::config()->reparseConfiguration();
+    const QString graphicsSystem = KConfigGroup(KSharedConfig::openConfig("kwinrc"), "Compositing").readEntry("GraphicsSystem", "");
+    if ((Extensions::nonNativePixmaps() && graphicsSystem == "native") ||
+        (!Extensions::nonNativePixmaps() && (graphicsSystem == "raster" || graphicsSystem == "raster")) ) {
+        restartKWin("explicitly reconfigured graphicsSystem change");
+        return;
+    }
 
     // Update any settings that can be set in the compositing kcm.
 #ifdef KWIN_BUILD_SCREENEDGES

workspace.h

@@ -702,6 +702,7 @@ private:
     void initShortcuts();
     void initDesktopPopup();
     void initActivityPopup();
+    void restartKWin(const QString &reason);
     void discardPopup();
     void setupWindowShortcut(Client* c);
     void checkCursorPos();