Disable PaintRedirector when non-composited

Without Compositing we do not really need the PaintRedirector,
it only adds overhead. This reverts the behavior to how it was before
the PaintRedirector was introduced by just not redirecting the paint
in the event filter when compositing is not active. This should have
the lowest impact on the existing source base.

The change breaks at least oxygen window decoration when compositing
is not active as the decoration is no longer double buffered. But
as written this is exactly the behavior as used before 4.3. Given
the push today there should be enough time for all affected decos
to adjust to the change.

REVIEW: 101413

client.cpp

@@ -500,8 +500,7 @@ void Client::repaintDecorationPending()
         const QRegion r = paintRedirector->scheduledRepaintRegion();
         if (!r.isEmpty())
             Workspace::self()->addRepaint(r.translated(x() - padding_left, y() - padding_top));
-    } else
+    }
-        ensureDecorationPixmapsPainted();
 }
 
 bool Client::decorationPixmapRequiresRepaint()
@@ -514,7 +513,7 @@ bool Client::decorationPixmapRequiresRepaint()
 
 void Client::ensureDecorationPixmapsPainted()
 {
-    if (!paintRedirector)
+    if (!paintRedirector || !compositing())
         return;
 
     QRegion r = paintRedirector->pendingRegion();
@@ -531,42 +530,7 @@ void Client::ensureDecorationPixmapsPainted()
     repaintDecorationPixmap(decorationPixmapTop, tr, p, r);
     repaintDecorationPixmap(decorationPixmapBottom, br, p, r);
 
-    if (!compositing()) {
+    XSync(display(), false);
-        // Blit the pixmaps to the frame window
-        layoutDecorationRects(lr, tr, rr, br, WindowRelative);
-#ifdef HAVE_XRENDER
-        if (Extensions::renderAvailable()) {
-            XRenderPictFormat* format = XRenderFindVisualFormat(display(), visual());
-            XRenderPictureAttributes pa;
-            pa.subwindow_mode = IncludeInferiors;
-            Picture pic = XRenderCreatePicture(display(), frameId(), format, CPSubwindowMode, &pa);
-            XRenderComposite(display(), PictOpSrc, decorationPixmapLeft.x11PictureHandle(), None, pic,
-                             0, 0, 0, 0, lr.x(), lr.y(), lr.width(), lr.height());
-            XRenderComposite(display(), PictOpSrc, decorationPixmapRight.x11PictureHandle(), None, pic,
-                             0, 0, 0, 0, rr.x(), rr.y(), rr.width(), rr.height());
-            XRenderComposite(display(), PictOpSrc, decorationPixmapTop.x11PictureHandle(), None, pic,
-                             0, 0, 0, 0, tr.x(), tr.y(), tr.width(), tr.height());
-            XRenderComposite(display(), PictOpSrc, decorationPixmapBottom.x11PictureHandle(), None, pic,
-                             0, 0, 0, 0, br.x(), br.y(), br.width(), br.height());
-            XRenderFreePicture(display(), pic);   // TODO don't recreate pictures all the time?
-        } else
-#endif
-        {
-            XGCValues values;
-            values.subwindow_mode = IncludeInferiors;
-            GC gc = XCreateGC(display(), rootWindow(), GCSubwindowMode, &values);
-            XCopyArea(display(), decorationPixmapLeft.handle(), frameId(), gc, 0, 0,
-                      lr.width(), lr.height(), lr.x(), lr.y());
-            XCopyArea(display(), decorationPixmapRight.handle(), frameId(), gc, 0, 0,
-                      rr.width(), rr.height(), rr.x(), rr.y());
-            XCopyArea(display(), decorationPixmapTop.handle(), frameId(), gc, 0, 0,
-                      tr.width(), tr.height(), tr.x(), tr.y());
-            XCopyArea(display(), decorationPixmapBottom.handle(), frameId(), gc, 0, 0,
-                      br.width(), br.height(), br.x(), br.y());
-            XFreeGC(display(), gc);
-        }
-    } else
-        XSync(display(), false);
 }
 
 void Client::repaintDecorationPixmap(QPixmap& pix, const QRect& r, const QPixmap& src, QRegion reg)
@@ -587,6 +551,11 @@ void Client::repaintDecorationPixmap(QPixmap& pix, const QRect& r, const QPixmap
 
 void Client::resizeDecorationPixmaps()
 {
+    if (!compositing()) {
+        // compositing disabled - we render directly on screen
+        triggerDecorationRepaint();
+        return;
+    }
     QRect lr, rr, tr, br;
     layoutDecorationRects(lr, tr, rr, br, DecorationRelative);
 

paintredirector.cpp

@@ -28,6 +28,7 @@ DEALINGS IN THE SOFTWARE.
 #include <qevent.h>
 #include <qpainter.h>
 #include <qmath.h>
+#include "utils.h"
 
 namespace KWin
 {
@@ -83,6 +84,9 @@ bool PaintRedirector::eventFilter(QObject* o, QEvent* e)
         break;
     }
     case QEvent::Paint: {
+        if (!compositing()) {
+            return false;
+        }
         if (!recursionCheck) {
             QPaintEvent* pe = static_cast< QPaintEvent* >(e);
             QWidget* w = static_cast< QWidget* >(o);