Don't bind the FBO if it's possible it won't get painted and unbound. That

could lead the the screen freezing while fullscreen windows are open. (LP: #1024911) Fixes LP: #1024911 (bzr r2501.2.1)

2 files changed, 45 insertions, 2 deletions

diff --git a/plugins/unityshell/src/unityshell.cpp b/plugins/unityshell/src/unityshell.cpp
index 34ad8880a..da6886a3b 100644
--- a/plugins/unityshell/src/unityshell.cpp
+++ b/plugins/unityshell/src/unityshell.cpp
@@ -1202,6 +1202,42 @@ void UnityWindow::handleEvent (XEvent *event)
 }
 }
 
+bool UnityScreen::shellCouldBeHidden(CompOutput const& output)
+{
+ std::vector<Window> const& nuxwins(nux::XInputWindow::NativeHandleList());
+
+ // Loop through windows from front to back
+ CompWindowList const& wins = screen->windows();
+ for ( CompWindowList::const_reverse_iterator r = wins.rbegin()
+ ; r != wins.rend()
+ ; r++
+ )
+ {
+ CompWindow* w = *r;
+
+ /*
+ * The shell is hidden if there exists any window that fully covers
+ * the output and is in front of all Nux windows on that output.
+ */
+ if (w->isMapped() &&
+ !(w->state () & CompWindowStateHiddenMask) &&
+ w->geometry().contains(output))
+ {
+ return true;
+ }
+ else
+ {
+ for (Window n : nuxwins)
+ {
+ if (w->id() == n && output.intersects(w->geometry()))
+ return false;
+ }
+ }
+ }
+
+ return false;
+}
+
 /* called whenever we need to repaint parts of the screen */
 bool UnityScreen::glPaintOutput(const GLScreenPaintAttrib& attrib,
 const GLMatrix& transform,
@@ -1234,8 +1270,13 @@ bool UnityScreen::glPaintOutput(const GLScreenPaintAttrib& attrib,
 * once an fbo is bound any further
 * attempts to bind it will only increment
 * its bind reference so make sure that
- * you always unbind as much as you bind */
- if (doShellRepaint)
+ * you always unbind as much as you bind
+ *
+ * But NOTE: It is only safe to bind the FBO if !shellCouldBeHidden.
+ * Otherwise it's possible painting won't occur and that would
+ * confuse the state of the FBO.
+ */
+ if (doShellRepaint && !shellCouldBeHidden(*output))
 _fbo->bind (nux::Geometry (output->x (), output->y (), output->width (), output->height ()));
 #endif
 
diff --git a/plugins/unityshell/src/unityshell.h b/plugins/unityshell/src/unityshell.h
index 999af973e..34e29975e 100644
--- a/plugins/unityshell/src/unityshell.h
+++ b/plugins/unityshell/src/unityshell.h
@@ -113,6 +113,8 @@ public:
 
 void damageRegion(const CompRegion &region);
 
+ bool shellCouldBeHidden(CompOutput const& output);
+
 /* paint on top of all windows if we could not find a window
 * to paint underneath */
 bool glPaintOutput(const GLScreenPaintAttrib&,