Take into account shaping in findRealWindow

It can happen that there is a window covering all the screen but it is shaped
to only take part of the screen. If that happens, besides the condition of
   QRect(attr.x,attr.y,attr.width,attr.height).contains(pos)
we also need to query the server for its region rectangles and make
sure the cursor is inside one of those rectangles. If that does not happen
we have to return 0 so the hierarchical XQueryTree search continues

Change-Id: Icb2204a50197e4a5e02e75601c67287525b290b0
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

3 files changed, 38 insertions, 3 deletions

diff --git a/src/gui/kernel/qapplication_x11.cpp b/src/gui/kernel/qapplication_x11.cpp
index ff039fa..d4782f9 100644
--- a/src/gui/kernel/qapplication_x11.cpp
+++ b/src/gui/kernel/qapplication_x11.cpp
@@ -2062,6 +2062,9 @@ void qt_init(QApplicationPrivate *priv, int,
             X11->ptrXFixesQueryVersion    = XFIXES_LOAD_V1(XFixesQueryVersion);
             X11->ptrXFixesSetCursorName   = XFIXES_LOAD_V2(XFixesSetCursorName);
             X11->ptrXFixesSelectSelectionInput = XFIXES_LOAD_V2(XFixesSelectSelectionInput);
+            X11->ptrXFixesCreateRegionFromWindow = XFIXES_LOAD_V2(XFixesCreateRegionFromWindow);
+            X11->ptrXFixesFetchRegion = XFIXES_LOAD_V2(XFixesFetchRegion);
+            X11->ptrXFixesDestroyRegion = XFIXES_LOAD_V2(XFixesDestroyRegion);
 
             if(X11->ptrXFixesQueryExtension && X11->ptrXFixesQueryVersion
                && X11->ptrXFixesQueryExtension(X11->display, &X11->xfixes_eventbase,
diff --git a/src/gui/kernel/qdnd_x11.cpp b/src/gui/kernel/qdnd_x11.cpp
index 031cc74..2b14743 100644
--- a/src/gui/kernel/qdnd_x11.cpp
+++ b/src/gui/kernel/qdnd_x11.cpp
@@ -71,6 +71,10 @@
 #include "qwidget_p.h"
 #include "qcursor_p.h"
 
+#ifndef QT_NO_XFIXES
+#include <X11/extensions/Xfixes.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 // #define DND_DEBUG
@@ -1432,6 +1436,7 @@ Window findRealWindow(const QPoint & pos, Window w, int md)
 
         if (attr.map_state == IsViewable
             && QRect(attr.x,attr.y,attr.width,attr.height).contains(pos)) {
+            bool windowContainsMouse = true;
             {
                 Atom   type = XNone;
                 int f;
@@ -1441,8 +1446,26 @@ Window findRealWindow(const QPoint & pos, Window w, int md)
                 XGetWindowProperty(X11->display, w, ATOM(XdndAware), 0, 0, False,
                                    AnyPropertyType, &type, &f,&n,&a,&data);
                 if (data) XFree(data);
-                if (type)
-                    return w;
+                if (type) {
+#ifndef QT_NO_XFIXES
+                    if (X11->use_xfixes && X11->ptrXFixesCreateRegionFromWindow && X11->ptrXFixesFetchRegion && X11->ptrXFixesDestroyRegion) {
+                        XserverRegion region = X11->ptrXFixesCreateRegionFromWindow(X11->display, w, WindowRegionBounding);
+                        int nrectanglesRet;
+                        XRectangle *rectangles = X11->ptrXFixesFetchRegion(X11->display, region, &nrectanglesRet);
+                        if (rectangles) {
+                            windowContainsMouse = false;
+                            for (int i = 0; !windowContainsMouse && i < nrectanglesRet; ++i)
+                                windowContainsMouse = QRect(rectangles[i].x, rectangles[i].y, rectangles[i].width, rectangles[i].height).contains(pos);
+                            XFree(rectangles);
+                        }
+                        X11->ptrXFixesDestroyRegion(X11->display, region);
+
+                        if (windowContainsMouse)
+                            return w;
+                    } else
+#endif
+                        return w;
+                }
             }
 
             Window r, p;
@@ -1463,7 +1486,10 @@ Window findRealWindow(const QPoint & pos, Window w, int md)
             }
 
             // No children!
-            return w;
+            if (!windowContainsMouse)
+                return 0;
+            else
+                return w;
         }
     }
     return 0;
diff --git a/src/gui/kernel/qt_x11_p.h b/src/gui/kernel/qt_x11_p.h
index ed7c146..579a2b3 100644
--- a/src/gui/kernel/qt_x11_p.h
+++ b/src/gui/kernel/qt_x11_p.h
@@ -209,6 +209,9 @@ typedef Bool (*PtrXFixesQueryExtension)(Display *, int *, int *);
 typedef Status (*PtrXFixesQueryVersion)(Display *, int *, int *);
 typedef void (*PtrXFixesSetCursorName)(Display *dpy, Cursor cursor, const char *name);
 typedef void (*PtrXFixesSelectSelectionInput)(Display *dpy, Window win, Atom selection, unsigned long eventMask);
+typedef void (*PtrXFixesDestroyRegion)(Display *dpy, /*XserverRegion*/ XID region);
+typedef /*XserverRegion*/ XID (*PtrXFixesCreateRegionFromWindow)(Display *dpy, Window window, int kind);
+typedef XRectangle *(*PtrXFixesFetchRegion)(Display *dpy, /*XserverRegion*/ XID region, int *nrectanglesRet);
 #endif // QT_NO_XFIXES
 
 #ifndef QT_NO_XCURSOR
@@ -419,6 +422,9 @@ struct QX11Data
     PtrXFixesQueryVersion ptrXFixesQueryVersion;
     PtrXFixesSetCursorName ptrXFixesSetCursorName;
     PtrXFixesSelectSelectionInput ptrXFixesSelectSelectionInput;
+    PtrXFixesDestroyRegion ptrXFixesDestroyRegion;
+    PtrXFixesCreateRegionFromWindow ptrXFixesCreateRegionFromWindow;
+    PtrXFixesFetchRegion ptrXFixesFetchRegion;
 #endif
 
 #ifndef QT_NO_XINPUT