xcb: minor cleanups around QT_CONFIG(xcb_xlib)

- Remove unused createVisualInfoForDefaultVisualId() function.
  This amends dff3c0f14f.

- Inline QXcbConnection::xlib_display().

- Don't nest QT_CONFIG(xcb_native_painting) in QT_CONFIG(xcb_xlib).
  configure.json already checks for the dependencies, we don't need
  to do that again in *.h/*.cpp.

Change-Id: If39912e67ce9baa31faf091bebe120bac5cf6876
Reviewed-by: Alexander Volkov <a.volkov@rusbitech.ru>
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

src/plugins/platforms/xcb/qxcbconnection.cpp

@@ -1610,29 +1610,6 @@ xcb_window_t QXcbConnection::clientLeader()
     return m_clientLeader;
 }
 
-#if QT_CONFIG(xcb_xlib)
-void *QXcbConnection::xlib_display() const
-{
-    return m_xlib_display;
-}
-
-void *QXcbConnection::createVisualInfoForDefaultVisualId() const
-{
-    if (m_defaultVisualId == UINT_MAX)
-        return 0;
-    XVisualInfo info;
-    memset(&info, 0, sizeof info);
-    info.visualid = m_defaultVisualId;
-
-    int count = 0;
-    Display *dpy = static_cast<Display *>(connection()->xlib_display());
-    XVisualInfo *retVisual = XGetVisualInfo(dpy, VisualIDMask, &info, &count);
-    Q_ASSERT(count < 2);
-    return retVisual;
-}
-
-#endif
-
 #if QT_CONFIG(xcb_xinput)
 static inline bool isXIType(xcb_generic_event_t *event, int opCode, uint16_t type)
 {

src/plugins/platforms/xcb/qxcbconnection.h

@@ -423,8 +423,7 @@ public:
     xcb_visualid_t defaultVisualId() const { return m_defaultVisualId; }
 
 #if QT_CONFIG(xcb_xlib)
-    void *xlib_display() const;
-    void *createVisualInfoForDefaultVisualId() const;
+    void *xlib_display() const { return m_xlib_display; }
 #endif
     void sync();
 

src/plugins/platforms/xcb/qxcbintegration.cpp

@@ -65,12 +65,12 @@
 
 #if QT_CONFIG(xcb_xlib)
 #include <X11/Xlib.h>
+#endif
 #if QT_CONFIG(xcb_native_painting)
 #include "qxcbnativepainting.h"
 #include "qpixmap_x11_p.h"
 #include "qbackingstore_x11_p.h"
 #endif
-#endif
 
 #include <qpa/qplatforminputcontextfactory_p.h>
 #include <private/qgenericunixthemes_p.h>