Port EffectWatcher to XCB

Saves quite a lot of roundtrips to the XServer. Most important we
fetch the atom only once which means we don't have to refetch when
checking the property notify events.

REVIEW: 112445

src/plasma/CMakeLists.txt

@@ -115,7 +115,7 @@ add_library(KF5Plasma ${Plasma_LIB_SRCS})
 add_library(KF5::Plasma ALIAS KF5Plasma)
 
 if(X11_FOUND)
-    set(PLASMA_EXTRA_LIBS ${PLASMA_EXTRA_LIBS} Qt5::X11Extras ${X11_LIBRARIES})
+    set(PLASMA_EXTRA_LIBS ${PLASMA_EXTRA_LIBS} Qt5::X11Extras ${X11_LIBRARIES} ${XCB_XCB_LIBRARY})
 endif()
 
 if(DL_LIBRARY)

src/plasma/private/effectwatcher.cpp

@@ -21,8 +21,6 @@
 
 #include <QCoreApplication>
 
-#include <X11/Xlib.h>
-#include <xcb/xcb.h>
 #include <QtX11Extras/QX11Info>
 
 namespace Plasma
@@ -30,19 +28,26 @@ namespace Plasma
 
 EffectWatcher::EffectWatcher(const QString& property, QObject *parent)
     : QObject(parent),
-      m_property(property)
+      m_property(XCB_ATOM_NONE)
 {
-    m_effectActive = isEffectActive();
-
     QCoreApplication::instance()->installNativeEventFilter(this);
 
-    Display *dpy = QX11Info::display();
-    Window root = DefaultRootWindow(dpy);
-    XWindowAttributes attrs;
-    //Don't reset eventual other masks already there
-    XGetWindowAttributes(dpy, root, &attrs);
-    attrs.your_event_mask |= PropertyChangeMask;
-    XSelectInput(dpy, root, attrs.your_event_mask);
+    xcb_connection_t *c = QX11Info::connection();
+    const QByteArray propertyName = property.toLatin1();
+    xcb_intern_atom_cookie_t atomCookie = xcb_intern_atom_unchecked(c, false, propertyName.length(), propertyName.constData());
+    xcb_get_window_attributes_cookie_t winAttrCookie = xcb_get_window_attributes_unchecked(c, QX11Info::appRootWindow());
+
+    QScopedPointer<xcb_intern_atom_reply_t, QScopedPointerPodDeleter> atom(xcb_intern_atom_reply(c, atomCookie, nullptr));
+    if (!atom.isNull()) {
+        m_property = atom->atom;
+    }
+    m_effectActive = isEffectActive();
+
+    QScopedPointer<xcb_get_window_attributes_reply_t, QScopedPointerPodDeleter> attrs(xcb_get_window_attributes_reply(c, winAttrCookie, nullptr));
+    if (!attrs.isNull()) {
+        uint32_t events = attrs->your_event_mask | XCB_EVENT_MASK_PROPERTY_CHANGE;
+        xcb_change_window_attributes(c, QX11Info::appRootWindow(), XCB_CW_EVENT_MASK, &events);
+    }
 }
 
 bool EffectWatcher::nativeEventFilter(const QByteArray& eventType, void *message, long *result)
@@ -52,13 +57,11 @@ bool EffectWatcher::nativeEventFilter(const QByteArray& eventType, void *message
         return false;
     xcb_generic_event_t* event = reinterpret_cast<xcb_generic_event_t *>(message);
     uint response_type = event->response_type & ~0x80;
-    if (response_type != XCB_PROPERTY_NOTIFY)
+    if (response_type != XCB_PROPERTY_NOTIFY || m_property == XCB_ATOM_NONE)
         return false;
 
     xcb_property_notify_event_t* prop_event = reinterpret_cast<xcb_property_notify_event_t *>(event);
-    Display *dpy = QX11Info::display();
-    Atom testAtom = XInternAtom(dpy, m_property.toLatin1(), False);
-    if (prop_event->atom == testAtom) {
+    if (prop_event->atom == m_property) {
         bool nowEffectActive = isEffectActive();
         if (m_effectActive != nowEffectActive) {
             m_effectActive = nowEffectActive;
@@ -70,17 +73,22 @@ bool EffectWatcher::nativeEventFilter(const QByteArray& eventType, void *message
 
 bool EffectWatcher::isEffectActive() const
 {
-    Display *dpy = QX11Info::display();
-    Atom testAtom = XInternAtom(dpy, m_property.toLatin1(), False);
-
-    bool nowEffectActive = false;
-    int cnt;
-    Atom *list = XListProperties(dpy, DefaultRootWindow(dpy), &cnt);
-    if (list != NULL) {
-        nowEffectActive = (qFind(list, list + cnt, testAtom) != list + cnt);
-        XFree(list);
+    if (m_property == XCB_ATOM_NONE) {
+        return false;
     }
-    return nowEffectActive;
+    xcb_connection_t *c = QX11Info::connection();
+    xcb_list_properties_cookie_t propsCookie = xcb_list_properties_unchecked(c, QX11Info::appRootWindow());
+    QScopedPointer<xcb_list_properties_reply_t, QScopedPointerPodDeleter> props(xcb_list_properties_reply(c, propsCookie, nullptr));
+    if (props.isNull()) {
+        return false;
+    }
+    xcb_atom_t *atoms = xcb_list_properties_atoms(props.data());
+    for (int i = 0; i < props->atoms_len; ++i) {
+        if (atoms[i] == m_property) {
+            return true;
+        }
+    }
+    return false;
 }
 
 } // namespace Plasma

src/plasma/private/effectwatcher_p.h

@@ -24,6 +24,8 @@
 
 #include <QAbstractNativeEventFilter>
 
+#include <xcb/xcb.h>
+
 namespace Plasma
 {
 
@@ -43,7 +45,7 @@ Q_SIGNALS:
     void effectChanged(bool on);
 
 private:
-    QString m_property;
+    xcb_atom_t m_property;
     bool m_effectActive;
 };