Fix mimedata updating and signal emision issues in xcb clipboard.

Clipboard should reacquire the clipboard whenever the content or metadata
(e.g the list of supported targets) changes. Patch enables us to monitor
changes to the clipboard through help of XFixes extension.

Cleanup xlib xa_* naming conventions

Task-number: QTBUG-26709
Change-Id: I9d47766ad9859b5628b0358b1c47e8af8fecef73
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

1 files changed, 38 insertions, 26 deletions

diff --git a/src/plugins/platforms/xcb/qxcbclipboard.cpp b/src/plugins/platforms/xcb/qxcbclipboard.cpp
index 85b28ea6b1..6ffc559fa3 100644
--- a/src/plugins/platforms/xcb/qxcbclipboard.cpp
+++ b/src/plugins/platforms/xcb/qxcbclipboard.cpp
@@ -81,6 +81,8 @@ public:
         }
     }
 
+    void reset() { formatList.clear(); }
+
 protected:
     QStringList formats_sys() const
     {
@@ -257,6 +259,9 @@ QMimeData * QXcbClipboard::mimeData(QClipboard::Mode mode)
         return 0;
 
     xcb_window_t clipboardOwner = getSelectionOwner(atomForMode(mode));
+    if (clipboardOwner == XCB_NONE)
+        return 0;
+
     if (clipboardOwner == owner()) {
         return m_clientClipboard[mode];
     } else {
@@ -269,20 +274,18 @@ QMimeData * QXcbClipboard::mimeData(QClipboard::Mode mode)
 
 void QXcbClipboard::setMimeData(QMimeData *data, QClipboard::Mode mode)
 {
-    if (mode > QClipboard::Selection)
+    if ((mode > QClipboard::Selection) || (mimeData(mode) == data))
         return;
 
     xcb_atom_t modeAtom = atomForMode(mode);
-
-    if (m_clientClipboard[mode] == data)
-        return;
-
     xcb_window_t newOwner = XCB_NONE;
 
-    if (m_clientClipboard[QClipboard::Clipboard] != m_clientClipboard[QClipboard::Selection])
-        delete m_clientClipboard[mode];
-    m_clientClipboard[mode] = 0;
-    m_timestamp[mode] = XCB_CURRENT_TIME;
+    if (m_clientClipboard[mode]) {
+        if (m_clientClipboard[QClipboard::Clipboard] != m_clientClipboard[QClipboard::Selection])
+            delete m_clientClipboard[mode];
+        m_clientClipboard[mode] = 0;
+        m_timestamp[mode] = XCB_CURRENT_TIME;
+    }
 
     if (data) {
         newOwner = owner();
@@ -294,7 +297,7 @@ void QXcbClipboard::setMimeData(QMimeData *data, QClipboard::Mode mode)
     xcb_set_selection_owner(xcb_connection(), newOwner, modeAtom, connection()->time());
 
     if (getSelectionOwner(modeAtom) != newOwner) {
-        qWarning("QXcbClipboard::setData: Cannot set X11 selection owner");
+        qWarning("QXcbClipboard::setMimeData: Cannot set X11 selection owner");
     }
 
     emitChanged(mode);
@@ -434,14 +437,18 @@ void QXcbClipboard::handleSelectionClearRequest(xcb_selection_clear_event_t *eve
 //          XGetSelectionOwner(dpy, XA_PRIMARY),
 //          xevent->xselectionclear.time, d->timestamp);
 
-//    if (!waiting_for_data) {
-    setMimeData(0, mode);
-    emitChanged(mode);
-//    } else {
-//        pending_selection_changed = true;
-//        if (! pending_timer_id)
-//            pending_timer_id = QApplication::clipboard()->startTimer(0);
-//    }
+    xcb_window_t newOwner = getSelectionOwner(event->selection);
+
+    /* If selection ownership was given up voluntarily from QClipboard::clear(), then we do nothing here
+    since its already handled in setMimeData. Otherwise, the event must have come from another client
+    as a result of a call to xcb_set_selection_owner in which case we need to delete the local mime data
+    */
+    if (newOwner != XCB_NONE) {
+        if (m_clientClipboard[QClipboard::Clipboard] != m_clientClipboard[QClipboard::Selection])
+            delete m_clientClipboard[mode];
+        m_clientClipboard[mode] = 0;
+        m_timestamp[mode] = XCB_CURRENT_TIME;
+    }
 }
 
 void QXcbClipboard::handleSelectionRequest(xcb_selection_request_event_t *req)
@@ -482,9 +489,9 @@ void QXcbClipboard::handleSelectionRequest(xcb_selection_request_event_t *req)
         return;
     }
 
-    xcb_atom_t xa_targets = atom(QXcbAtom::TARGETS);
-    xcb_atom_t xa_multiple = atom(QXcbAtom::MULTIPLE);
-    xcb_atom_t xa_timestamp = atom(QXcbAtom::TIMESTAMP);
+    xcb_atom_t targetsAtom = atom(QXcbAtom::TARGETS);
+    xcb_atom_t multipleAtom = atom(QXcbAtom::MULTIPLE);
+    xcb_atom_t timestampAtom = atom(QXcbAtom::TIMESTAMP);
 
     struct AtomPair { xcb_atom_t target; xcb_atom_t property; } *multi = 0;
     xcb_atom_t multi_type = XCB_NONE;
@@ -493,7 +500,7 @@ void QXcbClipboard::handleSelectionRequest(xcb_selection_request_event_t *req)
     int imulti = -1;
     bool multi_writeback = false;
 
-    if (req->target == xa_multiple) {
+    if (req->target == multipleAtom) {
         QByteArray multi_data;
         if (req->property == XCB_NONE
             || !clipboardReadProperty(req->requestor, req->property, false, &multi_data,
@@ -526,7 +533,7 @@ void QXcbClipboard::handleSelectionRequest(xcb_selection_request_event_t *req)
         xcb_atom_t ret = XCB_NONE;
         if (target == XCB_NONE || property == XCB_NONE) {
             ;
-        } else if (target == xa_timestamp) {
+        } else if (target == timestampAtom) {
             if (m_timestamp[mode] != XCB_CURRENT_TIME) {
                 xcb_change_property(xcb_connection(), XCB_PROP_MODE_REPLACE, req->requestor,
                                     property, XCB_ATOM_INTEGER, 32, 1, &m_timestamp[mode]);
@@ -534,7 +541,7 @@ void QXcbClipboard::handleSelectionRequest(xcb_selection_request_event_t *req)
             } else {
                 qWarning("QXcbClipboard: Invalid data timestamp");
             }
-        } else if (target == xa_targets) {
+        } else if (target == targetsAtom) {
             ret = sendTargetsSelection(d, req->requestor, property);
         } else {
             ret = sendSelection(d, target, req->requestor, property);
@@ -570,8 +577,13 @@ void QXcbClipboard::handleSelectionRequest(xcb_selection_request_event_t *req)
 void QXcbClipboard::handleXFixesSelectionRequest(xcb_xfixes_selection_notify_event_t *event)
 {
     QClipboard::Mode mode = modeForAtom(event->selection);
-    if (event->owner != owner() && m_clientClipboard[mode] && m_timestamp[mode] < event->selection_timestamp) {
-        setMimeData(0, mode);
+    // here we care only about the xfixes events that come from non Qt processes
+    if (event->owner != XCB_NONE && event->owner != owner()) {
+        if (!m_xClipboard[mode]) {
+            m_xClipboard[mode] = new QXcbClipboardMime(mode, this);
+        } else {
+            m_xClipboard[mode]->reset();
+        }
         emitChanged(mode);
     }
 }