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Only send active window changes to X11 root window if the X11 window changed

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Summary:
So far KWin always updated the active window property even if the actual
window id hasn't changed. E.g. if a Wayland window was active and another
Wayland window gets activated the window id was and stays 0.

Nevertheless KWin updated the property causing wakeups in X server and
any application listening to property changes on the root window.

Futhermore this situation is an information leak: we leak when a Wayland
window gets activated to X11.

To solve this problem RootInfo caches the active window id and only
updates if it changes.

Test Plan:
Verified with xev -root that the active window does not get
updated needlessly.

Reviewers: #kwin, #plasma

Subscribers: plasma-devel, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D7096
This commit is contained in:
Martin Flöser 2017-08-03 16:31:20 +02:00
parent 778b7d037f
commit 0455fa9ef9
3 changed files with 17 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
activation.cpp
View file

@ -271,7 +271,7 @@ void Workspace::setActiveClient(AbstractClient* c)
updateStackingOrder(); // e.g. fullscreens have different layer when active/not-active
if (rootInfo()) {
rootInfo()->setActiveWindow(active_client ? active_client->window() : 0);
rootInfo()->setActiveClient(active_client);
}
emit clientActivated(active_client);

11
netinfo.cpp
View file

@ -138,6 +138,7 @@ void RootInfo::destroy()
RootInfo::RootInfo(xcb_window_t w, const char *name, NET::Properties properties, NET::WindowTypes types,
NET::States states, NET::Properties2 properties2, NET::Actions actions, int scr)
: NETRootInfo(connection(), w, name, properties, types, states, properties2, actions, scr)
, m_activeWindow(activeWindow())
{
}
@ -224,6 +225,16 @@ void RootInfo::changeShowingDesktop(bool showing)
Workspace::self()->setShowingDesktop(showing);
}
void RootInfo::setActiveClient(AbstractClient *client)
{
const xcb_window_t w = client ? client->window() : xcb_window_t{XCB_WINDOW_NONE};
if (m_activeWindow == w) {
return;
}
m_activeWindow = w;
setActiveWindow(m_activeWindow);
}
// ****************************************
// WinInfo
// ****************************************

5
netinfo.h
View file

@ -30,6 +30,7 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
namespace KWin
{
class AbstractClient;
class Client;
/**
@ -44,6 +45,8 @@ public:
static RootInfo *create();
static void destroy();
void setActiveClient(AbstractClient *client);
protected:
virtual void changeNumberOfDesktops(int n) override;
virtual void changeCurrentDesktop(int d) override;
@ -60,6 +63,8 @@ private:
NET::States states, NET::Properties2 properties2, NET::Actions actions, int scr = -1);
static RootInfo *s_self;
friend RootInfo *rootInfo();
xcb_window_t m_activeWindow;
};
inline RootInfo *rootInfo()