I'm tinkering with X11 using Go and Xlib (using cgo) and I'm trying to program basic window management functionalities, but I'm having problems with input management (keyboard in this case).
So far I've created a basic reparenting window manager where client windows (i.e. windows managed by this program) are wrapped within container windows created by this program. Container windows are direct children of root window and client windows are direct children of their container windows.
I'm trying to grab the entire keyboard and check if a key event is directed towards the window manager in order to process certain things. In case this key event is not something related to the window manager I would like to pass it along to client windows. I know that there is the option to select only specific keys or modifiers (using XGrabKey) for this matter (I was able to do it), but I would like to be able to grab the entire keyboard in this case.
So far I have the following code which doesn't work and keys are not passed to client windows.
...
C.XGrabKeyboard(
display,
rootWindow,
0,
C.GrabModeAsync,
C.GrabModeAsync,
C.CurrentTime,
)
...
for {
var event C.XEvent
C.XNextEvent(display, &event)
eventType := (*C.int)(unsafe.Pointer(&event[0]))
switch *eventType {
...
case C.KeyPress:
eventPayload := (*C.XKeyEvent)(unsafe.Pointer(&event[0]))
// Value of eventPayload.root here equals rootWindow.
// Value of eventPayload.window here equals rootWindow.
// Value of eventPayload.subwindow here equals a ContainerWindow.
if SOME_CONDITIONS_ARE_MET {
// Key event is directed towards the window manager. Process this key event.
...
continue
}
// Window manager has nothing to do with this key event. Pass it along.
C.XAllowEvents(display, C.ReplayKeyboard, C.CurrentTime)
...
}
}
It is worth mentioning that in this case I've used C.XSynchronize(display, 1) so calling XSync is no longer required. Also calling XFlush after XAllowEvents did not solve the problem either.
By the way I originally saw the XAllowEvents solution in this Stack Overflow question and this website.
Related
I'm building a taskbar for an X11 desktop and so far I've been successful in detecting new and removed windows and changes to window titles and icons.
However, despite setting every event mask I can think of on the client windows, I've been unable to get any events when a test application adds the _NET_WM_STATE_DEMANDS_ATTENTION atom to its _NET_WM_STATE property.
I'm using Qt5 and capturing the incoming X11 events using installNativeEventFilter. However, I've also tried using xprop -spy and I see the same issue there: Even though polling the _NET_WM_STATE property shows the atom being added and removed, no property change event is ever received. Fluxbox also doesn't seem to pick up on it until something else causes it to re-query the window.
My event filter code resembles this:
xcb_generic_event_t* ev = static_cast<xcb_generic_event_t*>(message);
uint32_t type = ev->response_type;
switch (type) {
case XCB_PROPERTY_NOTIFY: {
xcb_property_notify_event_t* pev =
reinterpret_cast<xcb_property_notify_event_t*>(ev);
qDebug() << "property" << pev->window << pev->atom << (int)pev->state;
break;
/* snip */
default:
qDebug() << "unrecognized event" << type;
};
My test application uses QApplication::alert() on a timer to assert the attention flag.
Is there some special handling necessary for atom list properties? Am I doomed to poll for changes? I've tried looking at the source code for other window managers but I haven't been able to identify any specific differences.
It turns out that Qt5's native event filter on X11 doesn't pass everything through consistently. I haven't isolated that bug yet, but I wrote my own minimalist xcb event loop on a separate connection to handle window-management activities and it works fine.
I'm trying to enhance an existing Firefox extension which relies on nsIContentPolicy to detect and abort certain network loads (in order to block the resulting UI action, i.e. tab navigation). Then handle loading that resource internally. Under rare circumstances, only after handling the load, it turns out we shouldn't have interrupted the load at all, so we flag it to be ignored and re-start it.
Under e10s/multi-process, that means the parent (where the content policy is running) must send a message to the child (handling the UI for the content) to restart the load. Today, that's done by:
function findMessageManager(aContext) {
// With e10s off, context is a <browser> with a direct reference to
// the docshell loaded therein.
var docShell = aContext && aContext.docShell;
if (!docShell) {
// But with e10s on, context is a content window and we have to work hard
// to find the docshell, from which we can find the message manager.
docShell = aContext
.QueryInterface(Ci.nsIInterfaceRequestor)
.getInterface(Ci.nsIWebNavigation)
.QueryInterface(Ci.nsIDocShellTreeItem).rootTreeItem;
}
try {
return docShell
.QueryInterface(Ci.nsIInterfaceRequestor)
.getInterface(Ci.nsIContentFrameMessageManager);
} catch (e) {
return null;
}
};
Which is crazy complex, because e10s is crazy complex. But it works; it generates some object in the parent, upon which I can call .sendAsyncMessage(), and then the addMessageListener() handler in my frame/child script receives it, and does what it needs to do.
I'd like to switch from nsIContentPolicy to http-on-modify-request as it presents more information for making a better determination (block and handle this load?) earlier. Inside that observer I can do:
var browser = httpChannel
.notificationCallbacks.getInterface(Ci.nsILoadContext)
.topFrameElement;
Which gives me an object which has a .messageManager which is some kind of message manager, and which has a .sendAsyncMessage() method. But when I use that .sendAsyncMessage(), the message disappears, never to be observed by the child.
Context: https://github.com/greasemonkey/greasemonkey/issues/2280
This should work in principle, although the docshell tree traversal may do different things in e10s and non-e10s, so you have to be careful there. In e10s rootTreeItem -> nsIContentFrameMessageManager should give you the MM equivalent to a frame script and topFrameElement.frameLoader.messageManager should give you the <browser>'s MM, which pretty much is the parent side counterpart to it.
Potential sources of confusion:
e10s on vs. off
process MM vs. frame MM hierarchy
listening in the wrong frame for the message (registering in all frames might help for debugging purposes)
This is the function I use to find the content message manager:
function contentMMFromContentWindow_Method2(aContentWindow) {
if (!gCFMM) {
gCFMM = aContentWindow.QueryInterface(Ci.nsIInterfaceRequestor)
.getInterface(Ci.nsIDocShell)
.QueryInterface(Ci.nsIInterfaceRequestor)
.getInterface(Ci.nsIContentFrameMessageManager);
}
return gCFMM;
}
So maybe get the content window that triggered that request, and then use this function.
Does anyone know how to detect when the user changes the current input source in OSX?
I can call TISCopyCurrentKeyboardInputSource() to find out which input source ID is being used like this:
TISInputSourceRef isource = TISCopyCurrentKeyboardInputSource();
if ( isource == NULL )
{
cerr << "Couldn't get the current input source\n.";
return -1;
}
CFStringRef id = (CFStringRef)TISGetInputSourceProperty(
isource,
kTISPropertyInputSourceID);
CFRelease(isource);
If my input source is "German", then id ends up being "com.apple.keylayout.German", which is mostly what I want. Except:
The results of TISCopyCurrentKeyboardInputSource() doesn't change once my process starts? In particular, I can call TISCopyCurrentKeyboardInputSource() in a loop and switch my input source, but TISCopyCurrentKeyboardInputSource() keeps returning the input source that my process started with.
I'd really like to be notified when the input source changes. Is there any way of doing this? To get a notification or an event of some kind telling me that the input source has been changed?
You can observe the NSTextInputContextKeyboardSelectionDidChangeNotification notification posted by NSTextInputContext to the default Cocoa notification center. Alternatively, you can observe the kTISNotifySelectedKeyboardInputSourceChanged notification delivered via the Core Foundation distributed notification center.
However, any such change starts in a system process external to your app. The system then notifies the frameworks in each app process. The frameworks can only receive such notifications when it is allowed to run its event loop. Likewise, if you're observing the distributed notification yourself, that can only happen when the event loop (or at least the main thread's run loop) is allowed to run.
So, that explains why running a loop which repeatedly checks the result of TISCopyCurrentKeyboardInputSource() doesn't work. You're not allowing the frameworks to monitor the channel over which it would be informed of the change. If, rather than a loop, you were to use a repeating timer with a low enough frequency that other stuff has a chance to run, and you returned control to the app's event loop, you would see the result of TISCopyCurrentKeyboardInputSource() changing.
I'm writing a program that has an X11/Xlib interface, and my event processing loop looks like this:
while (XNextEvent(display, &ev) >= 0) {
switch (ev.type) {
// Process events
}
}
The problem is when the window is resized, I get a bunch of Expose events telling me which parts of the window to redraw. If I redraw them in direct response to the events, the redraw operation lags terribly because it is so slow (after resizing I get to see all the newly invalidated rectangles refresh one by one.)
What I would like to do is to record the updated window size as it changes, and only run one redraw operation on the entire window (or at least only two rectangles) when there are no more events left to process.
Unfortunately I can't see a way to do this. I tried this:
do {
XPeekEvent(display, &ev);
while (XCheckMaskEvent(display, ExposureMask | StructureNotifyMask, &ev)) {
switch (ev.type) {
// Process events, record but don't process redraw events
}
}
// No more events, do combined redraw here
}
Which does actually work, but it's a little inefficient, and if an event arrives that I am not interested in the XCheckMaskEvent call doesn't remove it from the queue, so it stays there stopping XPeekEvent from blocking, resulting in 100% CPU use.
I was just wondering whether there is a standard way to achieve the delayed/combined redraw that I am after? Many of the Xlib event processing functions seem to block, so they're not really suitable to use if you want to do some processing just before they block, but only if they would block!
EDIT: For the record, this is the solution I used. It's a simplified version of n.m.'s:
while (XNextEvent(display, &ev) >= 0) {
switch (ev.type) {
// Process events, remember any redraws needed later
}
if (!XPending(display)) {
// No more events, redraw if needed
}
}
FWIW a UI toolkit such as GTK+ does it this way:
for each window, maintains a "damage region" (union of all expose events)
when the damage region becomes non-empty, adds an "idle handler" which is a function the event loop will run when it doesn't have anything else to do
the idle handler will run when the event queue is empty AND the X socket has nothing to read (according to poll() on ConnectionNumber(dpy))
the idle handler of course repaints the damage region
In GTK+, they're changing this over to a more modern 3D-engine oriented way (clean up the damage region on vertical sync) in a future version, but it's worked in the fairly simple way above for many years.
When translated to raw Xlib, this looks about like n.m.'s answer: repaint when you have a damage region and !XPending(). So feel free to accept that answer I just figured I'd add a little extra info.
If you wanted things like timers and idles, you could consider something lke libev http://software.schmorp.de/pkg/libev.html it's designed to just drop a couple of source files in your app (it isn't set up to be an external dependency). You would add the display's file descriptor to the event loop.
For tracking damage regions, people often cut-and-paste the file "miregion.c" which is from the "machine independent" code in the X server. Just google for miregion.c or download the X server sources and look for it. A "region" here is simply a list of rectangles which supports operations such as union and intersect. To add damage, union it with the old region, to repair damage, subtract it, etc.
Try something like the following (not actually tested):
while (TRUE) {
if (XPending(display) || !pendingRedraws) {
// if an event is pending, fetch it and process it
// otherwise, we have neither events nor pending redraws, so we can
// safely block on the event queue
XNextEvent (display, &ev);
if (isExposeEvent(&ev)) {
pendingRedraws = TRUE;
}
else {
processEvent(&ev);
}
}
else {
// we must have a pending redraw
redraw();
pendingRedraws = FALSE;
}
}
It could be beneficial to wait for 10 ms or so before doing the redraw. Unfortunately the raw Xlib has no interface for timers. You need a higher-level toolkit for that (all toolkits including Xt have some kind of timer interface), or work directly with the underlying socket of the X11 connection.
I have a program that switches desktop and start a new process on it. When the process exits, the parent process restores the original desktop.
For testing purposes, I put a button in a plain win32 app that triggers the switch. It works, and closing the launched process (notepad), I go back to the original desktop.
In that same program, I have called WTSRegisterSessionNotification to receive a notification when a session is unlocked (WTS_SESSION_UNLOCK). I receive it.
But when I try to switch desktops in WTS_SESSION_UNLOCK message handler, SwitchDesktop fails and GetLastError is 0. The documentation says that last error is usually not set by SwitchDesktop.
Funny enough, if I put my call to switch desktop in a for loop, it works on the 5th iteration.
In short, this does not work :
case WM_WTSSESSION_CHANGE:
if(wParam == WTS_SESSION_UNLOCK)
{
SwitchDesktop(a_valid_desktop_handle);
}
break;
But this ugly hack works :
case WM_WTSSESSION_CHANGE:
if(wParam == WTS_SESSION_UNLOCK)
{
for(int i=0; i<10; ++i)
{
if(SwitchDesktop(a_valid_desktop_handle))
{
//This will work when i == 5, maybe 6.
break;
}
}
}
break;
Setting a timer (to exit the message loop) also works, but it is just a more convoluted form of loop with regards to this problem. SwitchDesktop will work on after a handfull of WM_TIMER messages. It looks like constant time, although I did not measure it.
MSDN documentation for SwitchDesktop mentions that this will fail with a custom Userinit process, which I use. But getting the name of the current desktop just before the switch :
wchar_t name[512];
GetUserObjectInformation(GetThreadDesktop(GetCurrentThreadId()), UOI_NAME, name, sizeof(name)/sizeof(*name), 0);
OutputDebugString(name);
Gives me default all the time. And since GetLastError is 0, not 5 (access denied) I am pretty sure the secure desktop is gone before I receive the WTS_SESSION_UNLOCK notification.
I known I can't switch desktop while the screen is locked, but is there a "grace period" after the desktop is unlocked in which I can't call SwitchDesktop ?
When the desktop gets locked, it switches to another desktop which is reserved for this purpose. It is quite possible that when you receive the message, that desktop is still in control and you're not allowed to switch because you're not running in the current desktop.
I can't test it right now but I would put the call to SwitchDesktop not on WTS_SESSION_UNLOCK but on WTS_CONSOLE_CONNECT. From what I gather WTS_SESSION_UNLOCK occurs first and then your get WTS_CONSOLE_CONNECT which would correspond to what you see with the "constand time"...
SwitchDesktop fails (with error 0) because (accordingly to MSDN) it belongs to a window station not (yet) visible. There is no user notification I know of that says "the HWINSTA become visible".