* Window flickering problem in XWin multiwindow mode
@ 2022-04-26 3:53 S.J. Luo
2022-04-30 1:40 ` S.J. Luo
2022-04-30 15:25 ` Jon Turney
0 siblings, 2 replies; 7+ messages in thread
From: S.J. Luo @ 2022-04-26 3:53 UTC (permalink / raw)
To: cygwin
Hi,
I have some EDA tools running on a Linux machine and display on my Windows
PC using xorg-server-21.1.3 XWin multiwindow mode
Sometimes the application window flickers forever for an unknown reason.
The problem became more severe after my PC upgrade to Windows10.
Googling the problem, I did not find such issue reported.
I decided to take advantage of open source nature and solve it by myself.
After re-compiling and debugging, I found a calling loop triggered.
Here I eliminate the detail of the cause. I may write later if someone requires.
Knowing the root cause, I am now able to demonstrate the issue with a small
test case as well as a patch that works for me. Both are attached below.
SL
The test case:
==============
/* Compile : gcc -o flicker2 flicker2.c -lX11 */
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void SetMax(Display *dpy, Window win, int val)
{
XEvent xev;
Atom wm_state = XInternAtom(dpy, "_NET_WM_STATE", False);
Atom max_horz = XInternAtom(dpy, "_NET_WM_STATE_MAXIMIZED_HORZ", False);
Atom max_vert = XInternAtom(dpy, "_NET_WM_STATE_MAXIMIZED_VERT", False);
memset(&xev, 0, sizeof(xev));
xev.type = ClientMessage;
xev.xclient.window = win;
xev.xclient.message_type = wm_state;
xev.xclient.format = 32;
xev.xclient.data.l[0] = val; // _NET_WM_STATE_ADD or _NET_WM_STATE_REMOVE
xev.xclient.data.l[1] = max_horz;
xev.xclient.data.l[2] = max_vert;
XSendEvent(dpy, DefaultRootWindow(dpy), False,
SubstructureNotifyMask, &xev);
}
int main(void) {
Display *display;
Window win;
XEvent X;
int screen;
if (!(display = XOpenDisplay(NULL)))
exit(1);
screen = DefaultScreen(display);
win = XCreateSimpleWindow(display, RootWindow(display, screen), 10,
10, 100, 100, 0,
BlackPixel(display, screen),
WhitePixel(display, screen));
XMapWindow(display, win);
SetMax(display, win, 1);
SetMax(display, win, 0);
XSelectInput(display, win, KeyPressMask | StructureNotifyMask);
while (1) {
XNextEvent(display, &X);
}
XCloseDisplay(display);
return 0;
}
==============
and the patch I have applied
=======================
--- a/hw/xwin/winmultiwindowwm.c
+++ b/hw/xwin/winmultiwindowwm.c
@@ -153,6 +153,9 @@ static void
static WMMsgNodePtr PopMessage(WMMsgQueuePtr pQueue, WMInfoPtr pWMInfo);
+static Bool
+ HaveMessage(WMMsgQueuePtr pQueue, UINT msg, xcb_window_t iWindow);
+
static Bool
InitQueue(WMMsgQueuePtr pQueue);
@@ -319,7 +322,6 @@ PopMessage(WMMsgQueuePtr pQueue, WMInfoPtr pWMInfo)
return pNode;
}
-#if 0
/*
* HaveMessage -
*/
@@ -331,12 +333,11 @@ HaveMessage(WMMsgQueuePtr pQueue, UINT msg,
xcb_window_t iWindow)
for (pNode = pQueue->pHead; pNode != NULL; pNode = pNode->pNext) {
if (pNode->msg.msg == msg && pNode->msg.iWindow == iWindow)
- return True;
+ return TRUE;
}
- return False;
+ return FALSE;
}
-#endif
/*
* InitQueue - Initialize the Window Manager message queue
@@ -1173,7 +1174,9 @@ winMultiWindowWMProc(void *pArg)
break;
case WM_WM_CHANGE_STATE:
- UpdateState(pWMInfo, pNode->msg.iWindow, pNode->msg.dwID);
+ if(!HaveMessage(&pWMInfo->wmMsgQueue, pNode->msg.msg,
pNode->msg.iWindow))
+ UpdateState(pWMInfo, pNode->msg.iWindow, pNode->msg.dwID);
+
break;
default:
=======================
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Window flickering problem in XWin multiwindow mode
2022-04-26 3:53 Window flickering problem in XWin multiwindow mode S.J. Luo
@ 2022-04-30 1:40 ` S.J. Luo
2022-04-30 2:06 ` Mark Geisert
2022-04-30 15:25 ` Jon Turney
1 sibling, 1 reply; 7+ messages in thread
From: S.J. Luo @ 2022-04-30 1:40 UTC (permalink / raw)
To: cygwin
SL on Apr 26, 2022:
> I have some EDA tools running on a Linux machine and display on my Windows
> PC using xorg-server-21.1.3 XWin multiwindow mode
> Sometimes the application window flickers forever for an unknown reason.
> The problem became more severe after my PC upgrade to Windows10.
> After re-compiling and debugging, I found a calling loop triggered.
> Knowing the root cause, I am now able to demonstrate the issue with a small
> test case as well as a patch that works for me. Both are attached below.
Any one successfully duplicated the issue?
I minor revised the test case so it won't silently go exit on wrong DISPLAY
setting and added some comment. The running steps:
gcc -o flicker2 flicker2.c -lX11
/usr/bin/XWin.exe :11 -ac -multiwindow &
DISPLAY=:11 flicker2.exe
On running, you would see a window switching rapidly between max and normal
states and never stops.
The key of triggering the window flickering(or flashing) are these two lines:
SetWindowMax(display, win, _NET_WM_STATE_ADD);
SetWindowMax(display, win, _NET_WM_STATE_REMOVE);
where they just set the window to be maximized and go back to normal.
Removing either of the two, the test case would become normal.
I've tried this test case on 3PCs including Windows 7 and Windows 10
and in all cases the issue happens.
This issue literally occurs on my work that runs some proprietary Linux
EDA software. I wish this can be solved on next update.
SL
flicker2.c
===================================================================
#include <X11/Xlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define _NET_WM_STATE_REMOVE 0
#define _NET_WM_STATE_ADD 1
void SetWindowMax(Display *dpy, Window win, int state)
{
XEvent xev;
Atom wm_state = XInternAtom(dpy, "_NET_WM_STATE", False);
Atom max_horz = XInternAtom(dpy, "_NET_WM_STATE_MAXIMIZED_HORZ", False);
Atom max_vert = XInternAtom(dpy, "_NET_WM_STATE_MAXIMIZED_VERT", False);
memset(&xev, 0, sizeof(xev));
xev.type = ClientMessage;
xev.xclient.window = win;
xev.xclient.message_type = wm_state;
xev.xclient.format = 32;
xev.xclient.data.l[0] = state;
xev.xclient.data.l[1] = max_horz;
xev.xclient.data.l[2] = max_vert;
XSendEvent(dpy, DefaultRootWindow(dpy), False,
SubstructureNotifyMask, &xev);
}
int main(void) {
Display *display;
Window win;
XEvent xev;
int screen;
if (!(display = XOpenDisplay(NULL))) {
printf("Cannot open display. Please check DISPLAY environmet setting.\n");
exit(1);
}
screen = DefaultScreen(display);
win = XCreateSimpleWindow(display, RootWindow(display, screen),
10, 10, 100, 100, 0,
BlackPixel(display, screen), WhitePixel(display, screen));
XMapWindow(display, win);
// Uncomment either of the following two lines
// and window would not go flashing
SetWindowMax(display, win, _NET_WM_STATE_ADD);
SetWindowMax(display, win, _NET_WM_STATE_REMOVE);
while(1) {
XNextEvent(display, &xev);
}
// It is supposed never get here
XCloseDisplay(display);
return 0;
}
===================================================================
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Window flickering problem in XWin multiwindow mode
2022-04-30 1:40 ` S.J. Luo
@ 2022-04-30 2:06 ` Mark Geisert
2022-04-30 3:58 ` Mark Geisert
0 siblings, 1 reply; 7+ messages in thread
From: Mark Geisert @ 2022-04-30 2:06 UTC (permalink / raw)
To: cygwin
Hello,
S.J. Luo wrote:
> SL on Apr 26, 2022:
>
>> I have some EDA tools running on a Linux machine and display on my Windows
>> PC using xorg-server-21.1.3 XWin multiwindow mode
>> Sometimes the application window flickers forever for an unknown reason.
>> The problem became more severe after my PC upgrade to Windows10.
>
>> After re-compiling and debugging, I found a calling loop triggered.
>> Knowing the root cause, I am now able to demonstrate the issue with a small
>> test case as well as a patch that works for me. Both are attached below.
>
> Any one successfully duplicated the issue?
I've reproduced it. That's a really annoying effect/issue you're seeing. I've
been waiting for the Cygwin X maintainer to respond. I'm not familiar enough with
X internals to know whether your patch is the most appropriate fix.
I will try to build the object you're patching, with your patch, and make that
available to you as a workaround. I'm assuming you haven't done that yourself
just yet.. Give me a day or so to work it out.
..mark
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Window flickering problem in XWin multiwindow mode
2022-04-30 2:06 ` Mark Geisert
@ 2022-04-30 3:58 ` Mark Geisert
0 siblings, 0 replies; 7+ messages in thread
From: Mark Geisert @ 2022-04-30 3:58 UTC (permalink / raw)
To: cygwin
Replying to myself..
> Hello,
>
> S.J. Luo wrote:
>> SL on Apr 26, 2022:
>>
>>> I have some EDA tools running on a Linux machine and display on my Windows
>>> PC using xorg-server-21.1.3 XWin multiwindow mode
>>> Sometimes the application window flickers forever for an unknown reason.
>>> The problem became more severe after my PC upgrade to Windows10.
>>
>>> After re-compiling and debugging, I found a calling loop triggered.
>>> Knowing the root cause, I am now able to demonstrate the issue with a small
>>> test case as well as a patch that works for me. Both are attached below.
>>
>> Any one successfully duplicated the issue?
>
> I've reproduced it. That's a really annoying effect/issue you're seeing. I've
> been waiting for the Cygwin X maintainer to respond. I'm not familiar enough with
> X internals to know whether your patch is the most appropriate fix.
>
> I will try to build the object you're patching, with your patch, and make that
> available to you as a workaround. I'm assuming you haven't done that yourself
> just yet.. Give me a day or so to work it out.
I may have misread your post. It now seems to me you've built an X server with
your patch for your own use; you were just needing some acknowledgement from the
Cygwin folks of the issue you reported.
In any case, anybody else who runs into the flickering window issue and needs a
workaround, you can pick up a patched X Window server (64-bit) that I've placed in
a public location: http://maxrnd.com/~mark/cygwin/x86_64/XWin.exe .
Cheers,
..mark
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Window flickering problem in XWin multiwindow mode
2022-04-26 3:53 Window flickering problem in XWin multiwindow mode S.J. Luo
2022-04-30 1:40 ` S.J. Luo
@ 2022-04-30 15:25 ` Jon Turney
[not found] ` <CAMoHPCZ18Q_G=JTwOwu2ij3feJ6cd9CHxddONuProrL3kwgBKw@mail.gmail.com>
1 sibling, 1 reply; 7+ messages in thread
From: Jon Turney @ 2022-04-30 15:25 UTC (permalink / raw)
To: S.J. Luo, The Cygwin Mailing List
On 26/04/2022 04:53, S.J. Luo wrote:
> I have some EDA tools running on a Linux machine and display on my Windows
> PC using xorg-server-21.1.3 XWin multiwindow mode
> Sometimes the application window flickers forever for an unknown reason.
> The problem became more severe after my PC upgrade to Windows10.
>
> Googling the problem, I did not find such issue reported.
> I decided to take advantage of open source nature and solve it by myself.
> After re-compiling and debugging, I found a calling loop triggered.
> Here I eliminate the detail of the cause. I may write later if someone requires.
>
> Knowing the root cause, I am now able to demonstrate the issue with a small
> test case as well as a patch that works for me. Both are attached below.
Thanks very much for taking the time to look into this, and writing a patch.
I will apply it.
But I'd like to add a bit more commentary, which perhaps you can supply,
about the analysis you did to determine:
1. how the code is misbehaving
2. how this change remedies that
3. how this change doesn't effect anything else
What your fix does is examine the queue of pending WM messages to
determine if there are any more pending for the window receiving a
WM_WM_CHANGE_STATE message, and if there are, ignore it.
It seems to me that is error prone, in a couple of ways:
1. it should check the message type as well, as e.g. a pending message
of a different type could cause a WM_WM_CHANGE_STATE message to be ignored.
2. even then, assuming that successive WM_WM_CHANGE_STATE messages
cancel out each other isn't always true e.g. consider a sequence of
_NET_WM_STATE_ADD _NET_WM_STATE_MAXIMIZED_VERT followed by
_NET_WM_STATE_ADD _NET_WM_STATE_MAXIMIZED_HORZ.
If you were to send other patches in future, please send them as
attachments, or even better, using git format-patch/git send-email, as
that makes it much easier to apply them without white-space damage and
with correct attribution.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-08-14 11:08 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-04-26 3:53 Window flickering problem in XWin multiwindow mode S.J. Luo
2022-04-30 1:40 ` S.J. Luo
2022-04-30 2:06 ` Mark Geisert
2022-04-30 3:58 ` Mark Geisert
2022-04-30 15:25 ` Jon Turney
[not found] ` <CAMoHPCZ18Q_G=JTwOwu2ij3feJ6cd9CHxddONuProrL3kwgBKw@mail.gmail.com>
2022-05-07 2:01 ` S.J. Luo
2022-08-14 11:08 ` Jon Turney
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).