Re: [hackers] [dwm][PATCH] Sort screens by horizontal origin

[Abdullah]

I never faced a single problem with multihead with dwm. But I'll try this patch.

On 27/09, Hiltjo Posthuma wrote:

I use xrandr.

On Fri, Sep 27, 2019 at 03:28:39PM +0200, Sebastian Sareyko wrote:

Doing a multi-head setup using other means than Xinerama may lead to
XineramaQueryScreens() returning the screens in an order that does not
actually represent the actual screen layout. This in turn may result
in dwm using the "wrong" monitor in monitor related
functions (focusmon(), tagmon(), applying rules, ...).

This change sorts the list of unique screens by their horizontal
origin to alleviate this problem.
The change does not solve (and may even provoke) the described issue
when screens are not only placed next to each other in a horizontal
way but also vertically.
---
 dwm.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/dwm.c b/dwm.c
index 4465af1..a8e9467 100644
--- a/dwm.c
+++ b/dwm.c
@@ -1847,6 +1847,24 @@ updateclientlist()
                                (unsigned char *) &(c->win), 1);
 }

+#ifdef XINERAMA
+void
+sortscreens(XineramaScreenInfo *screens, int n)
+{
+       int i, j;
+       XineramaScreenInfo *screen = ecalloc(1, sizeof(XineramaScreenInfo));
+
+       for (i = 0; i < n; i++)
+               for (j = i + 1; j < n; j++)
+                       if (screens[i].x_org > screens[j].x_org) {
+                               memcpy(&screen[0], &screens[i], 
sizeof(XineramaScreenInfo));
+                               memcpy(&screens[i], &screens[j], 
sizeof(XineramaScreenInfo));
+                               memcpy(&screens[j], &screen[0], 
sizeof(XineramaScreenInfo));
+                       }
+       XFree(screen);
+}
+#endif /* XINERAMA */
+
 int
 updategeom(void)
 {
@@ -1868,6 +1886,7 @@ updategeom(void)
                                memcpy(&unique[j++], &info[i], 
sizeof(XineramaScreenInfo));
                XFree(info);
                nn = j;
+               sortscreens(unique, nn);
                if (n <= nn) { /* new monitors available */
                        for (i = 0; i < (nn - n); i++) {
                                for (m = mons; m && m->next; m = m->next);
--
2.21.0

Have you tried xrandr to reorder the screens? It should probably be solved in a
different way.

--
Kind regards,
Hiltjo

Abdullah

https://abdullah.today

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