replicate dwm behavior for snap resize

README.md

@@ -1,8 +1,7 @@
 # dwl - dwm for Wayland
 
-Join us on our [Discord server]  
+Join us on our IRC channel: [#dwl on Libera Chat]  
-Or Matrix: [#dwl-official:matrix.org]  
+Or on the community-maintained [Discord server].
-Or on our IRC channel: [#dwl on Libera Chat]
 
 dwl is a compact, hackable compositor for [Wayland] based on [wlroots]. It is
 intended to fill the same space in the Wayland world that [dwm] does in X11,
@@ -24,14 +23,12 @@ with each release on the [release] page
 
 ### Development branch [main]
 Active development progresses on the `main` branch. The `main` branch is built
-against the latest release of [wlroots]. PRs should target this branch unless they
+against a late (and often changing) git commit of wlroots. While the adventurous
-depend on functionality that is not in the current release of `wlroots`.
+are welcome to use `main`, it is a rocky road. Using `main` requires that the
-
+user be willing to chase git commits of wlroots. Testing development pull
-### Preview branch [wlroots-next]
+requests may involve merging unmerged pull requests in [wlroots]' git repository
-The `wlroots-next` branch is built against the git version of [wlroots], which
+and/or git commits of wayland.
-is unstable and changes frequently. PRs requiring functionality from the git
+  
-version of `wlroots` should target this branch.
-
 ### Building dwl
 dwl has the following dependencies:
 - libinput
@@ -205,7 +202,6 @@ inspiration, and to the various contributors to the project, including:
 [dwl-patches]: https://codeberg.org/dwl/dwl-patches
 [list of useful resources on our wiki]: https://codeberg.org/dwl/dwl/wiki/Home#migrating-from-x
 [main]: https://codeberg.org/dwl/dwl/src/branch/main
-[wlroots-next]: https://codeberg.org/dwl/dwl/src/branch/wlroots-next
 [release]: https://codeberg.org/dwl/dwl/releases
 [runit]: http://smarden.org/runit/faq.html#userservices
 [s6]: https://skarnet.org/software/s6/
@@ -213,4 +209,3 @@ inspiration, and to the various contributors to the project, including:
 [wiki]: https://codeberg.org/dwl/dwl/wiki/Home#compatible-status-bars
 [Discord server]: https://discord.gg/jJxZnrGPWN
 [Wayland]: https://wayland.freedesktop.org/
-[#dwl-official:matrix.org]: https://matrix.to/#/#dwl-official:matrix.org

config.def.h

@@ -7,6 +7,7 @@
 static const int sloppyfocus               = 1;  /* focus follows mouse */
 static const int bypass_surface_visibility = 0;  /* 1 means idle inhibitors will disable idle tracking even if it's surface isn't visible  */
 static const unsigned int borderpx         = 1;  /* border pixel of windows */
+static const unsigned int snap             = 32; /* snap pixel */
 static const float rootcolor[]             = COLOR(0x222222ff);
 static const float bordercolor[]           = COLOR(0x444444ff);
 static const float focuscolor[]            = COLOR(0x005577ff);

dwl.c

@@ -586,7 +586,7 @@ arrangelayers(Monitor *m)
 		arrange(m);
 	}
 
-	/* Arrange non-exclusive surfaces from top->bottom */
+	/* Arrange non-exlusive surfaces from top->bottom */
 	for (i = 3; i >= 0; i--)
 		arrangelayer(m, &m->layers[i], &usable_area, 0);
 
@@ -1863,6 +1863,7 @@ void
 motionnotify(uint32_t time, struct wlr_input_device *device, double dx, double dy,
 		double dx_unaccel, double dy_unaccel)
 {
+	int nx, ny;
 	double sx = 0, sy = 0, sx_confined, sy_confined;
 	Client *c = NULL, *w = NULL;
 	LayerSurface *l = NULL;
@@ -1920,7 +1921,17 @@ motionnotify(uint32_t time, struct wlr_input_device *device, double dx, double d
 	/* If we are currently grabbing the mouse, handle and return */
 	if (cursor_mode == CurMove) {
 		/* Move the grabbed client to the new position. */
-		resize(grabc, (struct wlr_box){.x = (int)round(cursor->x) - grabcx, .y = (int)round(cursor->y) - grabcy,
+		nx = (int)round(cursor->x) - grabcx;
+		ny = (int)round(cursor->y) - grabcy;
+		if (abs(selmon->w.x - nx) < (int)snap)
+			nx = selmon->w.x;
+		else if (abs((selmon->w.x + selmon->w.width) - (nx + grabc->geom.width)) < (int)snap)
+			nx = selmon->w.x + selmon->w.width - grabc->geom.width;
+		if (abs(selmon->w.y - ny) < (int)snap)
+			ny = selmon->w.y;
+		else if (abs((selmon->w.y + selmon->w.height) - (ny + grabc->geom.height)) < (int)snap)
+			ny = selmon->w.y + selmon->w.height - grabc->geom.height;
+		resize(grabc, (struct wlr_box){.x = nx, .y = ny,
 			.width = grabc->geom.width, .height = grabc->geom.height}, 1);
 		return;
 	} else if (cursor_mode == CurResize) {
@@ -2134,7 +2145,7 @@ powermgrsetmode(struct wl_listener *listener, void *data)
 	if (!m)
 		return;
 
-	m->gamma_lut_changed = 1; /* Reapply gamma LUT when re-enabling the output */
+	m->gamma_lut_changed = 1; /* Reapply gamma LUT when re-enabling the ouput */
 	wlr_output_state_set_enabled(&state, event->mode);
 	wlr_output_commit_state(m->wlr_output, &state);
 
@@ -2456,7 +2467,7 @@ setup(void)
 	wlr_log_init(log_level, NULL);
 
 	/* The Wayland display is managed by libwayland. It handles accepting
-	 * clients from the Unix socket, managing Wayland globals, and so on. */
+	 * clients from the Unix socket, manging Wayland globals, and so on. */
 	dpy = wl_display_create();
 	event_loop = wl_display_get_event_loop(dpy);