Support for swaybg as a shell surface

This is a lot of work for a small payoff - the mouse cursor is now
correctly rendered over the background.

Containers can now specify a custom arrange function which will be
called during arrange_windows instead of the usual path for that
container type. For backgrounds, the function sends it to the back and
sets its geometry to the size of the screen.

This requires some changes I'm not too happy with in arrange_windows
with respect to how containers figure out the arrangemnet of their
children (special cases are undesirable).

Also, if anyone runs a debug build as their actual WM, you should know
that I've made it so swaybg is invoked as `./bin/swaybg` in debug builds
now.

This PR also includes a bunch of unrelated refactoring. This is a pretty
significant change and I can only test it under the x backend, so I'd
appreciate it if you kind folks would review+test it yourselves and
leave some 👍 if you like it.

include/container.h

@@ -77,6 +77,9 @@ struct sway_container {
 	bool is_focused;
 	bool sticky; // floating view always visible on its output
 
+	// Custom arrange function
+	void (*arrange)(struct sway_container *, double width, double height);
+
 	// Attributes that mostly views have.
 	char *name;
 	char *class;

include/extensions.h

@@ -5,9 +5,11 @@
 #include <wlc/wlc-wayland.h>
 #include "wayland-desktop-shell-server-protocol.h"
 #include "list.h"
+#include "container.h"
 
 struct background_config {
 	wlc_handle output;
+	wlc_handle handle;
 	wlc_resource surface;
 	// we need the wl_resource of the surface in the destructor
 	struct wl_resource *wl_surface_res;
@@ -40,5 +42,6 @@ struct swaylock_state {
 extern struct desktop_shell_state desktop_shell;
 
 void register_extensions(void);
+void arrange_background_view(swayc_t *view, double width, double height);
 
 #endif

include/output.h

@@ -16,4 +16,6 @@ void get_absolute_position(swayc_t *container, struct wlc_point *point);
 // given wlc_point.
 void get_absolute_center_position(swayc_t *container, struct wlc_point *point);
 
+struct output_config *config_for_output(wlc_handle output);
+
 #endif

sway/config.c

@@ -566,6 +566,7 @@ void apply_output_config(struct output_config *oc, swayc_t *output) {
 		snprintf(output_id, bufsize, "%d", output_i);
 		output_id[bufsize-1] = 0;
 
+#ifdef NDEBUG
 		char *const cmd[] = {
 			"swaybg",
 			output_id,
@@ -573,6 +574,15 @@ void apply_output_config(struct output_config *oc, swayc_t *output) {
 			oc->background_option,
 			NULL,
 		};
+#else
+		char *const cmd[] = {
+			"./bin/swaybg",
+			output_id,
+			oc->background,
+			oc->background_option,
+			NULL,
+		};
+#endif
 
 		output->bg_pid = fork();
 		if (output->bg_pid == 0) {

sway/container.c

@@ -11,6 +11,7 @@
 #include "layout.h"
 #include "input_state.h"
 #include "log.h"
+#include "output.h"
 
 #define ASSERT_NONNULL(PTR) \
 	sway_assert (PTR, #PTR "must be non-null")
@@ -90,21 +91,7 @@ swayc_t *new_output(wlc_handle handle) {
 
 	sway_log(L_DEBUG, "New output %lu:%s", handle, name);
 
-	struct output_config *oc = NULL;
+	struct output_config *oc = config_for_output(handle);
-	int i;
-	for (i = 0; i < config->output_configs->length; ++i) {
-		struct output_config *cur = config->output_configs->items[i];
-		if (strcasecmp(name, cur->name) == 0) {
-			sway_log(L_DEBUG, "Matched output config for %s", name);
-			oc = cur;
-			break;
-		}
-		if (strcasecmp("*", cur->name) == 0) {
-			sway_log(L_DEBUG, "Matched wildcard output config for %s", name);
-			oc = cur;
-			break;
-		}
-	}
 
 	if (oc && !oc->enabled) {
 		return NULL;
@@ -125,6 +112,7 @@ swayc_t *new_output(wlc_handle handle) {
 	// Create workspace
 	char *ws_name = NULL;
 	if (name) {
+		int i;
 		for (i = 0; i < config->workspace_outputs->length; ++i) {
 			struct workspace_output *wso = config->workspace_outputs->items[i];
 			if (strcasecmp(wso->output, name) == 0) {

sway/extensions.c

@@ -24,18 +24,6 @@ static struct panel_config *find_or_create_panel_config(struct wl_resource *reso
 	return config;
 }
 
-void background_surface_destructor(struct wl_resource *resource) {
-	sway_log(L_DEBUG, "Background surface killed");
-	int i;
-	for (i = 0; i < desktop_shell.backgrounds->length; ++i) {
-		struct background_config *config = desktop_shell.backgrounds->items[i];
-		if (config->wl_surface_res == resource) {
-			list_del(desktop_shell.backgrounds, i);
-			break;
-		}
-	}
-}
-
 void panel_surface_destructor(struct wl_resource *resource) {
 	sway_log(L_DEBUG, "Panel surface killed");
 	int i;
@@ -63,6 +51,21 @@ void lock_surface_destructor(struct wl_resource *resource) {
 	}
 }
 
+void arrange_background_view(swayc_t *view, double width, double height) {
+	sway_log(L_DEBUG, "Arranging background view %p", view);
+	int i;
+	for (i = 0; i < desktop_shell.backgrounds->length; ++i) {
+		struct background_config *config = desktop_shell.backgrounds->items[i];
+		if (config->handle == view->handle) {
+			struct wlc_size resolution = *wlc_output_get_resolution(config->output);
+			resolution.w = 100;
+			resolution.h = 100;
+			wlc_view_set_geometry(view->handle, WLC_RESIZE_EDGE_NONE, &(struct wlc_geometry){ wlc_origin_zero, resolution });
+			wlc_view_send_to_back(view->handle);
+		}
+	}
+}
+
 static void set_background(struct wl_client *client, struct wl_resource *resource,
 		struct wl_resource *_output, struct wl_resource *surface) {
 	wlc_handle output = wlc_handle_from_wl_output_resource(_output);
@@ -73,9 +76,14 @@ static void set_background(struct wl_client *client, struct wl_resource *resourc
 	struct background_config *config = malloc(sizeof(struct background_config));
 	config->output = output;
 	config->surface = wlc_resource_from_wl_surface_resource(surface);
+	config->handle = wlc_handle_from_wl_surface_resource(surface);
 	config->wl_surface_res = surface;
 	list_add(desktop_shell.backgrounds, config);
-	wl_resource_set_destructor(surface, background_surface_destructor);
+
+	swayc_t *view = swayc_by_handle(config->handle);
+	if (view) {
+		view->arrange = arrange_background_view;
+	}
 }
 
 static void set_panel(struct wl_client *client, struct wl_resource *resource,

sway/handlers.c

@@ -72,18 +72,11 @@ static void handle_output_destroyed(wlc_handle output) {
 	}
 }
 
-static void handle_output_pre_render(wlc_handle output) {
+static void handle_output_post_render(wlc_handle output) {
 	struct wlc_size resolution = *wlc_output_get_resolution(output);
+	swayc_t *swayc = swayc_by_handle(output);
 
 	int i;
-	for (i = 0; i < desktop_shell.backgrounds->length; ++i) {
-		struct background_config *config = desktop_shell.backgrounds->items[i];
-		if (config->output == output) {
-			wlc_surface_render(config->surface, &(struct wlc_geometry){ wlc_origin_zero, resolution });
-			break;
-		}
-	}
-
 	for (i = 0; i < desktop_shell.panels->length; ++i) {
 		struct panel_config *config = desktop_shell.panels->items[i];
 		if (config->output == output) {
@@ -119,6 +112,10 @@ static void handle_output_resolution_change(wlc_handle output, const struct wlc_
 	sway_log(L_DEBUG, "Output %u resolution changed to %d x %d", (unsigned int)output, to->w, to->h);
 	swayc_t *c = swayc_by_handle(output);
 	if (!c) return;
+	struct output_config *oc = config_for_output(output);
+	if (oc) {
+		apply_output_config(oc, c);
+	}
 	c->width = to->w;
 	c->height = to->h;
 	arrange_windows(&root_container, -1, -1);
@@ -203,12 +200,25 @@ static bool handle_view_created(wlc_handle handle) {
 	}
 
 	if (newview) {
+		int i;
 		set_focused_container(newview);
+
+		// Check if this view has a special role
+		wlc_resource resource = wlc_view_get_surface(handle);
+		for (i = 0; i < desktop_shell.backgrounds->length; ++i) {
+			struct background_config *config = desktop_shell.backgrounds->items[i];
+			if (config->surface == resource) {
+				sway_log(L_DEBUG, "Setting view %p as background", newview);
+				newview->handle = handle;
+				newview->arrange = arrange_background_view;
+			}
+		}
+
 		swayc_t *output = swayc_parent_by_type(newview, C_OUTPUT);
 		arrange_windows(output, -1, -1);
 		// check if it matches for_window in config and execute if so
 		list_t *criteria = criteria_for(newview);
-		for (int i = 0; i < criteria->length; i++) {
+		for (i = 0; i < criteria->length; i++) {
 			struct criteria *crit = criteria->items[i];
 			sway_log(L_DEBUG, "for_window '%s' matches new view %p, cmd: '%s'",
 					crit->crit_raw, newview, crit->cmdlist);
@@ -639,7 +649,7 @@ struct wlc_interface interface = {
 		.resolution = handle_output_resolution_change,
 		.focus = handle_output_focused,
 		.render = {
-			.pre = handle_output_pre_render
+			.post = handle_output_post_render
 		}
 	},
 	.view = {

sway/layout.c

@@ -445,6 +445,12 @@ static void arrange_windows_r(swayc_t *container, double width, double height) {
 	sway_log(L_DEBUG, "Arranging layout for %p %s %fx%f+%f,%f", container,
 		container->name, container->width, container->height, container->x, container->y);
 
+	if (container->arrange) {
+		sway_log(L_DEBUG, "Invoking arrangement override handler for container %p", container);
+		container->arrange(container, width, height);
+		return;
+	}
+
 	double x = 0, y = 0;
 	switch (container->type) {
 	case C_ROOT:
@@ -525,16 +531,26 @@ static void arrange_windows_r(swayc_t *container, double width, double height) {
 		break;
 	}
 	
+	int total_children = 0; // not including arrangement override containers
+	for (i = 0; i < container->children->length; ++i) {
+		swayc_t *child = container->children->items[i];
+		if (!child->arrange) {
+			total_children++;
+		}
+	}
+
 	double scale = 0;
 	switch (container->layout) {
 	case L_HORIZ:
 	default:
 		// Calculate total width
 		for (i = 0; i < container->children->length; ++i) {
-			double *old_width = &((swayc_t *)container->children->items[i])->width;
+			swayc_t *child = container->children->items[i];
+			if (child->arrange) continue;
+			double *old_width = &child->width;
 			if (*old_width <= 0) {
-				if (container->children->length > 1) {
+				if (total_children > 1) {
-					*old_width = width / (container->children->length - 1);
+					*old_width = width / (total_children - 1);
 				} else {
 					*old_width = width;
 				}
@@ -547,6 +563,7 @@ static void arrange_windows_r(swayc_t *container, double width, double height) {
 			sway_log(L_DEBUG, "Arranging %p horizontally", container);
 			for (i = 0; i < container->children->length; ++i) {
 				swayc_t *child = container->children->items[i];
+				if (child->arrange) continue;
 				sway_log(L_DEBUG, "Calculating arrangement for %p:%d (will scale %f by %f)", child, child->type, width, scale);
 				child->x = x;
 				child->y = y;
@@ -563,10 +580,12 @@ static void arrange_windows_r(swayc_t *container, double width, double height) {
 	case L_VERT:
 		// Calculate total height
 		for (i = 0; i < container->children->length; ++i) {
-			double *old_height = &((swayc_t *)container->children->items[i])->height;
+			swayc_t *child = container->children->items[i];
+			if (child->arrange) continue;
+			double *old_height = &child->height;
 			if (*old_height <= 0) {
-				if (container->children->length > 1) {
+				if (total_children > 1) {
-					*old_height = height / (container->children->length - 1);
+					*old_height = height / (total_children - 1);
 				} else {
 					*old_height = height;
 				}
@@ -579,6 +598,7 @@ static void arrange_windows_r(swayc_t *container, double width, double height) {
 			sway_log(L_DEBUG, "Arranging %p vertically", container);
 			for (i = 0; i < container->children->length; ++i) {
 				swayc_t *child = container->children->items[i];
+				if (child->arrange) continue;
 				sway_log(L_DEBUG, "Calculating arrangement for %p:%d (will scale %f by %f)", child, child->type, height, scale);
 				child->x = x;
 				child->y = y;

sway/output.c

@@ -1,4 +1,5 @@
 #include <strings.h>
+#include "config.h"
 #include "output.h"
 #include "log.h"
 
@@ -22,6 +23,26 @@ swayc_t *output_by_name(const char* name, const struct wlc_point *abs_pos) {
 	return NULL;
 }
 
+struct output_config *config_for_output(wlc_handle output) {
+	const char *name = wlc_output_get_name(output);
+	struct output_config *oc = NULL;
+	int i;
+	for (i = 0; i < config->output_configs->length; ++i) {
+		struct output_config *cur = config->output_configs->items[i];
+		if (strcasecmp(name, cur->name) == 0) {
+			sway_log(L_DEBUG, "Matched output config for %s", name);
+			oc = cur;
+			break;
+		}
+		if (strcasecmp("*", cur->name) == 0) {
+			sway_log(L_DEBUG, "Matched wildcard output config for %s", name);
+			oc = cur;
+			break;
+		}
+	}
+	return oc;
+}
+
 // Position is where on the edge (as absolute position) the adjacent output should be searched for.
 swayc_t *swayc_adjacent_output(swayc_t *output, enum movement_direction dir,
 		const struct wlc_point *abs_pos, bool pick_closest) {

swaybg/main.c

@@ -46,10 +46,10 @@ int main(int argc, const char **argv) {
 	}
 
 	int desired_output = atoi(argv[1]);
-	sway_log(L_INFO, "Using output %d of %d", desired_output, registry->outputs->length);
-	int i;
 	struct output_state *output = registry->outputs->items[desired_output];
-	struct window *window = window_setup(registry, output->width, output->height, false);
+	sway_log(L_INFO, "Using output %d of %d (%dx%d)", desired_output, registry->outputs->length, output->width, output->height);
+	int i;
+	struct window *window = window_setup(registry, output->width, output->height, true);
 	if (!window) {
 		sway_abort("Failed to create surfaces.");
 	}

wayland/window.c

@@ -67,7 +67,7 @@ struct window *window_setup(struct registry *registry, uint32_t width, uint32_t
 
 	window->surface = wl_compositor_create_surface(registry->compositor);
 	if (shell_surface) {
-		window->shell_surface = wl_shell_get_shell_surface(registry->shell, window->surface);
+		window->shell_surface = wl_shell_get_shell_surface(window->registry->shell, window->surface);
 		wl_shell_surface_add_listener(window->shell_surface, &surface_listener, window);
 		wl_shell_surface_set_toplevel(window->shell_surface);
 	}