swaybg: use output names instead of output indexes

sway/config/output.c

@@ -229,11 +229,11 @@ void apply_output_config(struct output_config *oc, struct sway_output *output) {
 		terminate_swaybg(output->bg_pid);
 	}
 	if (oc && oc->background && config->swaybg_command) {
-		wlr_log(WLR_DEBUG, "Setting background for output %d to %s",
+		wlr_log(WLR_DEBUG, "Setting background for output %s to %s",
-				output_i, oc->background);
+			wlr_output->name, oc->background);
 
-		size_t len = snprintf(NULL, 0, "%s %d \"%s\" %s %s",
+		size_t len = snprintf(NULL, 0, "%s \"%s\" \"%s\" %s %s",
-				config->swaybg_command, output_i, oc->background,
+			config->swaybg_command, wlr_output->name, oc->background,
 			oc->background_option,
 			oc->background_fallback ? oc->background_fallback : "");
 		char *command = malloc(len + 1);
@@ -241,8 +241,8 @@ void apply_output_config(struct output_config *oc, struct sway_output *output) {
 			wlr_log(WLR_DEBUG, "Unable to allocate swaybg command");
 			return;
 		}
-		snprintf(command, len + 1, "%s %d \"%s\" %s %s",
+		snprintf(command, len + 1, "%s \"%s\" \"%s\" %s %s",
-				config->swaybg_command, output_i, oc->background,
+			config->swaybg_command, wlr_output->name, oc->background,
 			oc->background_option,
 			oc->background_fallback ? oc->background_fallback : "");
 		wlr_log(WLR_DEBUG, "-> %s", command);
@@ -251,6 +251,7 @@ void apply_output_config(struct output_config *oc, struct sway_output *output) {
 		output->bg_pid = fork();
 		if (output->bg_pid == 0) {
 			execvp(cmd[0], cmd);
+			wlr_log_errno(WLR_ERROR, "Failed to execute swaybg");
 		} else {
 			free(command);
 		}

swaybg/main.c

@@ -8,13 +8,16 @@
 #include <wayland-client.h>
 #include <wlr/util/log.h>
 #include "background-image.h"
-#include "pool-buffer.h"
 #include "cairo.h"
+#include "pool-buffer.h"
 #include "util.h"
 #include "wlr-layer-shell-unstable-v1-client-protocol.h"
+#include "xdg-output-unstable-v1-client-protocol.h"
+
+struct swaybg_state;
 
 struct swaybg_args {
-	int output_idx;
+	const char *output;
 	const char *path;
 	enum background_mode mode;
 	const char *fallback;
@@ -25,23 +28,33 @@ struct swaybg_context {
 	cairo_surface_t *image;
 };
 
+struct swaybg_output {
+	struct wl_output *wl_output;
+	struct zxdg_output_v1 *xdg_output;
+	struct swaybg_state *state;
+	struct wl_list link;
+
+	int32_t scale;
+};
+
 struct swaybg_state {
 	const struct swaybg_args *args;
 	struct swaybg_context context;
 
 	struct wl_display *display;
 	struct wl_compositor *compositor;
-	struct zwlr_layer_shell_v1 *layer_shell;
 	struct wl_shm *shm;
+	struct wl_list outputs;
+	struct zwlr_layer_shell_v1 *layer_shell;
+	struct zxdg_output_manager_v1 *xdg_output_manager;
 
-	struct wl_output *output;
+	struct swaybg_output *output;
 	struct wl_surface *surface;
 	struct wl_region *input_region;
 	struct zwlr_layer_surface_v1 *layer_surface;
 
 	bool run_display;
 	uint32_t width, height;
-	int32_t scale;
 	struct pool_buffer buffers[2];
 	struct pool_buffer *current_buffer;
 };
@@ -65,8 +78,8 @@ bool is_valid_color(const char *color) {
 }
 
 static void render_frame(struct swaybg_state *state) {
-	int buffer_width = state->width * state->scale,
+	int buffer_width = state->width * state->output->scale,
-		buffer_height = state->height * state->scale;
+		buffer_height = state->height * state->output->scale;
 	state->current_buffer = get_next_buffer(state->shm,
 			state->buffers, buffer_width, buffer_height);
 	if (!state->current_buffer) {
@@ -89,7 +102,7 @@ static void render_frame(struct swaybg_state *state) {
 				state->args->mode, buffer_width, buffer_height);
 	}
 
-	wl_surface_set_buffer_scale(state->surface, state->scale);
+	wl_surface_set_buffer_scale(state->surface, state->output->scale);
 	wl_surface_attach(state->surface, state->current_buffer->buffer, 0, 0);
 	wl_surface_damage(state->surface, 0, 0, state->width, state->height);
 	wl_surface_commit(state->surface);
@@ -148,10 +161,14 @@ static void output_done(void *data, struct wl_output *output) {
 	// Who cares
 }
 
-static void output_scale(void *data, struct wl_output *output, int32_t factor) {
+static void output_scale(void *data, struct wl_output *wl_output,
-	struct swaybg_state *state = data;
+		int32_t scale) {
-	state->scale = factor;
+	struct swaybg_output *output = data;
-	if (state->run_display) {
+	struct swaybg_state *state = output->state;
+
+	output->scale = scale;
+
+	if (state->output == output && state->run_display) {
 		render_frame(state);
 	}
 }
@@ -163,26 +180,65 @@ static const struct wl_output_listener output_listener = {
 	.scale = output_scale,
 };
 
+static void xdg_output_handle_logical_position(void *data,
+		struct zxdg_output_v1 *xdg_output, int32_t x, int32_t y) {
+	// Who cares
+}
+
+static void xdg_output_handle_logical_size(void *data,
+		struct zxdg_output_v1 *xdg_output, int32_t width, int32_t height) {
+	// Who cares
+}
+
+static void xdg_output_handle_name(void *data,
+		struct zxdg_output_v1 *xdg_output, const char *name) {
+	struct swaybg_output *output = data;
+	struct swaybg_state *state = output->state;
+	if (strcmp(name, state->args->output) == 0) {
+		assert(state->output == NULL);
+		state->output = output;
+	}
+}
+
+static void xdg_output_handle_description(void *data,
+		struct zxdg_output_v1 *xdg_output, const char *description) {
+	// Who cares
+}
+
+static void xdg_output_handle_done(void *data,
+		struct zxdg_output_v1 *xdg_output) {
+	// Who cares
+}
+
+static const struct zxdg_output_v1_listener xdg_output_listener = {
+	.logical_position = xdg_output_handle_logical_position,
+	.logical_size = xdg_output_handle_logical_size,
+	.name = xdg_output_handle_name,
+	.description = xdg_output_handle_description,
+	.done = xdg_output_handle_done,
+};
+
 static void handle_global(void *data, struct wl_registry *registry,
 		uint32_t name, const char *interface, uint32_t version) {
 	struct swaybg_state *state = data;
 	if (strcmp(interface, wl_compositor_interface.name) == 0) {
-		state->compositor = wl_registry_bind(registry, name,
+		state->compositor =
-				&wl_compositor_interface, 3);
+			wl_registry_bind(registry, name, &wl_compositor_interface, 3);
 	} else if (strcmp(interface, wl_shm_interface.name) == 0) {
-		state->shm = wl_registry_bind(registry, name,
+		state->shm = wl_registry_bind(registry, name, &wl_shm_interface, 1);
-				&wl_shm_interface, 1);
 	} else if (strcmp(interface, wl_output_interface.name) == 0) {
-		static int output_idx = 0;
+		struct swaybg_output *output = calloc(1, sizeof(struct swaybg_output));
-		if (output_idx == state->args->output_idx) {
+		output->state = state;
-			state->output = wl_registry_bind(registry, name,
+		output->wl_output =
-					&wl_output_interface, 3);
+			wl_registry_bind(registry, name, &wl_output_interface, 3);
-			wl_output_add_listener(state->output, &output_listener, state);
+		wl_output_add_listener(output->wl_output, &output_listener, output);
-		}
+		wl_list_insert(&state->outputs, &output->link);
-		output_idx++;
 	} else if (strcmp(interface, zwlr_layer_shell_v1_interface.name) == 0) {
-		state->layer_shell = wl_registry_bind(
+		state->layer_shell =
-				registry, name, &zwlr_layer_shell_v1_interface, 1);
+			wl_registry_bind(registry, name, &zwlr_layer_shell_v1_interface, 1);
+	} else if (strcmp(interface, zxdg_output_manager_v1_interface.name) == 0) {
+		state->xdg_output_manager = wl_registry_bind(registry, name,
+			&zxdg_output_manager_v1_interface, 2);
 	}
 }
 
@@ -197,17 +253,19 @@ static const struct wl_registry_listener registry_listener = {
 };
 
 int main(int argc, const char **argv) {
-	struct swaybg_args args = {0};
-	struct swaybg_state state = {0};
-	state.args = &args;
 	wlr_log_init(WLR_DEBUG, NULL);
 
+	struct swaybg_args args = {0};
+	struct swaybg_state state = { .args = &args };
+	wl_list_init(&state.outputs);
+
 	if (argc < 4 || argc > 5) {
 		wlr_log(WLR_ERROR, "Do not run this program manually. "
-				"See man 5 sway and look for output options.");
+				"See `man 5 sway-output` and look for background options.");
 		return 1;
 	}
-	args.output_idx = atoi(argv[1]);
+
+	args.output = argv[1];
 	args.path = argv[2];
 
 	args.mode = parse_background_mode(argv[3]);
@@ -232,20 +290,36 @@ int main(int argc, const char **argv) {
 	struct wl_registry *registry = wl_display_get_registry(state.display);
 	wl_registry_add_listener(registry, &registry_listener, &state);
 	wl_display_roundtrip(state.display);
-	assert(state.compositor && state.layer_shell && state.output && state.shm);
+	if (state.compositor == NULL || state.shm == NULL ||
+			state.layer_shell == NULL || state.xdg_output_manager == NULL) {
+		wlr_log(WLR_ERROR, "Missing a required Wayland interface");
+		return 1;
+	}
 
-	// Second roundtrip to get output properties
+	struct swaybg_output *output;
+	wl_list_for_each(output, &state.outputs, link) {
+		output->xdg_output = zxdg_output_manager_v1_get_xdg_output(
+			state.xdg_output_manager, output->wl_output);
+		zxdg_output_v1_add_listener(output->xdg_output,
+			&xdg_output_listener, output);
+	}
+	// Second roundtrip to get xdg_output properties
 	wl_display_roundtrip(state.display);
+	if (state.output == NULL) {
+		wlr_log(WLR_ERROR, "Cannot find output '%s'", args.output);
+		return 1;
+	}
 
 	state.surface = wl_compositor_create_surface(state.compositor);
 	assert(state.surface);
 
+	// Empty input region
 	state.input_region = wl_compositor_create_region(state.compositor);
 	assert(state.input_region);
 	wl_surface_set_input_region(state.surface, state.input_region);
 
 	state.layer_surface = zwlr_layer_shell_v1_get_layer_surface(
-			state.layer_shell, state.surface, state.output,
+			state.layer_shell, state.surface, state.output->wl_output,
 			ZWLR_LAYER_SHELL_V1_LAYER_BACKGROUND, "wallpaper");
 	assert(state.layer_surface);
 
@@ -265,5 +339,6 @@ int main(int argc, const char **argv) {
 	while (wl_display_dispatch(state.display) != -1 && state.run_display) {
 		// This space intentionally left blank
 	}
+
 	return 0;
 }