debug: Add dump_scene command

The dump_scene commands dumps the scene tree to stderr.

include/sway/commands.h

@@ -125,6 +125,7 @@ sway_cmd cmd_create_output;
 sway_cmd cmd_default_border;
 sway_cmd cmd_default_floating_border;
 sway_cmd cmd_default_orientation;
+sway_cmd cmd_dump_scene;
 sway_cmd cmd_exec;
 sway_cmd cmd_exec_always;
 sway_cmd cmd_exit;

sway/commands.c

@@ -115,6 +115,7 @@ static const struct cmd_handler command_handlers[] = {
 	{ "allow_tearing", cmd_allow_tearing },
 	{ "border", cmd_border },
 	{ "create_output", cmd_create_output },
+	{ "dump_scene", cmd_dump_scene },
 	{ "exit", cmd_exit },
 	{ "floating", cmd_floating },
 	{ "fullscreen", cmd_fullscreen },

sway/commands/debug.c

@@ -0,0 +1,110 @@
+#include "sway/commands.h"
+#include "sway/tree/root.h"
+#include "sway/scene_descriptor.h"
+#include "log.h"
+
+struct prefix_stack {
+	struct prefix_stack *parent;
+	bool more_children;
+};
+
+static void print_prefix(struct prefix_stack *stack, bool top) {
+	if (stack->parent) {
+		print_prefix(stack->parent, false);
+	}
+	if (stack->more_children) {
+		fprintf(stderr, top ? "  ┣━" : "  ┃ ");
+	} else {
+		fprintf(stderr, top ? "  ┗━" : "    ");
+	}
+}
+
+static void node_type(struct wlr_scene_node *node) {
+	enum sway_scene_descriptor_type types[] = {
+		SWAY_SCENE_DESC_BUFFER_TIMER,
+		SWAY_SCENE_DESC_NON_INTERACTIVE,
+		SWAY_SCENE_DESC_CONTAINER,
+		SWAY_SCENE_DESC_VIEW,
+		SWAY_SCENE_DESC_LAYER_SHELL,
+		SWAY_SCENE_DESC_XWAYLAND_UNMANAGED,
+		SWAY_SCENE_DESC_POPUP,
+		SWAY_SCENE_DESC_DRAG_ICON,
+	};
+
+	const char *names[] = {
+		"buffer_timer",
+		"non_interactive",
+		"container",
+		"view",
+		"layer_shell",
+		"xwayland_unmanaged",
+		"popup",
+		"drag_icon",
+		NULL,
+	};
+	bool first = true;
+	for (size_t idx = 0; names[idx] != NULL; idx++) {
+		if (scene_descriptor_try_get(node, types[idx])) {
+			fprintf(stderr, first ? " %s" : ",%s", names[idx]);
+			first = false;
+		}
+	}
+	if (node->enabled) {
+		fprintf(stderr, "\n");
+	} else {
+		fprintf(stderr, first ? " disabled\n" : ",disabled\n");
+	}
+}
+
+void *scene_descriptor_try_get(struct wlr_scene_node *node,
+	enum sway_scene_descriptor_type type);
+
+static void _dump_tree(struct wlr_scene_node *node, struct prefix_stack *parent, int x, int y) {
+	if (parent) {
+		print_prefix(parent, true);
+	}
+	switch (node->type) {
+	case WLR_SCENE_NODE_TREE:
+		fprintf(stderr, "tree %d,%d (%p)", x, y, (void *)node);
+		break;
+	case WLR_SCENE_NODE_RECT:;
+		struct wlr_scene_rect *rect = (struct wlr_scene_rect *)node;
+		fprintf(stderr, "rect %d,%d %dx%d (%p)", x, y, rect->width, rect->height, (void *)node);
+		break;
+	case WLR_SCENE_NODE_BUFFER:;
+		struct wlr_scene_buffer *buffer = (struct wlr_scene_buffer *)node;
+		fprintf(stderr, "buffer %d,%d %dx%d (%p)", x, y, buffer->dst_width, buffer->dst_height, (void *)node);
+		break;
+	default:
+		fprintf(stderr, "UNKNOWN\n");
+		break;
+	}
+
+	node_type(node);
+	if (node->type != WLR_SCENE_NODE_TREE) {
+		return;
+	}
+	struct wlr_scene_tree *tree = (struct wlr_scene_tree *)node;
+
+	struct prefix_stack stack = {
+		.parent = parent,
+	};
+	struct wlr_scene_node *child;
+	wl_list_for_each(child, &tree->children, link) {
+		if (child->link.next == &tree->children) {
+			stack.more_children = false;
+		} else {
+			stack.more_children = true;
+		}
+		_dump_tree(child, &stack, x + child->x, y + child->y);
+	}
+}
+
+static void dump_tree(struct wlr_scene_node *node) {
+	_dump_tree(node, NULL, node->x, node->y);
+}
+
+struct cmd_results *cmd_dump_scene(int argc, char **argv) {
+	dump_tree(&root->root_scene->tree.node);
+	return cmd_results_new(CMD_SUCCESS, NULL);
+}

sway/meson.build

@@ -49,6 +49,7 @@ sway_sources = files(
 	'commands/border.c',
 	'commands/client.c',
 	'commands/create_output.c',
+	'commands/debug.c',
 	'commands/default_border.c',
 	'commands/default_floating_border.c',
 	'commands/default_orientation.c',