ssd: unify struct ssd_part with struct node_descriptor

struct ssd_part and struct node_descriptor seem to have essentially the
same purpose: tag a wlr_scene_node with some extra data indicating what
we're using it for.

Also, as with enum ssd_part_type (now lab_node_type), ssd_part is used
for several types of nodes that are not part of SSD.

So instead of the current chaining (node_descriptor -> ssd_part), let's
flatten/unify the two structs.

In detail:

- First, merge node_descriptor_type into lab_node_type.
- Add a separate view pointer in node_descriptor, since in the case of
  SSD buttons we need separate view and button data pointers.
- Rename ssd_part_button to simply ssd_button. It no longer contains
  an ssd_part as base.
- Add node_try_ssd_button_from_node() which replaces
  node_ssd_part_from_node() + button_try_from_ssd_part().
- Factor out ssd_button_free() to be called in node descriptor destroy.
- Finally, get_cursor_context() needs a little reorganization to handle
  the unified structs.

Overall, this simplifies the code a bit, and in my opinion makes it
easier to understand. No functional change intended.

src/ssd/meson.build

@@ -1,7 +1,7 @@
 labwc_sources += files(
   'resize-indicator.c',
   'ssd.c',
-  'ssd-part.c',
+  'ssd-button.c',
   'ssd-titlebar.c',
   'ssd-border.c',
   'ssd-extents.c',

src/ssd/ssd-button.c

@@ -7,55 +7,13 @@
 #include "node.h"
 #include "scaled-buffer/scaled-icon-buffer.h"
 #include "scaled-buffer/scaled-img-buffer.h"
+#include "ssd.h"
 #include "ssd-internal.h"
 
-/* Internal helpers */
-static void
-handle_node_destroy(struct wl_listener *listener, void *data)
-{
-	struct ssd_part *part = wl_container_of(listener, part, node_destroy);
-	wl_list_remove(&part->node_destroy.link);
-
-	struct ssd_part_button *button = button_try_from_ssd_part(part);
-	if (button) {
-		wl_list_remove(&button->link);
-	}
-
-	free(part);
-}
-
 /* Internal API */
 
-/*
- * Create a new node_descriptor containing a link to a new ssd_part struct.
- * Both will be destroyed automatically once the scene_node they are attached
- * to is destroyed.
- */
-static void
-init_ssd_part(struct ssd_part *part, enum lab_node_type type,
-		struct view *view, struct wlr_scene_node *node)
-{
-	part->type = type;
-	part->node = node;
-	part->view = view;
-
-	node_descriptor_create(node, LAB_NODE_DESC_SSD_PART, part);
-	part->node_destroy.notify = handle_node_destroy;
-	wl_signal_add(&node->events.destroy, &part->node_destroy);
-}
-
-struct ssd_part *
-attach_ssd_part(enum lab_node_type type, struct view *view,
-		struct wlr_scene_node *node)
-{
-	assert(!node_type_contains(LAB_NODE_BUTTON, type));
-	struct ssd_part *part = znew(*part);
-	init_ssd_part(part, type, view, node);
-	return part;
-}
-
-struct ssd_part_button *
-attach_ssd_part_button(struct wl_list *button_parts, enum lab_node_type type,
+struct ssd_button *
+attach_ssd_button(struct wl_list *button_parts, enum lab_node_type type,
 		struct wlr_scene_tree *parent,
 		struct lab_img *imgs[LAB_BS_ALL + 1],
 		int x, int y, struct view *view)
@@ -64,8 +22,10 @@ attach_ssd_part_button(struct wl_list *button_parts, enum lab_node_type type,
 	wlr_scene_node_set_position(&root->node, x, y);
 
 	assert(node_type_contains(LAB_NODE_BUTTON, type));
-	struct ssd_part_button *button = znew(*button);
-	init_ssd_part(&button->base, type, view, &root->node);
+	struct ssd_button *button = znew(*button);
+	button->node = &root->node;
+	button->type = type;
+	node_descriptor_create(&root->node, type, view, button);
 	wl_list_append(button_parts, &button->link);
 
 	/* Hitbox */
@@ -117,11 +77,9 @@ attach_ssd_part_button(struct wl_list *button_parts, enum lab_node_type type,
 	return button;
 }
 
-struct ssd_part_button *
-button_try_from_ssd_part(struct ssd_part *part)
+/* called from node descriptor destroy */
+void ssd_button_free(struct ssd_button *button)
 {
-	if (node_type_contains(LAB_NODE_BUTTON, part->type)) {
-		return (struct ssd_part_button *)part;
-	}
-	return NULL;
+	wl_list_remove(&button->link);
+	free(button);
 }

src/ssd/ssd-titlebar.c

@@ -34,7 +34,8 @@ ssd_titlebar_create(struct ssd *ssd)
 	int corner_width = ssd_get_corner_width();
 
 	ssd->titlebar.tree = wlr_scene_tree_create(ssd->tree);
-	attach_ssd_part(LAB_NODE_TITLEBAR, view, &ssd->titlebar.tree->node);
+	node_descriptor_create(&ssd->titlebar.tree->node,
+		LAB_NODE_TITLEBAR, view, /*data*/ NULL);
 
 	enum ssd_active_state active;
 	FOR_EACH_ACTIVE_STATE(active) {
@@ -78,8 +79,8 @@ ssd_titlebar_create(struct ssd *ssd)
 			subtree->tree, theme->titlebar_height,
 			theme->window[active].titlebar_pattern);
 		assert(subtree->title);
-		attach_ssd_part(LAB_NODE_TITLE,
-			view, &subtree->title->scene_buffer->node);
+		node_descriptor_create(&subtree->title->scene_buffer->node,
+			LAB_NODE_TITLE, view, /*data*/ NULL);
 
 		/* Buttons */
 		struct title_button *b;
@@ -94,7 +95,7 @@ ssd_titlebar_create(struct ssd *ssd)
 		wl_list_for_each(b, &rc.title_buttons_left, link) {
 			struct lab_img **imgs =
 				theme->window[active].button_imgs[b->type];
-			attach_ssd_part_button(&subtree->buttons_left, b->type, parent,
+			attach_ssd_button(&subtree->buttons_left, b->type, parent,
 				imgs, x, y, view);
 			x += theme->window_button_width + theme->window_button_spacing;
 		}
@@ -104,7 +105,7 @@ ssd_titlebar_create(struct ssd *ssd)
 			x -= theme->window_button_width + theme->window_button_spacing;
 			struct lab_img **imgs =
 				theme->window[active].button_imgs[b->type];
-			attach_ssd_part_button(&subtree->buttons_right, b->type, parent,
+			attach_ssd_button(&subtree->buttons_right, b->type, parent,
 				imgs, x, y, view);
 		}
 	}
@@ -134,7 +135,7 @@ ssd_titlebar_create(struct ssd *ssd)
 }
 
 static void
-update_button_state(struct ssd_part_button *button, enum lab_button_state state,
+update_button_state(struct ssd_button *button, enum lab_button_state state,
 		bool enable)
 {
 	if (enable) {
@@ -177,7 +178,7 @@ set_squared_corners(struct ssd *ssd, bool enable)
 		wlr_scene_node_set_enabled(&subtree->corner_right->node, !enable);
 
 		/* (Un)round the corner buttons */
-		struct ssd_part_button *button;
+		struct ssd_button *button;
 		wl_list_for_each(button, &subtree->buttons_left, link) {
 			update_button_state(button, LAB_BS_ROUNDED, !enable);
 			break;
@@ -196,15 +197,15 @@ set_alt_button_icon(struct ssd *ssd, enum lab_node_type type, bool enable)
 	FOR_EACH_ACTIVE_STATE(active) {
 		struct ssd_titlebar_subtree *subtree = &ssd->titlebar.subtrees[active];
 
-		struct ssd_part_button *button;
+		struct ssd_button *button;
 		wl_list_for_each(button, &subtree->buttons_left, link) {
-			if (button->base.type == type) {
+			if (button->type == type) {
 				update_button_state(button,
 					LAB_BS_TOGGLED, enable);
 			}
 		}
 		wl_list_for_each(button, &subtree->buttons_right, link) {
-			if (button->base.type == type) {
+			if (button->type == type) {
 				update_button_state(button,
 					LAB_BS_TOGGLED, enable);
 			}
@@ -251,16 +252,16 @@ update_visible_buttons(struct ssd *ssd)
 		struct ssd_titlebar_subtree *subtree = &ssd->titlebar.subtrees[active];
 		int button_count = 0;
 
-		struct ssd_part_button *button;
+		struct ssd_button *button;
 		wl_list_for_each(button, &subtree->buttons_left, link) {
-			wlr_scene_node_set_enabled(button->base.node,
+			wlr_scene_node_set_enabled(button->node,
 				button_count < button_count_left);
 			button_count++;
 		}
 
 		button_count = 0;
 		wl_list_for_each(button, &subtree->buttons_right, link) {
-			wlr_scene_node_set_enabled(button->base.node,
+			wlr_scene_node_set_enabled(button->node,
 				button_count < button_count_right);
 			button_count++;
 		}
@@ -317,9 +318,9 @@ ssd_titlebar_update(struct ssd *ssd)
 			MAX(width - bg_offset * 2, 0), theme->titlebar_height);
 
 		x = theme->window_titlebar_padding_width;
-		struct ssd_part_button *button;
+		struct ssd_button *button;
 		wl_list_for_each(button, &subtree->buttons_left, link) {
-			wlr_scene_node_set_position(button->base.node, x, y);
+			wlr_scene_node_set_position(button->node, x, y);
 			x += theme->window_button_width + theme->window_button_spacing;
 		}
 
@@ -330,7 +331,7 @@ ssd_titlebar_update(struct ssd *ssd)
 		x = width - theme->window_titlebar_padding_width + theme->window_button_spacing;
 		wl_list_for_each(button, &subtree->buttons_right, link) {
 			x -= theme->window_button_width + theme->window_button_spacing;
-			wlr_scene_node_set_position(button->base.node, x, y);
+			wlr_scene_node_set_position(button->node, x, y);
 		}
 	}
 
@@ -419,14 +420,14 @@ get_title_offsets(struct ssd *ssd, int *offset_left, int *offset_right)
 	*offset_left = padding_width;
 	*offset_right = padding_width;
 
-	struct ssd_part_button *button;
+	struct ssd_button *button;
 	wl_list_for_each(button, &subtree->buttons_left, link) {
-		if (button->base.node->enabled) {
+		if (button->node->enabled) {
 			*offset_left += button_width + button_spacing;
 		}
 	}
 	wl_list_for_each(button, &subtree->buttons_right, link) {
-		if (button->base.node->enabled) {
+		if (button->node->enabled) {
 			*offset_right += button_width + button_spacing;
 		}
 	}
@@ -494,17 +495,13 @@ ssd_update_title(struct ssd *ssd)
 void
 ssd_update_hovered_button(struct server *server, struct wlr_scene_node *node)
 {
-	struct ssd_part_button *button = NULL;
+	struct ssd_button *button = NULL;
 
 	if (node && node->data) {
-		struct node_descriptor *desc = node->data;
-		if (desc->type == LAB_NODE_DESC_SSD_PART) {
-			button = button_try_from_ssd_part(
-					node_ssd_part_from_node(node));
-			if (button == server->hovered_button) {
-				/* Cursor is still on the same button */
-				return;
-			}
+		button = node_try_ssd_button_from_node(node);
+		if (button == server->hovered_button) {
+			/* Cursor is still on the same button */
+			return;
 		}
 	}
 

src/ssd/ssd.c

@@ -14,6 +14,7 @@
 #include "common/scene-helpers.h"
 #include "config/rcxml.h"
 #include "labwc.h"
+#include "node.h"
 #include "ssd-internal.h"
 #include "theme.h"
 #include "view.h"
@@ -145,7 +146,8 @@ ssd_create(struct view *view, bool active)
 
 	ssd->view = view;
 	ssd->tree = wlr_scene_tree_create(view->scene_tree);
-	attach_ssd_part(LAB_NODE_NONE, view, &ssd->tree->node);
+	node_descriptor_create(&ssd->tree->node,
+		LAB_NODE_NONE, view, /*data*/ NULL);
 	wlr_scene_node_lower_to_bottom(&ssd->tree->node);
 	ssd->titlebar.height = view->server->theme->titlebar_height;
 	ssd_shadow_create(ssd);
@@ -265,7 +267,8 @@ ssd_destroy(struct ssd *ssd)
 	/* Maybe reset hover view */
 	struct view *view = ssd->view;
 	struct server *server = view->server;
-	if (server->hovered_button && server->hovered_button->base.view == view) {
+	if (server->hovered_button && node_view_from_node(
+			server->hovered_button->node) == view) {
 		server->hovered_button = NULL;
 	}
 
@@ -343,18 +346,6 @@ ssd_enable_keybind_inhibit_indicator(struct ssd *ssd, bool enable)
 	wlr_scene_rect_set_color(ssd->border.subtrees[SSD_ACTIVE].top, color);
 }
 
-enum lab_node_type
-ssd_part_get_type(const struct ssd_part *part)
-{
-	return part ? part->type : LAB_NODE_NONE;
-}
-
-struct view *
-ssd_part_get_view(const struct ssd_part *part)
-{
-	return part ? part->view : NULL;
-}
-
 bool
 ssd_debug_is_root_node(const struct ssd *ssd, struct wlr_scene_node *node)
 {