src/ssd: Convert button node descriptors to struct ssd_button

This allows for way easier button hover detection and future
features like toggling rounded corner buttons on maximize.

include/node.h

@@ -7,6 +7,7 @@ struct view;
 struct lab_layer_surface;
 struct lab_layer_popup;
 struct menuitem;
+struct ssd_button;
 
 enum node_descriptor_type {
 	LAB_NODE_DESC_NODE = 0,
@@ -27,6 +28,10 @@ struct node_descriptor {
 
 /**
  * node_descriptor_create - create node descriptor for wlr_scene_node user_data
+ *
+ * The node_descriptor will be destroyed automatically
+ * once the scene_node it is attached to is destroyed.
+ *
  * @scene_node: wlr_scene_node to attached node_descriptor to
  * @type: node descriptor type
  * @data: struct to point to as follows:
@@ -34,6 +39,8 @@ struct node_descriptor {
  *   - LAB_NODE_DESC_XDG_POPUP      struct view
  *   - LAB_NODE_DESC_LAYER_SURFACE  struct lab_layer_surface
  *   - LAB_NODE_DESC_LAYER_POPUP    struct lab_layer_popup
+ *   - LAB_NODE_DESC_MENUITEM       struct menuitem
+ *   - LAB_NODE_DESC_SSD_BUTTON     struct ssd_button
  */
 void node_descriptor_create(struct wlr_scene_node *scene_node,
 	enum node_descriptor_type type, void *data);
@@ -65,4 +72,11 @@ struct lab_layer_popup *node_layer_popup_from_node(
 struct menuitem *node_menuitem_from_node(
 	struct wlr_scene_node *wlr_scene_node);
 
+/**
+ * node_ssd_button_from_node - return ssd_button struct from node
+ * @wlr_scene_node: wlr_scene_node from which to return data
+ */
+struct ssd_button *node_ssd_button_from_node(
+	struct wlr_scene_node *wlr_scene_node);
+
 #endif /* __LABWC_NODE_DESCRIPTOR_H */

include/ssd.h

@@ -54,6 +54,14 @@ struct wl_list;
 struct wlr_box;
 struct wlr_scene_tree;
 
+struct ssd_button {
+	struct view *view;
+	enum ssd_part_type type;
+	struct wlr_scene_node *hover;
+
+	struct wl_listener destroy;
+};
+
 struct ssd_sub_tree {
 	struct wlr_scene_tree *tree;
 	struct wl_list parts; /* ssd_part::link */
@@ -120,7 +128,6 @@ struct ssd_part {
 
 struct ssd_hover_state {
 	struct view *view;
-	enum ssd_part_type type;
 	struct wlr_scene_node *node;
 };
 
@@ -132,9 +139,8 @@ void ssd_update_title(struct view *view);
 void ssd_update_geometry(struct view *view);
 void ssd_reload(struct view *view);
 void ssd_destroy(struct view *view);
-/* Returns hover overlay node so it can be disabled later on */
-struct wlr_scene_node *ssd_button_hover_enable(
-	struct view *view, enum ssd_part_type type);
+void ssd_update_button_hover(struct wlr_scene_node *node,
+	struct ssd_hover_state *hover_state);
 
 /* Public SSD helpers */
 enum ssd_part_type ssd_at(struct view *view, double lx, double ly);

src/cursor.c

@@ -274,25 +274,8 @@ process_cursor_motion(struct server *server, uint32_t time)
 		}
 	}
 
-	/* SSD button mouse-over */
-	struct ssd_hover_state *hover = &server->ssd_hover_state;
-	if (ssd_is_button(view_area)) {
-		/* Cursor entered new button area */
-		if (hover->view != view || hover->type != view_area) {
-			if (hover->node) {
-				wlr_scene_node_set_enabled(hover->node, false);
-			}
-			hover->view = view;
-			hover->type = view_area;
-			hover->node = ssd_button_hover_enable(view, view_area);
-		}
-	} else if (hover->node) {
-		/* Cursor left button area */
-		wlr_scene_node_set_enabled(hover->node, false);
-		hover->view = NULL;
-		hover->type = LAB_SSD_NONE;
-		hover->node = NULL;
-	}
+	/* TODO: ssd_hover_state should likely be located in server->seat */
+	ssd_update_button_hover(node, &server->ssd_hover_state);
 
 	if (server->seat.pressed.surface &&
 			server->seat.pressed.surface != surface &&

src/desktop.c

@@ -296,8 +296,10 @@ desktop_node_and_view_at(struct server *server, double lx, double ly,
 			}
 			if (desc->type == LAB_NODE_DESC_SSD_BUTTON) {
 				/* Always return the top scene node for SSD buttons */
+				struct ssd_button *button = node_ssd_button_from_node(node);
 				*scene_node = node;
-				goto has_view_data;
+				*view_area = button->type;
+				return button->view;
 			}
 			if (desc->type == LAB_NODE_DESC_LAYER_SURFACE) {
 				/* FIXME: we shouldn't have to set *view_area */

src/node.c

@@ -43,8 +43,7 @@ node_view_from_node(struct wlr_scene_node *wlr_scene_node)
 	assert(wlr_scene_node->data);
 	struct node_descriptor *node_descriptor = wlr_scene_node->data;
 	assert(node_descriptor->type == LAB_NODE_DESC_VIEW
-		|| node_descriptor->type == LAB_NODE_DESC_XDG_POPUP
-		|| node_descriptor->type == LAB_NODE_DESC_SSD_BUTTON);
+		|| node_descriptor->type == LAB_NODE_DESC_XDG_POPUP);
 	return (struct view *)node_descriptor->data;
 }
 
@@ -74,3 +73,12 @@ node_menuitem_from_node(struct wlr_scene_node *wlr_scene_node)
 	assert(node_descriptor->type == LAB_NODE_DESC_MENUITEM);
 	return (struct menuitem *)node_descriptor->data;
 }
+
+struct ssd_button *
+node_ssd_button_from_node(struct wlr_scene_node *wlr_scene_node)
+{
+	assert(wlr_scene_node->data);
+	struct node_descriptor *node_descriptor = wlr_scene_node->data;
+	assert(node_descriptor->type == LAB_NODE_DESC_SSD_BUTTON);
+	return (struct ssd_button *)node_descriptor->data;
+}

src/ssd/ssd.c

@@ -240,7 +240,6 @@ ssd_destroy(struct view *view)
 	hover_state = &view->server->ssd_hover_state;
 	if (hover_state->view == view) {
 		hover_state->view = NULL;
-		hover_state->type = LAB_SSD_NONE;
 		hover_state->node = NULL;
 	}
 

src/ssd/ssd_part.c

@@ -5,6 +5,36 @@
 #include "ssd.h"
 #include "node.h"
 
+/* Internal helpers */
+static void
+ssd_button_destroy_notify(struct wl_listener *listener, void *data)
+{
+	struct ssd_button *button = wl_container_of(listener, button, destroy);
+	wl_list_remove(&button->destroy.link);
+	free(button);
+}
+
+/*
+ * Create a new node_descriptor containing a link to a new ssd_button struct.
+ * Both will be destroyed automatically once the scene_node they are attached
+ * to is destroyed.
+ */
+static struct ssd_button *
+ssd_button_descriptor_create(struct wlr_scene_node *node)
+{
+	/* Create new ssd_button */
+	struct ssd_button *button = calloc(1, sizeof(struct ssd_button));
+
+	/* Let it destroy automatically when the scene node destroys */
+	button->destroy.notify = ssd_button_destroy_notify;
+	wl_signal_add(&node->events.destroy, &button->destroy);
+
+	/* And finally attach the ssd_button to a node descriptor */
+	node_descriptor_create(node, LAB_NODE_DESC_SSD_BUTTON, button);
+	return button;
+}
+
+/* Internal API */
 struct ssd_part *
 add_scene_part(struct wl_list *part_list, enum ssd_part_type type)
 {
@@ -85,17 +115,16 @@ add_scene_button(struct wl_list *part_list, enum ssd_part_type type,
 		struct wlr_scene_tree *parent, float *bg_color,
 		struct wlr_buffer *icon_buffer, int x, struct view *view)
 {
-	struct ssd_part *part;
+	struct wlr_scene_node *hover;
 	float hover_bg[4] = {0.15f, 0.15f, 0.15f, 0.3f};
 
 	struct ssd_part *button_root = add_scene_part(part_list, type);
 	parent = wlr_scene_tree_create(parent);
 	button_root->node = &parent->node;
 	wlr_scene_node_set_position(button_root->node, x, 0);
-	node_descriptor_create(button_root->node, LAB_NODE_DESC_SSD_BUTTON, view);
 
 	/* Background */
-	part = add_scene_rect(part_list, type, parent,
+	add_scene_rect(part_list, type, parent,
 		BUTTON_WIDTH, rc.theme->title_height, 0, 0, bg_color);
 
 	/* Icon */
@@ -104,10 +133,14 @@ add_scene_button(struct wl_list *part_list, enum ssd_part_type type,
 		(rc.theme->title_height - icon_buffer->height) / 2);
 
 	/* Hover overlay */
-	part = add_scene_rect(part_list, type, parent, BUTTON_WIDTH,
-		rc.theme->title_height, 0, 0, hover_bg);
-	wlr_scene_node_set_enabled(part->node, false);
+	hover = add_scene_rect(part_list, type, parent, BUTTON_WIDTH,
+		rc.theme->title_height, 0, 0, hover_bg)->node;
+	wlr_scene_node_set_enabled(hover, false);
 
+	struct ssd_button *button = ssd_button_descriptor_create(button_root->node);
+	button->type = type;
+	button->view = view;
+	button->hover = hover;
 	return button_root;
 }
 

src/ssd/ssd_titlebar.c

@@ -8,6 +8,7 @@
 #include "theme.h"
 #include "common/font.h"
 #include "common/scene-helpers.h"
+#include "node.h"
 
 #define FOR_EACH_STATE(view, tmp) FOR_EACH(tmp, \
 	&(view)->ssd.titlebar.active, \
@@ -271,52 +272,35 @@ ssd_update_title(struct view *view)
 	ssd_update_title_positions(view);
 }
 
-/*
- * Returns the wlr_scene_node for hover effect.
- * To disable the hover effect later on just call
- * wlr_scene_node_set_enabled(node, false).
- */
-struct wlr_scene_node *
-ssd_button_hover_enable(struct view *view, enum ssd_part_type type)
+void
+ssd_update_button_hover(struct wlr_scene_node *node,
+		struct ssd_hover_state *hover_state)
 {
-	if (!view->ssd.tree) {
-		wlr_log(WLR_ERROR, "%s() for destroyed view", __func__);
-		return NULL;
+	struct ssd_button *button = NULL;
+	if (!node || !node->data) {
+		goto disable_old_hover;
 	}
 
-	assert(ssd_is_button(type));
-	struct ssd_part *part;
-	struct ssd_sub_tree *subtree;
-	FOR_EACH_STATE(view, subtree) {
-		if (subtree->tree->node.enabled) {
-			/*
-			 * TODO: This function makes too many magic assumptions:
-			 * - It expects the returned part to be the tree for the button
-			 * - It expects the last node in that tree to be the hover overlay
-			 *
-			 * Both assumptions are valid as long as ssd_parts.c isn't changing
-			 * the way a button is created but this cries for introducing bugs
-			 * in the future if the button creation process or ssd_get_part()
-			 * lookup routine would ever change.
-			 */
-			part = ssd_get_part(&subtree->parts, type);
-			if (!part) {
-				wlr_log(WLR_ERROR, "hover enable failed to find button");
-				return NULL;
-			}
-			struct wlr_scene_node *child;
-			struct wlr_scene_tree *button = lab_scene_tree_from_node(part->node);
-			wl_list_for_each_reverse(child, &button->children, link) {
-				if (child->type == WLR_SCENE_NODE_RECT) {
-					wlr_scene_node_set_enabled(child, true);
-					return child;
+	struct node_descriptor *desc = node->data;
+	if (desc->type == LAB_NODE_DESC_SSD_BUTTON) {
+		button = node_ssd_button_from_node(node);
+		if (button->hover == hover_state->node) {
+			/* Cursor is still on the same button */
+			return;
 		}
 	}
-		}
-	} FOR_EACH_END
 
-	wlr_log(WLR_ERROR, "hover enable failed to find button");
-	return NULL;
+disable_old_hover:
+	if (hover_state->node) {
+		wlr_scene_node_set_enabled(hover_state->node, false);
+		hover_state->view = NULL;
+		hover_state->node = NULL;
+	}
+	if (button) {
+		wlr_scene_node_set_enabled(button->hover, true);
+		hover_state->view = button->view;
+		hover_state->node = button->hover;
+	}
 }
 
 #undef FOR_EACH_STATE