ssd: scale titlebar buttons to fit for very small views

include/ssd-internal.h

@@ -65,6 +65,7 @@ struct ssd {
 	/* The top of the view, containing buttons, title, .. */
 	struct {
 		int height;
+		int button_width;
 		struct wlr_scene_tree *tree;
 		struct ssd_sub_tree active;
 		struct ssd_sub_tree inactive;
@@ -129,15 +130,15 @@ struct ssd_part *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, struct wlr_buffer *hover_buffer,
-	int x, struct view *view);
+	int x, int width, struct view *view);
 void add_toggled_icon(struct ssd_button *button, struct wl_list *part_list,
 	enum ssd_part_type type, struct wlr_buffer *icon_buffer,
-	struct wlr_buffer *hover_buffer);
+	struct wlr_buffer *hover_buffer, int width);
 struct ssd_part *add_scene_button_corner(
 	struct wl_list *part_list, enum ssd_part_type type,
 	enum ssd_part_type corner_type, struct wlr_scene_tree *parent,
 	struct wlr_buffer *corner_buffer, struct wlr_buffer *icon_buffer,
-	struct wlr_buffer *hover_buffer, int x, struct view *view);
+	struct wlr_buffer *hover_buffer, int x, int width, struct view *view);
 
 /* SSD internal helpers */
 struct ssd_part *ssd_get_part(

src/ssd/ssd-border.c

@@ -22,6 +22,7 @@ ssd_border_create(struct ssd *ssd)
 	int width = view->current.width;
 	int height = view_effective_height(view, /* use_pending */ false);
 	int full_width = width + 2 * theme->border_width;
+	int button_width = ssd->titlebar.button_width;
 
 	float *color;
 	struct wlr_scene_tree *parent;
@@ -48,8 +49,8 @@ ssd_border_create(struct ssd *ssd)
 		add_scene_rect(&subtree->parts, LAB_SSD_PART_BOTTOM, parent,
 			full_width, theme->border_width, 0, height, color);
 		add_scene_rect(&subtree->parts, LAB_SSD_PART_TOP, parent,
-			width - 2 * theme->window_button_width, theme->border_width,
+			width - 2 * button_width, theme->border_width,
-			theme->border_width + theme->window_button_width,
+			theme->border_width + button_width,
 			-(ssd->titlebar.height + theme->border_width), color);
 	} FOR_EACH_END
 
@@ -93,6 +94,7 @@ ssd_border_update(struct ssd *ssd)
 	int width = view->current.width;
 	int height = view_effective_height(view, /* use_pending */ false);
 	int full_width = width + 2 * theme->border_width;
+	int button_width = ssd->titlebar.button_width;
 
 	/*
 	 * From here on we have to cover the following border scenarios:
@@ -121,10 +123,10 @@ ssd_border_update(struct ssd *ssd)
 		: 0;
 	int top_width = ssd->titlebar.height <= 0 || ssd->state.was_tiled_not_maximized
 		? full_width
-		: width - 2 * theme->window_button_width;
+		: width - 2 * button_width;
 	int top_x = ssd->titlebar.height <= 0 || ssd->state.was_tiled_not_maximized
 		? 0
-		: theme->border_width + theme->window_button_width;
+		: theme->border_width + button_width;
 
 	struct ssd_part *part;
 	struct wlr_scene_rect *rect;

src/ssd/ssd-extents.c

@@ -32,8 +32,8 @@ ssd_extents_create(struct ssd *ssd)
 	struct theme *theme = view->server->theme;
 	struct wl_list *part_list = &ssd->extents.parts;
 	int extended_area = SSD_EXTENDED_AREA;
-	int corner_size = extended_area + theme->border_width +
+	int corner_size = extended_area + theme->border_width
-		theme->window_button_width / 2;
+		+ ssd->titlebar.button_width / 2;
 
 	ssd->extents.tree = wlr_scene_tree_create(ssd->tree);
 	struct wlr_scene_tree *parent = ssd->extents.tree;
@@ -110,8 +110,8 @@ ssd_extents_update(struct ssd *ssd)
 	int full_height = height + theme->border_width * 2 + ssd->titlebar.height;
 	int full_width = width + 2 * theme->border_width;
 	int extended_area = SSD_EXTENDED_AREA;
-	int corner_size = extended_area + theme->border_width +
+	int corner_size = extended_area + theme->border_width
-		theme->window_button_width / 2;
+		+ ssd->titlebar.button_width / 2;
 	int side_width = full_width + extended_area * 2 - corner_size * 2;
 	int side_height = full_height + extended_area * 2 - corner_size * 2;
 

src/ssd/ssd-part.c

@@ -82,7 +82,7 @@ struct ssd_part *
 add_scene_button_corner(struct wl_list *part_list, enum ssd_part_type type,
 		enum ssd_part_type corner_type, struct wlr_scene_tree *parent,
 		struct wlr_buffer *corner_buffer, struct wlr_buffer *icon_buffer,
-		struct wlr_buffer *hover_buffer, int x, struct view *view)
+		struct wlr_buffer *hover_buffer, int x, int width, struct view *view)
 {
 	int offset_x;
 	float invisible[4] = { 0, 0, 0, 0 };
@@ -106,17 +106,29 @@ add_scene_button_corner(struct wl_list *part_list, enum ssd_part_type type,
 	 * Background, x and y adjusted for border_width which is
 	 * already included in rendered theme.c / corner_buffer
 	 */
+	struct ssd_part *corner_part =
 		add_scene_buffer(part_list, corner_type, parent, corner_buffer,
 			-offset_x, -rc.theme->border_width);
 
+	/*
+	 * Scale down corner if needed for very small views. The
+	 * rendering will not be perfect, but this is an abnormal case
+	 * so we probably don't care.
+	 */
+	wlr_scene_buffer_set_dest_size(
+		wlr_scene_buffer_from_node(corner_part->node),
+		width + rc.theme->border_width,
+		rc.theme->title_height + rc.theme->border_width);
+
 	/* Finally just put a usual theme button on top, using an invisible hitbox */
-	add_scene_button(part_list, type, parent, invisible, icon_buffer, hover_buffer, 0, view);
+	add_scene_button(part_list, type, parent, invisible, icon_buffer,
+		hover_buffer, 0, width, view);
 	return button_root;
 }
 
 static struct wlr_box
 get_scale_box(struct wlr_buffer *buffer, double container_width,
-		double container_height)
+		double container_height, double max_scale)
 {
 	struct wlr_box icon_geo = {
 		.width = buffer->width,
@@ -127,6 +139,7 @@ get_scale_box(struct wlr_buffer *buffer, double container_width,
 	if (icon_geo.width && icon_geo.height) {
 		double scale = MIN(container_width / icon_geo.width,
 			container_height / icon_geo.height);
+		scale = MIN(scale, max_scale);
 		if (scale < 1.0f) {
 			icon_geo.width = (double)icon_geo.width * scale;
 			icon_geo.height = (double)icon_geo.height * scale;
@@ -144,7 +157,7 @@ struct ssd_part *
 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, struct wlr_buffer *hover_buffer,
-		int x, struct view *view)
+		int x, int width, struct view *view)
 {
 	struct ssd_part *button_root = add_scene_part(part_list, type);
 	parent = wlr_scene_tree_create(parent);
@@ -153,13 +166,19 @@ add_scene_button(struct wl_list *part_list, enum ssd_part_type type,
 
 	/* Background */
 	struct ssd_part *bg_rect = add_scene_rect(part_list, type, parent,
-		rc.theme->window_button_width, rc.theme->title_height, 0, 0,
+		width, rc.theme->title_height, 0, 0, bg_color);
-		bg_color);
 
 	/* Icon */
 	struct wlr_scene_tree *icon_tree = wlr_scene_tree_create(parent);
+	/*
+	 * Always scale icon down proportionally if the button is
+	 * narrowed from the default (as for a very small view). The
+	 * hover icon is already pre-rendered in a default-size buffer
+	 * and so doesn't need this extra step.
+	 */
+	double max_icon_scale = (double)width / rc.theme->window_button_width;
 	struct wlr_box icon_geo = get_scale_box(icon_buffer,
-		rc.theme->window_button_width, rc.theme->title_height);
+		width, rc.theme->title_height, max_icon_scale);
 	struct ssd_part *icon_part = add_scene_buffer(part_list, type,
 		icon_tree, icon_buffer, icon_geo.x, icon_geo.y);
 
@@ -172,7 +191,7 @@ add_scene_button(struct wl_list *part_list, enum ssd_part_type type,
 	struct wlr_scene_tree *hover_tree = wlr_scene_tree_create(parent);
 	wlr_scene_node_set_enabled(&hover_tree->node, false);
 	struct wlr_box hover_geo = get_scale_box(hover_buffer,
-		rc.theme->window_button_width, rc.theme->title_height);
+		width, rc.theme->title_height, /*max_scale*/ 1.0);
 	struct ssd_part *hover_part = add_scene_buffer(part_list, type,
 		hover_tree, hover_buffer, hover_geo.x, hover_geo.y);
 
@@ -197,11 +216,18 @@ add_scene_button(struct wl_list *part_list, enum ssd_part_type type,
 void
 add_toggled_icon(struct ssd_button *button, struct wl_list *part_list,
 		enum ssd_part_type type, struct wlr_buffer *icon_buffer,
-		struct wlr_buffer *hover_buffer)
+		struct wlr_buffer *hover_buffer, int width)
 {
 	/* Alternate icon */
+	/*
+	 * Always scale icon down proportionally if the button is
+	 * narrowed from the default (as for a very small view). The
+	 * hover icon is already pre-rendered in a default-size buffer
+	 * and so doesn't need this extra step.
+	 */
+	double max_icon_scale = (double)width / rc.theme->window_button_width;
 	struct wlr_box icon_geo = get_scale_box(icon_buffer,
-		rc.theme->window_button_width, rc.theme->title_height);
+		width, rc.theme->title_height, max_icon_scale);
 
 	struct ssd_part *alticon_part = add_scene_buffer(part_list, type,
 		button->icon_tree, icon_buffer, icon_geo.x, icon_geo.y);
@@ -213,7 +239,7 @@ add_toggled_icon(struct ssd_button *button, struct wl_list *part_list,
 	wlr_scene_node_set_enabled(alticon_part->node, false);
 
 	struct wlr_box hover_geo = get_scale_box(hover_buffer,
-		rc.theme->window_button_width, rc.theme->title_height);
+		width, rc.theme->title_height, /*max_scale*/ 1.0);
 	struct ssd_part *althover_part = add_scene_buffer(part_list, type,
 		button->hover_tree, hover_buffer, hover_geo.x, hover_geo.y);
 

src/ssd/ssd-titlebar.c

@@ -27,6 +27,7 @@ ssd_titlebar_create(struct ssd *ssd)
 	struct view *view = ssd->view;
 	struct theme *theme = view->server->theme;
 	int width = view->current.width;
+	int button_width = ssd->titlebar.button_width;
 
 	float *color;
 	struct wlr_scene_tree *parent;
@@ -90,29 +91,30 @@ ssd_titlebar_create(struct ssd *ssd)
 
 		/* Title */
 		add_scene_rect(&subtree->parts, LAB_SSD_PART_TITLEBAR, parent,
-			width - theme->window_button_width * SSD_BUTTON_COUNT,
+			width - button_width * SSD_BUTTON_COUNT, theme->title_height,
-			theme->title_height, theme->window_button_width, 0, color);
+			button_width, 0, color);
 		/* Buttons */
 		add_scene_button_corner(&subtree->parts,
-			LAB_SSD_BUTTON_WINDOW_MENU, LAB_SSD_PART_CORNER_TOP_LEFT, parent,
+			LAB_SSD_BUTTON_WINDOW_MENU, LAB_SSD_PART_CORNER_TOP_LEFT,
-			corner_top_left, menu_button_unpressed, menu_button_hover, 0, view);
+			parent, corner_top_left, menu_button_unpressed,
+			menu_button_hover, 0, button_width, view);
 		add_scene_button(&subtree->parts, LAB_SSD_BUTTON_ICONIFY, parent,
 			color, iconify_button_unpressed, iconify_button_hover,
-			width - theme->window_button_width * 3, view);
+			width - button_width * 3, button_width, view);
 
 		/* Maximize button has an alternate state when maximized */
 		struct ssd_part *btn_max_root = add_scene_button(
 			&subtree->parts, LAB_SSD_BUTTON_MAXIMIZE, parent,
 			color, maximize_button_unpressed, maximize_button_hover,
-			width - theme->window_button_width * 2, view);
+			width - button_width * 2, button_width, view);
 		struct ssd_button *btn_max = node_ssd_button_from_node(btn_max_root->node);
 		add_toggled_icon(btn_max, &subtree->parts, LAB_SSD_BUTTON_MAXIMIZE,
-			restore_button_unpressed, restore_button_hover);
+			restore_button_unpressed, restore_button_hover, button_width);
 
 		add_scene_button_corner(&subtree->parts,
 			LAB_SSD_BUTTON_CLOSE, LAB_SSD_PART_CORNER_TOP_RIGHT, parent,
 			corner_top_right, close_button_unpressed, close_button_hover,
-			width - theme->window_button_width * 1, view);
+			width - button_width * 1, button_width, view);
 	} FOR_EACH_END
 
 	ssd_update_title(ssd);
@@ -189,8 +191,9 @@ void
 ssd_titlebar_update(struct ssd *ssd)
 {
 	struct view *view = ssd->view;
-	int width = view->current.width;
 	struct theme *theme = view->server->theme;
+	int width = view->current.width;
+	int button_width = ssd->titlebar.button_width;
 
 	bool maximized = view->maximized == VIEW_AXIS_BOTH;
 	bool tiled_not_maximized = view_is_tiled_and_notify_tiled(ssd->view)
@@ -218,25 +221,25 @@ ssd_titlebar_update(struct ssd *ssd)
 			case LAB_SSD_PART_TITLEBAR:
 				wlr_scene_rect_set_size(
 					wlr_scene_rect_from_node(part->node),
-					width - theme->window_button_width * SSD_BUTTON_COUNT,
+					width - button_width * SSD_BUTTON_COUNT,
 					theme->title_height);
 				continue;
 			case LAB_SSD_BUTTON_ICONIFY:
 				if (is_direct_child(part->node, subtree)) {
 					wlr_scene_node_set_position(part->node,
-						width - theme->window_button_width * 3, 0);
+						width - button_width * 3, 0);
 				}
 				continue;
 			case LAB_SSD_BUTTON_MAXIMIZE:
 				if (is_direct_child(part->node, subtree)) {
 					wlr_scene_node_set_position(part->node,
-						width - theme->window_button_width * 2, 0);
+						width - button_width * 2, 0);
 				}
 				continue;
 			case LAB_SSD_PART_CORNER_TOP_RIGHT:
 				if (is_direct_child(part->node, subtree)) {
 					wlr_scene_node_set_position(part->node,
-						width - theme->window_button_width * 1, 0);
+						width - button_width * 1, 0);
 				}
 				continue;
 			default:
@@ -270,6 +273,20 @@ ssd_titlebar_destroy(struct ssd *ssd)
 	ssd->titlebar.tree = NULL;
 }
 
+static int
+get_title_width(int view_width, int button_width)
+{
+	/*
+	 * Always return 0 if the button width is narrower than default.
+	 * Simply computing (width - button_width * SSD_BUTTON_COUNT)
+	 * gives undesired widths of 1 to (SSD_BUTTON_COUNT - 1) pixels
+	 * due to rounding errors (since button_width is an integer).
+	 */
+	int theme_button_width = rc.theme->window_button_width;
+	return (button_width < theme_button_width) ? 0
+		: view_width - theme_button_width * SSD_BUTTON_COUNT;
+}
+
 /*
  * For ssd_update_title* we do not early out because
  * .active and .inactive may result in different sizes
@@ -288,7 +305,8 @@ ssd_update_title_positions(struct ssd *ssd)
 	struct view *view = ssd->view;
 	struct theme *theme = view->server->theme;
 	int width = view->current.width;
-	int title_bg_width = width - theme->window_button_width * SSD_BUTTON_COUNT;
+	int button_width = ssd->titlebar.button_width;
+	int title_bg_width = get_title_width(width, button_width);
 
 	int x, y;
 	int buffer_height, buffer_width;
@@ -304,7 +322,7 @@ ssd_update_title_positions(struct ssd *ssd)
 
 		buffer_width = part->buffer ? part->buffer->width : 0;
 		buffer_height = part->buffer ? part->buffer->height : 0;
-		x = theme->window_button_width;
+		x = button_width;
 		y = (theme->title_height - buffer_height) / 2;
 
 		if (title_bg_width <= 0) {
@@ -314,7 +332,7 @@ ssd_update_title_positions(struct ssd *ssd)
 		wlr_scene_node_set_enabled(part->node, true);
 
 		if (theme->window_label_text_justify == LAB_JUSTIFY_CENTER) {
-			if (buffer_width + theme->window_button_width * 2 <= title_bg_width) {
+			if (buffer_width + button_width * 2 <= title_bg_width) {
 				/* Center based on the full width */
 				x = (width - buffer_width) / 2;
 			} else {
@@ -357,8 +375,8 @@ ssd_update_title(struct ssd *ssd)
 	struct ssd_part *part;
 	struct ssd_sub_tree *subtree;
 	struct ssd_state_title_width *dstate;
-	int title_bg_width = view->current.width
+	int title_bg_width = get_title_width(view->current.width,
-		- theme->window_button_width * SSD_BUTTON_COUNT;
+		ssd->titlebar.button_width);
 
 	FOR_EACH_STATE(ssd, subtree) {
 		if (subtree == &ssd->titlebar.active) {

src/ssd/ssd.c

@@ -176,6 +176,15 @@ ssd_resize_edges(enum ssd_part_type type)
 	}
 }
 
+static int
+get_button_width(int view_width)
+{
+	/* view_width may be 0 if view isn't mapped yet */
+	int theme_button_width = rc.theme->window_button_width;
+	return (view_width > 0 && view_width < theme_button_width * SSD_BUTTON_COUNT)
+		? view_width / SSD_BUTTON_COUNT : theme_button_width;
+}
+
 struct ssd *
 ssd_create(struct view *view, bool active)
 {
@@ -186,6 +195,7 @@ ssd_create(struct view *view, bool active)
 	ssd->tree = wlr_scene_tree_create(view->scene_tree);
 	wlr_scene_node_lower_to_bottom(&ssd->tree->node);
 	ssd->titlebar.height = view->server->theme->title_height;
+	ssd->titlebar.button_width = get_button_width(view->current.width);
 	ssd_shadow_create(ssd);
 	ssd_extents_create(ssd);
 	/*
@@ -223,6 +233,21 @@ ssd_update_margin(struct ssd *ssd)
 	ssd->margin = ssd_thickness(ssd->view);
 }
 
+/*
+ * Clears pointers to this view's SSD from the global hover state.
+ * Must be called before the SSD or any buttons are destroyed.
+ */
+static void
+ssd_reset_hover_state(struct ssd *ssd)
+{
+	struct ssd_hover_state *hover_state =
+		ssd->view->server->ssd_hover_state;
+	if (hover_state->view == ssd->view) {
+		hover_state->view = NULL;
+		hover_state->button = NULL;
+	}
+}
+
 void
 ssd_update_geometry(struct ssd *ssd)
 {
@@ -233,20 +258,9 @@ ssd_update_geometry(struct ssd *ssd)
 	struct wlr_box cached = ssd->state.geometry;
 	struct wlr_box current = ssd->view->current;
 
-	int min_view_width = rc.theme->window_button_width * SSD_BUTTON_COUNT;
 	int eff_width = current.width;
 	int eff_height = view_effective_height(ssd->view, /* use_pending */ false);
 
-	if (eff_width > 0 && eff_width < min_view_width) {
-		/*
-		 * Prevent negative values in calculations like
-		 * `width - SSD_BUTTON_WIDTH * SSD_BUTTON_COUNT`
-		 */
-		wlr_log(WLR_ERROR,
-			"view width is smaller than its minimal value");
-		return;
-	}
-
 	if (eff_width == cached.width && eff_height == cached.height) {
 		if (current.x != cached.x || current.y != cached.y) {
 			/* Dynamically resize extents based on position and usable_area */
@@ -274,6 +288,22 @@ ssd_update_geometry(struct ssd *ssd)
 		}
 		return;
 	}
+
+	/*
+	 * Rather than resizing/re-rendering individual buttons and
+	 * icons in ssd_titlebar_update(), it's simpler to just recreate
+	 * them all. This case is only hit for abnormally small views,
+	 * so it's probably not worth optimizing further.
+	 */
+	int button_width = get_button_width(current.width);
+	if (button_width != ssd->titlebar.button_width) {
+		/* Reset hover state before recreating buttons */
+		ssd_reset_hover_state(ssd);
+		ssd_titlebar_destroy(ssd);
+		ssd->titlebar.button_width = button_width;
+		ssd_titlebar_create(ssd);
+	}
+
 	ssd_extents_update(ssd);
 	ssd_titlebar_update(ssd);
 	ssd_border_update(ssd);
@@ -302,16 +332,9 @@ ssd_destroy(struct ssd *ssd)
 		return;
 	}
 
-	/* Maybe reset hover view */
-	struct view *view = ssd->view;
-	struct ssd_hover_state *hover_state;
-	hover_state = view->server->ssd_hover_state;
-	if (hover_state->view == view) {
-		hover_state->view = NULL;
-		hover_state->button = NULL;
-	}
-
 	/* Destroy subcomponents */
+	/* Reset hover state before destroying */
+	ssd_reset_hover_state(ssd);
 	ssd_titlebar_destroy(ssd);
 	ssd_border_destroy(ssd);
 	ssd_extents_destroy(ssd);