osd: support 'alt-tab' on screen display

The osd window shows title, app_id/class and shell of all views that can
be cycled between.

include/labwc.h

@@ -109,6 +109,7 @@ struct server {
 	double grab_x, grab_y;
 	struct wlr_box grab_box;
 	uint32_t resize_edges;
+	struct wlr_texture *osd;
 
 	struct wl_list outputs;
 	struct wl_listener new_output;
@@ -234,7 +235,7 @@ struct view {
 	struct wl_listener commit;
 	struct wl_listener request_move;
 	struct wl_listener request_resize;
-	struct wl_listener request_configure;
+	struct wl_listener request_configure;	/* xwayland only */
 	struct wl_listener request_maximize;
 	struct wl_listener set_title;
 	struct wl_listener new_popup;		/* xdg-shell only */
@@ -324,6 +325,7 @@ void desktop_focus_view(struct seat *seat, struct view *view);
 struct view *desktop_cycle_view(struct server *server, struct view *current);
 struct view *topmost_mapped_view(struct server *server);
 void desktop_focus_topmost_mapped_view(struct server *server);
+bool isfocusable(struct view *view);
 
 /**
  * desktop_view_at - find view or layer-surface at co-ordinate (lx, ly)
@@ -363,8 +365,7 @@ void server_finish(struct server *server);
 
 void action(struct server *server, const char *action, const char *command);
 
-void dbg_show_one_view(struct view *view);
+/* update onscreen display 'alt-tab' texture */
-void dbg_show_views(struct server *server);
+void osd_update(struct server *server);
-void dbg_show_keybinds();
 
 #endif /* __LABWC_H */

src/action.c

@@ -44,6 +44,7 @@ action(struct server *server, const char *action, const char *command)
 	} else if (!strcasecmp(action, "NextWindow")) {
 		server->cycle_view =
 			desktop_cycle_view(server, server->cycle_view);
+		osd_update(server);
 	} else if (!strcasecmp(action, "Reconfigure")) {
 		spawn_async_no_shell("killall -SIGHUP labwc");
 	} else if (!strcasecmp(action, "ShowMenu")) {

src/desktop.c

@@ -130,7 +130,7 @@ desktop_focus_view(struct seat *seat, struct view *view)
  * careful when cycling between views. The only views we should focus are
  * those that are already mapped and those that have been minimized.
  */
-static bool
+bool
 isfocusable(struct view *view)
 {
 	/* filter out those xwayland surfaces that have never been mapped */

src/keyboard.c

@@ -72,6 +72,8 @@ keyboard_key_notify(struct wl_listener *listener, void *data)
 			/* cycle to next */
 			server->cycle_view =
 				desktop_cycle_view(server, server->cycle_view);
+			osd_update(server);
+			damage_all_outputs(server);
 			return;
 		}
 	}

src/osd.c

@@ -1,118 +1,176 @@
 #include "config.h"
+#include <cairo.h>
+#include <drm_fourcc.h>
+#include <pango/pangocairo.h>
 #include <wlr/util/log.h>
-#include "config/keybind.h"
+#include "common/buf.h"
+#include "common/font.h"
 #include "config/rcxml.h"
 #include "labwc.h"
 
-#if HAVE_XWAYLAND
+#define OSD_ITEM_HEIGHT (20)
+#define OSD_ITEM_WIDTH (600)
+#define OSD_ITEM_PADDING (10)
+#define OSD_BORDER_WIDTH (6)
+#define OSD_TAB1 (120)
+#define OSD_TAB2 (300)
+
+static void
+set_source(cairo_t *cairo, float *c)
+{
+	cairo_set_source_rgba(cairo, c[0], c[1], c[2], c[3]);
+}
+
+/* is title different from app_id/class? */
 static int
-xwl_nr_parents(struct view *view)
+is_title_different(struct view *view)
 {
-	struct wlr_xwayland_surface *s = view->xwayland_surface;
+	switch (view->type) {
-	int i = 0;
+	case LAB_XDG_SHELL_VIEW:
-
+		return strcmp(view->impl->get_string_prop(view, "title"),
-	if (!s) {
+			view->impl->get_string_prop(view, "app_id"));
-		wlr_log(WLR_ERROR, "no xwayland surface");
-		return -1;
-	}
-	while (s->parent) {
-		s = s->parent;
-		++i;
-	}
-	return i;
-}
-#endif
-
-static void
-show_one_xdg_view(struct view *view)
-{
-	fprintf(stderr, "XDG  ");
-	switch (view->xdg_surface->role) {
-	case WLR_XDG_SURFACE_ROLE_NONE:
-		fprintf(stderr, "- ");
-		break;
-	case WLR_XDG_SURFACE_ROLE_TOPLEVEL:
-		fprintf(stderr, "0 ");
-		break;
-	case WLR_XDG_SURFACE_ROLE_POPUP:
-		fprintf(stderr, "? ");
-		break;
-	}
-	fprintf(stderr, "                   %p %s", (void *)view,
-		view->xdg_surface->toplevel->app_id);
-	fprintf(stderr, "  {%d, %d, %d, %d}\n", view->x, view->y, view->w,
-		view->h);
-}
-
 #if HAVE_XWAYLAND
-static void
+	case LAB_XWAYLAND_VIEW:
-show_one_xwl_view(struct view *view)
+		return strcmp(view->impl->get_string_prop(view, "title"),
-{
+			view->xwayland_surface->class);
-	fprintf(stderr, "XWL  ");
-	fprintf(stderr, "%d ", xwl_nr_parents(view));
-	fprintf(stderr, "     %d      ",
-		wl_list_length(&view->xwayland_surface->children));
-	if (view->mapped) {
-		fprintf(stderr, "Y");
-	} else {
-		fprintf(stderr, "-");
-	}
-	fprintf(stderr, "      %p %s {%d,%d,%d,%d}\n", (void *)view,
-		view->xwayland_surface->class, view->xwayland_surface->x,
-		view->xwayland_surface->y, view->xwayland_surface->width,
-		view->xwayland_surface->height);
-	/*
-	 * Other variables to consider printing:
-	 *
-	 * view->mapped,
-	 * view->xwayland_surface->override_redirect,
-	 * wlr_xwayland_or_surface_wants_focus(view->xwayland_surface));
-	 * view->xwayland_surface->saved_width,
-	 * view->xwayland_surface->saved_height);
-	 * view->xwayland_surface->surface->sx,
-	 * view->xwayland_surface->surface->sy);
-	 */
-}
-#endif
-
-void
-dbg_show_one_view(struct view *view)
-{
-	if (!view->surface) {
-		return;
-	}
-	if (!view->mapped && !view->minimized) {
-		return;
-	}
-	if (view->type == LAB_XDG_SHELL_VIEW) {
-		show_one_xdg_view(view);
-#if HAVE_XWAYLAND
-	} else if (view->type == LAB_XWAYLAND_VIEW) {
-		show_one_xwl_view(view);
 #endif
 	}
+	return 1;
 }
 
-void
+static const char *
-dbg_show_views(struct server *server)
+get_formatted_app_id(struct view *view)
 {
-	struct view *view;
+	char *s = (char *)view->impl->get_string_prop(view, "app_id");
-
+	/* remove the first two nodes of 'org.' strings */
-	fprintf(stderr, "---\n");
+	if (!strncmp(s, "org.", 4)) {
-	fprintf(stderr, "TYPE NR_PNT NR_CLD MAPPED VIEW-POINTER   NAME\n");
+		char *p = s + 4;
-	wl_list_for_each_reverse (view, &server->views, link) {
+		p = strchr(p, '.');
-		dbg_show_one_view(view);
+		if (p) {
-	}
+			return ++p;
-}
-
-void
-dbg_show_keybinds()
-{
-	struct keybind *keybind;
-	wl_list_for_each_reverse (keybind, &rc.keybinds, link) {
-		printf("KEY=%s-", keybind->action);
-		for (size_t i = 0; i < keybind->keysyms_len; i++) {
-			printf("    %d\n", keybind->keysyms[i]);
 		}
 	}
+	return s;
+}
+
+static int
+get_osd_height(struct wl_list *views)
+{
+	int height = 0;
+	struct view *view;
+	wl_list_for_each(view, views, link) {
+		if (!isfocusable(view)) {
+			continue;
+		}
+		height += OSD_ITEM_HEIGHT;
+	}
+	height += 2 * OSD_BORDER_WIDTH;
+	return height;
+}
+
+void
+osd_update(struct server *server)
+{
+	struct wlr_renderer *renderer = server->renderer;
+	int w = OSD_ITEM_WIDTH + 2 * OSD_BORDER_WIDTH;
+	int h = get_osd_height(&server->views);
+
+	cairo_surface_t *surf =
+		cairo_image_surface_create(CAIRO_FORMAT_ARGB32, w, h);
+	cairo_t *cairo = cairo_create(surf);
+
+	/* background */
+	set_source(cairo, (float[4]){1.0f, 1.0f, 1.0f, 1.0f});
+	cairo_rectangle(cairo, 0, 0, w, h);
+	cairo_fill(cairo);
+
+	/* highlight current application */
+	int y = OSD_BORDER_WIDTH;
+	struct view *view;
+	wl_list_for_each(view, &server->views, link) {
+		if (!isfocusable(view)) {
+			continue;
+		}
+		if (view == server->cycle_view) {
+			set_source(cairo, (float[4]){0.3f, 0.3f, 0.3f, 0.5f});
+			cairo_rectangle(cairo, OSD_BORDER_WIDTH, y,
+				OSD_ITEM_WIDTH, OSD_ITEM_HEIGHT);
+			cairo_fill(cairo);
+			break;
+		}
+		y += OSD_ITEM_HEIGHT;
+	}
+
+	/* text */
+	set_source(cairo, (float[4]){0.0f, 0.0f, 0.0f, 1.0f});
+	PangoLayout *layout = pango_cairo_create_layout(cairo);
+	pango_layout_set_width(layout, w * PANGO_SCALE);
+	pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_END);
+
+	/* TODO: use font description from config */
+	PangoFontDescription *desc =
+		pango_font_description_from_string("sans 10");
+	pango_layout_set_font_description(layout, desc);
+	pango_font_description_free(desc);
+
+	PangoTabArray *tabs = pango_tab_array_new_with_positions(2, TRUE,
+		PANGO_TAB_LEFT, OSD_TAB1, PANGO_TAB_LEFT, OSD_TAB2);
+	pango_layout_set_tabs(layout, tabs);
+	pango_tab_array_free(tabs);
+
+	pango_cairo_update_layout(cairo, layout);
+
+	struct buf buf;
+	buf_init(&buf);
+	y = OSD_BORDER_WIDTH;
+
+	/* vertically center align */
+	y += (OSD_ITEM_HEIGHT - font_height("sans 10")) / 2;
+
+	wl_list_for_each(view, &server->views, link) {
+		if (!isfocusable(view)) {
+			continue;
+		}
+		buf.len = 0;
+		cairo_move_to(cairo, OSD_BORDER_WIDTH + OSD_ITEM_PADDING, y);
+
+		switch (view->type) {
+		case LAB_XDG_SHELL_VIEW:
+			buf_add(&buf, "[xdg-shell]\t");
+			buf_add(&buf, get_formatted_app_id(view));
+			buf_add(&buf, "\t");
+			break;
+#if HAVE_XWAYLAND
+		case LAB_XWAYLAND_VIEW:
+			buf_add(&buf, "[xwayland]\t");
+			buf_add(&buf, view->impl->get_string_prop(view, "class"));
+			buf_add(&buf, "\t");
+			break;
+#endif
+		}
+
+		if (is_title_different(view)) {
+			buf_add(&buf, view->impl->get_string_prop(view, "title"));
+		}
+
+		pango_layout_set_text(layout, buf.buf, -1);
+		pango_cairo_show_layout(cairo, layout);
+		y += OSD_ITEM_HEIGHT;
+	}
+
+	g_object_unref(layout);
+
+	/* convert to wlr_texture */
+	cairo_surface_flush(surf);
+	unsigned char *data = cairo_image_surface_get_data(surf);
+	struct wlr_texture *texture = wlr_texture_from_pixels(renderer,
+		DRM_FORMAT_ARGB8888, cairo_image_surface_get_stride(surf),
+		w, h, data);
+
+	cairo_destroy(cairo);
+	cairo_surface_destroy(surf);
+	if (server->osd) {
+		wlr_texture_destroy(server->osd);
+	}
+	server->osd = texture;
 }

src/output.c

@@ -460,6 +460,28 @@ render_texture_helper(struct output *output, pixman_region32_t *output_damage,
 		matrix);
 }
 
+static void
+render_osd(struct output *output, pixman_region32_t *damage,
+		struct server *server)
+{
+	if (!server->osd) {
+		return;
+	}
+
+	/* show on screen display (osd) on all outputs */
+	struct output *o;
+	wl_list_for_each(o, &server->outputs, link) {
+		struct wlr_box usable = output_usable_area_in_layout_coords(o);
+		struct wlr_box box = {
+			.x = usable.x + (usable.width - server->osd->width) / 2,
+			.y = usable.y + (usable.height - server->osd->height) / 2,
+			.width = server->osd->width,
+			.height = server->osd->height,
+		};
+		render_texture_helper(output, damage, &box, server->osd);
+	}
+}
+
 static bool
 isbutton(enum ssd_part_type type)
 {
@@ -673,6 +695,7 @@ output_render(struct output *output, pixman_region32_t *damage)
 	/* 'alt-tab' border */
 	if (output->server->cycle_view) {
 		render_cycle_box(output, damage, output->server->cycle_view);
+		render_osd(output, damage, output->server);
 	}
 
 	render_layer_toplevel(output, damage,

src/xdg.c

@@ -265,7 +265,10 @@ xdg_toplevel_view_get_string_prop(struct view *view, const char *prop)
 	if (!strcmp(prop, "title")) {
 		return view->xdg_surface->toplevel->title;
 	}
-	return "none";
+	if (!strcmp(prop, "app_id")) {
+		return view->xdg_surface->toplevel->app_id;
+	}
+	return "";
 }
 
 static void

src/xwayland.c

@@ -134,7 +134,10 @@ get_string_prop(struct view *view, const char *prop)
 	if (!strcmp(prop, "title")) {
 		return view->xwayland_surface->title;
 	}
-	return "none";
+	if (!strcmp(prop, "class")) {
+		return view->xwayland_surface->class;
+	}
+	return "";
 }
 
 static bool