layer-shell: allow new values for keyboard-interactivity

Value is now an enum with a new value ("on-demand") that compositors can use to allow "normal" keyboard focus semantics regardless of the layer the client surface is on. An error is sent for invalid keyboard interactivity values. The old behavior is retained for clients using the previous version of the protocol.

Also adjusted the layer-shell example program to use the new keyboard interactivity options.

examples/layer-shell.c

@@ -50,7 +50,8 @@ static int32_t margin_top = 0;
 static double alpha = 1.0;
 static bool run_display = true;
 static bool animate = false;
-static bool keyboard_interactive = false;
+static enum zwlr_layer_surface_v1_keyboard_interactivity keyboard_interactive =
+	ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_NONE;
 static double frame = 0;
 static int cur_x = -1, cur_y = -1;
 static int buttons = 0;
@@ -453,8 +454,8 @@ static void handle_global(void *data, struct wl_registry *registry,
 				&wl_seat_interface, 1);
 		wl_seat_add_listener(seat, &seat_listener, NULL);
 	} else if (strcmp(interface, zwlr_layer_shell_v1_interface.name) == 0) {
-		layer_shell = wl_registry_bind(
-				registry, name, &zwlr_layer_shell_v1_interface, 1);
+		layer_shell = wl_registry_bind(registry, name,
+			&zwlr_layer_shell_v1_interface, version < 4 ? version : 4);
 	} else if (strcmp(interface, xdg_wm_base_interface.name) == 0) {
 		xdg_wm_base = wl_registry_bind(
 				registry, name, &xdg_wm_base_interface, 1);
@@ -478,7 +479,7 @@ int main(int argc, char **argv) {
 	int32_t margin_right = 0, margin_bottom = 0, margin_left = 0;
 	bool found;
 	int c;
-	while ((c = getopt(argc, argv, "knw:h:o:l:a:x:m:t:")) != -1) {
+	while ((c = getopt(argc, argv, "k:nw:h:o:l:a:x:m:t:")) != -1) {
 		switch (c) {
 		case 'o':
 			output = atoi(optarg);
@@ -558,9 +559,29 @@ int main(int argc, char **argv) {
 		case 'n':
 			animate = true;
 			break;
-		case 'k':
-			keyboard_interactive = true;
+		case 'k': {
+			const struct {
+				const char *name;
+				enum zwlr_layer_surface_v1_keyboard_interactivity value;
+			} kb_int[] = {
+				{ "none", ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_NONE },
+				{ "exclusive", ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_EXCLUSIVE },
+				{ "on_demand", ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_ON_DEMAND }
+			};
+			found = false;
+			for (size_t i = 0; i < sizeof(kb_int) / sizeof(kb_int[0]); ++i) {
+				if (strcmp(optarg, kb_int[i].name) == 0) {
+					keyboard_interactive = kb_int[i].value;
+					found = true;
+					break;
+				}
+			}
+			if (!found) {
+				fprintf(stderr, "invalid keyboard interactivity setting %s\n", optarg);
+				return 1;
+			}
 			break;
+		}
 		default:
 			break;
 		}

include/wlr/types/wlr_layer_shell_v1.h

@@ -49,7 +49,7 @@ struct wlr_layer_surface_v1_state {
 	struct {
 		uint32_t top, right, bottom, left;
 	} margin;
-	bool keyboard_interactive;
+	enum zwlr_layer_surface_v1_keyboard_interactivity keyboard_interactive;
 	uint32_t desired_width, desired_height;
 	uint32_t actual_width, actual_height;
 	enum zwlr_layer_shell_v1_layer layer;

protocol/wlr-layer-shell-unstable-v1.xml

@@ -25,7 +25,7 @@
     THIS SOFTWARE.
   </copyright>
 
-  <interface name="zwlr_layer_shell_v1" version="3">
+  <interface name="zwlr_layer_shell_v1" version="4">
     <description summary="create surfaces that are layers of the desktop">
       Clients can use this interface to assign the surface_layer role to
       wl_surfaces. Such surfaces are assigned to a "layer" of the output and
@@ -47,6 +47,12 @@
         or manipulate a buffer prior to the first layer_surface.configure call
         must also be treated as errors.
 
+        After creating a layer_surface object and setting it up, the client
+        must perform an initial commit without any buffer attached.
+        The compositor will reply with a layer_surface.configure event.
+        The client must acknowledge it and is then allowed to attach a buffer
+        to map the surface.
+
         You may pass NULL for output to allow the compositor to decide which
         output to use. Generally this will be the one that the user most
         recently interacted with.
@@ -94,7 +100,7 @@
     </request>
   </interface>
 
-  <interface name="zwlr_layer_surface_v1" version="3">
+  <interface name="zwlr_layer_surface_v1" version="4">
     <description summary="layer metadata interface">
       An interface that may be implemented by a wl_surface, for surfaces that
       are designed to be rendered as a layer of a stacked desktop-like
@@ -103,6 +109,14 @@
       Layer surface state (layer, size, anchor, exclusive zone,
       margin, interactivity) is double-buffered, and will be applied at the
       time wl_surface.commit of the corresponding wl_surface is called.
+
+      Attaching a null buffer to a layer surface unmaps it.
+
+      Unmapping a layer_surface means that the surface cannot be shown by the
+      compositor until it is explicitly mapped again. The layer_surface
+      returns to the state it had right after layer_shell.get_layer_surface.
+      The client can re-map the surface by performing a commit without any
+      buffer attached, waiting for a configure event and handling it as usual.
     </description>
 
     <request name="set_size">
@@ -189,21 +203,85 @@
       <arg name="left" type="int"/>
     </request>
 
+    <enum name="keyboard_interactivity">
+      <description summary="types of keyboard interaction possible for a layer shell surface">
+        Types of keyboard interaction possible for layer shell surfaces. The
+        rationale for this is twofold: (1) some applications are not interested
+        in keyboard events and not allowing them to be focused can improve the
+        desktop experience; (2) some applications will want to take exclusive
+        keyboard focus.
+      </description>
+
+      <entry name="none" value="0">
+        <description summary="no keyboard focus is possible">
+          This value indicates that this surface is not interested in keyboard
+          events and the compositor should never assign it the keyboard focus.
+
+          This is the default value, set for newly created layer shell surfaces.
+
+          This is useful for e.g. desktop widgets that display information or
+          only have interaction with non-keyboard input devices.
+        </description>
+      </entry>
+      <entry name="exclusive" value="1">
+        <description summary="request exclusive keyboard focus">
+          Request exclusive keyboard focus if this surface is above the shell surface layer.
+
+          For the top and overlay layers, the seat will always give
+          exclusive keyboard focus to the top-most layer which has keyboard
+          interactivity set to exclusive. If this layer contains multiple
+          surfaces with keyboard interactivity set to exclusive, the compositor
+          determines the one receiving keyboard events in an implementation-
+          defined manner. In this case, no guarantee is made when this surface
+          will receive keyboard focus (if ever).
+
+          For the bottom and background layers, the compositor is allowed to use
+          normal focus semantics.
+
+          This setting is mainly intended for applications that need to ensure
+          they receive all keyboard events, such as a lock screen or a password
+          prompt.
+        </description>
+      </entry>
+      <entry name="on_demand" value="2" since="4">
+        <description summary="request regular keyboard focus semantics">
+          This requests the compositor to allow this surface to be focused and
+          unfocused by the user in an implementation-defined manner. The user
+          should be able to unfocus this surface even regardless of the layer
+          it is on.
+
+          Typically, the compositor will want to use its normal mechanism to
+          manage keyboard focus between layer shell surfaces with this setting
+          and regular toplevels on the desktop layer (e.g. click to focus).
+          Nevertheless, it is possible for a compositor to require a special
+          interaction to focus or unfocus layer shell surfaces (e.g. requiring
+          a click even if focus follows the mouse normally, or providing a
+          keybinding to switch focus between layers).
+
+          This setting is mainly intended for desktop shell components (e.g.
+          panels) that allow keyboard interaction. Using this option can allow
+          implementing a desktop shell that can be fully usable without the
+          mouse.
+        </description>
+      </entry>
+    </enum>
+
     <request name="set_keyboard_interactivity">
       <description summary="requests keyboard events">
-        Set to 1 to request that the seat send keyboard events to this layer
-        surface. For layers below the shell surface layer, the seat will use
-        normal focus semantics. For layers above the shell surface layers, the
-        seat will always give exclusive keyboard focus to the top-most layer
-        which has keyboard interactivity set to true.
+        Set how keyboard events are delivered to this surface. By default,
+        layer shell surfaces do not receive keyboard events; this request can
+        be used to change this.
+
+        This setting is inherited by child surfaces set by the get_popup
+        request.
 
         Layer surfaces receive pointer, touch, and tablet events normally. If
         you do not want to receive them, set the input region on your surface
         to an empty region.
 
-        Events is double-buffered, see wl_surface.commit.
+        Keyboard interactivity is double-buffered, see wl_surface.commit.
       </description>
-      <arg name="keyboard_interactivity" type="uint"/>
+      <arg name="keyboard_interactivity" type="uint" enum="keyboard_interactivity"/>
     </request>
 
     <request name="get_popup">
@@ -288,6 +366,7 @@
       <entry name="invalid_surface_state" value="0" summary="provided surface state is invalid"/>
       <entry name="invalid_size" value="1" summary="size is invalid"/>
       <entry name="invalid_anchor" value="2" summary="anchor bitfield is invalid"/>
+      <entry name="invalid_keyboard_interactivity" value="3" summary="keyboard interactivity is invalid"/>
     </enum>
 
     <enum name="anchor" bitfield="true">

types/wlr_layer_shell_v1.c

@@ -11,7 +11,7 @@
 #include "util/signal.h"
 #include "wlr-layer-shell-unstable-v1-protocol.h"
 
-#define LAYER_SHELL_VERSION 3
+#define LAYER_SHELL_VERSION 4
 
 static void resource_handle_destroy(struct wl_client *client,
 		struct wl_resource *resource) {
@@ -158,7 +158,18 @@ static void layer_surface_handle_set_keyboard_interactivity(
 	if (!surface) {
 		return;
 	}
-	surface->client_pending.keyboard_interactive = !!interactive;
+
+	if (wl_resource_get_version(resource) < ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_ON_DEMAND_SINCE_VERSION) {
+		surface->client_pending.keyboard_interactive = !!interactive;
+	} else {
+		if (interactive > ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_ON_DEMAND) {
+			wl_resource_post_error(resource,
+				ZWLR_LAYER_SURFACE_V1_ERROR_INVALID_KEYBOARD_INTERACTIVITY,
+				"wrong keyboard interactivity value: %" PRIu32, interactive);
+		} else {
+			surface->client_pending.keyboard_interactive = interactive;
+		}
+	}
 }
 
 static void layer_surface_handle_get_popup(struct wl_client *client,