Implement wp_single_pixel_buffer_v1 protocol

This protocol allows clients to create single-pixel RGBA buffers. Now
that we have proper support for these buffers internally within Weston,
we can expose them to clients.

This bumps the build container version, as we now depend on
wayland-protocols v1.26.

Signed-off-by: Daniel Stone <daniels@collabora.com>

libweston/compositor.c

@@ -65,6 +65,7 @@
 #include "xdg-output-unstable-v1-server-protocol.h"
 #include "linux-explicit-synchronization-unstable-v1-server-protocol.h"
 #include "linux-explicit-synchronization.h"
+#include "single-pixel-buffer-v1-server-protocol.h"
 #include "shared/fd-util.h"
 #include "shared/helpers.h"
 #include "shared/os-compatibility.h"
@@ -2414,6 +2415,9 @@ destroy_surface(struct wl_resource *resource)
 	weston_surface_unref(surface);
 }
 
+static struct solid_buffer_values *
+single_pixel_buffer_get(struct wl_resource *resource);
+
 static void
 weston_buffer_destroy_handler(struct wl_listener *listener, void *data)
 {
@@ -2438,6 +2442,7 @@ weston_buffer_from_resource(struct weston_compositor *ec,
 	struct wl_shm_buffer *shm;
 	struct linux_dmabuf_buffer *dmabuf;
 	struct wl_listener *listener;
+	struct solid_buffer_values *solid;
 
 	listener = wl_resource_get_destroy_listener(resource,
 						    weston_buffer_destroy_handler);
@@ -2485,6 +2490,19 @@ weston_buffer_from_resource(struct weston_compositor *ec,
 			buffer->buffer_origin = ORIGIN_BOTTOM_LEFT;
 		else
 			buffer->buffer_origin = ORIGIN_TOP_LEFT;
+	} else if ((solid = single_pixel_buffer_get(buffer->resource))) {
+		buffer->type = WESTON_BUFFER_SOLID;
+		buffer->solid = *solid;
+		buffer->width = 1;
+		buffer->height = 1;
+		if (buffer->solid.a == 1.0) {
+			buffer->pixel_format =
+				pixel_format_get_info(DRM_FORMAT_XRGB8888);
+		} else {
+			buffer->pixel_format =
+				pixel_format_get_info(DRM_FORMAT_ARGB8888);
+		}
+		buffer->format_modifier = DRM_FORMAT_MOD_LINEAR;
 	} else {
 		/* Only taken for legacy EGL buffers */
 		if (!ec->renderer->fill_buffer_info ||
@@ -2701,6 +2719,97 @@ weston_buffer_destroy_solid(struct weston_buffer_reference *buffer_ref)
 	free(buffer_ref);
 }
 
+static void
+single_pixel_buffer_destroy(struct wl_resource *resource)
+{
+	struct solid_buffer_values *solid =
+		wl_resource_get_user_data(resource);
+	free(solid);
+}
+
+static void
+single_pixel_buffer_handle_buffer_destroy(struct wl_client *client,
+					  struct wl_resource *resource)
+{
+	wl_resource_destroy(resource);
+}
+
+static const struct wl_buffer_interface single_pixel_buffer_implementation = {
+	single_pixel_buffer_handle_buffer_destroy,
+};
+
+static struct solid_buffer_values *
+single_pixel_buffer_get(struct wl_resource *resource)
+{
+	if (!resource)
+		return NULL;
+
+	if (!wl_resource_instance_of(resource, &wl_buffer_interface,
+				     &single_pixel_buffer_implementation))
+		return NULL;
+
+	return wl_resource_get_user_data(resource);
+}
+
+static void
+single_pixel_buffer_manager_destroy(struct wl_client *client,
+				    struct wl_resource *resource)
+{
+	wl_resource_destroy(resource);
+}
+
+static void
+single_pixel_buffer_create(struct wl_client *client, struct wl_resource *resource,
+			   uint32_t id, uint32_t r, uint32_t g, uint32_t b, uint32_t a)
+{
+	struct solid_buffer_values *solid = zalloc(sizeof(*solid));
+	struct wl_resource *buffer;
+
+	if (!solid) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+
+	solid->r = r / (double) 0xffffffff;
+	solid->g = g / (double) 0xffffffff;
+	solid->b = b / (double) 0xffffffff;
+	solid->a = a / (double) 0xffffffff;
+
+	buffer = wl_resource_create(client, &wl_buffer_interface, 1, id);
+	if (!buffer) {
+		wl_client_post_no_memory(client);
+		free(solid);
+		return;
+	}
+	wl_resource_set_implementation(buffer,
+				       &single_pixel_buffer_implementation,
+				       solid, single_pixel_buffer_destroy);
+}
+
+static const struct wp_single_pixel_buffer_manager_v1_interface
+single_pixel_buffer_manager_implementation = {
+	single_pixel_buffer_manager_destroy,
+	single_pixel_buffer_create,
+};
+
+static void
+bind_single_pixel_buffer(struct wl_client *client, void *data, uint32_t version,
+			 uint32_t id)
+{
+	struct wl_resource *resource;
+
+	resource = wl_resource_create(client,
+				      &wp_single_pixel_buffer_manager_v1_interface, 1,
+				      id);
+	if (!resource) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+	wl_resource_set_implementation(resource,
+				       &single_pixel_buffer_manager_implementation,
+				       NULL, NULL);
+}
+
 static void
 weston_surface_attach(struct weston_surface *surface,
 		      struct weston_buffer *buffer)
@@ -8232,6 +8341,11 @@ weston_compositor_create(struct wl_display *display,
 			      ec, bind_presentation))
 		goto fail;
 
+	if (!wl_global_create(ec->wl_display,
+			      &wp_single_pixel_buffer_manager_v1_interface, 1,
+			      NULL, bind_single_pixel_buffer))
+		goto fail;
+
 	if (weston_input_init(ec) != 0)
 		goto fail;
 

libweston/meson.build

@@ -51,6 +51,8 @@ srcs_libweston = [
 	relative_pointer_unstable_v1_server_protocol_h,
 	weston_screenshooter_protocol_c,
 	weston_screenshooter_server_protocol_h,
+	single_pixel_buffer_v1_protocol_c,
+	single_pixel_buffer_v1_server_protocol_h,
 	text_cursor_position_protocol_c,
 	text_cursor_position_server_protocol_h,
 	text_input_unstable_v1_protocol_c,