alpha-modifier-v1: new protocol implementation

References: https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/287

include/wlr/types/wlr_alpha_modifier_v1.h

@@ -0,0 +1,33 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
+#ifndef WLR_TYPES_WLR_ALPHA_MODIFIER_V1_H
+#define WLR_TYPES_WLR_ALPHA_MODIFIER_V1_H
+
+#include <wayland-server-core.h>
+
+struct wlr_surface;
+
+struct wlr_alpha_modifier_surface_v1_state {
+	double multiplier; // between 0 and 1
+};
+
+struct wlr_alpha_modifier_v1 {
+	struct wl_global *global;
+
+	// private state
+
+	struct wl_listener display_destroy;
+};
+
+struct wlr_alpha_modifier_v1 *wlr_alpha_modifier_v1_create(struct wl_display *display);
+
+const struct wlr_alpha_modifier_surface_v1_state *wlr_alpha_modifier_v1_get_surface_state(
+	struct wlr_surface *surface);
+
+#endif

protocol/meson.build

@@ -1,5 +1,5 @@
 wayland_protos = dependency('wayland-protocols',
-	version: '>=1.33',
+	version: '>=1.35',
 	fallback: 'wayland-protocols',
 	default_options: ['tests=false'],
 )
@@ -19,6 +19,7 @@ protocols = {
 	'xdg-shell': wl_protocol_dir / 'stable/xdg-shell/xdg-shell.xml',
 
 	# Staging upstream protocols
+	'alpha-modifier-v1': wl_protocol_dir / 'staging/alpha-modifier/alpha-modifier-v1.xml',
 	'content-type-v1': wl_protocol_dir / 'staging/content-type/content-type-v1.xml',
 	'cursor-shape-v1': wl_protocol_dir / 'staging/cursor-shape/cursor-shape-v1.xml',
 	'drm-lease-v1': wl_protocol_dir / 'staging/drm-lease/drm-lease-v1.xml',

types/meson.build

@@ -33,6 +33,7 @@ wlr_files += files(
 	'buffer/dmabuf.c',
 	'buffer/readonly_data.c',
 	'buffer/resource.c',
+	'wlr_alpha_modifier_v1.c',
 	'wlr_compositor.c',
 	'wlr_content_type_v1.c',
 	'wlr_cursor_shape_v1.c',

types/wlr_alpha_modifier_v1.c

@@ -0,0 +1,185 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <wlr/types/wlr_alpha_modifier_v1.h>
+#include <wlr/types/wlr_compositor.h>
+#include <wlr/util/addon.h>
+#include "alpha-modifier-v1-protocol.h"
+
+#define ALPHA_MODIFIER_VERSION 1
+
+struct wlr_alpha_modifier_surface_v1 {
+	struct wl_resource *resource;
+	struct wlr_surface *surface;
+	struct wlr_addon addon;
+	struct wlr_surface_synced synced;
+	struct wlr_alpha_modifier_surface_v1_state pending, current;
+};
+
+static const struct wp_alpha_modifier_surface_v1_interface surface_impl;
+
+// Returns NULL if the wl_surface was destroyed
+static struct wlr_alpha_modifier_surface_v1 *surface_from_resource(struct wl_resource *resource) {
+	assert(wl_resource_instance_of(resource, &wp_alpha_modifier_surface_v1_interface,
+		&surface_impl));
+	return wl_resource_get_user_data(resource);
+}
+
+static void surface_destroy(struct wlr_alpha_modifier_surface_v1 *surface) {
+	if (surface == NULL) {
+		return;
+	}
+	wlr_surface_synced_finish(&surface->synced);
+	wlr_addon_finish(&surface->addon);
+	wl_resource_set_user_data(surface->resource, NULL);
+	free(surface);
+}
+
+static void surface_handle_resource_destroy(struct wl_resource *resource) {
+	struct wlr_alpha_modifier_surface_v1 *surface = surface_from_resource(resource);
+	surface_destroy(surface);
+}
+
+static void surface_handle_destroy(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static void surface_handle_set_multiplier(struct wl_client *client,
+		struct wl_resource *resource, uint32_t multiplier) {
+	struct wlr_alpha_modifier_surface_v1 *surface = surface_from_resource(resource);
+	if (surface == NULL) {
+		wl_resource_post_error(resource,
+			WP_ALPHA_MODIFIER_SURFACE_V1_ERROR_NO_SURFACE,
+			"The wl_surface object has been destroyed");
+		return;
+	}
+	surface->pending.multiplier = (double)multiplier / UINT32_MAX;
+}
+
+static const struct wp_alpha_modifier_surface_v1_interface surface_impl = {
+	.destroy = surface_handle_destroy,
+	.set_multiplier = surface_handle_set_multiplier,
+};
+
+static void surface_synced_init_state(void *_state) {
+	struct wlr_alpha_modifier_surface_v1_state *state = _state;
+	state->multiplier = 1;
+}
+
+static const struct wlr_surface_synced_impl surface_synced_impl = {
+	.state_size = sizeof(struct wlr_alpha_modifier_surface_v1_state),
+	.init_state = surface_synced_init_state,
+};
+
+static void surface_addon_destroy(struct wlr_addon *addon) {
+	struct wlr_alpha_modifier_surface_v1 *surface = wl_container_of(addon, surface, addon);
+	surface_destroy(surface);
+}
+
+static const struct wlr_addon_interface surface_addon_impl = {
+	.name = "wp_alpha_modifier_surface_v1",
+	.destroy = surface_addon_destroy,
+};
+
+static struct wlr_alpha_modifier_surface_v1 *surface_from_wlr_surface(
+		struct wlr_surface *wlr_surface) {
+	struct wlr_addon *addon = wlr_addon_find(&wlr_surface->addons, NULL, &surface_addon_impl);
+	if (addon == NULL) {
+		return NULL;
+	}
+	struct wlr_alpha_modifier_surface_v1 *surface = wl_container_of(addon, surface, addon);
+	return surface;
+}
+
+static void manager_handle_destroy(struct wl_client *client, struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static void manager_handle_get_surface(struct wl_client *client,
+		struct wl_resource *manager_resource, uint32_t id,
+		struct wl_resource *surface_resource) {
+	struct wlr_surface *wlr_surface = wlr_surface_from_resource(surface_resource);
+
+	if (surface_from_wlr_surface(wlr_surface) != NULL) {
+		wl_resource_post_error(manager_resource,
+			WP_ALPHA_MODIFIER_V1_ERROR_ALREADY_CONSTRUCTED,
+			"The wl_surface object already has a wp_alpha_modifier_surface_v1 object");
+		return;
+	}
+
+	struct wlr_alpha_modifier_surface_v1 *surface = calloc(1, sizeof(*surface));
+	if (surface == NULL) {
+		wl_resource_post_no_memory(manager_resource);
+		return;
+	}
+
+	if (!wlr_surface_synced_init(&surface->synced, wlr_surface,
+			&surface_synced_impl, &surface->pending, &surface->current)) {
+		free(surface);
+		wl_resource_post_no_memory(manager_resource);
+		return;
+	}
+
+	uint32_t version = wl_resource_get_version(manager_resource);
+	surface->resource = wl_resource_create(client,
+		&wp_alpha_modifier_surface_v1_interface, version, id);
+	if (surface->resource == NULL) {
+		wlr_surface_synced_finish(&surface->synced);
+		free(surface);
+		wl_resource_post_no_memory(manager_resource);
+		return;
+	}
+	wl_resource_set_implementation(surface->resource, &surface_impl,
+		surface, surface_handle_resource_destroy);
+
+	surface->surface = wlr_surface;
+	wlr_addon_init(&surface->addon, &wlr_surface->addons, NULL, &surface_addon_impl);
+}
+
+static const struct wp_alpha_modifier_v1_interface manager_impl = {
+	.destroy = manager_handle_destroy,
+	.get_surface = manager_handle_get_surface,
+};
+
+static void manager_bind(struct wl_client *client, void *data,
+		uint32_t version, uint32_t id) {
+	struct wl_resource *resource = wl_resource_create(client,
+		&wp_alpha_modifier_v1_interface, version, id);
+	if (resource == NULL) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+	wl_resource_set_implementation(resource, &manager_impl, NULL, NULL);
+}
+
+static void handle_display_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_alpha_modifier_v1 *manager = wl_container_of(listener, manager, display_destroy);
+	wl_list_remove(&manager->display_destroy.link);
+	wl_global_destroy(manager->global);
+	free(manager);
+}
+
+struct wlr_alpha_modifier_v1 *wlr_alpha_modifier_v1_create(struct wl_display *display) {
+	struct wlr_alpha_modifier_v1 *manager = calloc(1, sizeof(*manager));
+	if (manager == NULL) {
+		return NULL;
+	}
+
+	manager->global = wl_global_create(display, &wp_alpha_modifier_v1_interface,
+		ALPHA_MODIFIER_VERSION, NULL, manager_bind);
+	if (manager->global == NULL) {
+		free(manager);
+		return NULL;
+	}
+
+	manager->display_destroy.notify = handle_display_destroy;
+	wl_display_add_destroy_listener(display, &manager->display_destroy);
+
+	return manager;
+}
+
+const struct wlr_alpha_modifier_surface_v1_state *wlr_alpha_modifier_v1_get_surface_state(
+		struct wlr_surface *wlr_surface) {
+	struct wlr_alpha_modifier_surface_v1 *surface = surface_from_wlr_surface(wlr_surface);
+	return &surface->current;
+}