wp-fractional-scale-v1: new protocol implementation

This implements the WIP wp-fractional-scale-v1 protocol.

include/wlr/types/wlr_fractional_scale_v1.h

@@ -0,0 +1,34 @@
+/*
+ * 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_FRACTIONAL_SCALE_V1_H
+#define WLR_TYPES_WLR_FRACTIONAL_SCALE_V1_H
+
+#include <wayland-server-core.h>
+
+struct wlr_surface;
+
+struct wlr_fractional_scale_manager_v1 {
+	struct wl_global *global;
+
+	struct {
+		struct wl_signal destroy;
+	} events;
+
+	// private state
+
+	struct wl_listener display_destroy;
+};
+
+void wlr_fractional_scale_v1_notify_scale(
+		struct wlr_surface *surface, double scale);
+
+struct wlr_fractional_scale_manager_v1 *wlr_fractional_scale_manager_v1_create(
+		struct wl_display *display, uint32_t version);
+
+#endif

protocol/meson.build

@@ -22,6 +22,7 @@ protocols = {
 	'drm-lease-v1': wl_protocol_dir / 'staging/drm-lease/drm-lease-v1.xml',
 	'ext-idle-notify-v1': wl_protocol_dir / 'staging/ext-idle-notify/ext-idle-notify-v1.xml',
 	'ext-session-lock-v1': wl_protocol_dir / 'staging/ext-session-lock/ext-session-lock-v1.xml',
+	'fractional-scale-v1': wl_protocol_dir / 'staging/fractional-scale/fractional-scale-v1.xml',
 	'single-pixel-buffer-v1': wl_protocol_dir / 'staging/single-pixel-buffer/single-pixel-buffer-v1.xml',
 	'xdg-activation-v1': wl_protocol_dir / 'staging/xdg-activation/xdg-activation-v1.xml',
 	'xwayland-shell-v1': wl_protocol_dir / 'staging/xwayland-shell/xwayland-shell-v1.xml',

types/meson.build

@@ -73,6 +73,7 @@ wlr_files += files(
 	'wlr_shm.c',
 	'wlr_single_pixel_buffer_v1.c',
 	'wlr_subcompositor.c',
+	'wlr_fractional_scale_v1.c',
 	'wlr_switch.c',
 	'wlr_tablet_pad.c',
 	'wlr_tablet_tool.c',

types/wlr_fractional_scale_v1.c

@@ -0,0 +1,206 @@
+#define _POSIX_C_SOURCE 200809L
+#include <assert.h>
+#include <stdlib.h>
+#include <wlr/types/wlr_compositor.h>
+#include <wlr/types/wlr_fractional_scale_v1.h>
+#include <wlr/util/log.h>
+
+#include "fractional-scale-v1-protocol.h"
+
+#define FRACTIONAL_SCALE_VERSION 1
+
+struct wlr_fractional_scale_v1 {
+	struct wl_resource *resource;
+	struct wlr_addon addon;
+
+	// Used for dummy objects to store scale
+	double scale;
+};
+
+static const struct wp_fractional_scale_v1_interface fractional_scale_interface;
+
+static struct wlr_fractional_scale_v1 *fractional_scale_from_resource(
+		struct wl_resource *resource) {
+	assert(wl_resource_instance_of(resource,
+		&wp_fractional_scale_v1_interface, &fractional_scale_interface));
+	return wl_resource_get_user_data(resource);
+}
+
+static const struct wp_fractional_scale_manager_v1_interface scale_manager_interface;
+
+static void fractional_scale_destroy(struct wlr_fractional_scale_v1 *info) {
+	if (info == NULL) {
+		return;
+	}
+
+	// If this is a dummy object then we do not have a wl_resource
+	if (info->resource != NULL) {
+		wl_resource_set_user_data(info->resource, NULL);
+	}
+	wlr_addon_finish(&info->addon);
+	free(info);
+}
+
+static void fractional_scale_handle_resource_destroy(struct wl_resource *resource) {
+	struct wlr_fractional_scale_v1 *info = fractional_scale_from_resource(resource);
+	fractional_scale_destroy(info);
+}
+
+static void fractional_scale_handle_destroy(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static const struct wp_fractional_scale_v1_interface fractional_scale_interface = {
+	.destroy = fractional_scale_handle_destroy,
+};
+
+static void fractional_scale_addon_destroy(struct wlr_addon *addon) {
+	struct wlr_fractional_scale_v1 *info = wl_container_of(addon, info, addon);
+	fractional_scale_destroy(info);
+}
+
+static const struct wlr_addon_interface fractional_scale_addon_impl = {
+	.name = "wlr_fractional_scale_v1",
+	.destroy = fractional_scale_addon_destroy,
+};
+
+static uint32_t double_to_v120(double d) {
+	return round(d * 120);
+}
+
+void wlr_fractional_scale_v1_notify_scale(struct wlr_surface *surface, double scale) {
+	struct wlr_addon *addon = wlr_addon_find(&surface->addons,
+		NULL, &fractional_scale_addon_impl);
+
+	if (addon == NULL) {
+		// Create a dummy object to store the scale
+		struct wlr_fractional_scale_v1 *info = calloc(1, sizeof(*info));
+		if (info == NULL) {
+			return;
+		}
+
+		wlr_addon_init(&info->addon, &surface->addons, NULL, &fractional_scale_addon_impl);
+		info->scale = scale;
+		return;
+	}
+
+	struct wlr_fractional_scale_v1 *info = wl_container_of(addon, info, addon);
+	if (info->scale == scale) {
+		return;
+	}
+
+	info->scale = scale;
+
+	if (!info->resource) {
+		// Update existing dummy object
+		return;
+	}
+
+	wp_fractional_scale_v1_send_preferred_scale(info->resource, double_to_v120(scale));
+}
+
+static void handle_get_fractional_scale(struct wl_client *client,
+		struct wl_resource *mgr_resource, uint32_t id,
+		struct wl_resource *surface_resource) {
+	struct wlr_surface *surface = wlr_surface_from_resource(surface_resource);
+	struct wlr_fractional_scale_v1 *info = NULL;
+
+	// If no fractional_scale object had been created but scale had been set, then
+	// there will be a dummy object for us to fill out with a resource. Check if
+	// that's the case.
+	struct wlr_addon *addon = wlr_addon_find(&surface->addons, NULL, &fractional_scale_addon_impl);
+
+	if (addon != NULL) {
+		info = wl_container_of(addon, info, addon);
+		if (info->resource != NULL) {
+			wl_resource_post_error(mgr_resource,
+				WP_FRACTIONAL_SCALE_MANAGER_V1_ERROR_FRACTIONAL_SCALE_EXISTS,
+				"a surface scale object for that surface already exists");
+			return;
+		}
+	}
+
+	if (info == NULL) {
+		info = calloc(1, sizeof(*info));
+		if (info == NULL) {
+			wl_client_post_no_memory(client);
+			return;
+		}
+
+		wlr_addon_init(&info->addon, &surface->addons, NULL, &fractional_scale_addon_impl);
+	}
+
+	uint32_t version = wl_resource_get_version(mgr_resource);
+	info->resource = wl_resource_create(client, &wp_fractional_scale_v1_interface, version, id);
+	if (info->resource == NULL) {
+		wl_client_post_no_memory(client);
+		fractional_scale_destroy(info);
+		return;
+	}
+	wl_resource_set_implementation(info->resource,
+		&fractional_scale_interface, info,
+		fractional_scale_handle_resource_destroy);
+
+	if (info->scale != 0) {
+		wp_fractional_scale_v1_send_preferred_scale(info->resource, double_to_v120(info->scale));
+	}
+}
+
+static void fractional_scale_manager_handle_destroy(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static const struct wp_fractional_scale_manager_v1_interface scale_manager_interface = {
+	.destroy = fractional_scale_manager_handle_destroy,
+	.get_fractional_scale = handle_get_fractional_scale,
+};
+
+static void fractional_scale_manager_bind(struct wl_client *client, void *data,
+		uint32_t version, uint32_t id) {
+	struct wlr_fractional_scale_manager_v1 *mgr = data;
+
+	struct wl_resource *resource = wl_resource_create(client,
+		&wp_fractional_scale_manager_v1_interface, version, id);
+	if (resource == NULL) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+	wl_resource_set_implementation(resource, &scale_manager_interface, mgr, NULL);
+}
+
+static void handle_display_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_fractional_scale_manager_v1 *mgr =
+		wl_container_of(listener, mgr, display_destroy);
+	wl_signal_emit_mutable(&mgr->events.destroy, NULL);
+	assert(wl_list_empty(&mgr->events.destroy.listener_list));
+	wl_list_remove(&mgr->display_destroy.link);
+	free(mgr);
+}
+
+struct wlr_fractional_scale_manager_v1 *wlr_fractional_scale_manager_v1_create(
+		struct wl_display *display, uint32_t version) {
+	assert(version <= FRACTIONAL_SCALE_VERSION);
+
+	struct wlr_fractional_scale_manager_v1 *mgr = calloc(1, sizeof(*mgr));
+	if (mgr == NULL) {
+		return NULL;
+	}
+
+	mgr->global = wl_global_create(display,
+		&wp_fractional_scale_manager_v1_interface,
+		version, mgr, fractional_scale_manager_bind);
+	if (mgr->global == NULL) {
+		free(mgr);
+		return NULL;
+	}
+
+	mgr->display_destroy.notify = handle_display_destroy;
+	wl_display_add_destroy_listener(display, &mgr->display_destroy);
+
+	wl_signal_init(&mgr->events.destroy);
+
+	return mgr;
+}
+