gtk2/gtk/a11y/gtkatspicache.c
Emmanuele Bassi 9de2b4b0e1 a11y: Implement atspi.Cache
The AT-SPI cache interface is used to quickly populate the accessible
objects tree.

The tricky bit is ensuring that we emit change notifications on the
cache only when the cache is available, which means waiting until the
root is asynchronously registered.
2020-11-16 16:44:56 +00:00

398 lines
12 KiB
C

/* gtkatspicache.c: AT-SPI object cache
*
* Copyright 2020 holder
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include "gtkatspicacheprivate.h"
#include "gtkatspicontextprivate.h"
#include "gtkatspirootprivate.h"
#include "gtkatspiutilsprivate.h"
#include "gtkdebug.h"
#include "a11y/atspi/atspi-cache.h"
/* Cached item:
*
* (so): object ref
* (so): application ref
* (so): parent ref
* - parent.role == application ? desktop ref : null ref
* i: index in parent, or -1 for transient widgets/menu items
* i: child count, or -1 for defunct/menus
* as: interfaces
* s: name
* u: role
* s: description
* au: state set
*/
#define ITEM_SIGNATURE "(so)(so)(so)iiassusau"
#define GET_ITEMS_SIGNATURE "a(" ITEM_SIGNATURE ")"
struct _GtkAtSpiCache
{
GObject parent_instance;
char *cache_path;
GDBusConnection *connection;
/* HashTable<str, GtkAtSpiContext> */
GHashTable *contexts_by_path;
/* HashTable<GtkAtSpiContext, str> */
GHashTable *contexts_to_path;
};
enum
{
PROP_CACHE_PATH = 1,
PROP_CONNECTION,
N_PROPS
};
static GParamSpec *obj_props[N_PROPS];
G_DEFINE_TYPE (GtkAtSpiCache, gtk_at_spi_cache, G_TYPE_OBJECT)
static void
gtk_at_spi_cache_finalize (GObject *gobject)
{
GtkAtSpiCache *self = GTK_AT_SPI_CACHE (gobject);
g_clear_pointer (&self->contexts_to_path, g_hash_table_unref);
g_clear_pointer (&self->contexts_by_path, g_hash_table_unref);
g_clear_object (&self->connection);
g_free (self->cache_path);
G_OBJECT_CLASS (gtk_at_spi_cache_parent_class)->finalize (gobject);
}
static void
gtk_at_spi_cache_set_property (GObject *gobject,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GtkAtSpiCache *self = GTK_AT_SPI_CACHE (gobject);
switch (prop_id)
{
case PROP_CACHE_PATH:
g_free (self->cache_path);
self->cache_path = g_value_dup_string (value);
break;
case PROP_CONNECTION:
g_clear_object (&self->connection);
self->connection = g_value_dup_object (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
}
}
static void
collect_object (GtkAtSpiCache *self,
GVariantBuilder *builder,
GtkAtSpiContext *context)
{
g_variant_builder_add (builder, "@(so)", gtk_at_spi_context_to_ref (context));
GtkAtSpiRoot *root = gtk_at_spi_context_get_root (context);
g_variant_builder_add (builder, "@(so)", gtk_at_spi_root_to_ref (root));
g_variant_builder_add (builder, "@(so)", gtk_at_spi_context_get_parent_ref (context));
g_variant_builder_add (builder, "i", gtk_at_spi_context_get_index_in_parent (context));
g_variant_builder_add (builder, "i", gtk_at_spi_context_get_child_count (context));
g_variant_builder_add (builder, "@as", gtk_at_spi_context_get_interfaces (context));
char *name = gtk_at_context_get_name (GTK_AT_CONTEXT (context));
g_variant_builder_add (builder, "s", name ? name : "");
g_free (name);
guint atspi_role = gtk_atspi_role_for_context (GTK_AT_CONTEXT (context));
g_variant_builder_add (builder, "u", atspi_role);
char *description = gtk_at_context_get_description (GTK_AT_CONTEXT (context));
g_variant_builder_add (builder, "s", description ? description : "");
g_free (description);
g_variant_builder_add (builder, "@au", gtk_at_spi_context_get_states (context));
}
static void
collect_cached_objects (GtkAtSpiCache *self,
GVariantBuilder *builder)
{
GHashTable *collection = g_hash_table_new (NULL, NULL);
GHashTableIter iter;
gpointer key_p, value_p;
/* Serializing the contexts might re-enter, and end up modifying the hash
* table, so we take a snapshot here and return the items we have at the
* moment of the GetItems() call
*/
g_hash_table_iter_init (&iter, self->contexts_by_path);
while (g_hash_table_iter_next (&iter, &key_p, &value_p))
g_hash_table_add (collection, value_p);
g_hash_table_iter_init (&iter, collection);
while (g_hash_table_iter_next (&iter, &key_p, &value_p))
{
g_variant_builder_open (builder, G_VARIANT_TYPE ("(" ITEM_SIGNATURE ")"));
GtkAtSpiContext *context = value_p;
collect_object (self, builder, context);
g_variant_builder_close (builder);
}
g_hash_table_unref (collection);
}
static void
emit_add_accessible (GtkAtSpiCache *self,
GtkAtSpiContext *context)
{
GVariantBuilder builder = G_VARIANT_BUILDER_INIT (G_VARIANT_TYPE ("(" ITEM_SIGNATURE ")"));
collect_object (self, &builder, context);
g_dbus_connection_emit_signal (self->connection,
NULL,
self->cache_path,
"org.a11y.atspi.Cache",
"AddAccessible",
g_variant_builder_end (&builder),
NULL);
}
static void
emit_remove_accessible (GtkAtSpiCache *self,
GVariant *ref)
{
g_dbus_connection_emit_signal (self->connection,
NULL,
self->cache_path,
"org.a11y.atspi.Cache",
"RemoveAccessible",
ref,
NULL);
}
static void
handle_cache_method (GDBusConnection *connection,
const gchar *sender,
const gchar *object_path,
const gchar *interface_name,
const gchar *method_name,
GVariant *parameters,
GDBusMethodInvocation *invocation,
gpointer user_data)
{
GtkAtSpiCache *self = user_data;
GTK_NOTE (A11Y,
g_message ("[Cache] Method '%s' on interface '%s' for object '%s' from '%s'\n",
method_name, interface_name, object_path, sender));
if (g_strcmp0 (method_name, "GetItems") == 0)
{
GVariantBuilder builder = G_VARIANT_BUILDER_INIT (G_VARIANT_TYPE ("(" GET_ITEMS_SIGNATURE ")"));
g_variant_builder_open (&builder, G_VARIANT_TYPE (GET_ITEMS_SIGNATURE));
collect_cached_objects (self, &builder);
g_variant_builder_close (&builder);
g_dbus_method_invocation_return_value (invocation, g_variant_builder_end (&builder));
}
}
static GVariant *
handle_cache_get_property (GDBusConnection *connection,
const gchar *sender,
const gchar *object_path,
const gchar *interface_name,
const gchar *property_name,
GError **error,
gpointer user_data)
{
GVariant *res = NULL;
g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
"Unknown property '%s'", property_name);
return res;
}
static const GDBusInterfaceVTable cache_vtable = {
handle_cache_method,
handle_cache_get_property,
NULL,
};
static void
gtk_at_spi_cache_constructed (GObject *gobject)
{
GtkAtSpiCache *self = GTK_AT_SPI_CACHE (gobject);
g_assert (self->connection);
g_assert (self->cache_path);
g_dbus_connection_register_object (self->connection,
self->cache_path,
(GDBusInterfaceInfo *) &atspi_cache_interface,
&cache_vtable,
self,
NULL,
NULL);
GTK_NOTE (A11Y, g_message ("Cache registered at %s", self->cache_path));
G_OBJECT_CLASS (gtk_at_spi_cache_parent_class)->constructed (gobject);
}
static void
gtk_at_spi_cache_class_init (GtkAtSpiCacheClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_class->constructed = gtk_at_spi_cache_constructed;
gobject_class->set_property = gtk_at_spi_cache_set_property;
gobject_class->finalize = gtk_at_spi_cache_finalize;
obj_props[PROP_CACHE_PATH] =
g_param_spec_string ("cache-path", NULL, NULL,
NULL,
G_PARAM_WRITABLE |
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS);
obj_props[PROP_CONNECTION] =
g_param_spec_object ("connection", NULL, NULL,
G_TYPE_DBUS_CONNECTION,
G_PARAM_WRITABLE |
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS);
g_object_class_install_properties (gobject_class, N_PROPS, obj_props);
}
static void
gtk_at_spi_cache_init (GtkAtSpiCache *self)
{
self->contexts_by_path = g_hash_table_new_full (g_str_hash, g_str_equal,
g_free,
NULL);
self->contexts_to_path = g_hash_table_new (NULL, NULL);
}
GtkAtSpiCache *
gtk_at_spi_cache_new (GDBusConnection *connection,
const char *cache_path)
{
g_return_val_if_fail (G_IS_DBUS_CONNECTION (connection), NULL);
g_return_val_if_fail (cache_path != NULL, NULL);
return g_object_new (GTK_TYPE_AT_SPI_CACHE,
"connection", connection,
"cache-path", cache_path,
NULL);
}
static void
context_weak_unref (gpointer data,
GObject *stale_context)
{
GtkAtSpiCache *self = data;
const char *path = g_hash_table_lookup (self->contexts_to_path, stale_context);
if (path == NULL)
return;
/* By the time we get here, the context has already been dropped,
* so we need to generate the reference ourselves
*/
emit_remove_accessible (self, g_variant_new ("(so)",
g_dbus_connection_get_unique_name (self->connection),
path));
GTK_NOTE (A11Y, g_message ("Removing stale context '%s' from cache", path));
g_hash_table_remove (self->contexts_by_path, path);
g_hash_table_remove (self->contexts_to_path, stale_context);
}
void
gtk_at_spi_cache_add_context (GtkAtSpiCache *self,
GtkAtSpiContext *context)
{
g_return_if_fail (GTK_IS_AT_SPI_CACHE (self));
g_return_if_fail (GTK_IS_AT_SPI_CONTEXT (context));
const char *path = gtk_at_spi_context_get_context_path (context);
if (path == NULL)
return;
if (g_hash_table_contains (self->contexts_by_path, path))
return;
g_object_weak_ref (G_OBJECT (context), context_weak_unref, self);
char *path_key = g_strdup (path);
g_hash_table_insert (self->contexts_by_path, path_key, context);
g_hash_table_insert (self->contexts_to_path, context, path_key);
emit_add_accessible (self, context);
GTK_NOTE (A11Y, g_message ("Adding context '%s' to cache", path_key));
}
void
gtk_at_spi_cache_remove_context (GtkAtSpiCache *self,
GtkAtSpiContext *context)
{
g_return_if_fail (GTK_IS_AT_SPI_CACHE (self));
g_return_if_fail (GTK_IS_AT_SPI_CONTEXT (context));
const char *path = gtk_at_spi_context_get_context_path (context);
if (!g_hash_table_contains (self->contexts_by_path, path))
return;
emit_remove_accessible (self, gtk_at_spi_context_to_ref (context));
g_object_weak_unref (G_OBJECT (context), context_weak_unref, self);
/* The order is important: the value in contexts_by_path is the
* key in contexts_to_path
*/
g_hash_table_remove (self->contexts_to_path, context);
g_hash_table_remove (self->contexts_by_path, path);
GTK_NOTE (A11Y, g_message ("Removing context '%s' from cache", path));
}