core: Add MetaSelection and MetaSelectionSource

MetaSelectionSource represents a primary/clipboard/dnd selection owner,
it is an abstract type so wayland/x11/etc implementations can be provided.
These 3 selections are managed by the MetaSelection object, the current
selection owners will be set there, and signals will be emitted so the
previous selection owner can clean itself up.

The actual data transfer is done through the meta_selection_transfer_async()
call, which will take a GOutputStream and create a corresponding
GInputStream from the MetaSelectionSource in order to splice them.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/320

5 files changed, 580 insertions, 0 deletions

diff --git a/src/core/meta-selection-source.c b/src/core/meta-selection-source.c
new file mode 100644
index 000000000..4c0fbceba
--- /dev/null
+++ b/src/core/meta-selection-source.c
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2018 Red Hat
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Author: Carlos Garnacho <carlosg@gnome.org>
+ */
+
+#include "config.h"
+
+#include "core/meta-selection.h"
+#include "core/meta-selection-source.h"
+
+typedef struct MetaSelectionSourcePrivate MetaSelectionSourcePrivate;
+
+struct MetaSelectionSourcePrivate
+{
+  guint active : 1;
+};
+
+G_DEFINE_TYPE_WITH_PRIVATE (MetaSelectionSource,
+                            meta_selection_source,
+                            G_TYPE_OBJECT)
+
+enum
+{
+  ACTIVE,
+  INACTIVE,
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS] = { 0 };
+
+static void
+meta_selection_source_activated (MetaSelectionSource *source)
+{
+  MetaSelectionSourcePrivate *priv =
+    meta_selection_source_get_instance_private (source);
+
+  priv->active = TRUE;
+}
+
+static void
+meta_selection_source_deactivated (MetaSelectionSource *source)
+{
+  MetaSelectionSourcePrivate *priv =
+    meta_selection_source_get_instance_private (source);
+
+  priv->active = FALSE;
+}
+
+static void
+meta_selection_source_class_init (MetaSelectionSourceClass *klass)
+{
+  klass->activated = meta_selection_source_activated;
+  klass->deactivated = meta_selection_source_deactivated;
+
+  signals[ACTIVE] =
+    g_signal_new ("activated",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
+                  G_STRUCT_OFFSET (MetaSelectionSourceClass, activated),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
+  signals[INACTIVE] =
+    g_signal_new ("deactivated",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
+                  G_STRUCT_OFFSET (MetaSelectionSourceClass, deactivated),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
+}
+
+static void
+meta_selection_source_init (MetaSelectionSource *source)
+{
+}
+
+void
+meta_selection_source_read_async (MetaSelectionSource *source,
+                                  const gchar         *mimetype,
+                                  GCancellable        *cancellable,
+                                  GAsyncReadyCallback  callback,
+                                  gpointer             user_data)
+{
+  g_return_if_fail (META_IS_SELECTION_SOURCE (source));
+  g_return_if_fail (mimetype != NULL);
+  g_return_if_fail (callback != NULL);
+
+  META_SELECTION_SOURCE_GET_CLASS (source)->read_async (source,
+                                                        mimetype,
+                                                        cancellable,
+                                                        callback,
+                                                        user_data);
+}
+
+GInputStream *
+meta_selection_source_read_finish (MetaSelectionSource  *source,
+                                   GAsyncResult         *result,
+                                   GError              **error)
+{
+  g_return_val_if_fail (META_IS_SELECTION_SOURCE (source), NULL);
+  g_return_val_if_fail (g_task_is_valid (result, source), NULL);
+
+  return META_SELECTION_SOURCE_GET_CLASS (source)->read_finish (source,
+                                                                result,
+                                                                error);
+}
+
+GList *
+meta_selection_source_get_mimetypes (MetaSelectionSource  *source)
+{
+  g_return_val_if_fail (META_IS_SELECTION_SOURCE (source), NULL);
+
+  return META_SELECTION_SOURCE_GET_CLASS (source)->get_mimetypes (source);
+}
+
+gboolean
+meta_selection_source_is_active (MetaSelectionSource *source)
+{
+  MetaSelectionSourcePrivate *priv =
+    meta_selection_source_get_instance_private (source);
+
+  g_return_val_if_fail (META_IS_SELECTION_SOURCE (source), FALSE);
+
+  return priv->active;
+}
diff --git a/src/core/meta-selection-source.h b/src/core/meta-selection-source.h
new file mode 100644
index 000000000..579ebc783
--- /dev/null
+++ b/src/core/meta-selection-source.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2018 Red Hat
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Author: Carlos Garnacho <carlosg@gnome.org>
+ */
+
+#ifndef META_SELECTION_SOURCE_H
+#define META_SELECTION_SOURCE_H
+
+#include <gio/gio.h>
+
+typedef enum
+{
+  META_SELECTION_PRIMARY,
+  META_SELECTION_CLIPBOARD,
+  META_SELECTION_DND,
+  META_N_SELECTION_TYPES,
+} MetaSelectionType;
+
+typedef struct _MetaSelectionSourceClass MetaSelectionSourceClass;
+typedef struct _MetaSelectionSource MetaSelectionSource;
+
+#define META_TYPE_SELECTION_SOURCE (meta_selection_source_get_type ())
+
+G_DECLARE_DERIVABLE_TYPE (MetaSelectionSource,
+                          meta_selection_source,
+                          META, SELECTION_SOURCE,
+                          GObject)
+
+struct _MetaSelectionSourceClass
+{
+  GObjectClass parent_class;
+
+  void           (* activated)     (MetaSelectionSource *source);
+  void           (* deactivated)   (MetaSelectionSource *source);
+
+  GList *        (* get_mimetypes) (MetaSelectionSource  *source);
+
+  void           (* read_async)    (MetaSelectionSource  *source,
+                                    const gchar          *mimetype,
+                                    GCancellable         *cancellable,
+                                    GAsyncReadyCallback   callback,
+                                    gpointer              user_data);
+  GInputStream * (* read_finish)   (MetaSelectionSource  *source,
+                                    GAsyncResult         *result,
+                                    GError              **error);
+};
+
+void           meta_selection_source_read_async  (MetaSelectionSource  *source,
+                                                  const gchar          *mimetype,
+                                                  GCancellable         *cancellable,
+                                                  GAsyncReadyCallback   callback,
+                                                  gpointer              user_data);
+
+GInputStream * meta_selection_source_read_finish (MetaSelectionSource  *source,
+                                                  GAsyncResult         *result,
+                                                  GError              **error);
+
+GList *  meta_selection_source_get_mimetypes     (MetaSelectionSource  *source);
+
+gboolean meta_selection_source_is_active         (MetaSelectionSource  *source);
+
+#endif /* META_SELECTION_SOURCE_H */
diff --git a/src/core/meta-selection.c b/src/core/meta-selection.c
new file mode 100644
index 000000000..4815a8951
--- /dev/null
+++ b/src/core/meta-selection.c
@@ -0,0 +1,296 @@
+/*
+ * Copyright (C) 2018 Red Hat
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Author: Carlos Garnacho <carlosg@gnome.org>
+ */
+
+#include "config.h"
+
+#include "core/meta-selection.h"
+
+typedef struct TransferRequest TransferRequest;
+
+struct _MetaSelection
+{
+  GObject parent_instance;
+  MetaDisplay *display;
+  MetaSelectionSource *owners[META_N_SELECTION_TYPES];
+};
+
+struct TransferRequest
+{
+  MetaSelectionType selection_type;
+  GInputStream  *istream;
+  GOutputStream *ostream;
+  gssize len;
+};
+
+enum
+{
+  OWNER_CHANGED,
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS] = { 0 };
+
+G_DEFINE_TYPE (MetaSelection, meta_selection, G_TYPE_OBJECT)
+
+static void
+meta_selection_class_init (MetaSelectionClass *klass)
+{
+  signals[OWNER_CHANGED] =
+    g_signal_new ("owner-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 2,
+                  G_TYPE_UINT,
+                  META_TYPE_SELECTION_SOURCE);
+}
+
+static void
+meta_selection_init (MetaSelection *selection)
+{
+}
+
+MetaSelection *
+meta_selection_new (MetaDisplay *display)
+{
+  return g_object_new (META_TYPE_SELECTION,
+                       NULL);
+}
+
+void
+meta_selection_set_owner (MetaSelection       *selection,
+                          MetaSelectionType    selection_type,
+                          MetaSelectionSource *owner)
+{
+  g_return_if_fail (META_IS_SELECTION (selection));
+  g_return_if_fail (selection_type < META_N_SELECTION_TYPES);
+
+  if (selection->owners[selection_type] == owner)
+    return;
+
+  if (selection->owners[selection_type])
+    g_signal_emit_by_name (selection->owners[selection_type], "deactivated");
+
+  g_set_object (&selection->owners[selection_type], owner);
+  g_signal_emit_by_name (owner, "activated");
+  g_signal_emit (selection, signals[OWNER_CHANGED], 0, selection_type, owner);
+}
+
+void
+meta_selection_unset_owner (MetaSelection       *selection,
+                            MetaSelectionType    selection_type,
+                            MetaSelectionSource *owner)
+{
+  g_return_if_fail (META_IS_SELECTION (selection));
+  g_return_if_fail (selection_type < META_N_SELECTION_TYPES);
+
+  if (selection->owners[selection_type] == owner)
+    {
+      g_signal_emit_by_name (owner, "deactivated");
+      g_clear_object (&selection->owners[selection_type]);
+      g_signal_emit (selection, signals[OWNER_CHANGED], 0,
+                     selection_type, NULL);
+    }
+}
+
+GList *
+meta_selection_get_mimetypes (MetaSelection     *selection,
+                              MetaSelectionType  selection_type)
+{
+  g_return_val_if_fail (META_IS_SELECTION (selection), NULL);
+  g_return_val_if_fail (selection_type < META_N_SELECTION_TYPES, NULL);
+
+  if (!selection->owners[selection_type])
+    return NULL;
+
+  return meta_selection_source_get_mimetypes (selection->owners[selection_type]);
+}
+
+static TransferRequest *
+transfer_request_new (GOutputStream     *ostream,
+                      MetaSelectionType  selection_type,
+                      gssize             len)
+{
+  TransferRequest *request;
+
+  request = g_new0 (TransferRequest, 1);
+  request->ostream = g_object_ref (ostream);
+  request->selection_type = selection_type;
+  request->len = len;
+  return request;
+}
+
+static void
+transfer_request_free (TransferRequest *request)
+{
+  g_clear_object (&request->istream);
+  g_clear_object (&request->ostream);
+  g_free (request);
+}
+
+static void
+splice_cb (GOutputStream *stream,
+           GAsyncResult  *result,
+           GTask         *task)
+{
+  GError *error = NULL;
+
+  g_output_stream_splice_finish (stream, result, &error);
+  if (error)
+    {
+      g_task_return_error (task, error);
+      g_object_unref (task);
+      return;
+    }
+
+  g_task_return_boolean (task, TRUE);
+  g_object_unref (task);
+}
+
+static void
+write_cb (GOutputStream *stream,
+          GAsyncResult  *result,
+          GTask         *task)
+{
+  GError *error = NULL;
+
+  g_output_stream_write_bytes_finish (stream, result, &error);
+  if (error)
+    {
+      g_task_return_error (task, error);
+      g_object_unref (task);
+      return;
+    }
+
+  g_task_return_boolean (task, TRUE);
+  g_object_unref (task);
+}
+
+static void
+read_cb (GInputStream *stream,
+         GAsyncResult *result,
+         GTask        *task)
+{
+  TransferRequest *request;
+  GError *error = NULL;
+  GBytes *bytes;
+
+  bytes = g_input_stream_read_bytes_finish (stream, result, &error);
+  if (error)
+    {
+      g_task_return_error (task, error);
+      g_object_unref (task);
+      return;
+    }
+
+  request = g_task_get_task_data (task);
+  g_output_stream_write_bytes_async (request->ostream,
+                                     bytes,
+                                     G_PRIORITY_DEFAULT,
+                                     g_task_get_cancellable (task),
+                                     (GAsyncReadyCallback) write_cb,
+                                     task);
+  g_bytes_unref (bytes);
+}
+
+static void
+source_read_cb (MetaSelectionSource *source,
+                GAsyncResult        *result,
+                GTask               *task)
+{
+  TransferRequest *request;
+  GInputStream *stream;
+  GError *error = NULL;
+
+  stream = meta_selection_source_read_finish (source, result, &error);
+  if (!stream)
+    {
+      g_task_return_error (task, error);
+      return;
+    }
+
+  request = g_task_get_task_data (task);
+  request->istream = stream;
+
+  if (request->len < 0)
+    {
+      g_output_stream_splice_async (request->ostream,
+                                    request->istream,
+                                    G_OUTPUT_STREAM_SPLICE_CLOSE_SOURCE |
+                                    G_OUTPUT_STREAM_SPLICE_CLOSE_TARGET,
+                                    G_PRIORITY_DEFAULT,
+                                    g_task_get_cancellable (task),
+                                    (GAsyncReadyCallback) splice_cb,
+                                    task);
+    }
+  else
+    {
+      g_input_stream_read_bytes_async (request->istream,
+                                       (gsize) request->len,
+                                       G_PRIORITY_DEFAULT,
+                                       g_task_get_cancellable (task),
+                                       (GAsyncReadyCallback) read_cb,
+                                       task);
+    }
+}
+
+void
+meta_selection_transfer_async (MetaSelection        *selection,
+                               MetaSelectionType     selection_type,
+                               const char           *mimetype,
+                               gssize                size,
+                               GOutputStream        *output,
+                               GCancellable         *cancellable,
+                               GAsyncReadyCallback   callback,
+                               gpointer              user_data)
+{
+  GTask *task;
+
+  g_return_if_fail (META_IS_SELECTION (selection));
+  g_return_if_fail (selection_type < META_N_SELECTION_TYPES);
+  g_return_if_fail (G_IS_OUTPUT_STREAM (output));
+  g_return_if_fail (mimetype != NULL);
+
+  task = g_task_new (selection, cancellable, callback, user_data);
+  g_task_set_source_tag (task, meta_selection_transfer_async);
+
+  g_task_set_task_data (task,
+                        transfer_request_new (output, selection_type, size),
+                        (GDestroyNotify) transfer_request_free);
+  meta_selection_source_read_async (selection->owners[selection_type],
+                                    mimetype,
+                                    cancellable,
+                                    (GAsyncReadyCallback) source_read_cb,
+                                    task);
+}
+
+gboolean
+meta_selection_transfer_finish (MetaSelection  *selection,
+                                GAsyncResult   *result,
+                                GError        **error)
+{
+  g_return_val_if_fail (g_task_is_valid (result, selection), FALSE);
+  g_return_val_if_fail (g_task_get_source_tag (G_TASK (result)) ==
+                        meta_selection_transfer_async, FALSE);
+
+  return g_task_propagate_boolean (G_TASK (result), error);
+}
diff --git a/src/core/meta-selection.h b/src/core/meta-selection.h
new file mode 100644
index 000000000..275ca544d
--- /dev/null
+++ b/src/core/meta-selection.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2018 Red Hat
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Author: Carlos Garnacho <carlosg@gnome.org>
+ */
+
+#ifndef META_SELECTION_H
+#define META_SELECTION_H
+
+#include <gio/gio.h>
+
+#include "core/meta-selection-source.h"
+#include "meta/display.h"
+
+#define META_TYPE_SELECTION (meta_selection_get_type ())
+
+G_DECLARE_FINAL_TYPE (MetaSelection,
+                      meta_selection,
+                      META, SELECTION,
+                      GObject)
+
+MetaSelection *
+         meta_selection_new                  (MetaDisplay *display);
+
+void     meta_selection_set_owner            (MetaSelection        *selection,
+                                              MetaSelectionType     selection_type,
+                                              MetaSelectionSource  *owner);
+void     meta_selection_unset_owner          (MetaSelection        *selection,
+                                              MetaSelectionType     selection_type,
+                                              MetaSelectionSource  *owner);
+
+GList *  meta_selection_get_mimetypes        (MetaSelection        *selection,
+                                              MetaSelectionType     selection_type);
+
+void     meta_selection_transfer_async       (MetaSelection        *selection,
+                                              MetaSelectionType     selection_type,
+                                              const gchar          *mimetype,
+                                              gssize                size,
+                                              GOutputStream        *output,
+                                              GCancellable         *cancellable,
+                                              GAsyncReadyCallback   callback,
+                                              gpointer              user_data);
+gboolean meta_selection_transfer_finish      (MetaSelection        *selection,
+                                              GAsyncResult         *result,
+                                              GError              **error);
+
+#endif /* META_SELECTION_H */
diff --git a/src/meson.build b/src/meson.build
index b19b534be..812f42a42 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -340,6 +340,10 @@ mutter_sources = [
   'core/meta-inhibit-shortcuts-dialog-default.c',
   'core/meta-inhibit-shortcuts-dialog-default-private.h',
   'core/meta-launch-context.c',
+  'core/meta-selection.c',
+  'core/meta-selection.h',
+  'core/meta-selection-source.c',
+  'core/meta-selection-source.h',
   'core/meta-sound-player.c',
   'core/meta-workspace-manager.c',
   'core/meta-workspace-manager-private.h',