core: Add memory-based selection source

This is a simple implementation of a MetaSelectionSource, able to hold a
single mimetype, provided as GBytes.

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

src/core/meta-selection-source-memory.c

@@ -0,0 +1,125 @@
+/*
+ * 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-source-memory.h"
+
+struct _MetaSelectionSourceMemory
+{
+  MetaSelectionSource parent_instance;
+  char *mimetype;
+  GBytes *content;
+};
+
+G_DEFINE_TYPE (MetaSelectionSourceMemory,
+               meta_selection_source_memory,
+               META_TYPE_SELECTION_SOURCE)
+
+static void
+meta_selection_source_memory_read_async (MetaSelectionSource *source,
+                                         const char          *mimetype,
+                                         GCancellable        *cancellable,
+                                         GAsyncReadyCallback  callback,
+                                         gpointer             user_data)
+{
+  MetaSelectionSourceMemory *source_mem = META_SELECTION_SOURCE_MEMORY (source);
+  GInputStream *stream;
+  GTask *task;
+
+  if (g_strcmp0 (mimetype, source_mem->mimetype) != 0)
+    {
+      g_task_report_new_error (source, callback, user_data,
+                               meta_selection_source_memory_read_async,
+                               G_IO_ERROR, G_IO_ERROR_FAILED,
+                               "Mimetype not in selection");
+      return;
+    }
+
+  task = g_task_new (source, cancellable, callback, user_data);
+  g_task_set_source_tag (task, meta_selection_source_memory_read_async);
+
+  stream = g_memory_input_stream_new_from_bytes (source_mem->content);
+  g_task_return_pointer (task, stream, g_object_unref);
+}
+
+static GInputStream *
+meta_selection_source_memory_read_finish (MetaSelectionSource  *source,
+                                          GAsyncResult         *result,
+                                          GError              **error)
+{
+  g_assert (g_task_get_source_tag (G_TASK (result)) ==
+            meta_selection_source_memory_read_async);
+  return g_task_propagate_pointer (G_TASK (result), error);
+}
+
+static GList *
+meta_selection_source_memory_get_mimetypes (MetaSelectionSource *source)
+{
+  MetaSelectionSourceMemory *source_mem = META_SELECTION_SOURCE_MEMORY (source);
+
+  return g_list_prepend (NULL, g_strdup (source_mem->mimetype));
+}
+
+static void
+meta_selection_source_memory_finalize (GObject *object)
+{
+  MetaSelectionSourceMemory *source_mem = META_SELECTION_SOURCE_MEMORY (object);
+
+  g_bytes_unref (source_mem->content);
+  g_free (source_mem->mimetype);
+
+  G_OBJECT_CLASS (meta_selection_source_memory_parent_class)->finalize (object);
+}
+
+static void
+meta_selection_source_memory_class_init (MetaSelectionSourceMemoryClass *klass)
+{
+  MetaSelectionSourceClass *source_class = META_SELECTION_SOURCE_CLASS (klass);
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->finalize = meta_selection_source_memory_finalize;
+
+  source_class->read_async = meta_selection_source_memory_read_async;
+  source_class->read_finish = meta_selection_source_memory_read_finish;
+  source_class->get_mimetypes = meta_selection_source_memory_get_mimetypes;
+}
+
+static void
+meta_selection_source_memory_init (MetaSelectionSourceMemory *source)
+{
+}
+
+MetaSelectionSource *
+meta_selection_source_memory_new (const char  *mimetype,
+                                  GBytes      *content)
+{
+  MetaSelectionSourceMemory *source;
+
+  g_return_val_if_fail (mimetype != NULL, NULL);
+  g_return_val_if_fail (content != NULL, NULL);
+
+  source = g_object_new (META_TYPE_SELECTION_SOURCE_MEMORY, NULL);
+  source->mimetype = g_strdup (mimetype);
+  source->content = g_bytes_ref (content);
+
+  return META_SELECTION_SOURCE (source);
+}

src/core/meta-selection-source-memory.h

@@ -0,0 +1,36 @@
+/*
+ * 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_MEMORY_SELECTION_SOURCE_H
+#define META_MEMORY_SELECTION_SOURCE_H
+
+#include "core/meta-selection-source.h"
+
+#define META_TYPE_SELECTION_SOURCE_MEMORY (meta_selection_source_memory_get_type ())
+G_DECLARE_FINAL_TYPE (MetaSelectionSourceMemory,
+                      meta_selection_source_memory,
+                      META, SELECTION_SOURCE_MEMORY,
+                      MetaSelectionSource)
+
+MetaSelectionSource * meta_selection_source_memory_new (const char *mimetype,
+                                                        GBytes     *content);
+
+#endif /* META_SELECTION_SOURCE_MEMORY_H */

src/meson.build

@@ -344,6 +344,8 @@ mutter_sources = [
   'core/meta-selection.h',
   'core/meta-selection-source.c',
   'core/meta-selection-source.h',
+  'core/meta-selection-source-memory.c',
+  'core/meta-selection-source-memory.h',
   'core/meta-sound-player.c',
   'core/meta-workspace-manager.c',
   'core/meta-workspace-manager-private.h',