clipboard: Refactor gdk_clipboard_read() to be async

This allows us not just to pass any mime type to the read function, but
it also makes it possible to pass multiple mime types and the clipboard
can then try them in order until it finds a supported one.

This is so far not implemented though.

1 files changed, 99 insertions, 10 deletions

diff --git a/gdk/gdkclipboard.c b/gdk/gdkclipboard.c
index eee9284a9a..30b81fff3e 100644
--- a/gdk/gdkclipboard.c
+++ b/gdk/gdkclipboard.c
@@ -113,9 +113,30 @@ gdk_clipboard_finalize (GObject *object)
   G_OBJECT_CLASS (gdk_clipboard_parent_class)->finalize (object);
 }
 
+static void
+gdk_clipboard_real_read_async (GdkClipboard        *clipboard,
+                               GdkContentFormats   *formats,
+                               int                  io_priority,
+                               GCancellable        *cancellable,
+                               GAsyncReadyCallback  callback,
+                               gpointer             user_data)
+{
+  GTask *task;
+
+  task = g_task_new (clipboard, cancellable, callback, user_data);
+  g_task_set_priority (task, io_priority);
+  g_task_set_source_tag (task, gdk_clipboard_read_async);
+  g_task_set_task_data (task, gdk_content_formats_ref (formats), (GDestroyNotify) gdk_content_formats_unref);
+
+  g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED, "Reading local content not supported yet.");
+  g_object_unref (task);
+}
+
 static GInputStream *
-gdk_clipboard_real_read (GdkClipboard *clipboard,
-                         const char   *mime_type)
+gdk_clipboard_real_read_finish (GdkClipboard  *clipboard,
+                                const char   **out_mime_type,
+                                GAsyncResult  *result,
+                                GError       **error)
 {
   /* whoop whooop */
   return g_memory_input_stream_new ();
@@ -130,7 +151,8 @@ gdk_clipboard_class_init (GdkClipboardClass *class)
   object_class->set_property = gdk_clipboard_set_property;
   object_class->finalize = gdk_clipboard_finalize;
 
-  class->read = gdk_clipboard_real_read;
+  class->read_async = gdk_clipboard_real_read_async;
+  class->read_finish = gdk_clipboard_real_read_finish;
 
   /**
    * GdkClipboard:display:
@@ -237,17 +259,84 @@ gdk_clipboard_get_formats (GdkClipboard *clipboard)
   return priv->formats;
 }
 
-GInputStream *
-gdk_clipboard_read (GdkClipboard *clipboard,
-                    const char   *mime_type)
+static void
+gdk_clipboard_read_internal (GdkClipboard        *clipboard,
+                             GdkContentFormats   *formats,
+                             int                  io_priority,
+                             GCancellable        *cancellable,
+                             GAsyncReadyCallback  callback,
+                             gpointer             user_data)
 {
-  GdkClipboardPrivate *priv = gdk_clipboard_get_instance_private (clipboard);
+  return GDK_CLIPBOARD_GET_CLASS (clipboard)->read_async (clipboard,
+                                                          formats,
+                                                          io_priority,
+                                                          cancellable,
+                                                          callback,
+                                                          user_data);
+}
+
+/**
+ * gdk_clipboard_read_async:
+ * @clipboard: a #GdkClipboard
+ * @mime_types: a %NULL-terminated array of mime types to choose from
+ * @io_priority: the [I/O priority][io-priority]
+ * of the request. 
+ * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.
+ * @callback: (scope async): callback to call when the request is satisfied
+ * @user_data: (closure): the data to pass to callback function
+ *
+ * Asynchronously requests an input stream to read the @clipboard's
+ * contents from. When the operation is finished @callback will be called. 
+ * You can then call gdk_clipboard_read_finish() to get the result of the 
+ * operation.
+ *
+ * The clipboard will choose the most suitable mime type from the given list
+ * to fulfill the request, preferring the ones listed first. 
+ **/
+void
+gdk_clipboard_read_async (GdkClipboard        *clipboard,
+                          const char         **mime_types,
+                          int                  io_priority,
+                          GCancellable        *cancellable,
+                          GAsyncReadyCallback  callback,
+                          gpointer             user_data)
+{
+  GdkContentFormats *formats;
+
+  g_return_if_fail (GDK_IS_CLIPBOARD (clipboard));
+  g_return_if_fail (mime_types != NULL && mime_types[0] != NULL);
+  g_return_if_fail (callback != NULL);
+
+  formats = gdk_content_formats_new (mime_types, g_strv_length ((char **) mime_types));
+
+  gdk_clipboard_read_internal (clipboard, formats, io_priority, cancellable, callback, user_data);
+
+  gdk_content_formats_unref (formats);
+}
 
+/**
+ * gdk_clipboard_read_finish:
+ * @clipboard: a #GdkClipboard
+ * @out_mime_type: (out) (allow-none) (transfer none): pointer to store
+ *     the chosen mime type in or %NULL
+ * @result: a #GAsyncResult
+ * @error: a #GError location to store the error occurring, or %NULL to 
+ * ignore.
+ *
+ * Finishes an asynchronous clipboard read started with gdk_clipboard_read_async().
+ *
+ * Returns: (transfer full): a #GInputStream or %NULL on error.
+ **/
+GInputStream *
+gdk_clipboard_read_finish (GdkClipboard  *clipboard,
+                           const char   **out_mime_type,
+                           GAsyncResult  *result,
+                           GError       **error)
+{
   g_return_val_if_fail (GDK_IS_CLIPBOARD (clipboard), NULL);
-  g_return_val_if_fail (mime_type != NULL, NULL);
-  g_return_val_if_fail (gdk_content_formats_contain_mime_type (priv->formats, mime_type), NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
 
-  return GDK_CLIPBOARD_GET_CLASS (clipboard)->read (clipboard, mime_type);
+  return GDK_CLIPBOARD_GET_CLASS (clipboard)->read_finish (clipboard, out_mime_type, result, error);
 }
 
 GdkClipboard *