[gtk/wip/otte/for-master: 3/3] gtk-demo: Make clipboard demo paste from clipboard

[Benjamin Otte <otte src gnome org>]

commit 6b733d294354c349b4b5ef7d689c0b2ef162f797
Author: Benjamin Otte <otte redhat com>
Date:   Thu Aug 19 03:14:59 2021 +0200

    gtk-demo: Make clipboard demo paste from clipboard
    
    The old code was just pasting local clipboard data that we put there
    ourselves and was causing criticals on remote clipboard data. Now the
    code does the proper async paste.

 demos/gtk-demo/demoimage.c | 44 +++++++++++++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 11 deletions(-)
---
diff --git a/demos/gtk-demo/demoimage.c b/demos/gtk-demo/demoimage.c
index 8fdc4257a5..dc5776cc5b 100644
--- a/demos/gtk-demo/demoimage.c
+++ b/demos/gtk-demo/demoimage.c
@@ -146,24 +146,46 @@ copy_image (GtkWidget *widget,
     g_object_unref (paintable);
 }
 
+static void
+paste_image_cb (GObject      *source,
+                GAsyncResult *result,
+                gpointer      data)
+{
+  GdkClipboard *clipboard = GDK_CLIPBOARD (source);
+  DemoImage *demo = DEMO_IMAGE (data);
+  const GValue *value;
+
+  value = gdk_clipboard_read_value_finish (clipboard, result, NULL);
+  if (value == NULL)
+    {
+      gtk_widget_error_bell (GTK_WIDGET (demo));
+      g_object_unref (demo);
+      return;
+    }
+
+  gtk_image_set_from_paintable (GTK_IMAGE (demo->image), g_value_get_object (value));
+  g_object_unref (demo);
+}
+
 static void
 paste_image (GtkWidget *widget,
              const char *action_name,
              GVariant *parameter)
 {
   GdkClipboard *clipboard = gtk_widget_get_clipboard (widget);
-  DemoImage *demo = DEMO_IMAGE (widget);
-  GdkContentProvider *content = gdk_clipboard_get_content (clipboard);
-  GValue value = G_VALUE_INIT;
-  GdkPaintable *paintable;
+  GType type;
 
-  g_value_init (&value, GDK_TYPE_PAINTABLE);
-  if (!gdk_content_provider_get_value (content, &value, NULL))
-    return;
-
-  paintable = GDK_PAINTABLE (g_value_get_object (&value));
-  gtk_image_set_from_paintable (GTK_IMAGE (demo->image), paintable);
-  g_value_unset (&value);
+  if (gdk_content_formats_contain_gtype (gdk_clipboard_get_formats (clipboard), GDK_TYPE_TEXTURE))
+    type = GDK_TYPE_TEXTURE;
+  else
+    type = GDK_TYPE_PAINTABLE;
+
+  gdk_clipboard_read_value_async (clipboard, 
+                                  type,
+                                  G_PRIORITY_DEFAULT,
+                                  NULL,
+                                  paste_image_cb,
+                                  g_object_ref (widget));
 }
 
 static void