[gtk/wip/otte/dnd: 1/2] wayland: Use a magic mime type for local DND

[Benjamin Otte <otte src gnome org>]

commit 46bbb397e19adb71917f2d6ea581e44ab041aad3
Author: Benjamin Otte <otte redhat com>
Date:   Sat Feb 15 21:04:57 2020 +0100

    wayland: Use a magic mime type for local DND
    
    Otherwise the compositor gets all confused when it's trying to make
    drag happen but we know it's not going to happen.
    
    After all, we exchange data behind its back, we just need to keep it
    informed.

 gdk/wayland/gdkdevice-wayland.c  | 4 ++++
 gdk/wayland/gdkdrag-wayland.c    | 1 +
 gdk/wayland/gdkdrop-wayland.c    | 7 +++++++
 gdk/wayland/gdkprivate-wayland.h | 7 +++++++
 4 files changed, 19 insertions(+)
---
diff --git a/gdk/wayland/gdkdevice-wayland.c b/gdk/wayland/gdkdevice-wayland.c
index 4bc5a55b04..8ef0a3ae03 100644
--- a/gdk/wayland/gdkdevice-wayland.c
+++ b/gdk/wayland/gdkdevice-wayland.c
@@ -1127,6 +1127,10 @@ data_offer_offer (void                 *data,
       return;
     }
 
+  /* skip magic mime types */
+  if (g_str_equal (type, GDK_WAYLAND_LOCAL_DND_MIME_TYPE))
+    return;
+
   gdk_content_formats_builder_add_mime_type (seat->pending_builder, type);
 }
 
diff --git a/gdk/wayland/gdkdrag-wayland.c b/gdk/wayland/gdkdrag-wayland.c
index fd4dc9ec98..f7c2925c60 100644
--- a/gdk/wayland/gdkdrag-wayland.c
+++ b/gdk/wayland/gdkdrag-wayland.c
@@ -358,6 +358,7 @@ gdk_wayland_drag_create_data_source (GdkDrag *drag)
             g_message ("create data source, mime types=%s", s);
             g_free (s);});
 
+  wl_data_source_offer (drag_wayland->data_source, GDK_WAYLAND_LOCAL_DND_MIME_TYPE);
   for (i = 0; i < n_mimetypes; i++)
     wl_data_source_offer (drag_wayland->data_source, mimetypes[i]);
 
diff --git a/gdk/wayland/gdkdrop-wayland.c b/gdk/wayland/gdkdrop-wayland.c
index b7f74e8743..a638b6314f 100644
--- a/gdk/wayland/gdkdrop-wayland.c
+++ b/gdk/wayland/gdkdrop-wayland.c
@@ -97,6 +97,13 @@ gdk_wayland_drop_drop_set_status (GdkWaylandDrop *drop_wayland,
       const char *const *mimetypes;
       gsize i, n_mimetypes;
       
+      /* This is a local drag, treat it like that */
+      if (gdk_drop_get_drag (GDK_DROP (drop_wayland)))
+        {
+          wl_data_offer_accept (drop_wayland->offer, drop_wayland->serial, GDK_WAYLAND_LOCAL_DND_MIME_TYPE);
+          return;
+        }
+
       mimetypes = gdk_content_formats_get_mime_types (gdk_drop_get_formats (GDK_DROP (drop_wayland)), 
&n_mimetypes);
       for (i = 0; i < n_mimetypes; i++)
         {
diff --git a/gdk/wayland/gdkprivate-wayland.h b/gdk/wayland/gdkprivate-wayland.h
index 8130a323a1..233e972cc4 100644
--- a/gdk/wayland/gdkprivate-wayland.h
+++ b/gdk/wayland/gdkprivate-wayland.h
@@ -44,6 +44,13 @@
 #define WL_SURFACE_HAS_BUFFER_SCALE 3
 #define WL_POINTER_HAS_FRAME 5
 
+/* the magic mime type we use for local DND operations.
+ * We offer it to every dnd operation, but will strip it out on the drop
+ * site unless we can prove it's a local DND - then we will use only
+ * this type
+ */
+#define GDK_WAYLAND_LOCAL_DND_MIME_TYPE "application/x-gtk-local-dnd"
+
 GdkKeymap *_gdk_wayland_keymap_new (GdkDisplay *display);
 void       _gdk_wayland_keymap_update_from_fd (GdkKeymap *keymap,
                                                uint32_t   format,