[evolution] Drag&drop of attachment button from mail preview does nothing

[Milan Crha <mcrha src gnome org>]

commit 10ceb309102698f8925cd56d283b8337c0cae610
Author: Milan Crha <mcrha redhat com>
Date:   Thu Jan 4 19:04:46 2018 +0100

    Drag&drop of attachment button from mail preview does nothing
    
    It's using the same mime type, but the code to make it a real file
    or anything like that fails. With this change the button (or the image
    of it on the right side of the button) can be dragged into the folder
    tree or message list, importing it into the mail folder.

 src/mail/e-mail-display.c |  111 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 111 insertions(+), 0 deletions(-)
---
diff --git a/src/mail/e-mail-display.c b/src/mail/e-mail-display.c
index 0e68e8d..126f8f9 100644
--- a/src/mail/e-mail-display.c
+++ b/src/mail/e-mail-display.c
@@ -1777,6 +1777,71 @@ mail_display_suggest_filename (EWebView *web_view,
 }
 
 static void
+mail_display_save_part_for_drop (CamelMimePart *mime_part,
+                                GtkSelectionData *data)
+{
+       gchar *tmp, *path, *filename;
+       const gchar *part_filename;
+       CamelDataWrapper *dw;
+
+       g_return_if_fail (CAMEL_IS_MIME_PART (mime_part));
+       g_return_if_fail (data != NULL);
+
+       tmp = g_strdup_printf (PACKAGE "-%s-XXXXXX", g_get_user_name ());
+       path = e_mkdtemp (tmp);
+       g_free (tmp);
+
+       g_return_if_fail (path != NULL);
+
+       part_filename = camel_mime_part_get_filename (mime_part);
+       if (!part_filename || !*part_filename) {
+               CamelDataWrapper *content;
+
+               content = camel_medium_get_content (CAMEL_MEDIUM (mime_part));
+
+               if (CAMEL_IS_MIME_MESSAGE (content))
+                       part_filename = camel_mime_message_get_subject (CAMEL_MIME_MESSAGE (content));
+       }
+
+       if (!part_filename || !*part_filename)
+               part_filename = "mail-part";
+
+       tmp = g_strdup (part_filename);
+       e_filename_make_safe (tmp);
+
+       filename = g_build_filename (path, tmp, NULL);
+       g_free (tmp);
+
+       dw = camel_medium_get_content (CAMEL_MEDIUM (mime_part));
+       g_warn_if_fail (dw);
+
+       if (dw) {
+               CamelStream *stream;
+
+               stream = camel_stream_fs_new_with_name (filename, O_CREAT | O_TRUNC | O_WRONLY, 0666, NULL);
+               if (stream) {
+                       if (camel_data_wrapper_decode_to_stream_sync (dw, stream, NULL, NULL)) {
+                               tmp = g_filename_to_uri (filename, NULL, NULL);
+                               if (tmp) {
+                                       gtk_selection_data_set (
+                                               data,
+                                               gtk_selection_data_get_data_type (data),
+                                               gtk_selection_data_get_format (data),
+                                               (const guchar *) tmp, strlen (tmp));
+                                       g_free (tmp);
+                               }
+                       }
+
+                       camel_stream_close (stream, NULL, NULL);
+                       g_object_unref (stream);
+               }
+       }
+
+       g_free (filename);
+       g_free (path);
+}
+
+static void
 mail_display_drag_data_get (GtkWidget *widget,
                             GdkDragContext *context,
                             GtkSelectionData *data,
@@ -1800,6 +1865,52 @@ mail_display_drag_data_get (GtkWidget *widget,
 
        mime_part = camel_mime_part_from_cid (display, uri);
 
+       if (!mime_part && g_str_has_prefix (uri, "mail:")) {
+               SoupURI *soup_uri;
+               const gchar *soup_query;
+
+               soup_uri = soup_uri_new (uri);
+               if (soup_uri) {
+                       soup_query = soup_uri_get_query (soup_uri);
+                       if (soup_query) {
+                               GHashTable *query;
+                               const gchar *part_id_raw;
+
+                               query = soup_form_decode (soup_query);
+                               part_id_raw = query ? g_hash_table_lookup (query, "part_id") : NULL;
+                               if (part_id_raw && *part_id_raw) {
+                                       EMailPartList *part_list;
+                                       EMailPart *mail_part;
+
+                                       part_list = e_mail_display_get_part_list (display);
+                                       if (part_list) {
+                                               gchar *part_id = soup_uri_decode (part_id_raw);
+
+                                               mail_part = e_mail_part_list_ref_part (part_list, part_id);
+                                               g_free (part_id);
+
+                                               if (mail_part) {
+                                                       CamelMimePart *part;
+
+                                                       part = e_mail_part_ref_mime_part (mail_part);
+                                                       if (part) {
+                                                               mail_display_save_part_for_drop (part, data);
+                                                       }
+
+                                                       g_clear_object (&part);
+                                                       g_object_unref (mail_part);
+                                               }
+                                       }
+                               }
+
+                               if (query)
+                                       g_hash_table_unref (query);
+                       }
+
+                       soup_uri_free (soup_uri);
+               }
+       }
+
        if (!mime_part)
                goto out;