Support dragging multiple files on NS

This has to use a deprecated pasteboard type, since Emacs uses
the "old" (but not deprecated) dragImage: method for
drag-and-drop, which can't drop file URLs.

* lisp/term/ns-win.el (x-begin-drag): Update accordingly.
* src/nsselect.m (ns_decode_data_to_pasteboard):
(Fns_begin_drag): Allow files to be a list of filenames as well.

1 files changed, 42 insertions, 8 deletions

diff --git a/src/nsselect.m b/src/nsselect.m
index a4129b12f03..a719eef4e86 100644
--- a/src/nsselect.m
+++ b/src/nsselect.m
@@ -562,8 +562,12 @@ ns_decode_data_to_pasteboard (Lisp_Object type, Lisp_Object data,
                               NSPasteboard *pasteboard)
 {
   NSArray *types, *new;
+  NSMutableArray *temp;
+  Lisp_Object tem;
+  specpdl_ref count;
 
   types = [pasteboard types];
+  count = SPECPDL_INDEX ();
 
   CHECK_SYMBOL (type);
 
@@ -580,10 +584,11 @@ ns_decode_data_to_pasteboard (Lisp_Object type, Lisp_Object data,
     }
   else if (EQ (type, Qfile))
     {
-      CHECK_STRING (data);
-
 #if NS_USE_NSPasteboardTypeFileURL
-      new = [types arrayByAddingObject: NSPasteboardTypeFileURL];
+      if (CONSP (data))
+        new = [types arrayByAddingObject: NSPasteboardTypeURL];
+      else
+        new = [types arrayByAddingObject: NSPasteboardTypeFileURL];
 #else
       new = [types arrayByAddingObject: NSFilenamesPboardType];
 #endif
@@ -591,13 +596,41 @@ ns_decode_data_to_pasteboard (Lisp_Object type, Lisp_Object data,
       [pasteboard declareTypes: new
                          owner: nil];
 
+      if (STRINGP (data))
+        {
 #if NS_USE_NSPasteboardTypeFileURL
-      [pasteboard setString: [NSString stringWithLispString: data]
-                    forType: NSPasteboardTypeFileURL];
+          [pasteboard setString: [NSString stringWithLispString: data]
+                        forType: NSPasteboardTypeFileURL];
 #else
-      [pasteboard setString: [NSString stringWithLispString: data]
-                    forType: NSFilenamesPboardType];
+          [pasteboard setString: [NSString stringWithLispString: data]
+                        forType: NSFilenamesPboardType];
+#endif
+        }
+      else
+        {
+          CHECK_LIST (data);
+          temp = [[NSMutableArray alloc] init];
+          record_unwind_protect_ptr (ns_release_object, temp);
+
+          for (tem = data; CONSP (tem); tem = XCDR (tem))
+            {
+              CHECK_STRING (XCAR (tem));
+
+              [temp addObject: [NSString stringWithLispString: XCAR (tem)]];
+            }
+          CHECK_LIST_END (tem, data);
+#if NS_USE_NSPasteboardTypeFileURL
+          [pasteboard setPropertyList: temp
+                      /* We have to use this deprecated pasteboard
+                         type, since Apple doesn't let us use
+                         dragImage:at: to drag multiple file URLs.  */
+                              forType: @"NSFilenamesPboardType"];
+#else
+          [pasteboard setPropertyList: temp
+                              forType: NSFilenamesPboardType];
 #endif
+          unbind_to (count, Qnil);
+        }
     }
   else
     signal_error ("Unknown pasteboard type", type);
@@ -673,7 +706,8 @@ the meaning of DATA:
     be dragged to another program.
 
   - `file' means DATA should be a file URL that will be dragged to
-    another program.
+    another program.  DATA may also be a list of file names; that
+    means each file in the list will be dragged to another program.
 
 ACTION is the action that will be taken by the drop target towards the
 data inside PBOARD.