From 2ce686c049a7a35cdc3eb87626d8a94539388a35 Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Sat, 4 Jun 2022 15:45:41 +0800
Subject: [PATCH] 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.
---
 lisp/term/ns-win.el | 20 +++++++++++++-----
 src/nsselect.m      | 50 +++++++++++++++++++++++++++++++++++++--------
 2 files changed, 57 insertions(+), 13 deletions(-)

diff --git a/lisp/term/ns-win.el b/lisp/term/ns-win.el
index a36d5d11e79..2e021b9b29c 100644
--- a/lisp/term/ns-win.el
+++ b/lisp/term/ns-win.el
@@ -905,11 +905,21 @@ See the documentation of `create-fontset-from-fontset-spec' for the format.")
       (push (cons 'string ns-dnd-selection-value) pasteboard))
     (when (and (member "FILE_NAME" targets)
                (file-exists-p ns-dnd-selection-value))
-      (push (cons 'file
-                  (url-encode-url (concat "file://"
-                                          (expand-file-name
-                                           ns-dnd-selection-value))))
-            pasteboard))
+      (let ((value (if (stringp ns-dnd-selection-value)
+                       (or (get-text-property 0 'FILE_NAME
+                                              ns-dnd-selection-value)
+                           ns-dnd-selection-value)
+                     ns-dnd-selection-value)))
+        (if (vectorp value)
+            (push (cons 'file
+                        (cl-loop for file across value
+                                 collect (expand-file-name file)))
+                  pasteboard)
+          (push (cons 'file
+                      (url-encode-url (concat "file://"
+                                              (expand-file-name
+                                               ns-dnd-selection-value))))
+                pasteboard))))
     (ns-begin-drag frame pasteboard action return-frame allow-current-frame)))
 
 (defun ns-handle-drag-motion (frame x y)
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.
-- 
2.39.2