input: add insert-next support for drag-and-drop

This commit adds a DND_INSERT_NEXT action option for drag-and-drop,
allows for selecting it through the --drag-and-drop=insert-next option,
and adds the necessary plumbing to make that happen when something is
dragged onto the player.

DOCS/man/options.rst

@@ -3197,13 +3197,14 @@ Window
 ``--snap-window``
     (Windows only) Snap the player window to screen edges.
 
-``--drag-and-drop=<no|auto|replace|append>``
-    Controls the default behavior of drag and drop on platforms that support this.
-    ``auto`` will obey what the underlying os/platform gives mpv. Typically, holding
-    shift during the drag and drop will append the item to the playlist. Otherwise,
-    it will completely replace it. ``replace`` and ``append`` always force replacing
-    and appending to the playlist respectively. ``no`` disables all drag and drop
-    behavior.
+``--drag-and-drop=<no|auto|replace|append|insert-next>``
+    Controls the default behavior of drag and drop on platforms that support
+    this. ``auto`` will obey what the underlying os/platform gives mpv.
+    Typically, holding shift during the drag and drop will append the item to
+    the playlist. Otherwise, it will completely replace it. ``replace``,
+    ``append``, and ``insert-next`` always force replacing, appending to, and
+    inserting next into the playlist respectively. ``no`` disables all drag and
+    drop behavior.
 
 ``--ontop``
     Makes the player window stay on top of other windows.

input/event.c

@@ -37,6 +37,21 @@ void mp_event_drop_files(struct input_ctx *ictx, int num_files, char **files,
             };
             mp_input_run_cmd(ictx, cmd);
         }
+    } else if (action == DND_INSERT_NEXT) {
+        /* To insert the entries in the correct order, we iterate over them
+           backwards */
+        for (int i = num_files - 1; i >= 0; i--) {
+            const char *cmd[] = {
+                "osd-auto",
+                "loadfile",
+                files[i],
+                /* Since we're inserting in reverse, wait til the final item
+                   is added to start playing */
+                (i > 0) ? "insert-next" : "insert-next-play",
+                NULL
+            };
+            mp_input_run_cmd(ictx, cmd);
+        }
     } else {
         for (int i = 0; i < num_files; i++) {
             const char *cmd[] = {

input/event.h

@@ -24,16 +24,17 @@ struct input_ctx;
 enum mp_dnd_action {
     DND_REPLACE,
     DND_APPEND,
+    DND_INSERT_NEXT,
 };
 
 // Enqueue files for playback after drag and drop
 void mp_event_drop_files(struct input_ctx *ictx, int num_files, char **files,
-                         enum mp_dnd_action append);
+                         enum mp_dnd_action action);
 
 // Drop data in a specific format (identified by the mimetype).
 // Returns <0 on error, ==0 if data was ok but empty, >0 on success.
 int mp_event_drop_mime_data(struct input_ctx *ictx, const char *mime_type,
-                            bstr data, enum mp_dnd_action append);
+                            bstr data, enum mp_dnd_action action);
 
 // Many drag & drop APIs support multiple mime types, and this function returns
 // whether a type is preferred (higher integer score), or supported (scores

options/options.c

@@ -112,7 +112,9 @@ static const m_option_t mp_vo_opt_list[] = {
     {"vo", OPT_SETTINGSLIST(video_driver_list, &vo_obj_list)},
     {"taskbar-progress", OPT_BOOL(taskbar_progress)},
     {"drag-and-drop", OPT_CHOICE(drag_and_drop, {"no", -2}, {"auto", -1},
-        {"replace", DND_REPLACE}, {"append", DND_APPEND})},
+        {"replace", DND_REPLACE},
+        {"append", DND_APPEND},
+        {"insert-next", DND_INSERT_NEXT})},
     {"snap-window", OPT_BOOL(snap_window)},
     {"ontop", OPT_BOOL(ontop)},
     {"ontop-level", OPT_CHOICE(ontop_level, {"window", -1}, {"system", -2},

video/out/wayland_common.c

@@ -695,8 +695,14 @@ static void data_offer_action(void *data, struct wl_data_offer *wl_data_offer, u
             wl->dnd_action = dnd_action & WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY ?
                              DND_REPLACE : DND_APPEND;
         }
-        MP_VERBOSE(wl, "DND action is %s\n",
-                   wl->dnd_action == DND_REPLACE ? "DND_REPLACE" : "DND_APPEND");
+
+        static const char * const dnd_action_names[] = {
+            [DND_REPLACE] = "DND_REPLACE",
+            [DND_APPEND] = "DND_APPEND",
+            [DND_INSERT_NEXT] = "DND_INSERT_NEXT",
+        };
+
+        MP_VERBOSE(wl, "DND action is %s\n", dnd_action_names[wl->dnd_action]);
     }
 }