source/blender/windowmanager/CMakeLists.txt

@@ -210,3 +210,11 @@ blender_add_lib_nolist(bf_windowmanager "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")
 
 # RNA_prototypes.h
 add_dependencies(bf_windowmanager bf_rna)
+
+if(WITH_GTESTS)
+  set(TEST_SRC
+    intern/wm_dragdrop_test.cc
+  )
+  include(GTestTesting)
+  blender_add_test_lib(bf_wm_tests "${TEST_SRC}" "${INC};${TEST_INC}" "${INC_SYS}" "${LIB}")
+endif()

source/blender/windowmanager/intern/wm_dragdrop.cc

@@ -762,6 +762,7 @@ const ListBase *WM_drag_asset_list_get(const wmDrag *drag)
 
 wmDragPath *WM_drag_create_path_data(blender::Span<const char *> paths)
 {
+  BLI_assert(!paths.is_empty());
   wmDragPath *path_data = MEM_new<wmDragPath>("wmDragPath");
 
   path_data->file_type = ED_path_extension_type(paths[0]);
@@ -774,7 +775,7 @@ wmDragPath *WM_drag_create_path_data(blender::Span<const char *> paths)
 
   if (path_data->paths.size() > 1) {
     std::string path_count = std::to_string(path_data->paths.size());
-    path_data->tooltip = fmt::format(TIP_("Dragging {} files."), path_count);
+    path_data->tooltip = fmt::format(TIP_("Dragging {} files"), path_count);
   }
 
   return path_data;

source/blender/windowmanager/intern/wm_dragdrop_test.cc

@@ -0,0 +1,74 @@
+/* SPDX-FileCopyrightText: 2023 Blender Authors
+ *
+ * SPDX-License-Identifier: Apache-2.0 */
+
+#include "testing/testing.h"
+
+/* #bContextStore. */
+#include "BKE_context.h"
+
+/* #eFileSel_File_Types. */
+#include "DNA_space_types.h"
+
+#include "WM_api.hh"
+#include "WM_types.hh"
+
+namespace blender::tests {
+
+TEST(wm_dragdrop, create)
+{
+  {
+    /**
+     * NOTE: `WM_drag_create_path_data` gets the `file_type` from the first path in `paths` and
+     * only needs its extension, so there is no need to describe a full path here that can have a
+     * different format on Windows or Linux. However callers must ensure that they are valid paths.
+     */
+    blender::Vector<const char *> paths{"text_file.txt"};
+    wmDragPath *path_data = WM_drag_create_path_data(paths);
+    blender::Vector<std::string> expected_file_paths{"text_file.txt"};
+
+    EXPECT_EQ(path_data->paths.size(), 1);
+    EXPECT_EQ(path_data->tooltip, "text_file.txt");
+    EXPECT_EQ(path_data->paths, expected_file_paths);
+
+    /** Test `wmDrag` path data getters. */
+    wmDrag drag;
+    drag.type = WM_DRAG_PATH;
+    drag.poin = path_data;
+    EXPECT_STREQ(WM_drag_get_single_path(&drag), "text_file.txt");
+    EXPECT_EQ(WM_drag_get_path_file_type(&drag), FILE_TYPE_TEXT);
+    EXPECT_EQ(WM_drag_get_paths(&drag), expected_file_paths.as_span());
+
+    MEM_delete(path_data);
+  }
+  {
+    blender::Vector<const char *> paths = {"blender.blend", "text_file.txt", "image.png"};
+    wmDragPath *path_data = WM_drag_create_path_data(paths);
+    blender::Vector<std::string> expected_file_paths = {
+        "blender.blend", "text_file.txt", "image.png"};
+
+    EXPECT_EQ(path_data->paths.size(), 3);
+    EXPECT_EQ(path_data->tooltip, "Dragging 3 files");
+    EXPECT_EQ(path_data->paths, expected_file_paths);
+
+    /** Test `wmDrag` path data getters. */
+    wmDrag drag;
+    drag.type = WM_DRAG_PATH;
+    drag.poin = path_data;
+    EXPECT_STREQ(WM_drag_get_single_path(&drag), "blender.blend");
+    EXPECT_EQ(WM_drag_get_path_file_type(&drag), FILE_TYPE_BLENDER);
+    EXPECT_EQ(WM_drag_get_paths(&drag), expected_file_paths.as_span());
+
+    MEM_delete(path_data);
+  }
+  {
+    /** Test `wmDrag` path data getters when the drag type is different to `WM_DRAG_PATH`. */
+    wmDrag drag;
+    drag.type = WM_DRAG_COLOR;
+    EXPECT_EQ(WM_drag_get_single_path(&drag), nullptr);
+    EXPECT_EQ(WM_drag_get_path_file_type(&drag), 0);
+    EXPECT_EQ(WM_drag_get_paths(&drag).size(), 0);
+  }
+}
+
+}  // namespace blender::tests

source/blender/windowmanager/intern/wm_window.cc

@@ -15,6 +15,8 @@
 #include <cstring>
 #include <thread>
 
+#include "CLG_log.h"
+
 #include "DNA_listBase.h"
 #include "DNA_screen_types.h"
 #include "DNA_windowmanager_types.h"
@@ -63,6 +65,8 @@
 #include "ED_scene.hh"
 #include "ED_screen.hh"
 
+#include <fmt/format.h>
+
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
 
@@ -1569,13 +1573,17 @@ static bool ghost_event_proc(GHOST_EventHandle evt, GHOST_TUserDataPtr C_void_pt
         const GHOST_TStringArray *stra = static_cast<const GHOST_TStringArray *>(ddd->data);
 
         if (stra->count) {
-          /* try to get icon type from extension */
+          CLOG_INFO(WM_LOG_EVENTS, 1, "Drop %d files:", stra->count);
+          for (const char *path : blender::Span((char **)stra->strings, stra->count)) {
+            CLOG_INFO(WM_LOG_EVENTS, 1, "%s", path);
+          }
+          /* Try to get icon type from extension of the first path. */
           int icon = ED_file_extension_icon((char *)stra->strings[0]);
           wmDragPath *path_data = WM_drag_create_path_data(
               blender::Span((char **)stra->strings, stra->count));
           WM_event_start_drag(C, icon, WM_DRAG_PATH, path_data, 0.0, WM_DRAG_NOP);
           /* Void pointer should point to string, it makes a copy. */
-          break; /* only one drop element supported now */
+          break;
         }
       }