1 files changed, 144 insertions, 0 deletions
diff --git a/source/blender/editors/interface/interface_drag.cc b/source/blender/editors/interface/interface_drag.cc
new file mode 100644
index 00000000000..4c68870b2c7
--- /dev/null
+++ b/source/blender/editors/interface/interface_drag.cc
@@ -0,0 +1,144 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup edinterface
+ */
+
+#include "UI_interface.h"
+
+#include "WM_api.h"
+
+#include "interface_intern.h"
+
+void UI_but_drag_set_id(uiBut *but, ID *id)
+{
+  but->dragtype = WM_DRAG_ID;
+  if (but->dragflag & UI_BUT_DRAGPOIN_FREE) {
+    WM_drag_data_free(but->dragtype, but->dragpoin);
+    but->dragflag &= ~UI_BUT_DRAGPOIN_FREE;
+  }
+  but->dragpoin = (void *)id;
+}
+
+void UI_but_drag_attach_image(uiBut *but, struct ImBuf *imb, const float scale)
+{
+  but->imb = imb;
+  but->imb_scale = scale;
+}
+
+void UI_but_drag_set_asset(uiBut *but,
+                           const AssetHandle *asset,
+                           const char *path,
+                           struct AssetMetaData *metadata,
+                           int import_type,
+                           int icon,
+                           struct ImBuf *imb,
+                           float scale)
+{
+  wmDragAsset *asset_drag = WM_drag_create_asset_data(asset, metadata, path, import_type);
+
+  /* FIXME: This is temporary evil solution to get scene/viewlayer/etc in the copy callback of the
+   * #wmDropBox.
+   * TODO: Handle link/append in operator called at the end of the drop process, and NOT in its
+   * copy callback.
+   * */
+  asset_drag->evil_C = static_cast<bContext *>(but->block->evil_C);
+
+  but->dragtype = WM_DRAG_ASSET;
+  ui_def_but_icon(but, icon, 0); /* no flag UI_HAS_ICON, so icon doesn't draw in button */
+  if (but->dragflag & UI_BUT_DRAGPOIN_FREE) {
+    WM_drag_data_free(but->dragtype, but->dragpoin);
+  }
+  but->dragpoin = asset_drag;
+  but->dragflag |= UI_BUT_DRAGPOIN_FREE;
+  UI_but_drag_attach_image(but, imb, scale);
+}
+
+void UI_but_drag_set_rna(uiBut *but, PointerRNA *ptr)
+{
+  but->dragtype = WM_DRAG_RNA;
+  if (but->dragflag & UI_BUT_DRAGPOIN_FREE) {
+    WM_drag_data_free(but->dragtype, but->dragpoin);
+    but->dragflag &= ~UI_BUT_DRAGPOIN_FREE;
+  }
+  but->dragpoin = (void *)ptr;
+}
+
+void UI_but_drag_set_path(uiBut *but, const char *path, const bool use_free)
+{
+  but->dragtype = WM_DRAG_PATH;
+  if (but->dragflag & UI_BUT_DRAGPOIN_FREE) {
+    WM_drag_data_free(but->dragtype, but->dragpoin);
+    but->dragflag &= ~UI_BUT_DRAGPOIN_FREE;
+  }
+  but->dragpoin = (void *)path;
+  if (use_free) {
+    but->dragflag |= UI_BUT_DRAGPOIN_FREE;
+  }
+}
+
+void UI_but_drag_set_name(uiBut *but, const char *name)
+{
+  but->dragtype = WM_DRAG_NAME;
+  if (but->dragflag & UI_BUT_DRAGPOIN_FREE) {
+    WM_drag_data_free(but->dragtype, but->dragpoin);
+    but->dragflag &= ~UI_BUT_DRAGPOIN_FREE;
+  }
+  but->dragpoin = (void *)name;
+}
+
+void UI_but_drag_set_value(uiBut *but)
+{
+  but->dragtype = WM_DRAG_VALUE;
+}
+
+void UI_but_drag_set_image(
+    uiBut *but, const char *path, int icon, struct ImBuf *imb, float scale, const bool use_free)
+{
+  but->dragtype = WM_DRAG_PATH;
+  ui_def_but_icon(but, icon, 0); /* no flag UI_HAS_ICON, so icon doesn't draw in button */
+  if (but->dragflag & UI_BUT_DRAGPOIN_FREE) {
+    WM_drag_data_free(but->dragtype, but->dragpoin);
+    but->dragflag &= ~UI_BUT_DRAGPOIN_FREE;
+  }
+  but->dragpoin = (void *)path;
+  if (use_free) {
+    but->dragflag |= UI_BUT_DRAGPOIN_FREE;
+  }
+  UI_but_drag_attach_image(but, imb, scale);
+}
+
+void ui_but_drag_free(uiBut *but)
+{
+  if (but->dragpoin && (but->dragflag & UI_BUT_DRAGPOIN_FREE)) {
+    WM_drag_data_free(but->dragtype, but->dragpoin);
+  }
+}
+
+bool ui_but_drag_is_draggable(const uiBut *but)
+{
+  return but->dragpoin != nullptr;
+}
+
+void ui_but_drag_start(bContext *C, uiBut *but)
+{
+  wmDrag *drag = WM_event_start_drag(C,
+                                     but->icon,
+                                     but->dragtype,
+                                     but->dragpoin,
+                                     ui_but_value_get(but),
+                                     (but->dragflag & UI_BUT_DRAGPOIN_FREE) ? WM_DRAG_FREE_DATA :
+                                                                              WM_DRAG_NOP);
+  /* wmDrag has ownership over dragpoin now, stop messing with it. */
+  but->dragpoin = NULL;
+
+  if (but->imb) {
+    WM_event_drag_image(drag, but->imb, but->imb_scale);
+  }
+
+  /* Special feature for assets: We add another drag item that supports multiple assets. It
+   * gets the assets from context. */
+  if (ELEM(but->dragtype, WM_DRAG_ASSET, WM_DRAG_ID)) {
+    WM_event_start_drag(C, ICON_NONE, WM_DRAG_ASSET_LIST, NULL, 0, WM_DRAG_NOP);
+  }
+}