Don't show move drop target on non-move drag operations (#5219)

ui/v2.5/src/components/Shared/GridCard/dragMoveSelect.ts

@@ -1,11 +1,26 @@
 import { useState } from "react";
 import { useListContextOptional } from "src/components/List/ListProvider";
 
+// Enum representing the possible sides for a drag operation.
 export enum DragSide {
   BEFORE,
   AFTER,
 }
 
+/**
+ * Hook to manage drag and move selection functionality.
+ * Dragging while selecting will allow the user to select multiple items.
+ * Dragging from the drag handle will allow the user to move the item or selected items.
+ *
+ * @param props - The properties for the hook.
+ * @param props.selecting - Whether the one or more items have been selected.
+ * @param props.selected - Whether this item is currently selected.
+ * @param props.onSelectedChanged - Callback when the selected state changes.
+ * @param props.objectId - The ID of this object.
+ * @param props.onMove - Callback when a move operation occurs.
+ *
+ * @returns An object containing the drag event handlers and state.
+ */
 export function useDragMoveSelect(props: {
   selecting: boolean;
   selected: boolean;
@@ -15,8 +30,12 @@ export function useDragMoveSelect(props: {
 }) {
   const { selectedIds } = useListContextOptional();
 
+  // true if the mouse is over the drag handle
   const [inHandle, setInHandle] = useState(false);
+
+  // true if this is the source of a move operation
   const [moveSrc, setMoveSrc] = useState(false);
+  // the target side for a move operation
   const [moveTarget, setMoveTarget] = useState<DragSide | undefined>();
 
   const canSelect = props.onSelectedChanged && props.selecting;
@@ -75,6 +94,7 @@ export function useDragMoveSelect(props: {
       ev.dataTransfer.dropEffect = "copy";
       ev.preventDefault();
     } else if (ev.dataTransfer.effectAllowed === "move" && !moveSrc) {
+      // don't allow move on self
       doSetMoveTarget(event);
       ev.dataTransfer.dropEffect = "move";
       ev.preventDefault();
@@ -92,7 +112,8 @@ export function useDragMoveSelect(props: {
   }
 
   function onDragOver(event: React.DragEvent<HTMLElement>) {
-    if (event.dataTransfer.effectAllowed === "move" && moveSrc) {
+    // only set move target if move is allowed, or if this is not the source of the move
+    if (event.dataTransfer.effectAllowed !== "move" || moveSrc) {
       return;
     }