reactjs - React-DnD 中是否有任何选项可以根据拖动对象启用放置目标，该拖动对象与放置目标中超过 50% 的区域相交？

Question

我一直在研究 react-dnd（这是拖放组件）。因此，根据鼠标指针识别远放置目标，我想知道是否有任何选项可以更改它，需要根据拖动对象与放置目标的 50% 以上相交来识别放置目标。

这类似于 jQuery UI 拖放功能，在可放置元素中包含“公差：相交”。

Answer 1

查看 React-DnD 的可排序示例，特别是其中的悬停功能cardTarget：

const cardTarget = {
  hover(props, monitor, component) {
    const dragIndex = monitor.getItem().index;
    const hoverIndex = props.index;

    // Don't replace items with themselves
    if (dragIndex === hoverIndex) {
      return;
    }

    // Determine rectangle on screen
    const hoverBoundingRect = findDOMNode(component).getBoundingClientRect();

    // Get vertical middle
    const hoverMiddleY = (hoverBoundingRect.bottom - hoverBoundingRect.top) / 2;

    // Determine mouse position
    const clientOffset = monitor.getClientOffset();

    // Get pixels to the top
    const hoverClientY = clientOffset.y - hoverBoundingRect.top;

    // Only perform the move when the mouse has crossed half of the items height
    // When dragging downwards, only move when the cursor is below 50%
    // When dragging upwards, only move when the cursor is above 50%

    // Dragging downwards
    if (dragIndex < hoverIndex && hoverClientY < hoverMiddleY) {
      return;
    }

    // Dragging upwards
    if (dragIndex > hoverIndex && hoverClientY > hoverMiddleY) {
      return;
    }

    // Time to actually perform the action
    props.moveCard(dragIndex, hoverIndex);

    // Note: we're mutating the monitor item here!
    // Generally it's better to avoid mutations,
    // but it's good here for the sake of performance
    // to avoid expensive index searches.
    monitor.getItem().index = hoverIndex;
  }
};

我认为这两行是您正在寻找的：

// Dragging downwards
if (dragIndex < hoverIndex && hoverClientY < hoverMiddleY) {
  return;
}

// Dragging upwards
if (dragIndex > hoverIndex && hoverClientY > hoverMiddleY) {
  return;
}

它在悬停时检查，如果您悬停的项目超过了移动项目的 50% 阈值，那么它将执行重新排序操作。