2019-05-20

简介

• UGUI

• 图片拖拽排序

  
  demo.gif

DropZone.cs

• 拖拽Continer

public class DropZone : MonoBehaviour, IDropHandler, IPointerEnterHandler, IPointerExitHandler {

    public void OnPointerEnter(PointerEventData eventData) {

        if (eventData.pointerDrag == null)
            return;

        Draggable d = eventData.pointerDrag.GetComponent<Draggable>();
        if (d != null)
        {
            d.placeHolderParent = this.transform;
        }
    }

    public void OnPointerExit(PointerEventData eventData) {

        if (eventData.pointerDrag == null)
            return;

        Draggable d = eventData.pointerDrag.GetComponent<Draggable>();
        if (d != null && d.placeHolderParent == this.transform)
        {
            d.placeHolderParent = d.parentToReturnTo;
        }
    }

    public void OnDrop(PointerEventData eventData) {
        Debug.Log(eventData.pointerDrag.name + " dropped on " + gameObject.name);

        Draggable d = eventData.pointerDrag.GetComponent<Draggable>();
        if (d != null) {
            d.parentToReturnTo = this.transform;
        }
    }
}

1. PointerEventData.pointerDrag：触发OnPointerEnter的物体
2. OnPointerEnter：Called when a pointer enters the object
3. OnPointerExit：Called when a pointer exits the object
4. OnDrop：Called on the object where a drag finishes（有拖拽结束时调用）

Draggable.cs

• 拖拽Item
• 拖拽出去 原位置创建空物体占位置排序

public class Draggable : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler {

    [HideInInspector]
    public Transform parentToReturnTo = null;
    [HideInInspector]
    public Transform placeHolderParent = null;

    private GameObject placeHolder = null;

    public void OnBeginDrag(PointerEventData eventData) {
        placeHolder = new GameObject();
        placeHolder.transform.SetParent( this.transform.parent );
        LayoutElement le = placeHolder.AddComponent<LayoutElement>();
        le.preferredWidth = this.GetComponent<LayoutElement>().preferredWidth;
        le.preferredHeight = this.GetComponent<LayoutElement>().preferredHeight;
        le.flexibleWidth = 0;
        le.flexibleHeight = 0;

        placeHolder.transform.SetSiblingIndex(this.transform.GetSiblingIndex() );

        parentToReturnTo = this.transform.parent;
        placeHolderParent = parentToReturnTo;
        this.transform.SetParent(this.transform.parent.parent);

        this.GetComponent<CanvasGroup>().blocksRaycasts = false;
    }

    public void OnDrag(PointerEventData eventData) {
        this.transform.position = eventData.position;

        if (placeHolder.transform.parent != placeHolderParent)
        {
            placeHolder.transform.SetParent(placeHolderParent);
        }
        
        int newSiblingIndex = placeHolderParent.childCount;

        for (int i = 0; i < placeHolderParent.childCount; i++)
        {
            if (this.transform.position.x < placeHolderParent.GetChild(i).position.x)
            {
                newSiblingIndex = i;

                if (placeHolder.transform.GetSiblingIndex() < newSiblingIndex)
                    newSiblingIndex--;
                
                break;
            }
        }

        placeHolder.transform.SetSiblingIndex(newSiblingIndex);
    }

    public void OnEndDrag(PointerEventData eventData) {
        this.transform.SetParent(parentToReturnTo);
        this.transform.SetSiblingIndex(placeHolder.transform.GetSiblingIndex());
        this.GetComponent<CanvasGroup>().blocksRaycasts = true;
        Destroy(placeHolder);
    }
}

1. OnEndDrag会在OnDrop之后执行，保证松开时父物体改变

改善：

• 目前上下两横排，增加横竖排都可以穿插排序
• 目前两排，支持三排多排排序

public void OnDrag(PointerEventData eventData) {
        this.transform.position = eventData.position;

        if (placeHolder.transform.parent != placeHolderParent)
        {
            placeHolder.transform.SetParent(placeHolderParent);
            isVerticalLayout = (!placeHolder.transform.parent.GetComponent<HorizontalLayoutGroup>());
        }

        int newSiblingIndex = placeHolderParent.childCount;
        if (isVerticalLayout)
        {
            for (int i = 0; i < placeHolderParent.childCount; i++)
            {
                if (this.transform.position.y > placeHolderParent.GetChild(i).position.y)
                {
                    newSiblingIndex = i;

                    if (placeHolder.transform.GetSiblingIndex() < newSiblingIndex)
                        newSiblingIndex--;

                    break;
                }
            }
        }
        else
        {
            for (int i = 0; i < placeHolderParent.childCount; i++)
            {
                if (this.transform.position.x < placeHolderParent.GetChild(i).position.x)
                {
                    newSiblingIndex = i;

                    if (placeHolder.transform.GetSiblingIndex() < newSiblingIndex)
                        newSiblingIndex--;

                    break;
                }
            }
        }

        placeHolder.transform.SetSiblingIndex(newSiblingIndex);
    }

参考

https://lab.uwa4d.com/lab/5b6630ebd7f10a201ffa5aef