UIDragPanel.cs

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using System;
using UnityEngine;
using UnityEngine.EventSystems;
 
public class UIDragPanel : MonoBehaviour, IPointerDownHandler, IEventSystemHandler, IPointerUpHandler, IDragHandler, IChangeResolution, IInitializePotentialDragHandler
{
    public static bool dragging;
 
    private Vector2 originalLocalPointerPosition;
 
    private Vector3 originalPanelLocalPosition;
 
    public RectTransform target;
 
    public RectTransform bound;
 
    public RectTransform container;
 
    public bool axisY = true;
 
    public bool axisX = true;
 
    public bool enable = true;
 
    public bool autoAnchor;
 
    public bool clamp = true;
 
    public Action onDrag;
 
    private void Awake()
    {
        if (target == null)
        {
            target = base.transform.parent as RectTransform;
        }
        if (bound == null)
        {
            bound = target;
        }
    }
 
    public void SetTarget(RectTransform r)
    {
        target = (bound = r);
        container = target.parent as RectTransform;
    }
 
    public void OnChangeResolution()
    {
    }
 
    public void OnPointerDown(PointerEventData data)
    {
        if (enable && data.button == PointerEventData.InputButton.Left)
        {
            if (container == null)
            {
                container = target.parent as RectTransform;
            }
            originalPanelLocalPosition = target.localPosition;
            RectTransformUtility.ScreenPointToLocalPointInRectangle(container, data.position, data.pressEventCamera, out originalLocalPointerPosition);
            dragging = true;
        }
    }
 
    public void OnPointerUp(PointerEventData data)
    {
        if (enable && data.button == PointerEventData.InputButton.Left)
        {
            if (axisY && axisX && autoAnchor)
            {
                target.SetAnchor();
            }
            dragging = false;
        }
    }
 
    public void OnInitializePotentialDrag(PointerEventData ped)
    {
        ped.useDragThreshold = false;
    }
 
    public void OnDrag(PointerEventData data)
    {
        if (enable && data.button == PointerEventData.InputButton.Left && !(target == null) && !(container == null))
        {
            if (RectTransformUtility.ScreenPointToLocalPointInRectangle(container, data.position, data.pressEventCamera, out var localPoint))
            {
                Vector3 vector = localPoint - originalLocalPointerPosition;
                target.localPosition = originalPanelLocalPosition + vector;
            }
            if (clamp)
            {
                ClampToWindow();
            }
            if (onDrag != null)
            {
                onDrag();
            }
        }
    }
 
    private void ClampToWindow()
    {
        Vector3 localPosition = target.localPosition;
        Vector3 vector = container.rect.min - bound.rect.min;
        Vector3 vector2 = container.rect.max - bound.rect.max;
        if (axisX)
        {
            localPosition.x = (int)Mathf.Clamp(localPosition.x, vector.x - 20f, vector2.x + 20f);
        }
        if (axisY)
        {
            localPosition.y = (int)Mathf.Clamp(localPosition.y, vector.y - 20f, vector2.y + 20f);
        }
        target.localPosition = localPosition;
    }
}