unity3d用按钮进行拖拽放大或缩小panel

效果可以看下面的图，实现窗口的拖拽放大缩小

测试.gif

设置panel的瞄点为左上角，设置point值 X：0，Y：1，按钮的图右下角放置，瞄点为panel的右下角，按钮挂载当前脚本，赋值panel对象即可

设置.png

using UnityEngine;
using UnityEngine.EventSystems;

/// <summary>
/// unity实现窗口的放大缩小
/// </summary>
public class ResizePanel : MonoBehaviour, IPointerDownHandler, IDragHandler
{

    // 控制的面板
    public RectTransform panelRectTransform;
    // 最小缩放
    public Vector2 minSize = new Vector2(120, 120);
    // 最大缩放
    public Vector2 maxSize = new Vector2(800, 600);
    private Vector2 originalLocalPointerPosition;
    private Vector2 originalSizeDelta;


    public void OnPointerDown(PointerEventData data)
    {
        originalSizeDelta = panelRectTransform.sizeDelta;
        RectTransformUtility.ScreenPointToLocalPointInRectangle(panelRectTransform, data.position, data.pressEventCamera, out originalLocalPointerPosition);
    }

    public void OnDrag(PointerEventData data)
    {
        if (panelRectTransform == null)
            return;

        Vector2 localPointerPosition;
        RectTransformUtility.ScreenPointToLocalPointInRectangle(panelRectTransform, data.position, data.pressEventCamera, out localPointerPosition);
        Vector3 offsetToOriginal = localPointerPosition - originalLocalPointerPosition;

        Vector2 sizeDelta = originalSizeDelta + new Vector2(offsetToOriginal.x, -offsetToOriginal.y);
        sizeDelta = new Vector2(
            Mathf.Clamp(sizeDelta.x, minSize.x, maxSize.x),
            Mathf.Clamp(sizeDelta.y, minSize.y, maxSize.y)
        );

        panelRectTransform.sizeDelta = sizeDelta;
    }
}