using UnityEngine;
using UnityEngine.UI;
using UnityEngine.Sprites;
 
[RequireComponent(typeof(CanvasRenderer))]
public class CustomBorder : MaskableGraphic
{
    // 边框的厚度
    public float borderThickness = 5.0f;

    // 边框的颜色
    public Color borderColor = Color.black;

    protected override void Start()
    {
        base.Start();
        // 确保边框颜色使用图像模式
        //colorGradient = new ColorBlock { normal = borderColor };
    }

    protected override void OnPopulateMesh(VertexHelper vh)
    {
        vh.Clear();

        Rect rect = rectTransform.rect;
        Vector2 bottomLeft = new Vector2(rect.x, rect.y);
        Vector2 topRight = new Vector2(rect.xMax, rect.yMax);

        // 边框的四个顶点
        var v1 = new Vector2(bottomLeft.x, bottomLeft.y - borderThickness);
        var v2 = new Vector2(bottomLeft.x, topRight.y + borderThickness);
        var v3 = new Vector2(topRight.x + borderThickness, topRight.y);
        var v4 = new Vector2(topRight.x - borderThickness, bottomLeft.y);

        vh.AddUIVertexQuad(GetQuad(v1, v2, v3, v4));
    }

    private UIVertex[] GetQuad(Vector2 v1, Vector2 v2, Vector2 v3, Vector2 v4)
    {
        UIVertex[] vertexs = new UIVertex[4];

        vertexs[0] = new UIVertex();
        vertexs[0].position = v1;
        vertexs[1] = new UIVertex();
        vertexs[1].position = v2;
        vertexs[2] = new UIVertex();
        vertexs[2].position = v3;
        vertexs[3] = new UIVertex();
        vertexs[3].position = v4;

        return vertexs;
    }
}