CenterTiledImage.cs

using UnityEngine;
using UnityEngine.UI;

namespace UGuiExtension
{
    public class CenterTiledImage : Image
    {
        protected override void OnPopulateMesh(VertexHelper toFill)
        {
            if (type != Type.Tiled || 
                overrideSprite == null ||
                hasBorder ||
                overrideSprite.texture.wrapMode != TextureWrapMode.Repeat)
            {
                base.OnPopulateMesh(toFill);
                return;
            }

            Vector2 spriteSize = overrideSprite.rect.size;
            Rect rect = GetPixelAdjustedRect();
            float tileWidth = spriteSize.x / pixelsPerUnit;
            float tileHeight = spriteSize.y / pixelsPerUnit;
            
            float xMin = 0;
            float xMax = rect.width;
            float yMin = 0;
            float yMax = rect.height;
            
            toFill.Clear(); 
            
            if (tileWidth <= 0)
                tileWidth = xMax - xMin;

            if (tileHeight <= 0)
                tileHeight = yMax - yMin;
            
            Vector2 uvScale = new Vector2((xMax - xMin) / tileWidth, (yMax - yMin) / tileHeight);

            if (fillCenter)
            {
                AddQuad(toFill,
                    new Vector2(xMin, yMin) + rect.position,
                    new Vector2(xMax, yMax) + rect.position,
                    color,
                    Vector2.zero -0.5f * (uvScale - Vector2.one),
                    Vector2.one + 0.5f * (uvScale - Vector2.one));
            }
        }
        
        static void AddQuad(VertexHelper vertexHelper, Vector2 posMin, Vector2 posMax, Color32 color, Vector2 uvMin, Vector2 uvMax)
        {
            int startIndex = vertexHelper.currentVertCount;

            vertexHelper.AddVert(new Vector3(posMin.x, posMin.y, 0), color, new Vector2(uvMin.x, uvMin.y));
            vertexHelper.AddVert(new Vector3(posMin.x, posMax.y, 0), color, new Vector2(uvMin.x, uvMax.y));
            vertexHelper.AddVert(new Vector3(posMax.x, posMax.y, 0), color, new Vector2(uvMax.x, uvMax.y));
            vertexHelper.AddVert(new Vector3(posMax.x, posMin.y, 0), color, new Vector2(uvMax.x, uvMin.y));

            vertexHelper.AddTriangle(startIndex, startIndex + 1, startIndex + 2);
            vertexHelper.AddTriangle(startIndex + 2, startIndex + 3, startIndex);
        }
    }
}