自己实现Text控件 - 加入换行

效果，左侧为ugui的，右侧为自己实现的

 

using UnityEngine;
using UnityEngine.UI;

public class MyText : Graphic
{

    public Font m_Font;
    public string m_Text = "";
    public int m_FontSize = 40;

    protected MyText()
    {
        useLegacyMeshGeneration = false;
    }

    //这个必须要提供, OnPopulateMesh中的顶点的uv对应的是这个贴图上的
    public override Texture mainTexture
    {
        get
        {
            if (m_Font != null && m_Font.material != null && m_Font.material.mainTexture != null)
                return m_Font.material.mainTexture;

            return base.mainTexture; //默认的白色图片
        }
    }

    readonly UIVertex[] m_TempVerts = new UIVertex[4];

    protected override void OnPopulateMesh(VertexHelper vh)
    {
        vh.Clear();
        if (null == m_Font)
            return;

        var scale = (m_FontSize / m_Font.fontSize);
        var lineHeight = scale * m_Font.lineHeight;
        var ascent = scale * m_Font.ascent;
        var size = rectTransform.rect.size;
        var pivot = rectTransform.pivot;
        
        m_Font.RequestCharactersInTexture(m_Text, m_FontSize);

        var startPos = new Vector3(-pivot.x * size.x, (1 - pivot.y) * size.y - ascent, 0);
        Vector3 pos = startPos;
        m_Font.RequestCharactersInTexture(m_Text, m_FontSize);
        float lineWidth = 0;
        for (int i = 0; i < m_Text.Length; i++)
        {
            // Get character rendering information from the font
            m_Font.GetCharacterInfo(m_Text[i], out var ch, m_FontSize);

            if (lineWidth + ch.advance > size.x) //换行
            {
                lineWidth = 0;
                pos.y -= lineHeight;
                pos.x = startPos.x;
            }
            Debug.Log($"{m_Text[i]}, {ch.index}, min:({ch.minX}, {ch.minY}), max:({ch.maxX}, {ch.maxY}), {ch.glyphWidth}x{ch.glyphHeight}");

            m_TempVerts[0].position = pos + new Vector3(ch.minX, ch.maxY, 0); //左上角
            m_TempVerts[0].color = color;
            m_TempVerts[0].uv0 = ch.uvTopLeft;

            m_TempVerts[1].position = pos + new Vector3(ch.maxX, ch.maxY, 0);
            m_TempVerts[1].color = color;
            m_TempVerts[1].uv0 = ch.uvTopRight;

            m_TempVerts[2].position = pos + new Vector3(ch.maxX, ch.minY, 0);
            m_TempVerts[2].color = color;
            m_TempVerts[2].uv0 = ch.uvBottomRight;

            m_TempVerts[3].position = pos + new Vector3(ch.minX, ch.minY, 0);
            m_TempVerts[3].color = color;
            m_TempVerts[3].uv0 = ch.uvBottomLeft;

            //0,1,2; 0,2,3
            vh.AddUIVertexQuad(m_TempVerts);

            pos.x += ch.advance; // Advance character position
            lineWidth += ch.advance;
        }
    }

}