[feature][axis] support minor tick and minor split line

Runtime/Component/Axis/AxisMinorTick.cs

@@ -0,0 +1,63 @@
+using UnityEngine;
+
+namespace XCharts.Runtime
+{
+    /// <summary>
+    /// Settings related to axis minor tick.
+    /// |坐标轴次刻度相关设置。注意：次刻度无法再类目轴中使用。
+    /// </summary>
+    [System.Serializable]
+    [Since("v3.2.0")]
+    public class AxisMinorTick : BaseLine
+    {
+        [SerializeField] protected int m_SplitNumber = 5;
+        [SerializeField] private bool m_AutoColor;
+
+        /// <summary>
+        /// Number of segments that the axis is split into.
+        /// |分隔线之间分割的刻度数。
+        /// </summary>
+        public int splitNumber
+        {
+            get { return m_SplitNumber; }
+            set { if (PropertyUtil.SetStruct(ref m_SplitNumber, value)) SetAllDirty(); }
+        }
+        public bool autoColor { get { return m_AutoColor; } set { m_AutoColor = value; } }
+
+        public override bool vertsDirty { get { return m_VertsDirty || m_LineStyle.anyDirty; } }
+        public override void ClearVerticesDirty()
+        {
+            base.ClearVerticesDirty();
+            m_LineStyle.ClearVerticesDirty();
+        }
+        public static AxisMinorTick defaultMinorTick
+        {
+            get
+            {
+                var tick = new AxisMinorTick
+                {
+                    m_Show = false
+                };
+                return tick;
+            }
+        }
+
+        public AxisMinorTick Clone()
+        {
+            var axisTick = new AxisMinorTick();
+            axisTick.show = show;
+            axisTick.splitNumber = splitNumber;
+            axisTick.autoColor = autoColor;
+            axisTick.lineStyle = lineStyle.Clone();
+            return axisTick;
+        }
+
+        public void Copy(AxisMinorTick axisTick)
+        {
+            show = axisTick.show;
+            splitNumber = axisTick.splitNumber;
+            autoColor = axisTick.autoColor;
+            lineStyle.Copy(axisTick.lineStyle);
+        }
+    }
+}