[optimize][legend] support background and padding

Runtime/Component/Legend/Legend.cs

@@ -80,6 +80,8 @@ namespace XCharts.Runtime
         [SerializeField] private List<string> m_Data = new List<string>();
         [SerializeField] private List<Sprite> m_Icons = new List<Sprite>();
         [SerializeField] private List<Color> m_Colors = new List<Color>();
+        [SerializeField] protected ImageStyle m_Background = new ImageStyle() { show = false };
+        [SerializeField] protected Padding m_Padding = new Padding();
 
         public LegendContext context = new LegendContext();
 
@@ -213,6 +215,24 @@ namespace XCharts.Runtime
             set { if (PropertyUtil.SetClass(ref m_LabelStyle, value)) SetComponentDirty(); }
         }
         /// <summary>
+        /// the sytle of background.
+        /// |背景图样式。
+        /// </summary>
+        public ImageStyle background
+        {
+            get { return m_Background; }
+            set { if (PropertyUtil.SetClass(ref m_Background, value)) SetAllDirty(); }
+        }
+        /// <summary>
+        /// the paddinng of item and background.
+        /// |图例标记和背景的间距。
+        /// </summary>
+        public Padding padding
+        {
+            get { return m_Padding; }
+            set { if (PropertyUtil.SetClass(ref m_Padding, value)) SetAllDirty(); }
+        }
+        /// <summary>
         /// Data array of legend. An array item is usually a name representing string. (If it is a pie chart, 
         /// it could also be the name of a single data in the pie chart) of a series.
         /// |If data is not specified, it will be auto collected from series.

Runtime/Component/Legend/LegendContext.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using UnityEngine;
+using UnityEngine.UI;
 
 namespace XCharts.Runtime
 {
@@ -14,6 +15,7 @@ namespace XCharts.Runtime
         /// 运行时图例的总高度
         /// </summary>
         public float height { get; internal set; }
+        public Vector2 center { get; internal set; }
         /// <summary>
         /// the button list of legend.
         /// |图例按钮列表。
@@ -27,5 +29,6 @@ namespace XCharts.Runtime
         /// 单列高度
         /// </summary>
         internal float eachHeight { get; set; }
+        public Image background { get; set; }
     }
 }

Runtime/Component/Legend/LegendHandler.cs

@@ -56,6 +56,9 @@ namespace XCharts.Runtime
                 legend.gameObject = legendObject;
                 legendObject.hideFlags = chart.chartHideFlags;
                 SeriesHelper.UpdateSerieNameList(chart, ref chart.m_LegendRealShowName);
+                legend.context.background = ChartHelper.AddIcon("background", legendObject.transform, 0, 0);
+                legend.context.background.transform.SetSiblingIndex(0);
+                ChartHelper.SetBackground(legend.context.background, legend.background);
                 List<string> datas;
                 if (legend.show && legend.data.Count > 0)
                 {

Runtime/Component/Legend/LegendHelper.cs

@@ -52,6 +52,7 @@ namespace XCharts.Runtime
             var iconObj = ChartHelper.AddObject("icon", btnObj.transform, anchorMin, anchorMax, pivot, iconSizeDelta);
             var img = ChartHelper.GetOrAddComponent<Image>(btnObj);
             img.color = Color.clear;
+            img.raycastTarget = true;
             ChartHelper.GetOrAddComponent<Button>(btnObj);
             ChartHelper.GetOrAddComponent<Image>(iconObj);
 
@@ -69,9 +70,22 @@ namespace XCharts.Runtime
             item.SetIconImage(legend.GetIcon(i));
             item.SetContentPosition(legend.labelStyle.offset);
             item.SetContent(content);
+            //item.SetBackground(legend.background);
             return item;
         }
 
+        public static void SetLegendBackground(Legend legend, ImageStyle style)
+        {
+            var background = legend.context.background;
+            if (background == null) return;
+            ChartHelper.SetActive(background, style.show);
+            if (!style.show) return;
+            var rect = background.gameObject.GetComponent<RectTransform>();
+            rect.localPosition = legend.context.center;
+            rect.sizeDelta = new Vector2(legend.context.width, legend.context.height);
+            ChartHelper.SetBackground(background, style);
+        }
+
         public static void ResetItemPosition(Legend legend, Vector3 chartPos, float chartWidth, float chartHeight)
         {
             legend.location.UpdateRuntimeData(chartWidth, chartHeight);
@@ -122,8 +136,19 @@ namespace XCharts.Runtime
                     startY = chartPos.y + legendRuntimeHeight + legend.location.runtimeBottom;
                     break;
             }
+            if (!legend.padding.show)
+            {
+                legend.context.center = new Vector2(startX + legend.context.width / 2, startY - legend.context.height / 2);
+            }
+            else
+            {
+                legend.context.center = new Vector2(startX + legend.context.width / 2 - legend.padding.left,
+                    startY - legend.context.height / 2 + legend.padding.top);
+            }
+
             if (isVertical) SetVerticalItemPosition(legend, legendMaxHeight, startX, startY);
             else SetHorizonalItemPosition(legend, legendMaxWidth, startX, startY);
+            SetLegendBackground(legend, legend.background);
         }
 
         private static void SetVerticalItemPosition(Legend legend, float legendMaxHeight, float startX, float startY)
@@ -214,6 +239,11 @@ namespace XCharts.Runtime
                 legend.context.height = realHeight > 0 ? realHeight : height;
                 legend.context.width = realWidth + width;
             }
+            if (legend.padding.show)
+            {
+                legend.context.width += legend.padding.left + legend.padding.right;
+                legend.context.height += legend.padding.top + legend.padding.bottom;
+            }
         }
 
         private static bool IsBeyondWidth(Legend legend, float maxWidth)