修复Legend的Background区域在Horizonal模式下不对的问题

Documentation~/zh/changelog.md

@@ -81,6 +81,7 @@ slug: /changelog
 
 ## master
 
+* (2026.03.29) 修复`Legend`的`Background`区域在`Horizonal`模式下不对的问题
 * (2026.03.25) 增加`Chart`的`Json`导出导入
 * (2026.03.10) 增加`Sankey`的线条tooltip触发显示
 * (2026.03.10) 增加`UITable`的排序功能支持

Runtime/Component/Legend/LegendHelper.cs

@@ -198,11 +198,14 @@ namespace XCharts.Runtime
             legend.context.eachHeight = 0;
             if (legend.orient == Orient.Horizonal)
             {
+                var maxRowWidth = 0f;
                 foreach (var kv in legend.context.buttonList)
                 {
                     if (width + kv.Value.width > maxWidth)
                     {
                         realWidth = width - legend.itemGap;
+                        if (realWidth > maxRowWidth)
+                            maxRowWidth = realWidth;
                         realHeight += height + legend.itemGap;
                         if (legend.context.eachHeight < height + legend.itemGap)
                         {
@@ -216,8 +219,10 @@ namespace XCharts.Runtime
                         height = kv.Value.height;
                 }
                 width -= legend.itemGap;
+                if (width > maxRowWidth)
+                    maxRowWidth = width;
                 legend.context.height = realHeight + height;
-                legend.context.width = realWidth > 0 ? realWidth : width;
+                legend.context.width = maxRowWidth;
             }
             else
             {