1、定制Tab控件优化：肩线只绘制一次

Tools/MyControls/TabControlEx.cs

@@ -76,9 +76,19 @@ namespace Tools.MyControls
         /// <param name="e"></param>
         protected override void OnPaintBackground(PaintEventArgs e)
         {
+            var g = e.Graphics;
             //绘制控件背景
             var brush = new SolidBrush(this.BackgroundColor);
-            e.Graphics.FillRectangle(brush, e.ClipRectangle);
+            g.FillRectangle(brush, e.ClipRectangle);
+            //扩展：绘制肩线（仅绘制一次：用以突出选中效果）
+            Rectangle client = this.ClientRectangle;
+            var x = client.X;
+            var y = client.Y + this.ItemSize.Height + 2;
+            var location = new Point(x + 2, y); //左右各留2像素
+            var size = new Size(client.Width - 3, 2);
+            var shoulder = new Rectangle(location, size);
+            var shoulderBrush = new SolidBrush(this.TabActivedBackColor);  //肩线为激活颜色
+            g.FillRectangle(shoulderBrush, shoulder);
         }
         /// <summary>
         /// 重写：绘制方法
@@ -98,7 +108,6 @@ namespace Tools.MyControls
                 var BackColor = IsSelected ? TabActivedBackColor : isHover ? TabDeactivedBackColorHover : TabDeactivedBackColor;
                 var FontColor = IsSelected ? TabActivedFontColor : isHover ? TabDeactivedFontColorHover : TabDeactivedFontColor;
                 //画笔、画刷准备
-                var backPen = new Pen(BackColor);
                 var backBrush = new SolidBrush(BackColor);
                 var fontBrush = new SolidBrush(FontColor);
                 //绘制并填充矩形框：背景
@@ -106,21 +115,8 @@ namespace Tools.MyControls
                 //绘制标题
                 var title = this.TabPages[index].Text;
                 g.DrawString(title, this.Font, fontBrush, tabRect, this.fmt);
-                
-                //扩展：绘制肩线（每轮绘制一次）
-                if (index == 0)
-                {
-                    Rectangle client = this.ClientRectangle;
-                    var x = client.X;
-                    var y = client.Y + tabRect.Height + 2;
-                    var location = new Point(x + 2, y); //左右各留2像素
-                    var size = new Size(client.Width - 3, 2);
-                    var shoulder = new Rectangle(location, size);
-                    var shoulderBrush = new SolidBrush(this.TabActivedBackColor);  //肩线为激活颜色
-                    g.FillRectangle(shoulderBrush, shoulder);
-                }
             }
-            //扩展：绘制标签项边框线
+            //扩展：绘制标签项边框线（每轮绘制一次：用以突出选中效果）
             this.DrawTabsBorder(g);
         }