C# WinForms TabControl头部默认背景色无法移除问题求助

方法1：重写WndProc完全自定义绘制头部 #

WinForms TabControl的顶部默认背景是系统主题绘制的区域，默认自定义绘制仅覆盖标签本身，我们可以通过拦截WM_PAINT消息，手动绘制整个头部区域来覆盖默认背景。

示例代码：

public class CustomTabControl : TabControl
{
    protected override void WndProc(ref Message m)
    {
        base.WndProc(ref m);
        if (m.Msg == 0xF) // 拦截WM_PAINT消息
        {
            using (Graphics g = Graphics.FromHwnd(Handle))
            {
                // 绘制头部整体背景（替换为你需要的颜色）
                var headerRect = new Rectangle(0, 0, Width, ItemSize.Height + 2);
                g.FillRectangle(new SolidBrush(Color.FromArgb(45, 45, 48)), headerRect);
                
                // 逐个绘制标签的背景与文本
                for (int i = 0; i < TabCount; i++)
                {
                    var tabRect = GetTabRect(i);
                    var tabBgBrush = SelectedIndex == i 
                        ? new SolidBrush(Color.FromArgb(60, 60, 63)) 
                        : new SolidBrush(Color.FromArgb(45, 45, 48));
                    
                    g.FillRectangle(tabBgBrush, tabRect);
                    TextRenderer.DrawText(
                        g, 
                        TabPages[i].Text, 
                        Font, 
                        tabRect, 
                        SelectedIndex == i ? Color.White : Color.Gray,
                        TextFormatFlags.HorizontalCenter | TextFormatFlags.VerticalCenter
                    );
                }

                // 移除默认边框
                ControlPaint.DrawBorder(g, ClientRectangle, Color.Transparent, ButtonBorderStyle.None);
            }
        }
    }

    public CustomTabControl()
    {
        // 开启自定义绘制相关样式，避免闪烁和默认绘制干扰
        SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint | ControlStyles.DoubleBuffer, true);
        Appearance = TabAppearance.Normal;
        SizeMode = TabSizeMode.Fixed;
        ItemSize = new Size(120, 30);
    }
}

方法2：通过Region裁剪隐藏顶部默认背景 #

如果不想完全重绘，可通过裁剪TabControl的区域，隐藏顶部默认背景，同时调整标签位置使其正常显示：

示例代码：

public class CustomTabControl : TabControl
{
    protected override void OnSizeChanged(EventArgs e)
    {
        base.OnSizeChanged(e);
        // 裁剪掉顶部默认背景区域
        Region = new Region(new Rectangle(0, ItemSize.Height, Width, Height - ItemSize.Height));
        // 调整标签位置到顶部
        for (int i = 0; i < TabCount; i++)
        {
            var tabRect = GetTabRect(i);
            tabRect.Y = 0;
            SetTabRect(i, tabRect);
        }
    }

    public CustomTabControl()
    {
        SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint | ControlStyles.DoubleBuffer, true);
        Appearance = TabAppearance.Buttons;
        SizeMode = TabSizeMode.Fixed;
        ItemSize = new Size(120, 30);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        // 绘制每个标签的背景与文本
        foreach (TabPage page in TabPages)
        {
            int index = TabPages.IndexOf(page);
            var tabRect = GetTabRect(index);
            
            e.Graphics.FillRectangle(
                SelectedIndex == index ? new SolidBrush(Color.FromArgb(60, 60, 63)) : new SolidBrush(Color.FromArgb(45, 45, 48)),
                tabRect
            );
            TextRenderer.DrawText(
                e.Graphics,
                page.Text,
                Font,
                tabRect,
                SelectedIndex == index ? Color.White : Color.Gray,
                TextFormatFlags.HorizontalCenter | TextFormatFlags.VerticalCenter
            );
        }

        // 绘制TabPage区域边框（可选）
        var clientRect = ClientRectangle;
        clientRect.Y = ItemSize.Height;
        clientRect.Height -= ItemSize.Height;
        e.Graphics.DrawRectangle(Pens.DarkGray, clientRect);
    }
}

关键注意事项 #

• 必须开启ControlStyles.UserPaint、AllPaintingInWmPaint和DoubleBuffer，避免绘制闪烁和默认系统绘制的干扰
• 自定义绘制时要覆盖头部所有区域，不要依赖Appearance属性的默认样式
• 两种方法都需要将TabControl替换为自定义的CustomTabControl类使用

内容的提问来源于stack exchange，提问作者Kalababu