更改文本框的边框颜色

Question

当用户点击或关注文本框时，如何更改文本框的边框颜色？

Answer 1

如果控件有焦点，您可以处理TextBox 的WM_NCPAINT 消息并在控件的非客户区绘制边框。您可以使用任何颜色来绘制边框：

using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
public class ExTextBox : TextBox
{
    [DllImport("user32")]
    private static extern IntPtr GetWindowDC(IntPtr hwnd);
    private const int WM_NCPAINT = 0x85;
    protected override void WndProc(ref Message m)
    {
        base.WndProc(ref m);
        if (m.Msg == WM_NCPAINT && this.Focused)
        {
            var dc = GetWindowDC(Handle);
            using (Graphics g = Graphics.FromHdc(dc))
            {
                g.DrawRectangle(Pens.Red, 0, 0, Width - 1, Height - 1);
            }
        }
    }
}

结果

控件聚焦时的边框绘制完全无闪烁：

TextBox 的 BorderColor 属性

在当前帖子中，我只是更改焦点上的边框颜色。您还可以将BorderColor 属性添加到控件。然后您可以在设计时或运行时根据您的要求更改边框颜色。我发布了一个更完整的TextBox 版本，它具有BorderColor 属性： 在以下帖子中：

• BorderColor property for TextBox

Answer 2

试试这个

bool focus = false;
private void Form1_Paint(object sender, PaintEventArgs e)
{
    if (focus)
    {
        textBox1.BorderStyle = BorderStyle.None;
        Pen p = new Pen(Color.Red);
        Graphics g = e.Graphics;
        int variance = 3;
        g.DrawRectangle(p, new Rectangle(textBox1.Location.X - variance, textBox1.Location.Y - variance, textBox1.Width + variance, textBox1.Height +variance ));
    }
    else
    {
        textBox1.BorderStyle = BorderStyle.FixedSingle;
    }
}

private void textBox1_Enter(object sender, EventArgs e)
{
    focus = true;
    this.Refresh();
}

private void textBox1_Leave(object sender, EventArgs e)
{
    focus = false;
    this.Refresh();
}

Answer 3

这是设置TextBox边框颜色的终极解决方案：

public class BorderedTextBox : UserControl
{
    TextBox textBox;

    public BorderedTextBox()
    {
        textBox = new TextBox()
        {
            BorderStyle = BorderStyle.FixedSingle,
            Location = new Point(-1, -1),
            Anchor = AnchorStyles.Top | AnchorStyles.Bottom |
                     AnchorStyles.Left | AnchorStyles.Right
        };
        Control container = new ContainerControl()
        {
            Dock = DockStyle.Fill,
            Padding = new Padding(-1)
        };
        container.Controls.Add(textBox);
        this.Controls.Add(container);

        DefaultBorderColor = SystemColors.ControlDark;
        FocusedBorderColor = Color.Red;
        BackColor = DefaultBorderColor;
        Padding = new Padding(1);
        Size = textBox.Size;
    }

    public Color DefaultBorderColor { get; set; }
    public Color FocusedBorderColor { get; set; }

    public override string Text
    {
        get { return textBox.Text; }
        set { textBox.Text = value; }
    }

    protected override void OnEnter(EventArgs e)
    {
        BackColor = FocusedBorderColor;
        base.OnEnter(e);
    }

    protected override void OnLeave(EventArgs e)
    {
        BackColor = DefaultBorderColor;
        base.OnLeave(e);
    }

    protected override void SetBoundsCore(int x, int y,
        int width, int height, BoundsSpecified specified)
    {
        base.SetBoundsCore(x, y, width, textBox.PreferredHeight, specified);
    }
}

Answer 4

WinForms 从来不擅长这个，这有点痛苦。

您可以尝试的一种方法是在面板中嵌入一个文本框，然后从那里根据焦点管理绘图：

public class BorderTextBox : Panel {
  private Color _NormalBorderColor = Color.Gray;
  private Color _FocusBorderColor = Color.Blue;

  public TextBox EditBox;

  public BorderTextBox() {
    this.DoubleBuffered = true;
    this.Padding = new Padding(2);

    EditBox = new TextBox();
    EditBox.AutoSize = false;
    EditBox.BorderStyle = BorderStyle.None;
    EditBox.Dock = DockStyle.Fill;
    EditBox.Enter += new EventHandler(EditBox_Refresh);
    EditBox.Leave += new EventHandler(EditBox_Refresh);
    EditBox.Resize += new EventHandler(EditBox_Refresh);
    this.Controls.Add(EditBox);
  }

  private void EditBox_Refresh(object sender, EventArgs e) {
    this.Invalidate();
  }

  protected override void OnPaint(PaintEventArgs e) {
    e.Graphics.Clear(SystemColors.Window);
    using (Pen borderPen = new Pen(this.EditBox.Focused ? _FocusBorderColor : _NormalBorderColor)) {
      e.Graphics.DrawRectangle(borderPen, new Rectangle(0, 0, this.ClientSize.Width - 1, this.ClientSize.Height - 1));
    }
    base.OnPaint(e);
  }
}

Answer 5

使用OnPaint 在控件上绘制自定义边框很好。但是知道如何使用OnPaint 来保持效率，并将渲染时间降到最低。如果您在使用自定义绘制例程时遇到延迟的 GUI，请阅读此内容：What is the right way to use OnPaint in .Net applications?

因为 PraVn 的公认答案看似简单，但实际上效率低下。使用自定义控件，就像上面答案中发布的那样更好。

也许性能在您的应用程序中不是问题，因为它很小，但对于具有大量自定义 OnPaint 例程的大型应用程序，使用 PraVn 显示的方式是错误的方法。

Answer 6

将文本框边框样式设置为无 然后将此代码写入容器表单“绘制”事件

private void Form1_Paint(object sender, PaintEventArgs e)
{
    System.Drawing.Rectangle rect = new Rectangle(TextBox1.Location.X, 
    TextBox1.Location.Y, TextBox1.ClientSize.Width, TextBox1.ClientSize.Height);
                
                rect.Inflate(1, 1); // border thickness
                System.Windows.Forms.ControlPaint.DrawBorder(e.Graphics, rect, 
    Color.DeepSkyBlue, ButtonBorderStyle.Solid);
}

Answer 7

With PictureBox1
    .Visible = False
    .Width = TextBox1.Width + 4
    .Height = TextBox1.Height + 4
    .Left = TextBox1.Left - 2
    .Top = TextBox1.Top - 2
    .SendToBack()
    .Visible = True
End With

Answer 8

是不是很简单，

txtbox1.BorderColor = System.Drawing.Color.Red;