在 Windows 窗体中更改 ComboBox 边框颜色

问题描述

在我的应用程序中，我添加了组合框，如下图所示

我已将组合框属性设置为

cmbDatefilter.FlatStyle = System.Windows.Forms.FlatStyle.Flat;

现在我的问题是如何将边框样式设置为组合框以使其看起来不错.

我在下面的链接中进行了验证

使用系统；使用 System.Drawing；使用 System.Windows.Forms;公共类 FlatCombo : ComboBox{私有常量 int WM_PAINT = 0xF;private int buttonWidth = SystemInformation.Horizo​​ntalScrollBarArrowWidth;颜色 borderColor = Color.Blue;公共颜色边框颜色{得到 { 返回边框颜色；}设置 { 边框颜色 = 值；无效()；}}protected override void WndProc(ref Message m){base.WndProc(ref m);if (m.Msg == WM_PAINT && DropDownStyle != ComboBoxStyle.Simple){使用 (var g = Graphics.FromHwnd(Handle)){使用 (var p = new Pen(BorderColor)){g.DrawRectangle(p, 0, 0, 宽度 - 1, 高度 - 1);var d = FlatStyle == FlatStyle.Popup ?1:0；g.DrawLine(p, 宽度 - 按钮宽度 - d,0, 宽度 - 按钮宽度 - d, 高度);}}}}}

注意:

• 在上面的示例中，我使用前景色作为边框，您可以添加 BorderColor 属性或使用其他颜色.
• 如果您不喜欢下拉按钮的左边框，您可以注释该 DrawLine 方法.
• 当控件为RightToLeft时需要从(0, buttonWidth)到(Height, buttonWidth)
画线
• 要了解有关如何呈现平面组合框的更多信息，您可以查看内部

  In My Application i have added Combobox as shown in below picture

  i have set the combobox property as

  cmbDatefilter.FlatStyle = System.Windows.Forms.FlatStyle.Flat;
  

  And now my question is how to set border style to combobox so that it will look nice.

  I verified in below link

  Flat style Combo box

  My question is different from below link's.

  Generic ComboBox in Windows Forms Application

  How to override UserControl class to draw a custom border?

  解决方案

  You can inherit from ComboBox and override WndProc and handle WM_PAINT message and draw border for your combo box:

  using System;
  using System.Drawing;
  using System.Windows.Forms;
  
  public class FlatCombo : ComboBox
  {
      private const int WM_PAINT = 0xF;
      private int buttonWidth = SystemInformation.HorizontalScrollBarArrowWidth;
      Color borderColor = Color.Blue;
      public Color BorderColor
      {
          get { return borderColor; }
          set { borderColor = value; Invalidate(); }
      }
      protected override void WndProc(ref Message m)
      {
          base.WndProc(ref m);
          if (m.Msg == WM_PAINT && DropDownStyle != ComboBoxStyle.Simple)
          {
              using (var g = Graphics.FromHwnd(Handle))
              {
                  using (var p = new Pen(BorderColor))
                  {
                      g.DrawRectangle(p, 0, 0, Width - 1, Height - 1);
  
                      var d = FlatStyle == FlatStyle.Popup ? 1 : 0;
                      g.DrawLine(p, Width - buttonWidth - d,
                          0, Width - buttonWidth - d, Height);
                  }
              }
          }
      }
  }
  

  Note:

  • In the above example I used fore color for border, you can add a BorderColor property or use another color.
  • If you don't like the left border of dropdown button, you can comment that DrawLine method.
  • You need to draw line when the control is RightToLeft from (0, buttonWidth) to (Height, buttonWidth)
  • To learn more about how to render a flat combo box, you can take a look at source code of internal ComboBox.FlatComboAdapter class of .Net Framework.

  Flat ComboBox

  You may also like Flat ComboBox:

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