WinForm程序中的类TextBox的自定义控件, 添加失去焦点的功能

原理:

一、在控件的后台代码中, 添加布尔类型的属性CanFocus

二、在控件的构造函数中, 注册Enter事件的处理方法. 并在处理方法中,根据CanFocus属性的值来决定是否可以丢失焦点, 如果可以则调用Windows消息的发送类.

三、在处理方法中,调用User32.dll类库, 发送window消息.

 

示例代码:

//Windows消息的发送方法

//WMMessageHepler.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;



using System.Runtime.InteropServices;

using System.Windows.Forms;



namespace YXT.Common

{

    public class WMMessageHepler

    {

        private const int WM_KILLFOCUS = 0x0008;



        //发送失去焦点的Window消息

        public static void SendBlurMsg(IntPtr hWnd)

        {

            PostMessage(hWnd, WM_KILLFOCUS, 0, 0);

        }



        [DllImport("user32.dll")]

        private static extern void PostMessage(IntPtr hWnd, int msg, int wParam, int lParam);



        [DllImport("User32.dll", EntryPoint = "SendMessage")]

        private static extern int SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, string lParam);

    }

}

View Code

 

//自定义控件的关键代码

//WatermarkTextBox.cs

using System;

using System.Collections.Generic;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using YXT.Common;



namespace YXT.Client.Controls

{

    [ToolboxBitmap(typeof(TextBox))]

    public class WatermarkTextBox : TextBox

    {



        public WatermarkTextBox()

        {

            this.BorderStyle = BorderStyle.FixedSingle;

            this.Enter += new EventHandler(WatermarkTextBox_Enter);

        }



        void WatermarkTextBox_Enter(object sender, EventArgs e)

        {

            if (this.SetBlur)

            {

                this.OnBlur();

            }

        }



        private Color _borderColor = Color.Red;

        private string _watermarkTitle;

        private Color _watermarkColor = Color.DarkGray;

        private bool _setBlur = false;



        /// <summary>

        /// 控件是否失去焦点

        /// </summary>

        public bool SetBlur

        {

            get { return this._setBlur; }

            set

            {

                this._setBlur = value;

                Invalidate();

            }

        }



        /// <summary>

        /// 水印字体提示

        /// </summary>

        public string WatermarkTitle

        {

            get { return _watermarkTitle; }

            set

            {

                _watermarkTitle = value;

                Invalidate();

            }

        }



        /// <summary>

        /// 边框颜色

        /// </summary>

        public Color BorderColor

        {

            get { return _borderColor; }

            set

            {

                _borderColor = value;

                Invalidate();

            }

        }



        /// <summary>

        /// 水印颜色

        /// </summary>

        public Color WatermarkColor

        {

            get { return _watermarkColor; }

            set

            {

                _watermarkColor = value;

                Invalidate();

            }

        }



        private void OnBlur()

        {

            WMMessageHepler.SendBlurMsg(this.Handle);

        }



        protected override void WndProc(ref Message m)

        {



            base.WndProc(ref m);

            if (m.Msg == 0xf || m.Msg == 0x14 || m.Msg == 0x85)

            {

                if (this.BorderStyle == BorderStyle.FixedSingle)

                {

                    using (Graphics g = Graphics.FromHwnd(this.Handle))

                    {

                        using (var pen = new Pen(_borderColor))

                        {

                            g.DrawRectangle(pen, 0, 0, this.Width - 1, this.Height - 1);

                            WmPaint(ref m);

                        }

                    }

                }

            }

        }



        private void WmPaint(ref Message m)

        {

            using (Graphics graphics = Graphics.FromHwnd(base.Handle))

            {

                if (Text.Length == 0

                    && !string.IsNullOrEmpty(_watermarkTitle)

                    && !Focused)

                {

                    TextFormatFlags format =

                        TextFormatFlags.EndEllipsis |

                        TextFormatFlags.VerticalCenter;



                    if (RightToLeft == RightToLeft.Yes)

                    {

                        format |= TextFormatFlags.RightToLeft | TextFormatFlags.Right;

                    }



                    TextRenderer.DrawText(

                        graphics,

                        _watermarkTitle,

                        Font,

                        base.ClientRectangle,

                        _watermarkColor,

                        format);

                }

            }

        }

    }

}

View Code

 

 

//使用示例

//方法使用示例

ControlsEdintor(string controlsName)

        {

            //控件编辑时 修改样式

            foreach (var value in this.Controls)

            {

                var textBox = value as WatermarkTextBox;

                if (controlsName == "编辑")

                {

                    if (textBox != null)

                    {

                        textBox.BorderStyle = BorderStyle.FixedSingle;

                        textBox.ReadOnly = false;

                        textBox.SetBlur = false;

                    }

                }

                else

                {

                    if (textBox != null)

                    {

                        textBox.BorderStyle = BorderStyle.None;

                        textBox.ReadOnly = true;

                        textBox.SetBlur = true;

                    }

                }

            }

        }

View Code