ComBobox、TextBox控件扩展（Enable=false,灰色）

ComBobox、TextBox控件扩展（Enable=false,灰色）


注：
1.ComBoboxReadOnly控件主要是在ComBobox基础上扩展了ReadOnly属性、OnReadOnlyChanged事件。
2.通过这两个控件可以熟悉控件开发，掌握自定义控件属性、事件的处理。
3.控件源码如下：

TextBoxEnable.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
namespace pcd.Tools
{
    public class TextBoxEnable : System.Windows.Forms.TextBox
    {
        构造函数#region 构造函数
        public TextBoxEnable()
        {
            this.BorderStyle = BorderStyle.FixedSingle;
        }
        #endregion

        //重写OnEnabledChanged   
        protected override void OnEnabledChanged(EventArgs e)
        {
            if (Enabled == false)
            {
                SetStyle(ControlStyles.UserPaint, true);             
            }
            else
            {
                SetStyle(ControlStyles.UserPaint, false);
                this.Font = new Font("宋体", 9F);
            }
            base.OnEnabledChanged(e);
        }
        //重写OnPaint   
        protected override void OnPaint(PaintEventArgs pe)
        {
            base.OnPaint(pe);
            if (Enabled == false)
            {
                pe.Graphics.FillRectangle(new SolidBrush(SystemColors.ControlLight),
                pe.ClipRectangle);
                //文字描画   
                float x = 0, y = 0;
                Size s = pe.Graphics.MeasureString(Text, Font).ToSize();
                if (this.TextAlign == HorizontalAlignment.Left)
                {
                    x = 1;//←                  
                }
                else if (this.TextAlign == HorizontalAlignment.Right)
                {
                    x = Width - s.Width;//→                  
                }
                else if (this.TextAlign == HorizontalAlignment.Center)
                {
                    x = (Width - s.Width) / 2;
                }
                y = 5.5F;
             
              if (this.Multiline)
                    pe.Graphics.DrawString(this.Text, this.Font, Brushes.Black, new RectangleF(x, y, this.Width, this.Height));
                else
                    pe.Graphics.DrawString(this.Text, this.Font, Brushes.Black, new RectangleF(x, y, 1000, this.Height));//单行是，width可以设置成无限大。
                pe.Graphics.DrawRectangle(new Pen(Color.Black, 2), new Rectangle(0, 0, this.Width, this.Height));//pe.ClipRectangle

            }
        }
    }
}

ComBoboxReadOnly.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
using System.ComponentModel;
namespace pcd.Tools
{
    // 2.声明一个委托。
    public delegate void ReadOnlyEventHandler(object sender, ReadOnlyEventArgs args);
    public class ComboboxReadOnly : ComboBox
    {
        ReadOnly#region ReadOnly
        private bool _ReadOnle;
        [Bindable(true),
       Category("Data"),
       DefaultValue(false),
       Description("获取或者设置是否只读"),
       DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
        public bool ReadOnly
        {
            get
            {
                return this._ReadOnle;
            }
            set
            {

                ReadOnlyEventArgs roea = new ReadOnlyEventArgs(this._ReadOnle != value);
                this._ReadOnle = value;
                OnReadOnlyChanged(roea);
            }
        }
        #endregion

        定义事件readonlychanged#region 定义事件readonlychanged
        // 3.定义事件
        [
       Description("在更改控件的只读状态时发生。"),
       DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
        public event ReadOnlyEventHandler readonlychanged;
        // 4.事件发生后，通知其他对象的方法
        //这个方法是受保护的虚方法
        protected virtual void OnReadOnlyChanged(ReadOnlyEventArgs args)
        {

            if (ReadOnly)
            {
                SetStyle(ControlStyles.UserPaint, true);               
            }
            else
            {
                SetStyle(ControlStyles.UserPaint, false);
                this.Font = new Font("宋体", 9F);
            }

            if (readonlychanged != null)
            {
                readonlychanged(this, args);
            }
            //***
            Invalidate();//强制一个控件触发onPaint事件
        }
        #endregion

        构造函数#region 构造函数
        public ComboboxReadOnly()
        {
          this.DropDownStyle = ComboBoxStyle.DropDownList;
          this.TabStop = false;
        }
        #endregion

        override#region override
        //重写WndProc
        protected override void WndProc(ref Message m)
        {
            if (this._ReadOnle && (m.Msg == 0xa1 || m.Msg == 0x201 || m.Msg == 0x203))
            {
                return;
            }
            base.WndProc(ref m);
        }

        //重写OnPaint   
        protected override void OnPaint(PaintEventArgs pe)
        {
            base.OnPaint(pe);
            if (this.ReadOnly)
            {
                pe.Graphics.FillRectangle(new SolidBrush(SystemColors.ControlLight),
                  pe.ClipRectangle);
                //文字描画   
                int x = 0, y = 0;
                Size s = pe.Graphics.MeasureString(Text, Font).ToSize();
                y = (Height - s.Height) / 2;
                x = 1;//←
                pe.Graphics.DrawString(this.Text, this.Font, Brushes.Black, x, y);
                pe.Graphics.DrawRectangle(new Pen(Color.Black, 2), new Rectangle(0, 0, this.Width, this.Height));//pe.ClipRectangle
            }
        }

        重写OnEnabledChanged也可以。不过用readonly更好#region 重写OnEnabledChanged也可以。不过用readonly更好
        //重写OnEnabledChanged   
        //protected override void OnEnabledChanged(EventArgs e)
        //{
        //    if (Enabled == false)
        //    {
        //        SetStyle(ControlStyles.UserPaint, true);
        //    }
        //    else
        //    {
        //        SetStyle(ControlStyles.UserPaint, false);
        //    }
        //    base.OnEnabledChanged(e);
        //}

        //重写OnPaint   
        //protected override void OnPaint(PaintEventArgs pe)
        //{
        //base.OnPaint(pe);           
        //if (Enabled == false)
        //{

        //    pe.Graphics.FillRectangle(new SolidBrush(SystemColors.ControlLight),
        //    pe.ClipRectangle);
        //    //文字描画   
        //    int x = 0, y = 0;
        //    Size s = pe.Graphics.MeasureString(Text, Font).ToSize();
        //    // x = Width - s.Width;//→
        //    y = (Height - s.Height) / 2;
        //    x = 1;//←
        //    pe.Graphics.DrawString(this.Text, this.Font, Brushes.Black, x, y);
        //    pe.Graphics.DrawRectangle(new Pen(Color.Black, 2), pe.ClipRectangle);

        //}
        // }
        #endregion
        #endregion
    }

    1.定义一个携带事件信息的类。#region 1.定义一个携带事件信息的类。
    public class ReadOnlyEventArgs : EventArgs
    {
        private bool readvalue;
        public bool ReadValue
        {
            get { return readvalue; }
        }
        public ReadOnlyEventArgs(bool readonlyvalue)
        {
            this.readvalue = readonlyvalue;
        }

    }
    #endregion
}