通过绘制在datagridview控件列头添加一个checkbox控件

     众所周知，datagridview控件是CS架构中用的比较频繁的一个控件，里面提供了checkbox列的功能，可是却没有在列头给出checkbox控件用于全选/全部取消所有行的功能，确实是个遗憾，这里就通过绘制实现这个功能.

      该程序参考codeproject上的程序，网址如下：

      http://www.codeproject.com/KB/grid/CheckBoxHeaderCell.aspx  向其致敬!

一.创建一个表,里面包含bit字段，datagridview的DataGridViewCheckBoxColumn列会自动将其转换成checkbox列

见表语句如下，数据库名为testDB

CREATE TABLE [dbo].[UserInfo] (
 [RID] [varchar] (32) COLLATE Chinese_PRC_CI_AS NOT NULL ,
 [username] [varchar] (10) COLLATE Chinese_PRC_CI_AS NULL ,
 [gendar] [bit] NULL
) ON [PRIMARY]

二.主要代码

datagridviewCheckboxHeaderEventArgs类，用在在checkbox单击事件中提供类头checkbox的选择状态

 1    //定义包含列头checkbox选择状态的参数类
 2     class datagridviewCheckboxHeaderEventArgs : EventArgs
 3     {
 4         private bool checkedState = false;
 5 
 6         public bool CheckedState
 7         {
 8             get { return checkedState; }
 9             set { checkedState = value; }
         }
     }

datagridviewCheckboxHeaderCell类，这是个关键列，用于绘制列头checkbox和创建鼠标单击事件

 1   //定义继承于DataGridViewColumnHeaderCell的类，用于绘制checkbox，定义checkbox鼠标单击事件
 2     class datagridviewCheckboxHeaderCell : DataGridViewColumnHeaderCell
 3     {
 4         Point checkBoxLocation;
 5         Size checkBoxSize;
 6         bool _checked = false;
 7         Point _cellLocation = new Point();
 8         System.Windows.Forms.VisualStyles.CheckBoxState _cbState =
 9             System.Windows.Forms.VisualStyles.CheckBoxState.UncheckedNormal;
         public event datagridviewcheckboxHeaderEventHander OnCheckBoxClicked;
 
 
         //绘制列头checkbox
         protected override void Paint(System.Drawing.Graphics graphics,
            System.Drawing.Rectangle clipBounds,
            System.Drawing.Rectangle cellBounds,
            int rowIndex,
            DataGridViewElementStates dataGridViewElementState,
            object value,
            object formattedValue,
            string errorText,
            DataGridViewCellStyle cellStyle,
            DataGridViewAdvancedBorderStyle advancedBorderStyle,
            DataGridViewPaintParts paintParts)
         {
             base.Paint(graphics, clipBounds, cellBounds, rowIndex,
                 dataGridViewElementState, value,
                 formattedValue, errorText, cellStyle,
                 advancedBorderStyle, paintParts);
             Point p = new Point();
             Size s = CheckBoxRenderer.GetGlyphSize(graphics,
             System.Windows.Forms.VisualStyles.CheckBoxState.UncheckedNormal);
             p.X = cellBounds.Location.X +
                 (cellBounds.Width / 2) - (s.Width / 2) - 1;//列头checkbox的X坐标
             p.Y = cellBounds.Location.Y +
                 (cellBounds.Height / 2) - (s.Height / 2);//列头checkbox的Y坐标
             _cellLocation = cellBounds.Location;
             checkBoxLocation = p;
             checkBoxSize = s;
             if (_checked)
                 _cbState = System.Windows.Forms.VisualStyles.
                     CheckBoxState.CheckedNormal;
             else
                 _cbState = System.Windows.Forms.VisualStyles.
                     CheckBoxState.UncheckedNormal;
             CheckBoxRenderer.DrawCheckBox
             (graphics, checkBoxLocation, _cbState);
         }
 
 
 
         /// <summary>
         /// 点击列头checkbox单击事件
         /// </summary>
         protected override void OnMouseClick(DataGridViewCellMouseEventArgs e)
         {
 
             Point p = new Point(e.X + _cellLocation.X, e.Y + _cellLocation.Y);
             if (p.X >= checkBoxLocation.X && p.X <=
                 checkBoxLocation.X + checkBoxSize.Width
             && p.Y >= checkBoxLocation.Y && p.Y <=
                 checkBoxLocation.Y + checkBoxSize.Height)
             {
                 _checked = !_checked;
 
 
                 //获取列头checkbox的选择状态
                 datagridviewCheckboxHeaderEventArgs ex = new datagridviewCheckboxHeaderEventArgs();
                 ex.CheckedState = _checked;
 
                 object sender = new object();//此处不代表选择的列头checkbox，只是作为参数传递。应该列头checkbox是绘制出来的，无法获得它的实例
 
                 if (OnCheckBoxClicked != null)
                 {
                     OnCheckBoxClicked(sender, ex);//触发单击事件
                     this.DataGridView.InvalidateCell(this);
                 }
 
             }
             base.OnMouseClick(e);
         }
 
     }

还要定义和事件相关的委托：

    //定义触发单击事件的委托
    public delegate void datagridviewcheckboxHeaderEventHander(object sender, datagridviewCheckboxHeaderEventArgs e);

另外是界面操作代码：

 1   /// <summary>
 2         /// 加载数据
 3         /// </summary>
 4         private void btnLoadData_Click(object sender, EventArgs e)
 5         {
 6             DataTable dtTemp = new DataTable();
 7 
 8             using (SqlConnection con = new SqlConnection("server=.;uid=sa;pwd=sa;database=testdb;"))
 9             {
                 SqlDataAdapter sa = new SqlDataAdapter("select * from userinfo", con);
                 sa.Fill(dtTemp);
             }
 
             this.dataGridView1.DataSource = dtTemp;
         }
 
 
         /// <summary>
         /// 在checkbox列显示列头checkbox
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void button1_Click(object sender, EventArgs e)
         {
 
             datagridviewCheckboxHeaderCell ch = new datagridviewCheckboxHeaderCell();
             ch.OnCheckBoxClicked += new datagridviewcheckboxHeaderEventHander(ch_OnCheckBoxClicked);//关联单击事件
 
 
             //第三列为DataGridViewCheckBoxColumn
             DataGridViewCheckBoxColumn checkboxCol = this.dataGridView1.Columns[2] as DataGridViewCheckBoxColumn;
             checkboxCol.HeaderCell = ch;
             checkboxCol.HeaderCell.Value = string.Empty;//消除列头checkbox旁出现的文字
         }
 
         /// <summary>
         /// 单击事件
         /// </summary>
         private void ch_OnCheckBoxClicked(object sender, datagridviewCheckboxHeaderEventArgs e)
         {
             foreach (DataGridViewRow dgvRow in this.dataGridView1.Rows)
             {
                 if (e.CheckedState)
                 {
                     dgvRow.Cells[2].Value = true;
                 }
                 else
                 {
                     dgvRow.Cells[2].Value = false;
                 }
             }
         }

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