C# Winform中DataGridView 设置全选/取消

public partialclass Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        privatevoid button1_Click(object sender, EventArgs e)
        {
            DataTable dt =new DataTable();
            DataColumn column;

            for (int i= 0; i< 4; i++)
            {
                if (i== 3)
                {
                    column =new DataColumn();
                    column.ColumnName ="column"+ i;
                    column.DataType =typeof(Boolean);
                    dt.Columns.Add(column);
                    dataGridView1.DataSource = dt;
                }
                else
                {
                    column =new DataColumn();
                    column.ColumnName ="column"+ i;
                    column.DataType =typeof(string);
                    dt.Columns.Add(column);
                }
            }

            for (int i= 0; i< 4; i++)
            {
                DataRow row = dt.NewRow();

                for (int j= 0; j< 4; j++)
                {

                    if (j== 3)
                    {
                        row[j] =false;
                    }
                    else
                    {
                        row[j] = i.ToString();
                    }
                }
                dt.Rows.Add(row);
            }

            dataGridView1.DataSource = dt;

            datagridviewCheckboxHeaderCell ch =new datagridviewCheckboxHeaderCell();
            ch.OnCheckBoxClicked +=new datagridviewcheckboxHeaderEventHander(ch_OnCheckBoxClicked);

            //第四列为DataGridViewCheckBoxColumn
            DataGridViewCheckBoxColumn checkboxCol= this.dataGridView1.Columns[3]as DataGridViewCheckBoxColumn;
            checkboxCol.HeaderCell = ch;
            checkboxCol.HeaderCell.Value =string.Empty;//消除列头checkbox旁出现的文字
        }

        void ch_OnCheckBoxClicked(object sender, Form1.datagridviewCheckboxHeaderEventArgs e)
        {
            foreach (DataGridViewRow dgvRowin this.dataGridView1.Rows)
            {
                if (e.CheckedState)
                {
                    dgvRow.Cells[3].Value= true;
                }
                else
                {
                    dgvRow.Cells[3].Value= false;
                }
            }

        }

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


        //定义包含列头checkbox选择状态的参数类
        class datagridviewCheckboxHeaderEventArgs : EventArgs
        {
            privatebool checkedState= false;

            publicbool CheckedState
            {
                get {return checkedState; }
                set { checkedState= value; }
            }
        }

        //定义继承于DataGridViewColumnHeaderCell的类，用于绘制checkbox，定义checkbox鼠标单击事件
        class datagridviewCheckboxHeaderCell : DataGridViewColumnHeaderCell
        {
            Point checkBoxLocation;
            Size checkBoxSize;
            bool _checked= false;
            Point _cellLocation =new Point();
            System.Windows.Forms.VisualStyles.CheckBoxState _cbState =
                System.Windows.Forms.VisualStyles.CheckBoxState.UncheckedNormal;
            publicevent datagridviewcheckboxHeaderEventHander OnCheckBoxClicked;


            //绘制列头checkbox
            protectedoverride 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>
            protectedoverride 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= newobject();//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);
            }
        }
    }//end class