DataGridView控件列头添加CheckBox

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.

1. 添加一个帮助类DataGridViewCheckBoxHeaderCell，用于绘制列头checkbox和创建鼠标单击事件，代码如下：

    public class DataGridViewCheckBoxHeaderCell : DataGridViewColumnHeaderCell
       {
           public delegate void DataGridViewCheckBoxHeaderEventHander(object sender, DataGridViewCheckBoxHeaderEventArgs e);
   
           private Point checkBoxLocation;
           private Size checkBoxSize;
           private bool _checked = false;
           private Point _cellLocation = new Point();
   
           private System.Windows.Forms.VisualStyles.CheckBoxState _cbState =
               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);
           }
       }
   
       //定义包含列头checkbox选择状态的参数类
       public class DataGridViewCheckBoxHeaderEventArgs : EventArgs
       {
           private bool checkedState;
   
           public bool CheckedState
           {
               get { return checkedState; }
               set { checkedState = value; }
           }
       }

    

2. 在有DataGridView的界面，添加代码如下：

           /// <summary>
           ///给DataGridView添加checkbox列头
           /// </summary>
           private void AddCheckboxCell()
           {
               DataGridViewCheckBoxHeaderCell ch = new DataGridViewCheckBoxHeaderCell();
               ch.OnCheckBoxClicked += new DataGridViewCheckBoxHeaderCell.DataGridViewCheckBoxHeaderEventHander(ch_OnCheckBoxClicked);
               //第一列为DataGridViewCheckBoxColumn
               DataGridViewCheckBoxColumn checkboxCol = new DataGridViewCheckBoxColumn();
               checkboxCol.HeaderCell = ch;
               checkboxCol.HeaderCell.Value = string.Empty; //消除列头checkbox旁出现的文字
               this.dgvSelectAll.Columns.Insert(0, checkboxCol);
           }
           void ch_OnCheckBoxClicked(object sender, DataGridViewCheckBoxHeaderEventArgs e)
           {
               foreach (DataGridViewRow dgvRow in this.dgvSelectAll.Rows)
               {
                   dgvRow.Cells[0].Value = e.CheckedState;
               }
               this.dgvSelectAll.RefreshEdit();
           }