1、CellFormatting事件，一般重绘单元格属性。
private Bitmap highPriImage;
private Bitmap mediumPriImage;
private Bitmap lowPriImage;
private void dataGridView1_CellFormatting(object sender,
System.Windows.Forms.DataGridViewCellFormattingEventArgs e)
{
// Set the background to red for negative values in the Balance column.
if (dataGridView1.Columns[e.ColumnIndex].Name.Equals("Balance"))
{
Int32 intValue;
if (Int32.TryParse((String)e.Value, out intValue) &&
(intValue < 0))
{
e.CellStyle.BackColor = Color.Red;
e.CellStyle.SelectionBackColor = Color.DarkRed;
}
}
// Replace string values in the Priority column with images.
if (dataGridView1.Columns[e.ColumnIndex].Name.Equals("Priority"))
{
// Ensure that the value is a string.
String stringValue = e.Value as string;
if (stringValue == null) return;
// Set the cell ToolTip to the text value.
DataGridViewCell cell = dataGridView1[e.ColumnIndex, e.RowIndex];
cell.ToolTipText = stringValue;
// Replace the string value with the image value.
switch (stringValue)
{
case "high":
e.Value = highPriImage;
break;
case "medium":
e.Value = mediumPriImage;
break;
case "low":
e.Value = lowPriImage;
break;
}
}
}
2、CellPainting事件，一般用于合并单元格用
Windows Forms DataGridView 没有提供合并单元格的功能，要实现合并单元格的功能就要在CellPainting事件中使用Graphics.DrawLine和 Graphics.DrawString 自己来“画”。
下面的代码可以对DataGridView第1列内容相同的单元格进行合并：
#region"合并单元格的测试"
private int? nextrow = null;
private int? nextcol = null;
private void dataGridView1_CellFormatting(object sender, System.Windows.Forms.DataGridViewCellFormattingEventArgs e)
{
if (this.dataGridView1.Columns["description"].Index == e.ColumnIndex && e.RowIndex >= 0)
{
if (this.nextcol != null & e.ColumnIndex == this.nextcol)
{
e.CellStyle.BackColor = Color.LightBlue;
this.nextcol = null;
}
if (this.nextrow != null & e.RowIndex == nextrow)
{
e.CellStyle.BackColor = Color.LightPink;
this.nextrow = null;
}
if (e.RowIndex != this.dataGridView1.RowCount - 1)
{
if (e.Value.ToString() == this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value.ToString())
{
e.CellStyle.BackColor = Color.LightPink;
nextrow = e.RowIndex + 1;
}
}
}
if (this.dataGridView1.Columns["name"].Index == e.ColumnIndex && e.RowIndex >= 0)
{
if (e.Value.ToString() == this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value.ToString())
{
e.CellStyle.BackColor = Color.LightBlue;
nextcol = e.ColumnIndex + 1;
}
}
}
//==========================
//绘制单元格
private void dataGridView1_CellPainting(object sender, System.Windows.Forms.DataGridViewCellPaintingEventArgs e)
{
//纵向合并
if (this.dataGridView1.Columns["description"].Index == e.ColumnIndex && e.RowIndex >= 0)
{
using (
Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor),
backColorBrush = new SolidBrush(e.CellStyle.BackColor))
{
using (Pen gridLinePen = new Pen(gridBrush))
{
// 擦除原单元格背景
e.Graphics.FillRectangle(backColorBrush, e.CellBounds);
////绘制线条,这些线条是单元格相互间隔的区分线条,
////因为我们只对列name做处理,所以datagridview自己会处理左侧和上边缘的线条
if (e.RowIndex != this.dataGridView1.RowCount - 1)
{
if (e.Value.ToString() != this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value.ToString())
{
e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1,
e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);//下边缘的线
//绘制值
if (e.Value != null)
{
e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
Brushes.Crimson, e.CellBounds.X + 2,
e.CellBounds.Y + 2, StringFormat.GenericDefault);
}
}
}
else
{
e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1,
e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);//下边缘的线
//绘制值
if (e.Value != null)
{
e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
Brushes.Crimson, e.CellBounds.X + 2,
e.CellBounds.Y + 2, StringFormat.GenericDefault);
}
}
//右侧的线
e.Graphics.DrawLine(gridLinePen, e.CellBounds.Right - 1,
e.CellBounds.Top, e.CellBounds.Right - 1,
e.CellBounds.Bottom - 1);
e.Handled = true;
}
}
}
//横向合并
if (this.dataGridView1.Columns["name"].Index == e.ColumnIndex && e.RowIndex >= 0)
{
using (
Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor),
backColorBrush = new SolidBrush(e.CellStyle.BackColor))
{
using (Pen gridLinePen = new Pen(gridBrush))
{
// 擦除原单元格背景
e.Graphics.FillRectangle(backColorBrush, e.CellBounds);
if (e.Value.ToString() != this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value.ToString())
{
//右侧的线
e.Graphics.DrawLine(gridLinePen, e.CellBounds.Right - 1, e.CellBounds.Top,
e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);
//绘制值
if (e.Value != null)
{
e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
Brushes.Crimson, e.CellBounds.X + 2,
e.CellBounds.Y + 2, StringFormat.GenericDefault);
}
}
//下边缘的线
e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1,
e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);
e.Handled = true;
}
}
}
}
#endregion