DataGridView使用技巧

收集一些在DataGridVeiw使用技巧，备用。

一、DataGridView 单元格验证

1、定义单元格验证
要求：验证错误后焦点不离开。
实现：
单元格的验证可以使用dgv_details_CellValidating事件。
验证不通过时调用e.Cancel = true;终止事件链，单元格将保持编辑状态。
调用dgv_details.CancelEdit();可以使单元格的内容会滚到修改前的值。
使用System.Windows.Forms.SendKeys.Send("^a");将全选单元格的内容。

2、单元格选中并开始编辑状态
实现：

1. //DataGridView获得焦点
2. dgv_details.Focus();
3. //DataGridView指定当前单元格
4. dgv_details.CurrentCell = dgv_details[0, 0];
5. //开始编辑状态
6. dgv_details.BeginEdit(false);

3、定制自动生成绑定了列
实现：

1. dgv_details.AutoGenerateColumns = false;

4、设置列的背景色
实现：

1. Color GridReadOnlyColor = Color.LightGoldenrodYellow;
2. dgv_details.Columns[1].DefaultCellStyle.BackColor = WinKeys.GridReadOnlyColor;

5、DataGridView单元格验证的设计的问题
问题：绑定还是不绑定？
1）绑定的优势：比较简单，代码少。
2）绑定得缺点：DataGridView中的数据受数据源的影响（主键约束、值类型约束）。不一至时会激发DataError事件，输入的内容无法保存到单元格中和数据源中。特殊的验证（比如长度、格式等）还是需要另外写代码实现。
关于增加行的问题。增加新行时多主键的验证有问题，而且验证不通过时会将新行全部删除。限制很多，很不方便。
3）非绑定的优势：验证等处理比较灵活。不受数据源的约束。
4）非绑定得缺点：显示和向数据库更新数据时需要比较多的代码实现，效率比较低。
5）总的感觉在处理验证比较麻烦的场合，我还是比较喜欢非绑定的方式。如果数据量大，验证比较简单的场合使用绑定模式比较好。

二、DataGridView重绘代码

1、CellFormatting事件，一般重绘单元格属性。

1. private Bitmap highPriImage;
2. private Bitmap mediumPriImage;
3. private Bitmap lowPriImage;
4. private void dataGridView1_CellFormatting(object sender,
5.         System.Windows.Forms.DataGridViewCellFormattingEventArgs e)
6.     {
7. // Set the background to red for negative values in the Balance column.
8. if (dataGridView1.Columns[e.ColumnIndex].Name.Equals("Balance"))
9.         {
10.             Int32 intValue;
11. if (Int32.TryParse((String)e.Value, out intValue) &&
12.                 (intValue < 0))
13.             {
14.                 e.CellStyle.BackColor = Color.Red;
15.                 e.CellStyle.SelectionBackColor = Color.DarkRed;
16.             }
17.         }
19. // Replace string values in the Priority column with images.
20. if (dataGridView1.Columns[e.ColumnIndex].Name.Equals("Priority"))
21.         {
22. // Ensure that the value is a string.
23.             String stringValue = e.Value as string;
24. if (stringValue == null) return;
26. // Set the cell ToolTip to the text value.
27.             DataGridViewCell cell = dataGridView1[e.ColumnIndex, e.RowIndex];
28.             cell.ToolTipText = stringValue;
30. // Replace the string value with the image value.
31. switch (stringValue)
32.             {
33. case "high":
34.                     e.Value = highPriImage;
35. break;
36. case "medium":
37.                     e.Value = mediumPriImage;
38. break;
39. case "low":
40.                     e.Value = lowPriImage;
41. break;
42.             }
43.         }
44.     }

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：

1. #region"合并单元格的测试"
2. private int? nextrow = null;
3. private int? nextcol = null;
4. private void dataGridView1_CellFormatting(object sender, System.Windows.Forms.DataGridViewCellFormattingEventArgs e)
5. {
6. if (this.dataGridView1.Columns["description"].Index == e.ColumnIndex && e.RowIndex >= 0)
7.     {
8. if (this.nextcol != null & e.ColumnIndex == this.nextcol)
9.         {
10.             e.CellStyle.BackColor = Color.LightBlue;
11. this.nextcol = null;
12.         }
13. if (this.nextrow != null & e.RowIndex == nextrow)
14.         {
15.             e.CellStyle.BackColor = Color.LightPink;
16. this.nextrow = null;
17.         }
18. if (e.RowIndex != this.dataGridView1.RowCount - 1)
19.         {
20. if (e.Value.ToString() == this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value.ToString())
21.             {
22.                 e.CellStyle.BackColor = Color.LightPink;
23.                 nextrow = e.RowIndex + 1;
24.             }
25.         }
26.     }
27. if (this.dataGridView1.Columns["name"].Index == e.ColumnIndex && e.RowIndex >= 0)
28.     {
29. if (e.Value.ToString() == this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value.ToString())
30.         {
31.             e.CellStyle.BackColor = Color.LightBlue;
32.             nextcol = e.ColumnIndex + 1;
33.         }
34.     }
35. }
36. //==========================
38. //绘制单元格
39. private void dataGridView1_CellPainting(object sender, System.Windows.Forms.DataGridViewCellPaintingEventArgs e)
40. {
44. //纵向合并
45. if (this.dataGridView1.Columns["description"].Index == e.ColumnIndex && e.RowIndex >= 0)
46.     {
48. using (
49.             Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor),
50.             backColorBrush = new SolidBrush(e.CellStyle.BackColor))
51.         {
52. using (Pen gridLinePen = new Pen(gridBrush))
53.             {
54. // 擦除原单元格背景
55.                 e.Graphics.FillRectangle(backColorBrush, e.CellBounds);
56. 绘制线条,这些线条是单元格相互间隔的区分线条,
57. 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
58. if (e.RowIndex != this.dataGridView1.RowCount - 1)
59.                 {
60. if (e.Value.ToString() != this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value.ToString())
61.                     {
63.                         e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1,
64.                         e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);//下边缘的线
65. //绘制值
66. if (e.Value != null)
67.                         {
68.                             e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
69.                                 Brushes.Crimson, e.CellBounds.X + 2,
70.                                 e.CellBounds.Y + 2, StringFormat.GenericDefault);
71.                         }
72.                     }
73.                 }
74. else
75.                 {
76.                     e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1,
77.                         e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);//下边缘的线
78. //绘制值
79. if (e.Value != null)
80.                     {
81.                         e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
82.                             Brushes.Crimson, e.CellBounds.X + 2,
83.                             e.CellBounds.Y + 2, StringFormat.GenericDefault);
84.                     }
85.                 }
86. //右侧的线
87.                 e.Graphics.DrawLine(gridLinePen, e.CellBounds.Right - 1,
88.                     e.CellBounds.Top, e.CellBounds.Right - 1,
89.                     e.CellBounds.Bottom - 1);
91.                 e.Handled = true;
92.             }
93.         }
94.     }
96. //横向合并
97. if (this.dataGridView1.Columns["name"].Index == e.ColumnIndex && e.RowIndex >= 0)
98.     {
100. using (
101.             Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor),
102.             backColorBrush = new SolidBrush(e.CellStyle.BackColor))
103.         {
104. using (Pen gridLinePen = new Pen(gridBrush))
105.             {
106. // 擦除原单元格背景
107.                 e.Graphics.FillRectangle(backColorBrush, e.CellBounds);
109. if (e.Value.ToString() != this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value.ToString())
110.                 {
112. //右侧的线
113.                     e.Graphics.DrawLine(gridLinePen, e.CellBounds.Right - 1, e.CellBounds.Top,
114.                         e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);
115. //绘制值
116. if (e.Value != null)
117.                     {
118.                         e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
119.                             Brushes.Crimson, e.CellBounds.X + 2,
120.                             e.CellBounds.Y + 2, StringFormat.GenericDefault);
121.                     }
122.                 }
124. //下边缘的线
125.                 e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1,
126.                                             e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);
127.                 e.Handled = true;
128.             }
129.         }
131.     }
133. }
135. #endregion

三、在GridView中如何格式化Money型字段（downmoon)?

2. DataMember="DefaultView" DataSourceID="SqlDataSource1">
5. SortExpression="PKID" />
9.                            amount

这段代码中,
amount为Money型字段，无论如何只能显示成
1234.5600 
而不能显示成
1,234.56
用

也不行！
后来在MSDN上找到了答案

关键在于HtmlEncode="False"

http://blogs.msdn.com/danielfe/archive/2006/02/08/527628.aspx

（源文：http://blog.youkuaiyun.com/downmoon/archive/2007/11/01/1860611.aspx）

四、DataGridView合并单元格 编辑单元格

同事的一个项目需要将DataGridView单元格中的内容分不同颜色显示，想了想只有重绘了。
这种方法还可以用做合并单元格。

参考代码：

1. private void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
2.         {
3. if (e.RowIndex == 0 && e.ColumnIndex >= 0)
4.             {
5. int left = e.CellBounds.Left;
6. int top = e.CellBounds.Top;
7. int right = e.CellBounds.Right;
8. int bottom = e.CellBounds.Bottom;
9.                 e.Graphics.FillRectangle(new SolidBrush(Color.White), e.CellBounds);
10.                 e.Handled = true;
11.                 Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor);
12.                 Pen gridLinePen = new Pen(gridBrush);
13.                 e.Graphics.DrawLine(gridLinePen, right - 1,
14.                            top, right - 1,
15.                            bottom - 1);
16.                 e.Graphics.DrawLine(gridLinePen, left,
17.                            bottom - 1, right,
18.                            bottom - 1);
20.                 Brush b1 = new SolidBrush(Color.Black);
21.                 e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
22.                                         b1, left + 2,
23.                                         top + 1, StringFormat.GenericDefault);
25.                 Brush b2 = new SolidBrush(Color.Red);
26.                 e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
27.                                         b2, left + 2,
28.                                         top + 10, StringFormat.GenericDefault);
29.             }
31.             DataGridViewSelectedCellCollection dgvscc = this.dataGridView1.SelectedCells;
32. foreach (DataGridViewCell dgvc in dgvscc)
33.             {
34. if (e.RowIndex == 0
35.                         && e.RowIndex == dgvc.RowIndex
36.                         && e.ColumnIndex == dgvc.ColumnIndex)
37.                     {
38. int left = e.CellBounds.Left;
39. int top = e.CellBounds.Top;
40. int right = e.CellBounds.Right;
41. int bottom = e.CellBounds.Bottom;
42. // 绘制背景，覆盖单元格区域
43.                         e.Graphics.FillRectangle(new SolidBrush(Color.FromArgb(10,36,106)), e.CellBounds);
45. // 绘制边框
46.                         Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor);
47.                         Pen gridLinePen = new Pen(gridBrush);
48.                         e.Graphics.DrawLine(gridLinePen, right - 1,
49.                                    top, right - 1,
50.                                    bottom - 1);
51.                         e.Graphics.DrawLine(gridLinePen, left,
52.                                    bottom - 1, right,
53.                                    bottom - 1);
55. // 绘制文字
56.                         Brush b1 = new SolidBrush(Color.White);
57.                         e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
58.                                                 b1, left + 2,
59.                                                 top + 1, StringFormat.GenericDefault);
61.                         Brush b2 = new SolidBrush(Color.White);
62.                         e.Graphics.DrawString((String)e.Value, e.CellStyle.Font,
63.                                                 b2, left + 2,
64.                                                 top + 10, StringFormat.GenericDefault);
65.                     }
66.             }
68.             e.Handled = true;           
70.         }

感谢各位作者。