昨天被问到一个问题：怎么把WinForms里的DataGrid的绑定了数据库bit字段的列默认显示的CheckBox换成“男”和“女”，也就是说怎么样像ASP.NET的模板列那样可以自定义。（此处不考虑在SQL在用Case把数据结果转换了）
由于，基本没有搞过WinForms，所以这个问题弄了很久才搞掂，可能对于WinForms高手来说，这是一个很简单的问题。（我搜了一下网页，没有找到直接的解决方案，问了一些搞过WinForms的朋友，也没有直接的解决方案，所以把我的解决方案放在博客园首页，DUDU如觉不适合，请移除。）解决这个问题的副作用就是对WinForms的机制有了一点了解。
最终实现效果：
开始的思路还是ASP.NET的思路，企图用WinForms的DataGrid的事件来实现。试了ControlAdde，BindingComplated等事件，都没有用，有些能拿到绑定时的控件，却拿不到对应的数据。
后来有朋友启发用CurrencyManager来实现，试了半天，能拿到数据，又拿不到对应的绑定生成的控件了。
晕，后来还是控件开发的思想，既然可以用DataGridTextBoxColumnStyle和DataGridBoolColumnStyle分别生成TextBox和CheckBox，为什么不可以自定义一个DataGridColumnStyle来实现自定义呢？
结果还真是可行的：
//用Label显示"男"和"女"，并且点击一次变成相反的 class DataGridCustomBoolColumnStyle : DataGridColumnStyle
{
private Label _customLabel = new Label(); private bool _isEditing = false; public DataGridCustomBoolColumnStyle()
{ _customLabel.Visible = false; _customLabel.Click +=new EventHandler(_customLabel_Click);
} protected override void Abort(int rowNum) { _isEditing = false; Invalidate(); } void _customLabel_Click(object sender, EventArgs e) { Label lbl = sender as Label; if (lbl.Text == "男") lbl.Text = "女"; else lbl.Text = "男"; this._isEditing = true; base.ColumnStartedEditing(_customLabel); } protected override object GetColumnValueAtRow(CurrencyManager source, int rowNum) { object o = base.GetColumnValueAtRow(source, rowNum); bool value = true; if (Convert.IsDBNull(o)) value = true; else { value = (bool)o; } return value; } protected override void SetDataGridInColumn(DataGrid value) { base.SetDataGridInColumn(value); if (_customLabel.Parent != null) { _customLabel.Parent.Controls.Remove(_customLabel); } if (value != null) { value.Controls.Add(_customLabel); } } protected override bool Commit(CurrencyManager dataSource, int rowNum) { _customLabel.Bounds = Rectangle.Empty; _customLabel.Visible = false; if (!_isEditing) return true; _isEditing = false; try { bool value = (_customLabel.Text == "男"); SetColumnValueAtRow(dataSource, rowNum, value); } catch (Exception) { Abort(rowNum); return false; } Invalidate(); return true; } protected override void Edit(CurrencyManager source, int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string displayText, bool cellIsVisible) { bool value = (bool)GetColumnValueAtRow(source, rowNum); if (cellIsVisible) { _customLabel.Bounds = new Rectangle(bounds.X + 2, bounds.Y + 2, bounds.Width - 4, bounds.Height - 4); _customLabel.Visible = true; } else { _customLabel.Visible = false; } _customLabel.Text = value ? "男" : "女"; if (_customLabel.Visible) { DataGridTableStyle.DataGrid.Invalidate(bounds); } _customLabel.BackColor = Color.Red; } protected override int GetMinimumHeight() { return _customLabel.PreferredHeight + 4; } protected override int GetPreferredHeight(System.Drawing.Graphics g, object value) { return _customLabel.PreferredHeight + 4; } protected override System.Drawing.Size GetPreferredSize(System.Drawing.Graphics g, object value) { return new Size(40, _customLabel.PreferredHeight + 4); } protected override void Paint(System.Drawing.Graphics g, System.Drawing.Rectangle bounds, CurrencyManager source, int rowNum, System.Drawing.Brush backBrush, System.Drawing.Brush foreBrush, bool alignToRight) { bool value = (bool)GetColumnValueAtRow(source, rowNum); g.FillRectangle(backBrush, bounds); bounds.Offset(0, 2); bounds.Height -= 2; g.DrawString(value ? "男" : "女", DataGridTableStyle.DataGrid.Font, foreBrush, bounds); } protected override void Paint(Graphics g,Rectangle bounds,CurrencyManager source,int rowNum) { Paint(g, bounds, source, rowNum, false); } protected override void Paint(Graphics g, Rectangle bounds, CurrencyManager source,int rowNum,bool alignToRight) { Brush coreBrush = _isEditing ? Brushes.Red : Brushes.White; Brush backBrush = _isEditing ? Brushes.Blue : Brushes.Black; Paint( g, bounds, source, rowNum, coreBrush, backBrush, alignToRight); }
}
//使用方法 DataGridTableStyle dgts = new DataGridTableStyle(); dgts.MappingName = this.dataSet11.Employees.TableName; this.dataGrid1.TableStyles.Add(dgts); GridColumnStylesCollection gcsc = dataGrid1.TableStyles[0].GridColumnStyles; DataGridBoolColumn dgbc = gcsc[gcsc.Count - 1] as DataGridBoolColumn; DataGridCustomBoolColumnStyle dgcbc = new DataGridCustomBoolColumnStyle(); dgcbc.MappingName = dgbc.MappingName; gcsc.Remove(dgbc); gcsc.Add(dgcbc); this.employeesTableAdapter.Fill(this.dataSet11.Employees); this.dataGrid1.DataSource = this.dataSet11.Employees;这个实现很简单，数据与显示之间的映射是固定的，既然简单的能实现，我们再来实现个复杂的，用ComboBox来表示一些固定值的选择，比如enum和bool,因为数据库中的数据并没有enum，所以，这个DataGridComboBoxColumnStyle提供两个委托，可以数据到ComboBox项和ComboBox项到数据之间做一个处理
//可以灵活适应各种情况的ComboBox列样式 public delegate string FormatValueToString(object value); public delegate object ParseStringToValue(string value); class DataGridComboBoxColumnStyle:DataGridColumnStyle { public FormatValueToString FormartDelegate; public ParseStringToValue ParseDelegate; private bool _isEditing = false; private ComboBox _combo = new ComboBox(); public ComboBox InnerComboBox { get { return _combo; } } public DataGridComboBoxColumnStyle() { _combo.SelectedIndexChanged += new EventHandler(_combo_SelectedIndexChanged); _combo.Visible = false; } void _combo_SelectedIndexChanged(object sender, EventArgs e) { this._isEditing = true; base.ColumnStartedEditing(_combo); } protected override void Abort(int rowNum) { _isEditing = false; Invalidate(); } protected override void SetDataGridInColumn(DataGrid value) { base.SetDataGridInColumn(value); if (_combo.Parent != null) { _combo.Parent.Controls.Remove(_combo); } if (value != null) { value.Controls.Add(_combo); } } protected override bool Commit(CurrencyManager dataSource, int rowNum) { _combo.Bounds = Rectangle.Empty; _combo.Visible = false; if (!_isEditing) return true; _isEditing = false; try { string value = _combo.SelectedText; SetColumnValueAtRow(dataSource, rowNum, value); } catch (Exception) { Abort(rowNum); return false; } Invalidate(); return true; } protected override object GetColumnValueAtRow(CurrencyManager source, int rowNum) { object value = base.GetColumnValueAtRow(source, rowNum); if (Convert.IsDBNull(value)) { value = this.NullText; } if (FormartDelegate != null) { value = FormartDelegate(value); } return value; } protected override void SetColumnValueAtRow(CurrencyManager source, int rowNum, object value) { if(ParseDelegate != null) { value = ParseDelegate((string)value); } base.SetColumnValueAtRow(source, rowNum, value); } protected override void Edit(CurrencyManager source, int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string displayText, bool cellIsVisible) { string value = (string)GetColumnValueAtRow(source, rowNum); if (cellIsVisible) { _combo.Bounds = new Rectangle(bounds.X + 2, bounds.Y + 2, bounds.Width - 4, bounds.Height - 4); _combo.Visible = true; } else { _combo.Visible = false; } for (int i = 0; i < _combo.Items.Count; i++) { if (value == (string)_combo.Items[i]) { _combo.SelectedIndex = i; break; } } if (_combo.Visible) { DataGridTableStyle.DataGrid.Invalidate(bounds); } } protected override int GetMinimumHeight() { return _combo.PreferredHeight + 4; } protected override int GetPreferredHeight(System.Drawing.Graphics g, object value) { return _combo.PreferredHeight + 4; } protected override System.Drawing.Size GetPreferredSize(System.Drawing.Graphics g, object value) { return new Size(100, _combo.PreferredHeight + 4); } protected override void Paint(System.Drawing.Graphics g, System.Drawing.Rectangle bounds, CurrencyManager source, int rowNum, System.Drawing.Brush backBrush, System.Drawing.Brush foreBrush, bool alignToRight) { string value = (string)GetColumnValueAtRow(source, rowNum); g.FillRectangle(backBrush, bounds); bounds.Offset(0, 2); bounds.Height -= 2; g.DrawString(value, DataGridTableStyle.DataGrid.Font, foreBrush, bounds); } protected override void Paint(Graphics g,Rectangle bounds,CurrencyManager source,int rowNum) { Paint(g, bounds, source, rowNum, false); } protected override void Paint(Graphics g, Rectangle bounds, CurrencyManager source,int rowNum,bool alignToRight) { Brush coreBrush = _isEditing ? Brushes.Red : Brushes.White; Brush backBrush = _isEditing ? Brushes.Blue : Brushes.Black; Paint( g, bounds, source, rowNum, coreBrush, backBrush, alignToRight); } }
//使用方法 DataGridTableStyle dgts = new DataGridTableStyle(); dgts.MappingName = this.dataSet11.Employees.TableName; this.dataGrid1.TableStyles.Add(dgts); GridColumnStylesCollection gcsc = dataGrid1.TableStyles[0].GridColumnStyles; DataGridBoolColumn dgbc = gcsc[gcsc.Count - 1] as DataGridBoolColumn; DataGridComboBoxColumnStyle dgcbc = new DataGridComboBoxColumnStyle(); dgcbc.MappingName = dgbc.MappingName; //这里定义ComboBOx的样式和项，因为整个ComboBox都公开了，所以随你怎么设置都行 dgcbc.InnerComboBox.Items.Add("男"); dgcbc.InnerComboBox.Items.Add("女"); dgcbc.InnerComboBox.DropDownStyle = ComboBoxStyle.DropDownList; //这里定义数据和ComboBOx项之间如何转换 dgcbc.ParseDelegate = new ParseStringToValue(ParseStringToBool); dgcbc.FormartDelegate = new FormatValueToString(FormatBoolToString); gcsc.Remove(dgbc); gcsc.Add(dgcbc); this.employeesTableAdapter.Fill(this.dataSet11.Employees); this.dataGrid1.DataSource = this.dataSet11.Employees;
熟悉WinForms的设计思路之后，我们又可以像用ASP.NET的DataGird一样用DataGrid了。
WinForms我是新手，请多指教。。。
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覆盖优化 - 附代码)
