WPF案例：如何设计搜索框（自定义控件的原则和方法）

我们平时自定义WPF控件的方法有：Style，DataTemplate，ControlTemplate， DependencyProperty， CustomControl等几个方法。按照优先顺序应该是从左到右。（所谓Style，这里仅包括Setter）

对于搜索框，其组成也就是TextBox+Button（清空），这里我们用CustomControl的方法比较合适。
1.创建SearchBox继承于TextBox，并声明2个Part属性， 表明此控件组成

[TemplatePart(Name = "PART_SearchTextBox", Type = typeof(TextBox))]

[TemplatePart(Name = "PART_ClearButton", Type = typeof(Button))]

public class SearchBox : TextBox

2.创建2个子控件的Style， 注意ControlTemplate中的子控件命名和上述属性声明一致

<Style TargetType="{x:Type local:SearchBox}">

<Setter Property="Template">

<Setter.Value>

<ControlTemplate TargetType="{x:Type local:SearchBox}">

<!-------------子控件PART_SearchTextBox,PART_ClearButton及其它设置--------------->

</ControlTemplate>

</Setter.Value>

</Setter>

</Style>

3.如果在当前程序集里，必须放在.\Themes文件夹下; 必须在程序集的AssemblyInfo.cs里指定ThemeInfo（用来指定控件默认Style）

[assembly: ThemeInfo(
ResourceDictionaryLocation.None, //where theme specific resource dictionaries are located
//(used if a resource is not found in the page,
// or application resource dictionaries)
ResourceDictionaryLocation.SourceAssembly //where the generic resource dictionary is located
//(used if a resource is not found in the page,
// app, or any theme specific resource dictionaries)
)]

4.在自定义控件的实现中注册路由事件等等其它逻辑处理

比如：对子元素Clear按钮进行处理

public override void OnApplyTemplate()

{
base.OnApplyTemplate();

Button btnClear = base.GetTemplateChild("PART_ClearButton") as Button;
if (btnClear != null)

{
btnClear.Click += new RoutedEventHandler(OnClearButton_Click);

}
}

private void OnClearButton_Click(Object sender, RoutedEventArgs e)

{
TextBox txtSearch = base.GetTemplateChild("PART_SearchTextBox") as TextBox;

if (txtSearch!= null)

{
txtSearch.Text = String.Empty;

txtSearch.Focus();

}
}