访问ControlTemplate内部的元素

需要用到code behind

注意要给需要访问的元素命名x:Name="PART_TextBlock"

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

                    xmlns:local="clr-namespace:CustomControlLib">





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

        <Setter Property="Template">

            <Setter.Value>

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

                    <Border Background="{TemplateBinding Background}"

                            BorderBrush="{TemplateBinding BorderBrush}"

                            BorderThickness="{TemplateBinding BorderThickness}">

                        <StackPanel>

                            <TextBlock x:Name="PART_TextBlock" />

                        </StackPanel>

                    </Border>

                </ControlTemplate>

            </Setter.Value>

        </Setter>

    </Style>

</ResourceDictionary>

custom control的程序部分

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Shapes;



namespace CustomControlLib

{

    

    public class MyControl : Button

    {

        private const string TextBlockPart = "PART_TextBlock";

        TextBlock textBlock;

        static MyControl()

        {

            DefaultStyleKeyProperty.OverrideMetadata(typeof(MyControl), new FrameworkPropertyMetadata(typeof(MyControl)));

        }

        public override void OnApplyTemplate() //OnApplyTemplate get called everytime a template is applied to the control,control update

        {

            base.OnApplyTemplate(); //Button有自己的OnApplyTemplate我们需要call这个beofre call我们自己写的OnApplyTemplate方法

            if (textBlock != null) //避免memory leak每次call OnApplyTemplate方法时都给同一个textBlock加上event

            {

                textBlock.TextInput -= new TextCompositionEventHandler(textBlock_TextInput);

            }

            

            textBlock = GetTemplateChild(TextBlockPart) as TextBlock;

            if (textBlock != null)

            {

                textBlock.Text = "Set from code";

                textBlock.TextInput +=new TextCompositionEventHandler(textBlock_TextInput);

            }

                

        }



        private void textBlock_TextInput(object sender, TextCompositionEventArgs e)

        {

            

        }

    }

}

使用该control
<Window x:Class="CustomControlDemo.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

        xmlns:cc="clr-namespace:CustomControlLib;assembly=CustomControlLib"

        Title="MainWindow"

        Width="525"

        Height="350">

    <Grid>

        <cc:MyControl />

    </Grid>

</Window>

改进：上面的方法不好，设想如果controlTemaplte里有很多element都需要访问，每一个元素都需要后台程序这样访问的话，会很乱

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Shapes;



namespace CustomControlLib

{

    [TemplatePart(Name = TextBlockPart, Type = typeof(TextBlock))] //告诉使用template的作者这里x:Name为PART_TextBlock的control一定要是TextBlock类型的

    public class MyControl : Button

    {

        private const string TextBlockPart = "PART_TextBlock";

        TextBlock _textBlock; //避免每一次call OnApplyTemplate都在方法体里创建一个TextBlock，在方法前定义一个变量来储存

        protected TextBlock TextBlock

        {

            get {return _textBlock; }

            set

            {

                if (_textBlock != null) //避免memory leak每次call OnApplyTemplate方法时都给同一个textBlock加上event

                {

                    _textBlock.TextInput -= new TextCompositionEventHandler(textBlock_TextInput);

                }



                _textBlock = value;



                if (_textBlock != null)

                {

                    _textBlock.Text = "Set from code";

                    _textBlock.TextInput += new TextCompositionEventHandler(textBlock_TextInput);

                }

            }

        }

        static MyControl()

        {

            DefaultStyleKeyProperty.OverrideMetadata(typeof(MyControl), new FrameworkPropertyMetadata(typeof(MyControl)));

        }

        public override void OnApplyTemplate() //OnApplyTemplate get called everytime a template is applied to the control,control update

        {

            base.OnApplyTemplate(); //Button有自己的OnApplyTemplate我们需要call这个beofre call我们自己写的OnApplyTemplate方法

            

            TextBlock = GetTemplateChild(TextBlockPart) as TextBlock; //每次call都赋值属性 

        }



        private void textBlock_TextInput(object sender, TextCompositionEventArgs e)

        {

            

        }

    }

}

 

TemplatePart(Name="PART_Decrease", Type=typeof(RepeatButton))

一直没明白这是干嘛用的，搜了一下，记载一下。

以Button的定义为例：

namespace System.Windows.Controls

{

    // Summary:

    //     Represents a button control, which reacts to the Click event.

    [TemplatePart(Name = "Normal State", Type = typeof(Storyboard))]

    [TemplatePart(Name = "MouseOver State", Type = typeof(Storyboard))]

    [TemplatePart(Name = "RootElement", Type = typeof(FrameworkElement))]

    [TemplatePart(Name = "Pressed State", Type = typeof(Storyboard))]

    [TemplatePart(Name = "FocusVisualElement", Type = typeof(UIElement))]

    [TemplatePart(Name = "Disabled State", Type = typeof(Storyboard))]

    public class Button : ButtonBase

    {

        // Summary:

        //     Initializes a new instance of the Button class.

        public Button();

        // Summary:

        //     Apply a template to the Button.

        protected override void OnApplyTemplate();

        //

        // Summary:

        //     Called when the IsEnabled property changes.

        //

        // Parameters:

        //   isEnabled:

        //     New value of the IsEnabled property.

        protected override void OnIsEnabledChanged(bool isEnabled);

    }

}

 [TemplatePart(Name = "Normal State", Type = typeof(Storyboard))] 这种东东是做什么用的 ， 其实这是一种契约 ， 是一种推荐的控件设计模式（只是推荐） ， 意思是告诉要来写ControlTemplate的用户 ， 你的ControlTemplate中需要有一个x:Name为“Normal State” , 类型为Storyboard ， 当然这个类型可以是继承来的， 为什么一定要包含这些契约规定的元素 ， 因为逻辑部分对这些东西进行了引用，它们将对控件的默认行为起着关键作用， 可以理解为这个控件的最基本元素 ， 是实现默认行为的最小集合， 自然，你的ControlTemplate中如果没有包含契约中的内容 ， 则相应的逻辑将无法实现。

所以说白了，就是提示用的.....这么写比较规范。