How to make a More button on the end of a listbox

问题:

I added this resource on App.xaml

<Style x:Key="ListBoxMore" TargetType="ListBox">
    <Setter Property="Background" Value="Transparent"/>
    <Setter Property="Foreground" Value="{StaticResource PhoneForegroundBrush}"/>
    <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled"/>
    <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
    <Setter Property="BorderThickness" Value="0"/>
    <Setter Property="BorderBrush" Value="Transparent"/>
    <Setter Property="Padding" Value="0"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="ListBox">
                <ScrollViewer x:Name="ScrollViewer" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Foreground="{TemplateBinding Foreground}" Padding="{TemplateBinding Padding}">
                    <StackPanel>
                        <ItemsPresenter/>
                        <Button Content="More" Name="moreButton"></Button>
                    </StackPanel>
                </ScrollViewer>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

And my listbox adds this style

Style="{StaticResource ListBoxMore}"

And it works, but the question is...

How can I get this button in the code-behind? I need to add properties to this button and handle the click, how do I get this button?

回答1:

A common approach is to create a custom control:

using System;
using System.Windows;
using System.Windows.Controls;

namespace WpfApplication2
{
    [TemplatePart(Name=PartMoreButtonName, Type=typeof(Button))]
    public class MyListBox : ListBox
    {
        private const string PartMoreButtonName = "PART_MoreButton";
        private Button _moreButton;

        public override void  OnApplyTemplate()
        {
            // unhook any handlers from _moreButton to prevent a memory leak

            _moreButton = GetTemplateChild(PartMoreButtonName) as Button;

            // do stuff with _moreButton, register handlers, etc.
        }
    }
}

Notice the use of the string PART_MoreButton in both the TemplatePartAttribute and in the override of OnApplyTemplate. This attribute tells consumers of your control that you expect any ControlTemplate that they provide must have a control of type Button with the name PART_MoreButton:

<StackPanel>
    <l:MyListBox>
        <l:MyListBox.Style>
            <Style TargetType="ListBox">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="ListBox">
                            <ScrollViewer x:Name="ScrollViewer">
                                <StackPanel>
                                    <ItemsPresenter/>
                                    <Button x:Name="PART_MoreButton" Content="More"></Button>
                                </StackPanel>
                            </ScrollViewer>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </l:MyListBox.Style>
    </l:MyListBox>
</StackPanel>

When WPF inflates the template for each instance of your control, the override is called. At this point you will have access to your button and can register event handlers, etc. Hope this helps!