【发布时间】：2011-07-21 09:59:58
【问题描述】：
我有以下场景：
我用过一个ItemsControl。
根据ItemsSource生成Button给它？
现在，
当我点击nextbutton时。[看看mainwindow.xaml]。
ItemsControl(pageControl) 的 ItemsSource 变化
并且还必须更改button 的background，根据我的情况，其内容等于CurrentPage 属性。
假设，
第 1 步：在按钮的点击事件中首先我将更改ItemsSource 的ItemsControl。
第 2 步：然后我会改变 特定按钮的Background。
但不是在背景中发生变化，而是我得到以下错误。
This operation is valid only on elements that have this template applied.
注意：- 如果我直接更改Background 而不对ItemsSource 进行任何更改，我没有任何问题。
看看下面的代码。
Mainwindow.xaml
<Window x:Class="CurrentPageProblem.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<Style TargetType="Button" x:Key="buttonStyle">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Button">
<Border CornerRadius="2,2,2,2" HorizontalAlignment="Center" x:Name="borderTemplate" Background="{TemplateBinding Background}">
<ContentPresenter/>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="true">
<Setter TargetName="borderTemplate" Property="Border.BorderBrush" Value="Gray" />
<Setter TargetName="borderTemplate" Property="Border.BorderThickness" Value="1" />
</Trigger>
<Trigger Property="IsPressed" Value="true">
<Setter TargetName="borderTemplate" Property="Border.BorderBrush" Value="Lime" />
</Trigger>
<Trigger Property="IsFocused" Value="true">
<Setter TargetName="borderTemplate" Property="Border.Background" Value="#FD7" />
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter TargetName="borderTemplate" Property="Border.Background" Value="LightGray"></Setter>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="47*" />
<RowDefinition Height="264*" />
</Grid.RowDefinitions>
<ItemsControl Name="pageControl" ItemsSource="{Binding Path=PageCollection}" Grid.Row="0">
<ItemsControl.Template>
<ControlTemplate TargetType="ItemsControl">
<Border >
<StackPanel>
<ItemsPresenter></ItemsPresenter>
</StackPanel>
</Border>
</ControlTemplate>
</ItemsControl.Template>
<ItemsControl.ItemsPanel x:Uid="pageItemTemplate">
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button x:Name="pageNumberButton" Margin="3,4" Style="{StaticResource buttonStyle}" Content="{Binding Path=Page_Number}"></Button>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
<Button Content="Next" Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="136,98,0,0" Name="nextButton" VerticalAlignment="Top" Width="75" Click="button1_Click" />
</Grid>
</Window>
Mainwindow.xaml.cs
public partial class MainWindow : Window,INotifyPropertyChanged
{
ObservableCollection<PageNumber> pageCollection = new ObservableCollection<PageNumber>();
public MainWindow()
{
InitializeComponent();
pageCollection.Add(new PageNumber(" 0 "));
pageCollection.Add(new PageNumber(" 1 "));
pageCollection.Add(new PageNumber(" 2 "));
pageCollection.Add(new PageNumber(" 3 "));
pageCollection.Add(new PageNumber(" 4 "));
pageCollection.Add(new PageNumber(" 5 "));
this.DataContext = this;
}
public ObservableCollection<PageNumber> PageCollection
{
get { return this.pageCollection; }
set
{
this.pageCollection = value;
this.OnPropertyChanged("PageCollection");
}
}
private int currentPage;
public int CurrentPage
{
get { return currentPage; }
set
{
currentPage = value;
this.OnPropertyChanged("CurrentPage");
}
}
private void button1_Click(object sender, RoutedEventArgs e)
{
#region -- IF I COMMENT THIS MUCH CODE THEN THERE IS NO PROBLEM,,,PROBLEM OCCURES WHEN I UNCOMMENT THE CODE,,, --
pageCollection.Clear();
pageCollection.Add(new PageNumber(" 0 "));
pageCollection.Add(new PageNumber(" 1 "));
pageCollection.Add(new PageNumber(" 2 "));
#endregion
for (int i = 0; i < pageControl.Items.Count; i++)
{
var container = pageControl.ItemContainerGenerator.ContainerFromIndex(i) as ContentPresenter;
var button = container.ContentTemplate.FindName("pageNumberButton", container) as Button;
if (button.Content.Equals(string.Format(" {0} ", currentPage)))
{
button.Background = Brushes.NavajoWhite;
}
else
{
button.Background = nextButton.Background;
}
}
currentPage++;
}
#region -- INotifyPropertyChanged Members --
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyNameArg)
{
PropertyChangedEventHandler handler = this.PropertyChanged;
if (handler != null)
{
handler(this,new PropertyChangedEventArgs(propertyNameArg));
}
}
#endregion
}
public class PageNumber
{
private string page_Number;
public PageNumber(string pageNumberArg)
{
this.page_Number = pageNumberArg;
}
public string Page_Number
{
get { return page_Number; }
set
{
page_Number = value;
}
}
}
【问题讨论】：
-
我有这样的场景，当按钮（下一个按钮）被点击
CurrentPage时，为了向用户显示CurrentPage，我正在更改Button的background，其内容等于CurrentPage。谢谢....