Question

我使用Listpicker来允许用户选择颜色。所以我使用了一个Toolkit Listpicker和一个DataTemplate，它包含Textbox来显示它的列表项。我想要的是当页面加载时，自动选择先前选择的颜色（项目）。但它给了我一个明显的System.InvalidOperationException＆＃39;异常，因为项目不是简单地添加，而是通过datatemplate文本框。请帮帮我：

 <toolkit:ListPicker x:Name="BackgroundColor"  FullModeHeader="Select Background Color:" Header="Background Color:" BorderThickness="0" FullModeItemTemplate="{StaticResource PickerFullModeItemTemplate}" ItemTemplate="{StaticResource PickerItemTemplate}" Background="#FF09043C" SelectionChanged="BackgroundColor_SelectionChanged" >

           </toolkit:ListPicker>

             <phone:PhoneApplicationPage.Resources>
    <DataTemplate x:Name="PickerItemTemplate">
        <TextBlock Text="{Binding BackGroundColorString}" />
    </DataTemplate>

    <DataTemplate x:Name="PickerFullModeItemTemplate" >
        <Grid x:Name="rootGrid" Margin="0">

            <StackPanel Orientation="Horizontal">
                <TextBlock Name="BackgroundColor" 
                   Text="{Binding BackGroundColorString}"
                          />
            </StackPanel>
        </Grid>
    </DataTemplate>
                     </phone:PhoneApplicationPage.Resources>

if (SunderGutkaSettings.Contains(SG_KEY_BACKGROUNDCOLOR)) //check if key is not present, read value  
        {
            if (BackGroundColorList.Count != 0)//test if list if not empty
            {

                var ListPickerBackGroundColorRead = BackGroundColorList[singletonInstance.SelectedFontColorIndex] as BackGroundlistPickerClass; //pull whole class

                string ListPickerBackGroundColorReadString = ListPickerBackGroundColorRead.BackGroundColorString;

                int ListPickerBackGroundColorReadStringToIndex = BackGroundColorList.FindIndex(x => x.BackGroundColorString.StartsWith(ListPickerBackGroundColorReadString));

                BackgroundColor.SelectedIndex = ListPickerBackGroundColorReadStringToIndex; //DISABLE FOR testing                    


            }

实际上，在简单地编写代码时： BackgroundColor.SelectedIndex = 0;不起作用也没有 BackgroundColor.SelectedItem =＆＃34;红色＆＃34 ;;

帮帮我

Answer 1

设置项目

This.BackgroundColor.SelectedItem = YourObject;

这就是你如何获得ListPicker的选择项，可能你需要转换为你绑定到列表Picker的对象

    private void BackgroundColor_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
      var item = (sender as ListPicker).SelectedItem;
    }

带有DataTemplate的ListPicker的SelectedIndex或SelectedItem

1 个答案: