如何切换image显示？

Question

请问：
一个ListView绑定到数据库表，表中有一bool列:IsHidden
想依据此值，决定是否显示image,但image的Visibility属性设置为bool类型是无效的，请问如何做这个绑定？
如能做得到在xaml代码中依据此值切换显示两幅image显示则最好不过。

Answer 1

可以使用Converter来做，请参看文章： http://msdn.microsoft.com/en-us/library/ms752091.aspx 以及示例代码： C:\Program Files\Microsoft SDKs\Windows\v6.0\Samples\WPFSamples\ConnectedData\DataBindingLab C:\Program Files\Microsoft SDKs\Windows\v6.0\Samples\WPFSamples\ConnectedData\BindConversionMarkup

Answer 2

您好，

 

Killmyday 在上一个贴子中提供了你这个问题的方法，下面是我一个现成的小例子：

XAML code:

 

<Window x:Class="WpfValueConverterTest.Window1"

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

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

    xmlns:local="clr-namespace:WpfValueConverterTest"

    Title="Window3" Height="300" Width="300"  Name="win3" >

    <Window.Resources>

        <local:People  x:Key="data" />

        <local:BoolToVisbilityConverter x:Key="converter" />

    </Window.Resources>

    <StackPanel>

        <ListView ItemsSource="{Binding Source={StaticResource data}}">

            <ListView.View>

                <GridView>

                    <GridViewColumn  Header="Name">

                        <GridViewColumn.CellTemplate>

                            <DataTemplate>

                                <TextBlock Text="{Binding Path=Name}"

                                           Visibility="{Binding Path=IsHidden,Converter={StaticResource converter}}" />

                            </DataTemplate>

                        </GridViewColumn.CellTemplate>

                    </GridViewColumn>

                    <GridViewColumn  DisplayMemberBinding="{Binding IsHidden}" Header="IsHidden" />

                </GridView>

            </ListView.View>

        </ListView>

    </StackPanel>

</Window>

 

后台code:

using System;

using System.Windows;

using System.Windows.Data;

using System.Collections.ObjectModel;

namespace WpfValueConverterTest

{

    public partial class Window1 : Window

    {

        public Window1()

        {

            InitializeComponent();

        }

    }

    public class People : ObservableCollection<Person>

    {

        public People()

        {

            for (int i = 0; i < 10; i++)

            {

                this.Add(new Person()

                {

                    Name = "Name" + i.ToString(),

                    IsHidden = (i % 2 == 0) ? true : false

                });

            }

        }

    }

    public class Person

    {

        public string Name { get; set; }

        public bool IsHidden { get; set; }

    }

    public class BoolToVisbilityConverter : IValueConverter

    {

        #region IValueConverter Members

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)

        {

            bool flag = false;

            bool.TryParse(value.ToString(), out flag);

            if (flag == true)

            {

                return Visibility.Visible;

            }

            else return Visibility.Hidden;

        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)

        {

            throw new NotImplementedException();

        }

        #endregion

    }

}

 

如有不明白的地方请继续回复。

 

谢谢。

---

Jim Zhou -MSFT

Answer 3

就 bool 到 Visibility 的转换而言, 根本不需要自己写一个 Converter 类.
因为 System.Windows.Controls 下已经内置了这个类: BooleanToVisibilityConverter.

一个例子:

  <Grid x:Name="layoutRoot">
   <Grid.Resources>
    <BooleanToVisibilityConverter x:Key="bToV"/>
   </Grid.Resources>
   <StackPanel>
    <Button Visibility="{Binding Path=IsChecked, ElementName=chk, Converter={StaticResource bToV}}">Afx</Button>
    <CheckBox Name="chk"/>
   </StackPanel>
  </Grid>

在 System.Windows.Controls 下有几个内置的 Converter 类 (可以为一些常用操作带来方便, 而不必再写一个类):
AlternationConverter                             IValueConverter
BooleanToVisibilityConverter                  IValueConverter
BorderGapMaskConverter                      IMultiValueConverter
MenuScrollingVisibilityConverter             IMultiValueConverter

---

Hello, everyone