WPF应用Binding之数据转换

有时数据源的类型与目标类型不一致时，需要把源通过一定的转换之后才能绑定到目标之上。

本例：

(1) 把车的类型转换成车所对应的图片路径；

(2) 把车的运行状态转换成CheckBox的状态；

1、类/类型定义

    public enum Category//车的类型    {        Car,        Bus,    }    public enum State//车的状态    {        Running,        Stop,        Unknow,    }    public class Vehicle    {        public string Name { get; set; }        public Category Category { get; set; }        public State State { get; set; }    }

2、车的类型转换类

    public class CategoryToPictureConverter : IValueConverter    {        /* 数据从Source到Targe时，Convert被调用 */        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)        {            Category category = (Category)value;            switch (category)            {                case Category.Car:                    return @"\Icons\car.jpg";                case Category.Bus:                    return @"\Icons\bus.jpg";                default:                    break;            }            return null;        }        /*          * 数据从Targe到Source时，ConvertBack被调用         * 目前不会被调用         */        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)        {            throw new NotImplementedException();        }    }

3、车的状态转换类

    public class StateToNullableBoolConverter : IValueConverter    {        /* 将State转换为bool? */        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)        {            State state = (State)value;            switch (state)            {                case State.Running:                    return true;                case State.Stop:                    return false;                case State.Unknow:                default:                    break;            }            return null;        }        /* 将bool?转换为State */        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)        {            bool? b = (bool?)value;            if (null == b)            {                return State.Unknow;            }            switch (b)            {                case true:                    return State.Running;                case false:                    return State.Stop;                default:                    break;            }            return State.Unknow;        }    }

4、XAML

<Window.Resources>        <local:CategoryToPictureConverter x:Key="c2pc"/>        <local:StateToNullableBoolConverter x:Key="s2bc"/>    </Window.Resources>    <Grid>        <ListBox x:Name="ListBoxVehicle" ScrollViewer.VerticalScrollBarVisibility="Auto" VerticalAlignment="Center" Margin="5">            <ListBox.ItemTemplate>                <DataTemplate>                    <StackPanel Orientation="Horizontal">                        <Image Width="80" Height="60" Source="{Binding Path=Category, Converter={StaticResource c2pc}}" VerticalAlignment="Center"/>                        <TextBlock Text="{Binding Path=Name}" MinWidth="60" VerticalAlignment="Center" Margin="5"/>                        <CheckBox IsThreeState="True" IsChecked="{Binding Path=State, Converter={StaticResource s2bc}}" VerticalAlignment="Center"/>                    </StackPanel>                </DataTemplate>            </ListBox.ItemTemplate>        </ListBox>    </Grid>

5、C#数据初始化

        public MainWindow()        {            InitializeComponent();            LoadDatas();        }        private void LoadDatas()        {            List<Vehicle> vehicleList = new List<Vehicle>()            {                new Vehicle(){Category = Category.Car, Name="Audo A4", State = State.Unknow},                new Vehicle(){Category = Category.Car, Name="Audo A4 L", State = State.Unknow},                new Vehicle(){Category = Category.Car, Name="Audo A6", State = State.Unknow},                new Vehicle(){Category = Category.Car, Name="Audo A6 L", State = State.Unknow},                new Vehicle(){Category = Category.Bus, Name="金龙客车A1", State = State.Unknow},                new Vehicle(){Category = Category.Bus, Name="金龙客车A2", State = State.Unknow},                new Vehicle(){Category = Category.Bus, Name="宇通客车X1", State = State.Unknow},                new Vehicle(){Category = Category.Bus, Name="宇通客车X2", State = State.Unknow},            };            ListBoxVehicle.ItemsSource = vehicleList;        }

6、图片