WPF学习——转换器

来源：互联网发布：淘宝交易快照怎么看编辑：程序博客网时间：2024/06/07 02:46

WPF进行数据绑定时，不同类型的数据是不能直接绑定的，需要将数据类型进行转换，数据转换包括单值转换和多值转换。

转换器的创建非常简单，只需要新建一个类，以IValueConverter（单值转换）或IMultiValueConverter（多值转换）为基类即可。如：

    public class MyConver : IValueConverter //单值转换    {        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)        {            if (value == null)                return DependencyProperty.UnsetValue;            string str = (string)value;            return "(" + str.Split(',').Length + ")";        }        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)        {            throw new NotImplementedException();        }    }    public class MyMultiConver : IMultiValueConverter //多值转换    {        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)        {            if (values == null || values.Length < 3)                return null;            int a = ((string)values[0]).Split(',').Length;            int b = ((string)values[1]).Split(',').Length;            int c = ((string)values[2]).Split(',').Length;            if (!(a == b && a == c))            {                return new SolidColorBrush(Colors.Red);            }            return DependencyProperty.UnsetValue;        }        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)        {            throw new NotImplementedException();        }    }    public class MyErrorConver : IValueConverter //单值转换    {        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)        {            try            {                Array.ConvertAll(((string)value).Split(','), s => double.Parse(s));            }            catch            {                return new SolidColorBrush(Colors.Red);            }            return DependencyProperty.UnsetValue;        }        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)        {            throw new NotImplementedException();        }    }

以上代码中，MyConver类是将字符串转换成以逗号分隔之后的长度；MyMultiConver类是分别将三个字符串各取以逗号分隔之后的长度，并判断是否相等，如果不等则返回红色；MyErrorConver类是将字符串以逗号分隔并转换成数字，如果转换错误则返回红色。

转换器创建好之后，接下来就要使用转换器了。在xaml代码中：

    <Window.Resources>        <local:MyConver x:Key="cvtLength"/>        <local:MyMultiConver x:Key="cvtColor"/>        <local:MyErrorConver x:Key="cvtErrorColor"/>        <Style x:Key="txtStyle" TargetType="TextBox">            <Setter Property="VerticalContentAlignment" Value="Center"/>            <Setter Property="Margin" Value="5,0,0,0"/>            <Setter Property="InputMethod.IsInputMethodEnabled" Value="False"/>        </Style>        <Style x:Key="gStyle" TargetType="Grid">            <Setter Property="Margin" Value="5"/>        </Style>        <Style x:Key="lblStyle" TargetType="Label">            <Setter Property="Margin" Value="-15,0,0,0"/>            <Setter Property="Grid.Column" Value="1"/>            <Setter Property="Foreground">                <Setter.Value>                    <MultiBinding Converter="{StaticResource cvtColor}">                        <Binding ElementName="txtRadii" Path="Text"/>                        <Binding ElementName="txtEnergy" Path="Text"/>                        <Binding ElementName="txtHeight" Path="Text"/>                    </MultiBinding>                </Setter.Value>            </Setter>        </Style>    </Window.Resources>

引用Window.Resources，定义所有转换器。

    <StackPanel Margin="0,5,0,0">        <Grid Style="{StaticResource gStyle}">            <Grid.ColumnDefinitions>                <ColumnDefinition Width="Auto"/>                <ColumnDefinition Width="Auto"/>                <ColumnDefinition Width="*"/>            </Grid.ColumnDefinitions>            <Label Content="每圈半径" Foreground="{Binding ElementName=txtRadii,Path=Text,Converter={StaticResource cvtErrorColor}}"/>            <Label Style="{StaticResource lblStyle}" Content="{Binding ElementName=txtRadii,Path=Text,Converter={StaticResource cvtLength}}"/>            <TextBox Name="txtRadii" Grid.Column="2" Text="0,10" Style="{StaticResource txtStyle}" PreviewMouseDoubleClick="txtRadii_PreviewMouseDoubleClick"/>        </Grid>        <Grid Style="{StaticResource gStyle}">            <Grid.ColumnDefinitions>                <ColumnDefinition Width="Auto"/>                <ColumnDefinition Width="Auto"/>                <ColumnDefinition Width="*"/>            </Grid.ColumnDefinitions>            <Label Content="每圈能量" Foreground="{Binding ElementName=txtEnergy,Path=Text,Converter={StaticResource cvtErrorColor}}"/>            <Label Style="{StaticResource lblStyle}" Content="{Binding ElementName=txtEnergy,Path=Text,Converter={StaticResource cvtLength}}"/>            <TextBox Name="txtEnergy" Grid.Column="2" Text="1,1" Style="{StaticResource txtStyle}" MouseDoubleClick="txtRadii_PreviewMouseDoubleClick"/>        </Grid>        <Grid Style="{StaticResource gStyle}">            <Grid.ColumnDefinitions>                <ColumnDefinition Width="Auto"/>                <ColumnDefinition Width="Auto"/>                <ColumnDefinition Width="*"/>            </Grid.ColumnDefinitions>            <Label Content="每圈高度" Foreground="{Binding ElementName=txtHeight,Path=Text,Converter={StaticResource cvtErrorColor}}"/>            <Label Style="{StaticResource lblStyle}" Content="{Binding ElementName=txtHeight,Path=Text,Converter={StaticResource cvtLength}}"/>            <TextBox Name="txtHeight" Grid.Column="2" Text="0.02,0.01" Style="{StaticResource txtStyle}" MouseDoubleClick="txtRadii_PreviewMouseDoubleClick"/>        </Grid>        <Button Name="btnStart" Content="开始生成" Width="100" Height="40" Click="BtnStart_Click"/>    </StackPanel>

阅读全文

0 0