《深入浅出WPF》读书笔记.6binding系统(下)

背景

主要讲数据校验和数据转换以及multibinding

代码

binding的数据校验

<Window x:Class="BindingSysDemo.ValidationRulesDemo"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:BindingSysDemo"
        mc:Ignorable="d"
        Title="ValidationRulesDemo" Height="200" Width="400">
    <StackPanel VerticalAlignment="Center">
        <TextBox x:Name="tb1" Margin="5"></TextBox>
        <Slider x:Name="sld1" Minimum="-10" Maximum="110" Margin="5"></Slider>
    </StackPanel>
</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace BindingSysDemo
{
    /// <summary>
    /// ValidationRulesDemo.xaml 的交互逻辑
    /// </summary>
    public partial class ValidationRulesDemo : Window
    {
        public ValidationRulesDemo()
        {
            InitializeComponent();

            Binding binding = new Binding("Value") { Source = this.sld1, UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged };
            RangeValidationRule rule = new RangeValidationRule();
            //此参数用来校验source数据
            rule.ValidatesOnTargetUpdated = true;
            binding.ValidationRules.Add(rule);
            //通过路由事件获取校验的报错信息
            //信号在UI树上传递的过程乘坐路由事件
            binding.NotifyOnValidationError = true;

            this.tb1.SetBinding(TextBox.TextProperty, binding);
            //监听校验失败错误
            this.tb1.AddHandler(Validation.ErrorEvent, new RoutedEventHandler(this.ValidationError));
        }

        private void ValidationError(object sender, RoutedEventArgs e)
        {
            if (Validation.GetErrors(this.tb1).Count > 0)
            {
                this.tb1.ToolTip = Validation.GetErrors(this.tb1)[0].ErrorContent.ToString();
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Controls;

namespace BindingSysDemo
{
    public class RangeValidationRule : ValidationRule
    {
        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
        {
            //throw new NotImplementedException();
            double d = 0;
            if (double.TryParse(value.ToString(), out d))
            {
                if (d >= 0 && d <= 100)
                {
                    return new ValidationResult(true, null);
                }
            }
            return new ValidationResult(false, "Validation failed!");
        }
    }
}

binding的数据转换

<Window x:Class="BindingSysDemo.BindingConverterDemo"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:BindingSysDemo"
        mc:Ignorable="d"
        Title="BindingConverterDemo" Height="500" Width="600">
    <Window.Resources>
        <local:Category2SourceConverter x:Key="c2s"></local:Category2SourceConverter>
        <local:State2NullableBoolConverter x:Key="s2b"></local:State2NullableBoolConverter>
    </Window.Resources>
    <StackPanel Background="AliceBlue">
        <ListBox x:Name="listBoxPlane" Height="300" Margin="5">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <Image Width="40" Height="20" Source="{Binding Path=Category, Converter={StaticResource c2s}}"></Image>
                        <TextBlock Text="{Binding Path=Name}" Width="60" Margin="80,0"></TextBlock>
                        <CheckBox IsThreeState="True" IsChecked="{Binding Path=State, Converter={StaticResource s2b}}"></CheckBox>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
        <Button x:Name="btnLoad" Content="Load" Height="25" Margin="5" Click="btnLoad_Click"></Button>
        <Button x:Name="btnSave" Content="Save" Height="25" Margin="5" Click="btnSave_Click"></Button>
    </StackPanel>
</Window>

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace BindingSysDemo
{
    /// <summary>
    /// BindingConverterDemo.xaml 的交互逻辑
    /// </summary>
    public partial class BindingConverterDemo : Window
    {
        public BindingConverterDemo()
        {
            InitializeComponent();
        }

        private void btnLoad_Click(object sender, RoutedEventArgs e)
        {
            List<Plane> planes = new List<Plane>()
            {
                new Plane(){Category=Category.Bomber,Name="B-1",State=State.Unknown},
                new Plane(){Category=Category.Bomber,Name="B-2",State=State.Unknown},
                new Plane(){Category=Category.Fighter,Name="F-22",State=State.Unknown},
                new Plane(){Category=Category.Fighter,Name="Su-47",State=State.Unknown},
                new Plane(){Category=Category.Bomber,Name="B-52",State=State.Unknown},
                new Plane(){Category=Category.Fighter,Name="J-10",State=State.Unknown}
            };
            this.listBoxPlane.ItemsSource = planes;
        }

        private void btnSave_Click(object sender, RoutedEventArgs e)
        {
            StringBuilder sb = new StringBuilder();
            foreach (Plane p in listBoxPlane.Items)
            {
                sb.AppendLine(string.Format("Category ={0},Name={1},State={2}", p.Category, p.Name, p.State));
            }
            File.WriteAllText(AppDomain.CurrentDomain.BaseDirectory + "PlaneList.txt", sb.ToString());
            MessageBox.Show("保存成功!");
        }
    }

    public enum Category
    {
        Bomber,
        Fighter
    }

    public enum State
    {
        Available,
        Locked,
        Unknown
    }

    public class Plane
    {
        public Category Category { get; set; }
        public State State { get; set; }
        public string Name { get; set; }
    }

}

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Data;

namespace BindingSysDemo
{
    public class Category2SourceConverter : IValueConverter
    {
        //将Category转换成Uri
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            Category category = (Category)value;
            switch (category)
            {
                case Category.Fighter:
                    return @"\Icon\Fighter.png";
                case Category.Bomber:
                    return @"\Icon\Bomber.png";
                default:
                    return null;
            }
        }

        //不会被调用
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

    public class State2NullableBoolConverter : IValueConverter
    {
        //将State转换成bool
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {

            State state = (State)value;
            switch (state)
            {
                case State.Locked:
                    return false;
                case State.Available:
                    return true;
                case State.Unknown:
                default:
                    return null;
            }
        }

        //不会被调用
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            bool? nb = (bool?)value;
            switch (nb)
            {
                case true:
                    return State.Available;
                case false:
                    return State.Locked;
                case null:
                default:
                    return State.Unknown;
            }
        }
    }
}

multibinding

当页面显示信息不仅由一个控件来决定，就可以使用multibinding。凡是使用binding的地方都可以使用multibinding

<Window x:Class="BindingSysDemo.MultiBindingDemo"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:BindingSysDemo"
        mc:Ignorable="d"
        Title="MultiBindingDemo" Height="400" Width="600">
    <StackPanel>
        <TextBox x:Name="tb1" Height="23" Margin="5"></TextBox>
        <TextBox x:Name="tb2" Height="23" Margin="5"></TextBox>
        <TextBox x:Name="tb3" Height="23" Margin="5"></TextBox>
        <TextBox x:Name="tb4" Height="23" Margin="5"></TextBox>
        <Button x:Name="btn1" Content="Submit" Width="80" Margin="5"></Button>
    </StackPanel>
</Window>

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace BindingSysDemo
{
    /// <summary>
    /// MultiBindingDemo.xaml 的交互逻辑
    /// </summary>
    public partial class MultiBindingDemo : Window
    {
        public MultiBindingDemo()
        {
            InitializeComponent();
            this.SetMultiBinding();
        }

        private void SetMultiBinding()
        {
            //准备基础binding
            Binding b1 = new Binding("Text") { Source = this.tb1 };
            Binding b2 = new Binding("Text") { Source = this.tb2 };
            Binding b3 = new Binding("Text") { Source = this.tb3 };
            Binding b4 = new Binding("Text") { Source = this.tb4 };

            //multibinding
            MultiBinding mb = new MultiBinding();
            mb.Bindings.Add(b1);
            mb.Bindings.Add(b2);
            mb.Bindings.Add(b3);
            mb.Bindings.Add(b4);
            mb.Converter = new LoginMultiBindingConverter();

            this.btn1.SetBinding(Button.IsEnabledProperty, mb);
        }
    }

    public class LoginMultiBindingConverter : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            if (!values.Cast<string>().Any(o => string.IsNullOrEmpty(o)) && values[0].ToString() == values[2].ToString()
                && values[1].ToString() == values[3].ToString())
            {

                return true;
            }
            return false;
        }

        public object[] ConvertBack(object value, Type[] targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

}

git代码

GitHub - wanghuayu-hub2021/WpfBookDemo: 深入浅出WPF的demo

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