CustomControl之內(nèi)置命令

    在打造CustomControl時(shí), 我們可能會(huì)遇到這樣的情況: 希望模板中的Button能執(zhí)行Control中某些特定的邏輯.

    對(duì)于這種情況,有兩種解決方法:TemplatePartAttribute和Command.

    TemplatePartAttribute就是對(duì)UI中的元素命名, 然后在后臺(tái)尋找此元素進(jìn)行相應(yīng)的操作. 很可惜, 這會(huì)使得UI與邏輯耦合, 這與CustomControl的初衷相悖.當(dāng)外部程序改寫(xiě)Template時(shí),很有可能失去作用.

    而Command則十分可靠, 因?yàn)樗苁筓I和邏輯分離. 外部改寫(xiě)UI后, 只需對(duì)相應(yīng)的元素重新綁定內(nèi)置的Command就可以正常地工作. 下面為大家如何內(nèi)置Command和如何進(jìn)行綁定.

    在下面的后臺(tái)代碼中, 對(duì)TestCommand進(jìn)行聲明和初始化. 然后在靜態(tài)構(gòu)造函數(shù)中通過(guò)CommandManager.RegisterClassCommandBinding(Type,CommandBinding)的方法進(jìn)行類綁定(當(dāng)然, 你也可以在構(gòu)造函數(shù)中使用公共的CommandBindings集合,但這并不可靠,因?yàn)樗耸褂么丝丶r(shí)可以隨意修改CommandBindings)

    public class CustomControl1 : Control
    {
        public static readonly RoutedUICommand TestCommand;
        
        static CustomControl1()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(CustomControl1), new FrameworkPropertyMetadata(typeof(CustomControl1)));
            TestCommand = new RoutedUICommand("Test", "TestCommand", typeof(CustomControl1));
            CommandManager.RegisterClassCommandBinding(typeof(CustomControl1), new CommandBinding(TestCommand, TestExecute, TestCanExecute));
        
        }

        private static void TestCanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            CustomControl1 c = sender as CustomControl1;
            if (c == null) return;
            e.CanExecute = c.CanExecute;
        }

        private static void TestExecute(object sender, ExecutedRoutedEventArgs e)
        {
            CustomControl1 c = sender as CustomControl1;
            if (c == null) return;

            Console.WriteLine("---TestCommand Executed---");
        }


        public bool CanExecute;

        public CustomControl1()
        {
           
        }

    }

    接下來(lái),看看Generic.xaml中的UI代碼:

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfCustomControlLibrary1">
    <Style TargetType="{x:Type local:CustomControl1}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:CustomControl1}">
                    <Border Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}">
                        <Button Command="local:CustomControl1.TestCommand"  Content="abc"/>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

    在上面代碼的Button中, Command只需要這樣就可以對(duì)內(nèi)置的命令進(jìn)行綁定.

    以上就是在CustomControl中內(nèi)置Command的方法.

PS: Button的Content不會(huì)自動(dòng)綁定RoutedUICommand中的Text屬性,可以將Content綁定Command.Text , 如下: Content="{Binding Path=Command.Text,RelativeSource={RelativeSource Self}}"