如何将命令绑定到本地事件? [英] How can I bind a command to a local event?

问题描述

我有一个可以捕获 KeyDown/KeyUp 事件的表单.

I have a form that should capture KeyDown/KeyUp events.

此代码因 NRE 而失败，因为它在我当前的视图中查找 KeyDown 控件:

This code fails with NRE, because it looks for KeyDown control on my current view:

this.BindCommand(ViewModel, vm => vm.KeyDown, "KeyDown");

我所做的是创建了一个具有表单属性的包装类，所以我可以使用这个重载:

What I've done is created wrapper class that has form as a property, so I can use this overload:

this.BindCommand(ViewModel, vm => vm.KeyDown, v => v.Form, "KeyDown");

虽然它有效，但对我来说似乎是一个黑客.是否有适当的方法绑定到本地事件?

While it works, it seems like a hack to me. Is there a proper way to bind to local events?

推荐答案

如果您使用 BindCommand，这是正确的方法.如果你想摆脱字符串并且你正在使用 ReactiveUI.Events，你也可以这样做:

That's the right way to do it if you're using BindCommand. If you want to get rid of the string and you're using ReactiveUI.Events, you could also do:

this.Form.Events().KeyDown
    .InvokeCommand(this, x => x.ViewModel.KeyDown);

顺便说一句，KeyDown"不是一个非常 MVVM 的命令.我会在 View 层写你的 key => 命令映射，像这样(通过 TextArea 编码，忽略语法错误):

As an aside, "KeyDown" isn't a very MVVM'y command. I'd write your key => command mappings at the View layer, like this (coding via TextArea, ignore syntax bugs):

this.Form.Events().KeyDown
    .Where(x => x.Key == Key.C && (x.Modifier & Modifier.Ctrl))
    .InvokeCommand(this, x => x.ViewModel.CopyText;

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