onKeyEvent 修饰符在 Jetpack Compose 中不起作用 [英] onKeyEvent Modifier doesn't work in Jetpack Compose

问题描述

return ComposeView(requireContext()).apply {
    setContent {
        Box(
            Modifier
                .onKeyEvent {
                    if (it.isCtrlPressed && it.key == Key.A) {
                        println("Ctrl + A is pressed")
                        true
                    } else {
                        false
                    }
                }
                .focusable()
        )
    }
}

为什么在使用平板电脑的硬件键盘时无法在片段中调用按键事件?

Why the key event cannot be called in fragment while using hardware keyboard of tablet?

推荐答案

作为 onKeyEvent 的文档说:

将允许它在它(或其子代之一)获得焦点时拦截硬件关键事件.

will allow it to intercept hardware key events when it (or one of its children) is focused.

这意味着你需要让你的盒子聚焦，而不仅仅是聚焦.为此，您需要一个 FocusRequester，在我的示例中，我要求在视图呈现时获得焦点.在这篇文章

Which means you need to make your box focused, not just focusable. To do this you need a FocusRequester, in my example I'm asking focus when view renders. Check out more in this article

以后注意，如果用户点击文本字段，您的框将失去焦点，但是如果此文本字段在框中，onKeyEvent 仍然可以工作

For the future note, that if user taps on a text field, your box will loose focus, but onKeyEvent still gonna work if this txt field is inside the box

看起来空框无法聚焦，因此您需要使用修饰符添加一些大小.它仍然是隐形的:

Looks like empty box cannot become focused, so you need to add some size with a modifier. It still will be invisible:

val requester = remember { FocusRequester() }
Box(
    Modifier
        .onKeyEvent {
            if (it.isCtrlPressed && it.key == Key.A) {
                println("Ctrl + A is pressed")
                true
            } else {
                false
            }
        }
        .focusRequester(requester)
        .focusable()
        .size(10.dp)
)
LaunchedEffect(Unit) {
    requester.requestFocus()
}

或者只是将内容添加到 Box 中，这样它就会拉伸并且不再需要 .size 修饰符

Alternatively just add content to Box so it will stretch and .size modifier won't be needed anymore

此代码适用于我的蓝牙键盘 + android 智能手机，模拟器似乎无法识别 CTRL

This code works fine with my Bluetooth keyboard + android smartphone, emulator seems not recognizing CTRL

这篇关于onKeyEvent 修饰符在 Jetpack Compose 中不起作用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！