Android开发焦点与TV

新弟發表於 2022-3-31 16:14:00

<h1>前言</h1>
 　　焦点一般在TV设备，投影仪设备开发中使用很多。因为这些设备不带触控与键鼠输入，而是使用遥控器。本博客讲解与记录焦点开发的一些功能与细节。 
<h1>在xml里关于焦点的属性</h1>
<div class="cnblogs_code">
<pre> 
<attr name="focusable" format="boolean|enum">


<attr name="focusableInTouchMode" format="boolean" />


<attr name="focusedByDefault" format="boolean" />


<attr name="defaultFocusHighlightEnabled" format="boolean" />


<attr name="screenReaderFocusable" format="boolean" /></pre>
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下面的焦点指定通常并不需要设置，因为系统会自动检索焦点目标，除非你有特殊的需求
android:nextFocusForward="@+id/code_et" 下一个焦点目标
android:nextFocusUp="@id/book"  定义指定方向的焦点
android:nextFocusDown="@id/book" 定义指定方向的焦点
android:nextFocusLeft="@id/book" 定义指定方向的焦点
android:nextFocusRight="@id/book" 定义指定方向的焦点
android:nextClusterForward="@id/book" 定义下一个键盘导航集群
<h1>android:descendantFocusability属性</h1>
android:descendantFocusability是View的一个属性。可以理解是viewGroup和其子控件焦点相关的属性。
<ul>
<li>
beforeDescendants ：viewGroup会优先其子类控件而获取到焦点
</li>
<li>
afterDescendants ：viewGroup只有当其子类控件不需要获取焦点时才获取焦点
</li>
<li>
blocksDescendants ：viewGroup会覆盖子类控件而直接获得焦点
</li>
</ul>
<h1>设置默认焦点</h1>
<div class="cnblogs_code">
<pre>mBinding.piano.requestFocus()</pre>
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<h1>监听某个view的焦点变化</h1>
获得焦点或者失去焦点
<div class="cnblogs_code">
<pre> mBinding.piano.setOnFocusChangeListener { view, b ->
 Log.e("zh", "piano $b ")
 }</pre>
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<h1>监听指定View的焦点按下的键值</h1>
<div class="cnblogs_code">
<pre> mBinding.brightnessSeekBar.setOnKeyListener(View.OnKeyListener { view, i, keyEvent ->
 if (i == KeyEvent.KEYCODE_ENTER) {
 if (mUnfoldBrightnessLayout) {
 mUnfoldBrightnessLayout = false
 mBinding.brightnessLayout.isFocusable = true
 mBinding.brightnessLayout.isSelected = false
 mBinding.unfoldBrightnessGroup.visibility = View.GONE
 mBinding.brightnessLayout.requestFocus()
 animationUp(mBinding.brightnessIcon2)
 }
 true
 }
 false
 })</pre>
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<h1>监听全局焦点</h1>
<div class="cnblogs_code">
<pre>private val focusChangeListener: ViewTreeObserver.OnGlobalFocusChangeListener = object : ViewTreeObserver.OnGlobalFocusChangeListener {
 override fun onGlobalFocusChanged(oldFocus: View?, newFocus: View?) {
 Log.e("zh", "oldFocus ==" + oldFocus + " id:" + oldFocus?.id)
 Log.e("zh", "newFocus ==" + newFocus + " id:" + newFocus?.id)
 if (newFocus != null) {
 if (mBinding.viewPage.currentItem == 1 && (newFocus.id == R.id.hut
 || newFocus.id == R.id.tv || newFocus.id == R.id.song || newFocus.id == R.id.story)
 ) {
 mBinding.viewPage.currentItem = 0
 return
 }
 if (mBinding.viewPage.currentItem == 1 && (newFocus.id == R.id.draw
 || newFocus.id == R.id.book || newFocus.id == R.id.piano || newFocus.id == R.id.chess)
 ) {
 mBinding.viewPage.currentItem = 2
 return
 }
 if ((mBinding.viewPage.currentItem == 0 || mBinding.viewPage.currentItem == 2) && (newFocus.id == R.id.news
 || newFocus.id == R.id.lwlx || newFocus.id == R.id.time || newFocus.id == R.id.chest
 || newFocus.id == R.id.film || newFocus.id == R.id.applicationMarket || newFocus.id == R.id.weather
 || newFocus.id == R.id.music)
 ) {
 mBinding.viewPage.currentItem = 1
 return
 }
 }
 }
}</pre>
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注册
<div class="cnblogs_code">
<pre> override fun onCreate(savedInstanceState: Bundle?) {
 //略。。
 mBinding.root.getViewTreeObserver().addOnGlobalFocusChangeListener(focusChangeListener)
}

override fun onDestroy() {
 super.onDestroy()
 mBinding.root.viewTreeObserver.removeOnGlobalFocusChangeListener(focusChangeListener)
}</pre>
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<h1>子View焦点状态跟随父布局</h1>
<div class="cnblogs_code">
<pre>android:duplicateParentState="true"</pre>
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<h1>TV开发中常用函数</h1>
<div class="cnblogs_code">
<pre>/**
* 设置焦点放大
*/
fun View.setFocusEnlarge(float: Float) {
this.setOnFocusChangeListener { view, b ->
 if (b) {
 this.scaleX = float
 this.scaleY = float
 } else {
 this.scaleX = 1.0f
 this.scaleY = 1.0f
 }
}
}

/**
* 鼠标选中放大
*/
fun View.setHoverEnlarge(float: Float){
this.setOnHoverListener { v, event ->
 when(event.action){
 MotionEvent.ACTION_HOVER_ENTER->{
 this.scaleX = float
 this.scaleY = float
 }
 MotionEvent.ACTION_HOVER_EXIT->{
 this.scaleX = 1.0f
 this.scaleY = 1.0f
 }
 MotionEvent.ACTION_HOVER_MOVE->{}
 }
 false
}
}</pre>
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本文来自博客园，作者：观心静，转载请注明原文链接：https://www.cnblogs.com/guanxinjing/p/16082399.html 
<div style="color:orange;font-size:16px;">本文版权归作者和博客园共有，欢迎转载，但必须给出原文链接，并保留此段声明，否则保留追究法律责任的权利。 </div>
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来源：https://www.cnblogs.com/guanxinjing/p/16082399.html

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Android开发 焦点与TV

Android开发焦点与TV