TV 应用的某些用例可能会导致依赖 TalkBack 的用户难以使用该应用。如需为这些用户提供更好的 TalkBack 体验，请查看本指南中的每个部分，并在必要时在应用中实施更改。如果您的应用使用自定义视图，您还应参阅介绍如何通过自定义视图支持无障碍功能的相应指南。
处理嵌套视图
嵌套视图可能使 TalkBack 用户难以浏览。应尽可能使父视图或子视图可由 TalkBack 聚焦，但不能同时聚焦于两者。
如需使某个视图可通过 TalkBack 聚焦，请将 focusable 和 focusableInTouchMode 属性设置为 true。必须执行此步骤，因为某些 TV 设备可能会在 TalkBack 处于启用状态时进入和退出触摸模式。
如需使视图不可聚焦，只需将 focusable 属性设置为 false 即可。不过，如果该视图是可操作（即，其对应的 AccessibilityNodeInfo 具有 ACTION_CLICK），它可能仍然可聚焦。
更改操作的说明
默认情况下，TalkBack 会读出“按选择激活”以获取可操作视图。对于某些操作，“激活”一词可能不太合适。如需提供更准确的说明，您可以进行更改：
Kotlin
findViewById<View>(R.id.custom_actionable_view).accessibilityDelegate = object : View.AccessibilityDelegate() {
override fun onInitializeAccessibilityNodeInfo(host: View, info: AccessibilityNodeInfo) {
super.onInitializeAccessibilityNodeInfo(host, info)
info.addAction(
AccessibilityAction(
AccessibilityAction.ACTION_CLICK.id,
getString(R.string.custom_label)
)
)
}
}
Java
findViewById(R.id.custom_actionable_view).setAccessibilityDelegate(new AccessibilityDelegate() {
@Override
public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfo info) {
super.onInitializeAccessibilityNodeInfo(host, info);
AccessibilityAction action = new AccessibilityAction(
AccessibilityAction.ACTION_CLICK.getId(), getString(R.string.custom_label));
info.addAction(action);
}
});
添加对滑块的支持
TV 上的 TalkBack 对滑块提供特殊支持。如需启用滑块模式，请将 ACTION_SET_PROGRESS 与 RangeInfo 对象一起添加到视图中。
用户通过按电视遥控器中间的按钮进入滑块模式。在此模式下，箭头按钮会生成 ACTION_SCROLL_FORWARD 和 ACTION_SCROLL_BACKWARD 无障碍操作。
以下示例实现了音量滑块，其级别为 1 到 10：
Kotlin
/**
* This example only provides slider functionality for TalkBack users. Additional logic should
* be added for other users. Such logic may reuse the increase and decrease methods.
*/
class VolumeSlider(context: Context?, attrs: AttributeSet?) : LinearLayout(context, attrs) {
private val min = 1
private val max = 10
private var current = 5
private var textView: TextView? = null
init {
isFocusable = true
isFocusableInTouchMode = true
val rangeInfo =
AccessibilityNodeInfo.RangeInfo(
AccessibilityNodeInfo.RangeInfo.RANGE_TYPE_INT,
min.toFloat(),
max.toFloat(),
current.toFloat()
)
accessibilityDelegate =
object : AccessibilityDelegate() {
override fun onInitializeAccessibilityNodeInfo(host: View, info: AccessibilityNodeInfo) {
super.onInitializeAccessibilityNodeInfo(host, info)
info.addAction(AccessibilityNodeInfo.AccessibilityAction.ACTION_SET_PROGRESS)
info.rangeInfo = rangeInfo
}
override fun performAccessibilityAction(host: View, action: Int, args: Bundle?): Boolean {
if (action == AccessibilityNodeInfo.AccessibilityAction.ACTION_SCROLL_FORWARD.id) {
increase()
return true
}
if (action == AccessibilityNodeInfo.AccessibilityAction.ACTION_SCROLL_BACKWARD.id) {
decrease()
return true
}
return super.performAccessibilityAction(host, action, args)
}
}
}
override fun onFinishInflate() {
super.onFinishInflate()
textView = findViewById(R.id.text)
textView!!.text = context.getString(R.string.level, current)
}
private fun increase() {
update((current + 1).coerceAtMost(max))
}
private fun decrease() {
update((current - 1).coerceAtLeast(min))
}
private fun update(newLevel: Int) {
if (textView == null) {
return
}
val newText = context.getString(R.string.level, newLevel)
// Update the user interface with the new volume.
textView!!.text = newText
// Announce the new volume.
announceForAccessibility(newText)
current = newLevel
}
}
Java
/**
* This example only provides slider functionality for TalkBack users. Additional logic should
* be added for other users. Such logic can reuse the increase and decrease methods.
*/
public class VolumeSlider extends LinearLayout {
private final int min = 1;
private final int max = 10;
private int current = 5;
private TextView textView;
public VolumeSlider(Context context, AttributeSet attrs) {
super(context, attrs);
setFocusable(true);
setFocusableInTouchMode(true);
RangeInfo rangeInfo = new RangeInfo(RangeInfo.RANGE_TYPE_INT, min, max, current);
setAccessibilityDelegate(
new AccessibilityDelegate() {
@Override
public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfo info) {
super.onInitializeAccessibilityNodeInfo(host, info);
info.addAction(AccessibilityAction.ACTION_SET_PROGRESS);
info.setRangeInfo(rangeInfo);
}
@Override
public boolean performAccessibilityAction(View host, int action, Bundle args) {
if (action == AccessibilityAction.ACTION_SCROLL_FORWARD.getId()) {
increase();
return true;
}
if (action == AccessibilityAction.ACTION_SCROLL_BACKWARD.getId()) {
decrease();
return true;
}
return super.performAccessibilityAction(host, action, args);
}
});
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
textView = findViewById(R.id.text);
textView.setText(getContext().getString(R.string.level, current));
}
private void increase() {
update(Math.min(current + 1, max));
}
private void decrease() {
update(Math.max(current - 1, min));
}
private void update(int newLevel) {
if (textView == null) {
return;
}
String newText = getContext().getString(R.string.level, newLevel);
// Update the user interface with the new volume.
textView.setText(newText);
// Announce the new volume.
announceForAccessibility(newText);
current = newLevel;
}
}