如何取消Talkback对Progress Bar进度百分比的自动朗读？

问题描述 #

开发中遇到Talkback会自动朗读Story进度条的百分比，尝试给承载进度条的LinearLayout设置importantForAccessibility="no"但无效，相关代码如下：

private fun setupAccessibility () {
        if(position == 0) view?.announceForAccessibility(tvEnterStorySmallText.text)
        view?.announceForAccessibility(tvEnterStoryTitle.text)
        view?.announceForAccessibility("Story ${position +1} de ${viewModel.getLastPosition()}")

    }

    private fun StoryState.setupStoryProgressBar() {
        if (binding.linearLayoutStoryProgressBar.childCount == 0) { createProgressBars() }
        setProgressBarAnimation(
            binding.linearLayoutStoryProgressBar.getChildAt(currentPosition) as LinearProgressIndicator,
            currentStoryScreen.storyTimeout.toLong(),
            getColorByMode(currentStoryScreen.mode.value)
        )
    }

    private fun StoryState.createProgressBars() {
        var progressBarWidth = context?.resources?.displayMetrics?.widthPixels?.div(stories.size) ?: STORY_PROGRESS_BAR
        progressBarWidth -= (STORY_PROGRESS_BAR_SPACING * 2)
        (0 until stories.size).forEach { _ ->
            val progressBar=LinearProgressIndicator(requireContext())
            progressBar.layoutParams = LinearLayout.LayoutParams(progressBarWidth, STORY_PROGRESS_BAR_SPACING, 1f)
            progressBar.setIndicatorColor(getColorByMode(currentStoryScreen.mode.value))
            progressBar.trackCornerRadius = STORY_PROGRESS_BAR_SPACING
            progressBar.trackThickness = STORY_PROGRESS_BAR_SPACING
            progressBar.trackColor = Color.parseColor("#A79AA9")
            progressBar.alpha = STORY_PROGRESS_BAR_ALPHA
            progressBar.setPadding(STORY_PROGRESS_BAR_SPACING, 0, STORY_PROGRESS_BAR_SPACING, 0)
            binding.linearLayoutStoryProgressBar.addView(progressBar)
        }
        binding.linearLayoutStoryProgressBar.requestLayout()
    }

    private fun setProgressBarAnimation(progressBar: LinearProgressIndicator, seconds: Long, color: Int) {
        resetProgressBars(color)
        val animator = ObjectAnimator.ofInt(progressBar, "progress", 0, STORY_PROGRESS_BAR)
        animator.duration = seconds * STORY_PROGRESS_BAR_ANIMATION_DURATION
        val screenPosition = viewModel.getCurrentPosition()
        animator.start()
        animator.setAutoCancel(true)
        animator.doOnEnd {
            if (viewModel.getCurrentPosition() == screenPosition && isTalkbackOff()) {
                goToNextStory()
            }
        }
    }

    private fun isTalkbackOff(): Boolean {
        val accessibilityManager = binding.root.context
            .getSystemService(AppCompatActivity.ACCESSIBILITY_SERVICE) as AccessibilityManager
        return accessibilityManager.isEnabled.not() &&
            accessibilityManager.isTouchExplorationEnabled.not()
    }

解决方案 #

1. 直接禁用单个ProgressBar的可访问性 #

LinearLayout的importantForAccessibility设置不会覆盖子View的属性，需要给每个创建的LinearProgressIndicator单独设置：
在createProgressBars方法中，添加以下代码到progressBar初始化后：

progressBar.importantForAccessibility = View.IMPORTANT_FOR_ACCESSIBILITY_NO

这样Talkback会完全忽略这个进度条，不会播报任何相关内容。

2. 仅禁用进度变化的播报（保留基础可访问性） #

如果不想完全移除进度条的可访问性，只是不想让Talkback播报进度变化，可以设置accessibilityLiveRegion为NONE，同时清空内容描述：

progressBar.accessibilityLiveRegion = View.ACCESSIBILITY_LIVE_REGION_NONE
progressBar.contentDescription = ""

这样即使进度变化，也不会触发Talkback的自动播报。

3. 检查动画触发的Accessibility事件 #

因为用ObjectAnimator修改progress属性时，系统会自动发送Accessibility事件。如果上面的方法无效，可以尝试在动画期间临时禁用可访问性，动画结束后恢复（不过一般前两种方法足够解决问题）。

内容的提问来源于stack exchange，提问作者Rayssa Vanessa