android - 亚行可访问性重点变更

Question

我想知道如何在 Talkback 开启时让 ADB 调整可访问性焦点。我努力了:

adb shell input trackball roll 0 1
adb shell input [stylusdpad|keyboard|mouse|touchpad|gamepad|touchnavigation|joystick|touchscreen|stylus|trackball] swipe 180 780 540 780
adb shell input keyboard keyevent KEYCODE_TAB
adb shell input keyevent KEYCODE_NAVIGATE_NEXT
adb shell "input keyevent KEYCODE_ALT_LEFT & input keyevent KEYCODE_DPAD_LEFT"

我还尝试使用 adb shell getevent 记录事件并在没有成功的情况下播放它们。
但是我总是必须物理地滑动屏幕(即 ADB 滑动不起作用 )才能改变可访问性焦点。有没有办法通过可访问性来做到这一点，只是下一个和上一个 Action ？
我找到了这个 article by Google :

Navigation

• Move to next item: Alt + Right arrowNote: In continuous reading mode, this shortcut fast-forwards through the text.
• Move to previous item: Alt + Left arrowNote: In continuous reading mode, this shortcut rewinds the text.

这意味着我只需要一次发送多个按键，对吗？我试过这个， based on another SO answer :

device="/dev/input/event3"
ALT_KEY=57#18 #KEYCODE_ALT_LEFT
LEFT_KEY=21#37 #KEYCODE_DPAD_RIGHT
RIGHT_KEY=22#39 #KEYCODE_DPAD_RIGHT

device="/dev/input/event0"
adb shell "sendevent $device 1 $ALT_KEY 1 & sendevent $device 0 0 0 & sendevent $device 1 $RIGHT_KEY 1 & sendevent $device 0 0 0"
device="/dev/input/event1"
adb shell "sendevent $device 1 $ALT_KEY 1 & sendevent $device 0 0 0 & sendevent $device 1 $RIGHT_KEY 1 & sendevent $device 0 0 0"
device="/dev/input/event2"
adb shell "sendevent $device 1 $ALT_KEY 1 & sendevent $device 0 0 0 & sendevent $device 1 $RIGHT_KEY 1 & sendevent $device 0 0 0"
device="/dev/input/event3"
adb shell "sendevent $device 1 $ALT_KEY 1 & sendevent $device 0 0 0 & sendevent $device 1 $RIGHT_KEY 1 & sendevent $device 0 0 0"

device="/dev/input/event0"
adb shell "sendevent $device 1 $ALT_KEY 1 && sendevent $device 0 0 0 && sendevent $device 1 $RIGHT_KEY 1 && sendevent $device 0 0 0"
device="/dev/input/event1"
adb shell "sendevent $device 1 $ALT_KEY 1 && sendevent $device 0 0 0 && sendevent $device 1 $RIGHT_KEY 1 && sendevent $device 0 0 0"
device="/dev/input/event2"
adb shell "sendevent $device 1 $ALT_KEY 1 && sendevent $device 0 0 0 && sendevent $device 1 $RIGHT_KEY 1 && sendevent $device 0 0 0"
device="/dev/input/event3"
adb shell "sendevent $device 1 $ALT_KEY 1 && sendevent $device 0 0 0 && sendevent $device 1 $RIGHT_KEY 1 && sendevent $device 0 0 0"

device="/dev/input/event0"
adb shell "sendevent $device 1 $ALT_KEY 1 && sendevent $device 1 $RIGHT_KEY 1 && sendevent $device 0 0 0"
device="/dev/input/event1"
adb shell "sendevent $device 1 $ALT_KEY 1 && sendevent $device 1 $RIGHT_KEY 1 && sendevent $device 0 0 0"
device="/dev/input/event2"
adb shell "sendevent $device 1 $ALT_KEY 1 && sendevent $device 1 $RIGHT_KEY 1 && sendevent $device 0 0 0"
device="/dev/input/event3"
adb shell "sendevent $device 1 $ALT_KEY 1 && sendevent $device 1 $RIGHT_KEY 1 && sendevent $device 0 0 0"

(虽然我知道 device0 实际上是键盘设备，但我还是想尝试一下)

Answer 1

我在这里的回答将尽可能简洁。我的完整代码可在 GitHub 上获得.
据我所知，开发人员无法通过 ADB 执行可访问性操作，他们必须创建 Accessibility service为了act on behalf of an Accessibility user并创建一个 Broadcast Receiver这样它就可以通过亚行接受输入。这是答案的三分之二，需要多一个组件，因为开发人员无法通过 ADB 激活无障碍服务!这必须手动完成 每次切换可访问性 或通过accessibility shortcuts - 其中只能有一个。 编辑 我也想通了这一点:)
无障碍服务
开发者文档为 Accessibility Service 提供了一种机制。 :

An accessibility service is an application that provides user interface enhancements to assist users with disabilities, or who may temporarily be unable to fully interact with a device. For example, users who are driving, taking care of a young child or attending a very loud party might need additional or alternative interface feedback.

我关注了 Google Codelab构建一个可以对用户采取行动的服务。这是该服务的一个 fragment ，用于左右滑动(用户导航):

    fun swipeHorizontal(leftToRight: Boolean) {
        val swipePath = Path()
        if (leftToRight) {
            swipePath.moveTo(halfWidth - quarterWidth, halfHeight)
            swipePath.lineTo(halfWidth + quarterWidth, halfHeight)
        } else {
            swipePath.moveTo(halfWidth + quarterWidth, halfHeight)
            swipePath.lineTo(halfWidth - quarterWidth, halfHeight)
        }
        val gestureBuilder = GestureDescription.Builder()
        gestureBuilder.addStroke(StrokeDescription(swipePath, 0, 500))
        dispatchGesture(gestureBuilder.build(), GestureResultCallback(baseContext), null)
    }

广播接收器。
需要注意的是，启用服务时会注册 Receiver:

    override fun onServiceConnected() {
        IntentFilter().apply {
            addAction(ACCESSIBILITY_CONTROL_BROADCAST_ACTION)

            priority = 100

            registerReceiver(accessibilityActionReceiver, this)           
        }
   // REMEMBER TO DEREGISTER!

然后接收者可以响应 Intent 并调用服务:

    override fun onReceive(context: Context?, intent: Intent?) {
        require(intent != null) { "Intent is required" }
        val serviceReference = //get a reference to the service somehow

        intent.getStringExtra(ACCESSIBILITY_ACTION)?.let {
            serviceReference.apply {
                when (it) {
                    ACTION_NEXT -> swipeHorizontal(true)
                    ACTION_PREV -> swipeHorizontal(false)
                    //...

adb 上的示例用法:

adb shell am broadcast -a com.balsdon.talkback.accessibility -e ACTION "ACTION_PREV"

编辑
通过 adb 启动服务:
感谢 this comment

TALKBACK="com.google.android.marvin.talkback/com.google.android.marvin.talkback.TalkBackService"
ALLYDEV="com.balsdon.accessibilityBroadcastService/.AccessibilityBroadcastService"
adb shell settings put secure enabled_accessibility_services $TALKBACK:$ALLYDEV

辅助功能快捷方式
** 编辑:不再需要，但无论如何我都会把它留在这里 **
可能最烦人的事情是每次切换可访问性时，服务都会关闭。所以我添加了我的 service as a shortcut按下 VOLUME_UP 和 VOLUME_DOWN 键。 Thanks to this question .

  INPUT_DEVICE="/dev/input/event1" # VOLUME KEYS EVENT FILE
  VOLUME_DOWN=114 #0x0072
  VOLUME_UP=115   #0x0073
  BLANK_EVENT="sendevent $INPUT_DEVICE 0 0 0"

  INST_DN="sendevent $INPUT_DEVICE 1 $VOLUME_DOWN 1 && $BLANK_EVENT && sendevent $INPUT_DEVICE 1 $VOLUME_UP 1 && $BLANK_EVENT"
  INST_UP="sendevent $INPUT_DEVICE 1 $VOLUME_DOWN 0 && $BLANK_EVENT && sendevent $INPUT_DEVICE 1 $VOLUME_UP 0 && $BLANK_EVENT"
  adb shell "$INST_DN"
  sleep 3
  adb shell "$INST_UP"

我已经有了 toggling accessibility on/off 的脚本，所以我只是在此基础上添加了这一点，并且每次都可以运行我的服务。
编辑 2
我在 AOSP 上提出问题关于开发人员需要编写“滑动服务”而不是“导航服务”这一事实。这是有问题的，因为可以修改手势，然后我的系统将无法按预期运行。相反，我应该能够调用我想要执行的特定操作 NAVIGATE TO NEXT ELEMENT或 NAVIGATE TO PREVIOUS ELEMENT与“向右滑动”和“向左滑动”相反——阅读了 WCAG 指南后，我不认为这违反了原则。