fixed a bug

android/sample-app/src/main/java/cn/learningpad/oraltrainer/sample/MainActivity.kt

@@ -93,7 +93,7 @@ class MainActivity : Activity() {
     private val mainHandler = Handler(Looper.getMainLooper())
     private var mediaRecorder: MediaRecorder? = null
     private var recordingFile: File? = null
-    private val dubSegments = mutableListOf<File>()
+    private val dubSegments = mutableMapOf<Int, File>()
     private var mergedDubFile: File? = null
     private var dubbingPlayback = false
 
@@ -103,6 +103,7 @@ class MainActivity : Activity() {
     private var catalogStatusTextValue = "正在同步"
     private var activeModule = Module.TRAIN
     private var continuousPlaybackEnabled = false
+    private var testSubtitleVisible = false
     private var landscapeSubtitleVisible = true
 
     private val screenActionReceiver = object : BroadcastReceiver() {
@@ -298,8 +299,12 @@ class MainActivity : Activity() {
         return LinearLayout(this).apply {
             orientation = LinearLayout.VERTICAL
             setBackgroundColor(COLOR_BACKGROUND)
+            if (testSubtitleVisible) {
                 addView(createPlayerSection())
                 addView(createSentenceSection())
+            } else {
+                addView(createPlayerSection())
+            }
             addView(createTestSection())
         }
     }
@@ -334,8 +339,9 @@ class MainActivity : Activity() {
                 }
                 activeModule = module
                 controller.setContinuousPlayback(
-                    if (activeModule == Module.TRAIN) continuousPlaybackEnabled else true
+                    if (activeModule == Module.TRAIN) continuousPlaybackEnabled else false
                 )
+                landscapeSubtitleVisible = activeModule == Module.TRAIN || testSubtitleVisible
                 setContentView(createContentView())
                 renderCatalog()
                 refreshCurrentUi()
@@ -767,6 +773,30 @@ class MainActivity : Activity() {
             }
         }
 
+        val subtitleToggle = LinearLayout(this).apply {
+            orientation = LinearLayout.HORIZONTAL
+            gravity = Gravity.CENTER_VERTICAL
+            setPadding(0, 10.dp, 0, 0)
+            addView(TextView(this@MainActivity).apply {
+                text = "显示字幕"
+                setTextColor(COLOR_TEXT_DARK)
+                textSize = 13f
+                typeface = Typeface.DEFAULT_BOLD
+                layoutParams = LinearLayout.LayoutParams(0, ViewGroup.LayoutParams.WRAP_CONTENT, 1f)
+            })
+            addView(Switch(this@MainActivity).apply {
+                isChecked = testSubtitleVisible
+                buttonTintList = ColorStateList.valueOf(COLOR_ACCENT)
+                setOnCheckedChangeListener { _, checked ->
+                    testSubtitleVisible = checked
+                    landscapeSubtitleVisible = checked
+                    setContentView(createContentView())
+                    refreshCurrentUi()
+                    refreshTestUi()
+                }
+            })
+        }
+
         playDubButton = dubButton("播放配音", {}).apply { isEnabled = false }
         mergeDubButton = dubButton("生成配音", {}).apply { isEnabled = false }
         shareDubButton = dubButton("分享配音", {}).apply { isEnabled = false }
@@ -798,6 +828,7 @@ class MainActivity : Activity() {
                 textSize = 16f
                 typeface = Typeface.DEFAULT_BOLD
             })
+            addView(subtitleToggle, 0)
             addView(testStatusText)
             addView(controlRow)
             addView(recordButton)
@@ -816,10 +847,15 @@ class MainActivity : Activity() {
         if (!::testStatusText.isInitialized) {
             return
         }
+        applyTestSubtitleVisibility()
         recordButton.text = if (mediaRecorder == null) "开始录音" else "停止并评测"
-        val segmentLabel = if (dubSegments.isEmpty()) "" else " · 已保存 ${dubSegments.size} 段"
         val item = controller.currentTrainingItem()
         val sentence = controller.currentSentence()
+        val currentRecording = sentence?.let { dubSegments[it.index] }
+        val segmentLabel = when {
+            currentRecording != null -> " · 本句已录音，重录将覆盖"
+            else -> ""
+        }
         testStatusText.text = if (item == null || sentence == null) {
             "请先在训练模块选择课程$segmentLabel"
         } else {
@@ -828,6 +864,20 @@ class MainActivity : Activity() {
         refreshDubButtons()
     }
 
+    private fun applyTestSubtitleVisibility() {
+        if (activeModule != Module.TEST) {
+            return
+        }
+        landscapeSubtitleVisible = testSubtitleVisible
+        if (!::sentenceText.isInitialized || !::progressBar.isInitialized) {
+            return
+        }
+        val visibility = if (testSubtitleVisible) View.VISIBLE else View.GONE
+        sentenceMetaText.visibility = visibility
+        sentenceText.visibility = visibility
+        progressBar.visibility = visibility
+    }
+
     private fun startRecording() {
         controller.pause()
         if (!::testStatusText.isInitialized) {
@@ -853,10 +903,20 @@ class MainActivity : Activity() {
             recorder.setOutputFile(file.absolutePath)
             recorder.prepare()
             recorder.start()
+            val sentence = controller.currentSentence()
+            if (sentence != null) {
+                controller.seekTo(sentence.startMs)
+                controller.setVolume(0f)
+            }
+            controller.play()
             mediaRecorder = recorder
             recordingFile = file
             recordButton.text = "停止并保存"
-            testStatusText.text = "正在录音…读完当前句子后点击“停止并保存”"
+            testStatusText.text = if (sentence == null) {
+                "正在录音…读完当前句子后点击“停止并保存”"
+            } else {
+                "正在录音…请对照静音视频口形，读完点击“停止并保存”"
+            }
         } catch (error: Throwable) {
             testStatusText.text = "录音启动失败：${error.message.orEmpty()}"
             runCatching { recorder.release() }
@@ -878,7 +938,18 @@ class MainActivity : Activity() {
         } finally {
             runCatching { recorder.release() }
         }
-        dubSegments.add(file)
+        controller.pause()
+        controller.setVolume(1f)
+        val sentenceIndex = controller.currentSentence()?.index
+        if (sentenceIndex == null) {
+            testStatusText.text = "没有可归属的句子，本次录音已丢弃"
+            file.delete()
+            recordingFile = null
+            refreshTestUi()
+            return
+        }
+        dubSegments[sentenceIndex]?.delete()
+        dubSegments[sentenceIndex] = file
         mergedDubFile = null
         recordingFile = null
         submitAssessment(Uri.fromFile(file))
@@ -907,9 +978,11 @@ class MainActivity : Activity() {
         playDubButton.isEnabled = dubSegments.isNotEmpty() && !dubbingPlayback
         mergeDubButton.isEnabled = dubSegments.size >= 2 && !dubbingPlayback
         shareDubButton.isEnabled = mergedDubFile?.exists() == true && !dubbingPlayback
+        val activeAudio = controller.currentSentence()?.let { dubSegments[it.index] }
         playDubButton.text = when {
             dubbingPlayback -> "停止配音"
             mergedDubFile?.exists() == true -> "播放配音"
+            activeAudio != null -> "播放本句配音"
             else -> "播放录音（${dubSegments.size}）"
         }
     }
@@ -919,7 +992,14 @@ class MainActivity : Activity() {
             stopDubPlayback("已停止配音播放")
             return
         }
-        startDubPlayback(mergedDubFile ?: dubSegments.lastOrNull() ?: return)
+        startDubPlayback(mergedDubFile ?: activeAudioForPlayback() ?: return)
+    }
+
+    private fun activeAudioForPlayback(): File? {
+        if (mergedDubFile != null) {
+            return mergedDubFile
+        }
+        return controller.currentSentence()?.let { sentence -> dubSegments[sentence.index] }
     }
 
     private fun startDubPlayback(audioFile: File) {
@@ -978,7 +1058,7 @@ class MainActivity : Activity() {
             var muxerAudioTrack = -1
             var presentationTimeUs = 0L
 
-            dubSegments.forEach { segment ->
+            dubSegments.toSortedMap().values.forEach { segment ->
                 val extractor = MediaExtractor().apply { setDataSource(segment.absolutePath) }
                 try {
                     val trackIndex = (0 until extractor.trackCount).firstOrNull { index ->