From cb72fb0d5a3d44e64e6664b6f0006bffed9ad80f Mon Sep 17 00:00:00 2001
From: Eoin Mcloughlin <helloworld@eoinrul.es>
Date: Sun, 28 Aug 2022 10:01:55 +0100
Subject: [PATCH] Use sound generator to calculate real lesson duration

Approximation of farnsworth WPM wasn't accurate enough.
This can go a second or two over, but that feels alright.
---
 .../java/es/eoinrul/ecwt/DitDahGenerator.kt   | 19 +++++++++++++++++--
 .../java/es/eoinrul/ecwt/TrainingActivity.kt  | 10 ++++------
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/app/src/main/java/es/eoinrul/ecwt/DitDahGenerator.kt b/app/src/main/java/es/eoinrul/ecwt/DitDahGenerator.kt
index 2249698..3baecbc 100644
--- a/app/src/main/java/es/eoinrul/ecwt/DitDahGenerator.kt
+++ b/app/src/main/java/es/eoinrul/ecwt/DitDahGenerator.kt
@@ -414,7 +414,7 @@ class DitDahSoundStream {
         // Apply an attack and release envelope to each of the samples to avoid a pop
         // in the audio that's generated. Empirically, 8ms seems to eliminate it while
         // still being fast enough that it works on the fastest WPM setting:
-        var attackReleaseDuration = 0.008f;
+        val attackReleaseDuration = 0.008f;
         val attackReleaseTimeInSamples = (attackReleaseDuration * mAudioSampleRate).toInt();
         for(i in 0 until attackReleaseTimeInSamples) {
             val frac = i.toFloat() / attackReleaseTimeInSamples.toFloat();
@@ -436,6 +436,21 @@ class DitDahSoundStream {
         }
     }
 
+    // Returns the duration of the sequence, in seconds
+    fun durationOf(symbols : List<SoundTypes>): Float {
+        var numSamples = 0
+        for(sym in symbols) {
+            numSamples += when(sym) {
+                SoundTypes.DIT -> mDitSound
+                SoundTypes.DAH -> mDahSound
+                SoundTypes.LETTER_SPACE -> mCharacterSpacingSound
+                SoundTypes.WORD_SPACE -> mWordSpacingSound
+            }.size
+        }
+
+        return numSamples.toFloat() / mAudioSampleRate.toFloat();
+    }
+
     fun quit() {
         mShouldQuit = true;
 
@@ -539,4 +554,4 @@ class DitDahSoundStream {
         .setTransferMode(AudioTrack.MODE_STREAM)
         .setBufferSizeInBytes(mAudioSampleRate)
         .build();
-}
\ No newline at end of file
+}
diff --git a/app/src/main/java/es/eoinrul/ecwt/TrainingActivity.kt b/app/src/main/java/es/eoinrul/ecwt/TrainingActivity.kt
index 6026978..f59f08a 100644
--- a/app/src/main/java/es/eoinrul/ecwt/TrainingActivity.kt
+++ b/app/src/main/java/es/eoinrul/ecwt/TrainingActivity.kt
@@ -79,8 +79,6 @@ class TrainingActivity : AppCompatActivity(),
         if(mLessonStarted)
             return
 
-         val generatorSettings = DitDahGeneratorSettings()
-
         val sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this)
 
         val lessonLengthInMinutes = sharedPreferences.getInt(getString(R.string.setting_koch_lesson_length_key), 1)
@@ -93,12 +91,12 @@ class TrainingActivity : AppCompatActivity(),
 
         var sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this)
         val shortLessonDebug = sharedPrefs.getBoolean("debug_override_lesson_length", false)
-        val numberOfWords = if(shortLessonDebug) {
+        val lessonDurationS = if(shortLessonDebug) {
             // This makes it much faster to test functionality, if enabled in preferences
-            2
+            15
         } else {
             // This is only an approximation
-            generatorSettings.farnsworthWordsPerMinute * lessonLengthInMinutes
+            lessonLengthInMinutes * 60
         }
 
         // If selected in preferences, modify the alphabet used for the lesson so that
@@ -117,7 +115,7 @@ class TrainingActivity : AppCompatActivity(),
         // Create the actual text used for the lesson
         var lessonText = String()
         var rng = Random.Default
-        for(i in 0 until numberOfWords) {
+        while(mSoundPlayer!!.durationOf(StringToSoundSequence(lessonText)) < lessonDurationS) {
             val thisWordSize = rng.nextInt(minWordSize, maxWordSize + 1)
             for(c in 0 until thisWordSize) {
                 val randomLetterIndex = rng.nextInt(0, lessonAlphabet.length)