make reverting autocorrect on backspace optional

fixes GH-210

app/src/main/java/helium314/keyboard/latin/inputlogic/InputLogic.java

@@ -1198,7 +1198,7 @@ public final class InputLogic {
             }
             inputTransaction.setRequiresUpdateSuggestions();
         } else {
-            if (mLastComposedWord.canRevertCommit()) {
+            if (mLastComposedWord.canRevertCommit() && inputTransaction.getMSettingsValues().mBackspaceRevertsAutocorrect) {
                 final String lastComposedWord = mLastComposedWord.mTypedWord;
                 revertCommit(inputTransaction);
                 StatsUtils.onRevertAutoCorrect();

app/src/main/java/helium314/keyboard/latin/settings/Defaults.kt

@@ -63,6 +63,7 @@ object Defaults {
     const val PREF_MORE_AUTO_CORRECTION = false
     const val PREF_AUTO_CORRECT_THRESHOLD = 0.185f
     const val PREF_AUTOCORRECT_SHORTCUTS = true
+    const val PREF_BACKSPACE_REVERTS_AUTOCORRECT = true
     const val PREF_CENTER_SUGGESTION_TEXT_TO_ENTER = false
     const val PREF_SHOW_SUGGESTIONS = true
     const val PREF_ALWAYS_SHOW_SUGGESTIONS = false

app/src/main/java/helium314/keyboard/latin/settings/Settings.java

@@ -71,6 +71,7 @@ public final class Settings implements SharedPreferences.OnSharedPreferenceChang
     public static final String PREF_MORE_AUTO_CORRECTION = "more_auto_correction";
     public static final String PREF_AUTO_CORRECT_THRESHOLD = "auto_correct_threshold";
     public static final String PREF_AUTOCORRECT_SHORTCUTS = "autocorrect_shortcuts";
+    public static final String PREF_BACKSPACE_REVERTS_AUTOCORRECT = "backspace_reverts_autocorrect";
     public static final String PREF_CENTER_SUGGESTION_TEXT_TO_ENTER = "center_suggestion_text_to_enter";
     public static final String PREF_SHOW_SUGGESTIONS = "show_suggestions";
     public static final String PREF_ALWAYS_SHOW_SUGGESTIONS = "always_show_suggestions";

app/src/main/java/helium314/keyboard/latin/settings/SettingsValues.java

@@ -135,6 +135,7 @@ public class SettingsValues {
     public final boolean mAutoCorrectionEnabledPerUserSettings;
     public final boolean mAutoCorrectEnabled;
     public final float mAutoCorrectionThreshold;
+    public final boolean mBackspaceRevertsAutocorrect;
     public final int mScoreLimitForAutocorrect;
     public final boolean mAutoCorrectShortcuts;
     private final boolean mSuggestionsEnabledPerUserSettings;
@@ -199,6 +200,7 @@ public class SettingsValues {
         mScoreLimitForAutocorrect = (mAutoCorrectionThreshold < 0) ? 600000 // very aggressive
                 : (mAutoCorrectionThreshold < 0.07 ? 800000 : 950000); // aggressive or modest
         mAutoCorrectShortcuts = prefs.getBoolean(Settings.PREF_AUTOCORRECT_SHORTCUTS, Defaults.PREF_AUTOCORRECT_SHORTCUTS);
+        mBackspaceRevertsAutocorrect = prefs.getBoolean(Settings.PREF_BACKSPACE_REVERTS_AUTOCORRECT, Defaults.PREF_BACKSPACE_REVERTS_AUTOCORRECT);
         mBigramPredictionEnabled = prefs.getBoolean(Settings.PREF_BIGRAM_PREDICTIONS, Defaults.PREF_BIGRAM_PREDICTIONS);
         mSuggestClipboardContent = prefs.getBoolean(Settings.PREF_SUGGEST_CLIPBOARD_CONTENT, Defaults.PREF_SUGGEST_CLIPBOARD_CONTENT);
         mDoubleSpacePeriodTimeout = 1100; // ms

app/src/main/java/helium314/keyboard/settings/screens/TextCorrectionScreen.kt

@@ -59,6 +59,7 @@ fun TextCorrectionScreen(
         if (autocorrectEnabled) Settings.PREF_MORE_AUTO_CORRECTION else null,
         if (autocorrectEnabled) Settings.PREF_AUTOCORRECT_SHORTCUTS else null,
         if (autocorrectEnabled) Settings.PREF_AUTO_CORRECT_THRESHOLD else null,
+        if (autocorrectEnabled) Settings.PREF_BACKSPACE_REVERTS_AUTOCORRECT else null,
         Settings.PREF_AUTO_CAP,
         R.string.settings_category_space,
         Settings.PREF_KEY_USE_DOUBLE_SPACE_PERIOD,
@@ -123,6 +124,9 @@ fun createCorrectionSettings(context: Context) = listOf(
         // todo: consider making it a slider, and maybe somehow adjust range so we can show %
         ListPreference(it, items, Defaults.PREF_AUTO_CORRECT_THRESHOLD)
     },
+    Setting(context, Settings.PREF_BACKSPACE_REVERTS_AUTOCORRECT, R.string.backspace_reverts_autocorrect) {
+        SwitchPreference(it, Defaults.PREF_BACKSPACE_REVERTS_AUTOCORRECT)
+    },
     Setting(context, Settings.PREF_AUTO_CAP,
         R.string.auto_cap, R.string.auto_cap_summary
     ) {

app/src/main/res/values/strings.xml

@@ -128,6 +128,8 @@
     <string name="auto_correct_shortcuts">Auto-correct shortcuts</string>
     <!-- Description for auto_correct_shortcuts -->
     <string name="auto_correct_shortcuts_summary">When enabled shortcuts might be expanded by autocorrect</string>
+    <!-- Option to undo auto correction with backspace -->
+    <string name="backspace_reverts_autocorrect">Backspace reverts autocorrect</string>
     <!-- Option to disable auto correction. -->
     <string name="auto_correction_threshold_mode_off">Off</string>
     <!-- Option to suggest auto correction suggestions modestly. Auto-corrects only to a word which has small edit distance from typed word. -->

app/src/test/java/helium314/keyboard/latin/InputLogicTest.kt

@@ -639,13 +639,20 @@ class InputLogicTest {
 
     @Test fun `revert autocorrect on delete`() {
         reset()
+        setInputType(InputType.TYPE_CLASS_TEXT or InputType.TYPE_TEXT_FLAG_AUTO_CORRECT)
         chainInput("hullo")
         getAutocorrectedWithSpaceAfter("hello", "hullo")
+        assertEquals("hello ", text)
         functionalKeyPress(KeyCode.DELETE)
         assertEquals("hullo", text)
 
-        // todo: now we want some way to disable revert on backspace, either per setting or something else
+        reset()
-        //  need to avoid getting into the mLastComposedWord.canRevertCommit() part of handleBackspaceEvent
+        setInputType(InputType.TYPE_CLASS_TEXT or InputType.TYPE_TEXT_FLAG_AUTO_CORRECT)
+        latinIME.prefs().edit { putBoolean(Settings.PREF_BACKSPACE_REVERTS_AUTOCORRECT, false) }
+        chainInput("hullo")
+        getAutocorrectedWithSpaceAfter("hello", "hullo")
+        functionalKeyPress(KeyCode.DELETE)
+        assertEquals("hello", text)
     }
 
     @Test fun `remove glide typing word on delete`() {
@@ -803,7 +810,7 @@ class InputLogicTest {
         val info = SuggestedWordInfo(suggestion, "", 0, 0, null, 0, 0)
         val typedInfo = SuggestedWordInfo(typedWord, "", 0, 0, null, 0, 0)
         val sw = SuggestedWords(ArrayList(listOf(typedInfo, info)), null, typedInfo, false, true, false, 0, 0)
-        latinIME.mInputLogic.setSuggestedWords(sw)
+        latinIME.mInputLogic.setSuggestedWords(sw) // this prepares for autocorrect
         input(' ')
         checkConnectionConsistency()
     }