Use code point plus CJK Block penalty when unranked

Fixes <#12>.

Author: yawnoc

CHANGELOG.md

@@ -3,6 +3,12 @@
 
 ## [Unreleased]
 
+- Sorted unranked candidates by code point plus CJK Block penalty
+  (fixes [Candidate order changes between Android 7 and 8])
+
+[Candidate order changes between Android 7 and 8]:
+  https://github.com/stroke-input/stroke-input-android/issues/12
+
 
 ## [v0.9.26] (48) Mouth besides (2023-01-15)
 

app/src/main/java/io/github/yawnoc/strokeinput/StrokeInputService.java

@@ -108,9 +108,13 @@ public class StrokeInputService
   private static final String PHRASES_FILE_NAME_SIMPLIFIED = "phrases-simplified.txt";
 
   private static final int LAG_PREVENTION_CODE_POINT_COUNT = 1400;
-  private static final int LARGISH_SORTING_RANK = 3000;
-  private static final int RANKING_PENALTY_PER_CHAR = 2 * LARGISH_SORTING_RANK;
-  private static final int RANKING_PENALTY_UNPREFERRED = 10 * LARGISH_SORTING_RANK;
+  private static final int CJK_MAIN_CODE_POINT_START = 0x4E00;
+  private static final int CJK_MAIN_CODE_POINT_END = 0x9FFF;
+  private static final int CJK_EXTENSION_CODE_POINT_MIN = 0x3400;
+  private static final int CJK_EXTENSION_CODE_POINT_MAX = 0x2CEAF;
+  private static final int RANKING_PENALTY_CJK_EXTENSION = CJK_MAIN_CODE_POINT_END - CJK_EXTENSION_CODE_POINT_MIN + 1;
+  private static final int RANKING_PENALTY_PER_CHAR = 2 * CJK_EXTENSION_CODE_POINT_MAX;
+  private static final int RANKING_PENALTY_UNPREFERRED = 10 * CJK_EXTENSION_CODE_POINT_MAX;
   private static final int MAX_PREFIX_MATCH_COUNT = 30;
   private static final int MAX_PHRASE_LENGTH = 6;
 
@@ -794,10 +798,14 @@ private int computeCandidateRank(
     final boolean firstCodePointMatchesPhraseCompletionCandidate = phraseCompletionIndex > 0;
 
     final Integer sortingRank = sortingRankFromCodePoint.get(firstCodePoint);
+    final int cjkBlockPenalty =
+            (firstCodePoint < CJK_MAIN_CODE_POINT_START || firstCodePoint > CJK_MAIN_CODE_POINT_END)
+              ? RANKING_PENALTY_CJK_EXTENSION
+              : 0;
     final int sortingRankNonNull =
             (sortingRank != null)
               ? sortingRank
-              : LARGISH_SORTING_RANK;
+              : firstCodePoint + cjkBlockPenalty;
 
     final int lengthPenalty = (stringLength - 1) * RANKING_PENALTY_PER_CHAR;
     final int unpreferredPenalty =