diff --git a/native/jni/src/dictionary.cpp b/native/jni/src/dictionary.cpp
index e0b7f87..10ea9fe 100644
--- a/native/jni/src/dictionary.cpp
+++ b/native/jni/src/dictionary.cpp
@@ -44,7 +44,8 @@
             fullWordMultiplier, maxWordLength, maxWords, options);
     mBigramDictionary = new BigramDictionary(mDict + headerSize, maxWordLength);
     mGestureDecoder = new GestureDecoder(maxWordLength, maxWords);
-    mGestureDecoder->setDict(mUnigramDictionary, mBigramDictionary);
+    mGestureDecoder->setDict(mUnigramDictionary, mBigramDictionary,
+            mDict + headerSize /* dict root */, 0 /* root pos */);
 }
 
 Dictionary::~Dictionary() {
diff --git a/native/jni/src/gesture/gesture_decoder_impl.h b/native/jni/src/gesture/impl/gesture_decoder_impl.h
similarity index 100%
rename from native/jni/src/gesture/gesture_decoder_impl.h
rename to native/jni/src/gesture/impl/gesture_decoder_impl.h
diff --git a/native/jni/src/gesture/incremental_decoder_impl.h b/native/jni/src/gesture/impl/incremental_decoder_impl.h
similarity index 94%
rename from native/jni/src/gesture/incremental_decoder_impl.h
rename to native/jni/src/gesture/impl/incremental_decoder_impl.h
index 5731ad8..84121e8 100644
--- a/native/jni/src/gesture/incremental_decoder_impl.h
+++ b/native/jni/src/gesture/impl/incremental_decoder_impl.h
@@ -28,7 +28,8 @@
 
  public:
      IncrementalDecoderImpl(int maxWordLength, int maxWords) { };
-     void setDict(const UnigramDictionary *dict, const BigramDictionary *bigram) { };
+     void setDict(const UnigramDictionary *dict, const BigramDictionary *bigram,
+             const uint8_t *dictRoot, int rootPos) { };
      void setPrevWord(const int32_t *prevWord, int prevWordLength) { };
      void reset() { };
 
diff --git a/native/jni/src/gesture/incremental_decoder_interface.h b/native/jni/src/gesture/incremental_decoder_interface.h
index d34b0da..c5404a4 100644
--- a/native/jni/src/gesture/incremental_decoder_interface.h
+++ b/native/jni/src/gesture/incremental_decoder_interface.h
@@ -31,7 +31,8 @@
             int *pointerIds, int *codes, int inputSize, int commitPoint, bool isMainDict,
             unsigned short *outWords, int *frequencies, int *outputIndices) = 0;
     virtual void reset() = 0;
-    virtual void setDict(const UnigramDictionary *dict, const BigramDictionary *bigram) = 0;
+    virtual void setDict(const UnigramDictionary *dict, const BigramDictionary *bigram,
+            const uint8_t *dictRoot, int rootPos) = 0;
     virtual void setPrevWord(const int32_t *prevWord, int prevWordLength) = 0;
     virtual ~IncrementalDecoderInterface() { };
 };
diff --git a/native/jni/src/proximity_info.cpp b/native/jni/src/proximity_info.cpp
index 2ba244a..a4a6411 100644
--- a/native/jni/src/proximity_info.cpp
+++ b/native/jni/src/proximity_info.cpp
@@ -15,6 +15,7 @@
  */
 
 #include <assert.h>
+#include <math.h>
 #include <stdio.h>
 #include <string>
 
@@ -210,4 +211,25 @@
     }
     return mCodeToKeyIndex[baseLowerC];
 }
+
+// TODO: [Staging] Optimize
+void ProximityInfo::getCenters(int *centerXs, int *centerYs, int *codeToKeyIndex,
+        int *keyToCodeIndex, int *keyCount, int *keyWidth) const {
+    *keyCount = KEY_COUNT;
+    *keyWidth = sqrt((float)MOST_COMMON_KEY_WIDTH_SQUARE);
+
+    for (int i = 0; i < KEY_COUNT; ++i) {
+        const int code = mKeyCharCodes[i];
+        const int lowerCode = toBaseLowerCase(code);
+        centerXs[i] = mKeyXCoordinates[i] + mKeyWidths[i] / 2;
+        centerYs[i] = mKeyYCoordinates[i] + mKeyHeights[i] / 2;
+        codeToKeyIndex[code] = i;
+        if (code != lowerCode && lowerCode >= 0 && lowerCode <= MAX_CHAR_CODE) {
+            codeToKeyIndex[lowerCode] = i;
+            keyToCodeIndex[i] = lowerCode;
+        } else {
+            keyToCodeIndex[i] = code;
+        }
+    }
+}
 } // namespace latinime
diff --git a/native/jni/src/proximity_info.h b/native/jni/src/proximity_info.h
index fec6555..d58935c 100644
--- a/native/jni/src/proximity_info.h
+++ b/native/jni/src/proximity_info.h
@@ -98,6 +98,10 @@
         return GRID_HEIGHT;
     }
 
+    // Returns the keyboard key-center information.
+    void getCenters(int *centersX, int *centersY, int *codeToKeyIndex, int *keyToCodeIndex,
+            int *keyCount, int *keyWidth) const;
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(ProximityInfo);
     // The max number of the keys in one keyboard layout