Using distance to the edge of key as proximity detection

Because there may be very long key, such as space bar on tablet, we
should not use the distance between the touch point and the center of
key as proximity detection.  Instead of that, this change uses the
distance between the point and the nearest edge of key as proximity
detection.

Also this change fixes the bug that space key (code 32) was not
counted in proximity detection.

Bug: 3164020
Bug: 3168138
Change-Id: I687f1ce94a8e944c3f6eea0fe00e18ed6e68e278

1 files changed, 17 insertions, 26 deletions

diff --git a/java/src/com/android/inputmethod/latin/ProximityKeyDetector.java b/java/src/com/android/inputmethod/latin/ProximityKeyDetector.java
index 01122ebb7..35bdc6728 100644
--- a/java/src/com/android/inputmethod/latin/ProximityKeyDetector.java
+++ b/java/src/com/android/inputmethod/latin/ProximityKeyDetector.java
@@ -36,41 +36,34 @@ class ProximityKeyDetector extends KeyDetector {
         final Key[] keys = getKeys();
         final int touchX = getTouchX(x);
         final int touchY = getTouchY(y);
+
         int primaryIndex = BaseKeyboardView.NOT_A_KEY;
-        int closestKey = BaseKeyboardView.NOT_A_KEY;
+        int closestKeyIndex = BaseKeyboardView.NOT_A_KEY;
         int closestKeyDist = mProximityThresholdSquare + 1;
-        int[] distances = mDistances;
+        final int[] distances = mDistances;
         Arrays.fill(distances, Integer.MAX_VALUE);
-        int [] nearestKeyIndices = mKeyboard.getNearestKeys(touchX, touchY);
-        final int keyCount = nearestKeyIndices.length;
-        for (int i = 0; i < keyCount; i++) {
-            final Key key = keys[nearestKeyIndices[i]];
-            int dist = 0;
-            boolean isInside = key.isInside(touchX, touchY);
-            if (isInside) {
-                primaryIndex = nearestKeyIndices[i];
-            }
-
-            if (((mProximityCorrectOn
-                    && (dist = key.squaredDistanceFrom(touchX, touchY)) < mProximityThresholdSquare)
-                    || isInside)
-                    && key.codes[0] > 32) {
-                // Find insertion point
-                final int nCodes = key.codes.length;
+        for (final int index : mKeyboard.getNearestKeys(touchX, touchY)) {
+            final Key key = keys[index];
+            final boolean isInside = key.isInside(touchX, touchY);
+            if (isInside)
+                primaryIndex = index;
+            final int dist = key.squaredDistanceToEdge(touchX, touchY);
+            if (isInside || (mProximityCorrectOn && dist < mProximityThresholdSquare)) {
                 if (dist < closestKeyDist) {
                     closestKeyDist = dist;
-                    closestKey = nearestKeyIndices[i];
+                    closestKeyIndex = index;
                 }
 
                 if (allKeys == null) continue;
-
+                final int nCodes = key.codes.length;
+                // Find insertion point
                 for (int j = 0; j < distances.length; j++) {
                     if (distances[j] > dist) {
                         // Make space for nCodes codes
                         System.arraycopy(distances, j, distances, j + nCodes,
-                                distances.length - j - nCodes);
+                                distances.length - (j + nCodes));
                         System.arraycopy(allKeys, j, allKeys, j + nCodes,
-                                allKeys.length - j - nCodes);
+                                allKeys.length - (j + nCodes));
                         System.arraycopy(key.codes, 0, allKeys, j, nCodes);
                         Arrays.fill(distances, j, j + nCodes, dist);
                         break;
@@ -78,9 +71,7 @@ class ProximityKeyDetector extends KeyDetector {
                 }
             }
         }
-        if (primaryIndex == BaseKeyboardView.NOT_A_KEY) {
-            primaryIndex = closestKey;
-        }
-        return primaryIndex;
+
+        return primaryIndex == BaseKeyboardView.NOT_A_KEY ? closestKeyIndex : primaryIndex;
     }
 }