Add keyHysteresisDistance xml attribute

This change also introduces MiniKeyboardKeyDetector and
mini_keyboad_slide_allowance parameter to tune the key detection
behavior.

Bug: 2993769
Change-Id: I1932b0a382e172cb77b9e098ae182049c834dfe0

1 files changed, 59 insertions, 0 deletions

diff --git a/java/src/com/android/inputmethod/latin/MiniKeyboardKeyDetector.java b/java/src/com/android/inputmethod/latin/MiniKeyboardKeyDetector.java
new file mode 100644
index 000000000..709d082be
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/MiniKeyboardKeyDetector.java
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2010 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.android.inputmethod.latin;
+
+import android.inputmethodservice.Keyboard.Key;
+
+class MiniKeyboardKeyDetector extends KeyDetector {
+    private static final int MAX_NEARBY_KEYS = 1;
+
+    private final int mSlideAllowanceSquare;
+    private final int mSlideAllowanceSquareTop;
+
+    public MiniKeyboardKeyDetector(float slideAllowance) {
+        super();
+        mSlideAllowanceSquare = (int)(slideAllowance * slideAllowance);
+        // Top slide allowance is slightly longer (sqrt(2) times) than other edges.
+        mSlideAllowanceSquareTop = mSlideAllowanceSquare * 2;
+    }
+
+    @Override
+    protected int getMaxNearbyKeys() {
+        return MAX_NEARBY_KEYS;
+    }
+
+    @Override
+    public int getKeyIndexAndNearbyCodes(int x, int y, int[] allKeys) {
+        final Key[] keys = getKeys();
+        final int touchX = getTouchX(x);
+        final int touchY = getTouchY(y);
+        int closestKey = LatinKeyboardBaseView.NOT_A_KEY;
+        int closestKeyDist = (y < 0) ? mSlideAllowanceSquareTop : mSlideAllowanceSquare;
+        final int keyCount = keys.length;
+        for (int i = 0; i < keyCount; i++) {
+            final Key key = keys[i];
+            int dist = key.squaredDistanceFrom(touchX, touchY);
+            if (dist < closestKeyDist) {
+                closestKey = i;
+                closestKeyDist = dist;
+            }
+        }
+        if (allKeys != null && closestKey != LatinKeyboardBaseView.NOT_A_KEY)
+            allKeys[0] = closestKey;
+        return closestKey;
+    }
+}