1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not 5 * use this file except in compliance with the License. You may obtain a copy of 6 * the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 13 * License for the specific language governing permissions and limitations under 14 * the License. 15 */ 16 17 package com.android.inputmethod.keyboard; 18 19 import android.util.Log; 20 21 import java.util.Arrays; 22 import java.util.List; 23 24 public class KeyDetector { 25 private static final String TAG = KeyDetector.class.getSimpleName(); 26 private static final boolean DEBUG = false; 27 28 public static final int NOT_A_CODE = -1; 29 public static final int NOT_A_KEY = -1; 30 31 private final int mKeyHysteresisDistanceSquared; 32 33 private Keyboard mKeyboard; 34 private int mCorrectionX; 35 private int mCorrectionY; 36 private boolean mProximityCorrectOn; 37 private int mProximityThresholdSquare; 38 39 // working area 40 private static final int MAX_NEARBY_KEYS = 12; 41 private final int[] mDistances = new int[MAX_NEARBY_KEYS]; 42 private final int[] mIndices = new int[MAX_NEARBY_KEYS]; 43 44 /** 45 * This class handles key detection. 46 * 47 * @param keyHysteresisDistance if the pointer movement distance is smaller than this, the 48 * movement will not been handled as meaningful movement. The unit is pixel. 49 */ KeyDetector(float keyHysteresisDistance)50 public KeyDetector(float keyHysteresisDistance) { 51 mKeyHysteresisDistanceSquared = (int)(keyHysteresisDistance * keyHysteresisDistance); 52 } 53 setKeyboard(Keyboard keyboard, float correctionX, float correctionY)54 public void setKeyboard(Keyboard keyboard, float correctionX, float correctionY) { 55 if (keyboard == null) 56 throw new NullPointerException(); 57 mCorrectionX = (int)correctionX; 58 mCorrectionY = (int)correctionY; 59 mKeyboard = keyboard; 60 final int threshold = keyboard.mMostCommonKeyWidth; 61 mProximityThresholdSquare = threshold * threshold; 62 } 63 getKeyHysteresisDistanceSquared()64 public int getKeyHysteresisDistanceSquared() { 65 return mKeyHysteresisDistanceSquared; 66 } 67 getTouchX(int x)68 protected int getTouchX(int x) { 69 return x + mCorrectionX; 70 } 71 getTouchY(int y)72 protected int getTouchY(int y) { 73 return y + mCorrectionY; 74 } 75 getKeyboard()76 public Keyboard getKeyboard() { 77 if (mKeyboard == null) 78 throw new IllegalStateException("keyboard isn't set"); 79 return mKeyboard; 80 } 81 setProximityCorrectionEnabled(boolean enabled)82 public void setProximityCorrectionEnabled(boolean enabled) { 83 mProximityCorrectOn = enabled; 84 } 85 isProximityCorrectionEnabled()86 public boolean isProximityCorrectionEnabled() { 87 return mProximityCorrectOn; 88 } 89 setProximityThreshold(int threshold)90 public void setProximityThreshold(int threshold) { 91 mProximityThresholdSquare = threshold * threshold; 92 } 93 alwaysAllowsSlidingInput()94 public boolean alwaysAllowsSlidingInput() { 95 return false; 96 } 97 98 /** 99 * Computes maximum size of the array that can contain all nearby key indices returned by 100 * {@link #getKeyIndexAndNearbyCodes}. 101 * 102 * @return Returns maximum size of the array that can contain all nearby key indices returned 103 * by {@link #getKeyIndexAndNearbyCodes}. 104 */ getMaxNearbyKeys()105 protected int getMaxNearbyKeys() { 106 return MAX_NEARBY_KEYS; 107 } 108 109 /** 110 * Allocates array that can hold all key indices returned by {@link #getKeyIndexAndNearbyCodes} 111 * method. The maximum size of the array should be computed by {@link #getMaxNearbyKeys}. 112 * 113 * @return Allocates and returns an array that can hold all key indices returned by 114 * {@link #getKeyIndexAndNearbyCodes} method. All elements in the returned array are 115 * initialized by {@link #NOT_A_CODE} value. 116 */ newCodeArray()117 public int[] newCodeArray() { 118 int[] codes = new int[getMaxNearbyKeys()]; 119 Arrays.fill(codes, NOT_A_CODE); 120 return codes; 121 } 122 initializeNearbyKeys()123 private void initializeNearbyKeys() { 124 Arrays.fill(mDistances, Integer.MAX_VALUE); 125 Arrays.fill(mIndices, NOT_A_KEY); 126 } 127 128 /** 129 * Insert the key into nearby keys buffer and sort nearby keys by ascending order of distance. 130 * If the distance of two keys are the same, the key which the point is on should be considered 131 * as a closer one. 132 * 133 * @param keyIndex index of the key. 134 * @param distance distance between the key's edge and user touched point. 135 * @param isOnKey true if the point is on the key. 136 * @return order of the key in the nearby buffer, 0 if it is the nearest key. 137 */ sortNearbyKeys(int keyIndex, int distance, boolean isOnKey)138 private int sortNearbyKeys(int keyIndex, int distance, boolean isOnKey) { 139 final int[] distances = mDistances; 140 final int[] indices = mIndices; 141 for (int insertPos = 0; insertPos < distances.length; insertPos++) { 142 final int comparingDistance = distances[insertPos]; 143 if (distance < comparingDistance || (distance == comparingDistance && isOnKey)) { 144 final int nextPos = insertPos + 1; 145 if (nextPos < distances.length) { 146 System.arraycopy(distances, insertPos, distances, nextPos, 147 distances.length - nextPos); 148 System.arraycopy(indices, insertPos, indices, nextPos, 149 indices.length - nextPos); 150 } 151 distances[insertPos] = distance; 152 indices[insertPos] = keyIndex; 153 return insertPos; 154 } 155 } 156 return distances.length; 157 } 158 getNearbyKeyCodes(final int[] allCodes)159 private void getNearbyKeyCodes(final int[] allCodes) { 160 final List<Key> keys = getKeyboard().mKeys; 161 final int[] indices = mIndices; 162 163 // allCodes[0] should always have the key code even if it is a non-letter key. 164 if (indices[0] == NOT_A_KEY) { 165 allCodes[0] = NOT_A_CODE; 166 return; 167 } 168 169 int numCodes = 0; 170 for (int j = 0; j < indices.length && numCodes < allCodes.length; j++) { 171 final int index = indices[j]; 172 if (index == NOT_A_KEY) 173 break; 174 final int code = keys.get(index).mCode; 175 // filter out a non-letter key from nearby keys 176 if (code < Keyboard.CODE_SPACE) 177 continue; 178 allCodes[numCodes++] = code; 179 } 180 } 181 182 /** 183 * Finds all possible nearby key indices around a touch event point and returns the nearest key 184 * index. The algorithm to determine the nearby keys depends on the threshold set by 185 * {@link #setProximityThreshold(int)} and the mode set by 186 * {@link #setProximityCorrectionEnabled(boolean)}. 187 * 188 * @param x The x-coordinate of a touch point 189 * @param y The y-coordinate of a touch point 190 * @param allCodes All nearby key code except functional key are returned in this array 191 * @return The nearest key index 192 */ getKeyIndexAndNearbyCodes(int x, int y, final int[] allCodes)193 public int getKeyIndexAndNearbyCodes(int x, int y, final int[] allCodes) { 194 final List<Key> keys = getKeyboard().mKeys; 195 final int touchX = getTouchX(x); 196 final int touchY = getTouchY(y); 197 198 initializeNearbyKeys(); 199 int primaryIndex = NOT_A_KEY; 200 for (final int index : mKeyboard.getNearestKeys(touchX, touchY)) { 201 final Key key = keys.get(index); 202 final boolean isOnKey = key.isOnKey(touchX, touchY); 203 final int distance = key.squaredDistanceToEdge(touchX, touchY); 204 if (isOnKey || (mProximityCorrectOn && distance < mProximityThresholdSquare)) { 205 final int insertedPosition = sortNearbyKeys(index, distance, isOnKey); 206 if (insertedPosition == 0 && isOnKey) 207 primaryIndex = index; 208 } 209 } 210 211 if (allCodes != null && allCodes.length > 0) { 212 getNearbyKeyCodes(allCodes); 213 if (DEBUG) { 214 Log.d(TAG, "x=" + x + " y=" + y 215 + " primary=" 216 + (primaryIndex == NOT_A_KEY ? "none" : keys.get(primaryIndex).mCode) 217 + " codes=" + Arrays.toString(allCodes)); 218 } 219 } 220 221 return primaryIndex; 222 } 223 } 224