/ime/latinime/src/com/googlecode/eyesfree/inputmethod/latin/KeyDetector.java

  1/*
  2 * Copyright (C) 2010 Google Inc.
  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
 17package com.googlecode.eyesfree.inputmethod.latin;
 18
 19import android.inputmethodservice.Keyboard;
 20import android.inputmethodservice.Keyboard.Key;
 21
 22import java.util.Arrays;
 23import java.util.List;
 24
 25abstract class KeyDetector {
 26    protected Keyboard mKeyboard;
 27
 28    private Key[] mKeys;
 29
 30    protected int mCorrectionX;
 31
 32    protected int mCorrectionY;
 33
 34    protected boolean mProximityCorrectOn;
 35
 36    protected int mProximityThresholdSquare;
 37
 38    public Key[] setKeyboard(Keyboard keyboard, float correctionX, float correctionY) {
 39        if (keyboard == null)
 40            throw new NullPointerException();
 41        mCorrectionX = (int)correctionX;
 42        mCorrectionY = (int)correctionY;
 43        mKeyboard = keyboard;
 44        List<Key> keys = mKeyboard.getKeys();
 45        Key[] array = keys.toArray(new Key[keys.size()]);
 46        mKeys = array;
 47        return array;
 48    }
 49
 50    protected int getTouchX(int x) {
 51        return x + mCorrectionX;
 52    }
 53
 54    protected int getTouchY(int y) {
 55        return y + mCorrectionY;
 56    }
 57
 58    protected Key[] getKeys() {
 59        if (mKeys == null)
 60            throw new IllegalStateException("keyboard isn't set");
 61        // mKeyboard is guaranteed not to be null at setKeybaord() method if mKeys is not null
 62        return mKeys;
 63    }
 64
 65    public void setProximityCorrectionEnabled(boolean enabled) {
 66        mProximityCorrectOn = enabled;
 67    }
 68
 69    public boolean isProximityCorrectionEnabled() {
 70        return mProximityCorrectOn;
 71    }
 72
 73    public void setProximityThreshold(int threshold) {
 74        mProximityThresholdSquare = threshold * threshold;
 75    }
 76
 77    /**
 78     * Allocates array that can hold all key indices returned by {@link #getKeyIndexAndNearbyCodes}
 79     * method. The maximum size of the array should be computed by {@link #getMaxNearbyKeys}.
 80     *
 81     * @return Allocates and returns an array that can hold all key indices returned by
 82     *         {@link #getKeyIndexAndNearbyCodes} method. All elements in the returned array are
 83     *         initialized by {@link LatinKeyboardBaseView#NOT_A_KEY} value.
 84     */
 85    public int[] newCodeArray() {
 86        int[] codes = new int[getMaxNearbyKeys()];
 87        Arrays.fill(codes, LatinKeyboardBaseView.NOT_A_KEY);
 88        return codes;
 89    }
 90
 91    /**
 92     * Computes maximum size of the array that can contain all nearby key indices returned by
 93     * {@link #getKeyIndexAndNearbyCodes}.
 94     *
 95     * @return Returns maximum size of the array that can contain all nearby key indices returned
 96     *         by {@link #getKeyIndexAndNearbyCodes}.
 97     */
 98    abstract protected int getMaxNearbyKeys();
 99
100    /**
101     * Finds all possible nearby key indices around a touch event point and returns the nearest key
102     * index. The algorithm to determine the nearby keys depends on the threshold set by
103     * {@link #setProximityThreshold(int)} and the mode set by
104     * {@link #setProximityCorrectionEnabled(boolean)}.
105     *
106     * @param x The x-coordinate of a touch point
107     * @param y The y-coordinate of a touch point
108     * @param allKeys All nearby key indices are returned in this array
109     * @return The nearest key index
110     */
111    abstract public int getKeyIndexAndNearbyCodes(int x, int y, int[] allKeys);
112}