KeyDetector.java revision 5c641a9f59735f0eaa772bde027993275b1bdfd7 
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
17package com.android.inputmethod.keyboard;
18
19
20public class KeyDetector {
21    public static final int NOT_A_CODE = -1;
22
23    private final int mKeyHysteresisDistanceSquared;
24
25    private Keyboard mKeyboard;
26    private int mCorrectionX;
27    private int mCorrectionY;
28    private boolean mProximityCorrectOn;
29
30    /**
31     * This class handles key detection.
32     *
33     * @param keyHysteresisDistance if the pointer movement distance is smaller than this, the
34     * movement will not been handled as meaningful movement. The unit is pixel.
35     */
36    public KeyDetector(float keyHysteresisDistance) {
37        mKeyHysteresisDistanceSquared = (int)(keyHysteresisDistance * keyHysteresisDistance);
38    }
39
40    public void setKeyboard(Keyboard keyboard, float correctionX, float correctionY) {
41        if (keyboard == null)
42            throw new NullPointerException();
43        mCorrectionX = (int)correctionX;
44        mCorrectionY = (int)correctionY;
45        mKeyboard = keyboard;
46    }
47
48    public int getKeyHysteresisDistanceSquared() {
49        return mKeyHysteresisDistanceSquared;
50    }
51
52    public int getTouchX(int x) {
53        return x + mCorrectionX;
54    }
55
56    // TODO: Remove vertical correction.
57    public int getTouchY(int y) {
58        return y + mCorrectionY;
59    }
60
61    public Keyboard getKeyboard() {
62        if (mKeyboard == null)
63            throw new IllegalStateException("keyboard isn't set");
64        return mKeyboard;
65    }
66
67    public void setProximityCorrectionEnabled(boolean enabled) {
68        mProximityCorrectOn = enabled;
69    }
70
71    public boolean isProximityCorrectionEnabled() {
72        return mProximityCorrectOn;
73    }
74
75    public boolean alwaysAllowsSlidingInput() {
76        return false;
77    }
78
79    /**
80     * Detect the key whose hitbox the touch point is in.
81     *
82     * @param x The x-coordinate of a touch point
83     * @param y The y-coordinate of a touch point
84     * @return the key that the touch point hits.
85     */
86    public Key detectHitKey(int x, int y) {
87        final int touchX = getTouchX(x);
88        final int touchY = getTouchY(y);
89
90        int minDistance = Integer.MAX_VALUE;
91        Key primaryKey = null;
92        for (final Key key: mKeyboard.getNearestKeys(touchX, touchY)) {
93            final boolean isOnKey = key.isOnKey(touchX, touchY);
94            final int distance = key.squaredDistanceToEdge(touchX, touchY);
95            // To take care of hitbox overlaps, we compare mCode here too.
96            if (primaryKey == null || distance < minDistance
97                    || (distance == minDistance && isOnKey && key.mCode > primaryKey.mCode)) {
98                minDistance = distance;
99                primaryKey = key;
100            }
101        }
102        return primaryKey;
103    }
104
105    public static String printableCode(Key key) {
106        return key != null ? Keyboard.printableCode(key.mCode) : "none";
107    }
108
109    public static String printableCodes(int[] codes) {
110        final StringBuilder sb = new StringBuilder();
111        boolean addDelimiter = false;
112        for (final int code : codes) {
113            if (code == NOT_A_CODE) break;
114            if (addDelimiter) sb.append(", ");
115            sb.append(Keyboard.printableCode(code));
116            addDelimiter = true;
117        }
118        return "[" + sb + "]";
119    }
120}
121