KeyDetector.java revision 3f00c6151fb7140fb7752bad3b978daacd9ec5aa 
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
19import com.android.inputmethod.latin.Constants;
20
21
22public class KeyDetector {
23    private final int mKeyHysteresisDistanceSquared;
24
25    private Keyboard mKeyboard;
26    private int mCorrectionX;
27    private int mCorrectionY;
28
29    /**
30     * This class handles key detection.
31     *
32     * @param keyHysteresisDistance if the pointer movement distance is smaller than this, the
33     * movement will not been handled as meaningful movement. The unit is pixel.
34     */
35    public KeyDetector(float keyHysteresisDistance) {
36        mKeyHysteresisDistanceSquared = (int)(keyHysteresisDistance * keyHysteresisDistance);
37    }
38
39    public void setKeyboard(Keyboard keyboard, float correctionX, float correctionY) {
40        if (keyboard == null) {
41            throw new NullPointerException();
42        }
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        }
65        return mKeyboard;
66    }
67
68    public boolean alwaysAllowsSlidingInput() {
69        return false;
70    }
71
72    /**
73     * Detect the key whose hitbox the touch point is in.
74     *
75     * @param x The x-coordinate of a touch point
76     * @param y The y-coordinate of a touch point
77     * @return the key that the touch point hits.
78     */
79    public Key detectHitKey(int x, int y) {
80        final int touchX = getTouchX(x);
81        final int touchY = getTouchY(y);
82
83        int minDistance = Integer.MAX_VALUE;
84        Key primaryKey = null;
85        for (final Key key: mKeyboard.getNearestKeys(touchX, touchY)) {
86            // An edge key always has its enlarged hitbox to respond to an event that occurred in
87            // the empty area around the key. (@see Key#markAsLeftEdge(KeyboardParams)} etc.)
88            if (!key.isOnKey(touchX, touchY)) {
89                continue;
90            }
91            final int distance = key.squaredDistanceToEdge(touchX, touchY);
92            if (distance > minDistance) {
93                continue;
94            }
95            // To take care of hitbox overlaps, we compare mCode here too.
96            if (primaryKey == null || distance < minDistance || key.mCode > primaryKey.mCode) {
97                minDistance = distance;
98                primaryKey = key;
99            }
100        }
101        return primaryKey;
102    }
103
104    public static String printableCode(Key key) {
105        return key != null ? Keyboard.printableCode(key.mCode) : "none";
106    }
107
108    public static String printableCodes(int[] codes) {
109        final StringBuilder sb = new StringBuilder();
110        boolean addDelimiter = false;
111        for (final int code : codes) {
112            if (code == Constants.NOT_A_CODE) break;
113            if (addDelimiter) sb.append(", ");
114            sb.append(Keyboard.printableCode(code));
115            addDelimiter = true;
116        }
117        return "[" + sb + "]";
118    }
119}
120