1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of 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,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under 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    private final int mKeyHysteresisDistanceForSlidingModifierSquared;
25
26    private Keyboard mKeyboard;
27    private int mCorrectionX;
28    private int mCorrectionY;
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 be handled as meaningful movement. The unit is pixel.
35     */
36    public KeyDetector(float keyHysteresisDistance) {
37        this(keyHysteresisDistance, keyHysteresisDistance);
38    }
39
40    /**
41     * This class handles key detection.
42     *
43     * @param keyHysteresisDistance if the pointer movement distance is smaller than this, the
44     * movement will not be handled as meaningful movement. The unit is pixel.
45     * @param keyHysteresisDistanceForSlidingModifier the same parameter for sliding input that
46     * starts from a modifier key such as shift and symbols key.
47     */
48    public KeyDetector(float keyHysteresisDistance, float keyHysteresisDistanceForSlidingModifier) {
49        mKeyHysteresisDistanceSquared = (int)(keyHysteresisDistance * keyHysteresisDistance);
50        mKeyHysteresisDistanceForSlidingModifierSquared = (int)(
51                keyHysteresisDistanceForSlidingModifier * keyHysteresisDistanceForSlidingModifier);
52    }
53
54    public void setKeyboard(Keyboard keyboard, float correctionX, float correctionY) {
55        if (keyboard == null) {
56            throw new NullPointerException();
57        }
58        mCorrectionX = (int)correctionX;
59        mCorrectionY = (int)correctionY;
60        mKeyboard = keyboard;
61    }
62
63    public int getKeyHysteresisDistanceSquared(boolean isSlidingFromModifier) {
64        return isSlidingFromModifier
65                ? mKeyHysteresisDistanceForSlidingModifierSquared : mKeyHysteresisDistanceSquared;
66    }
67
68    public int getTouchX(int x) {
69        return x + mCorrectionX;
70    }
71
72    // TODO: Remove vertical correction.
73    public int getTouchY(int y) {
74        return y + mCorrectionY;
75    }
76
77    public Keyboard getKeyboard() {
78        if (mKeyboard == null) {
79            throw new IllegalStateException("keyboard isn't set");
80        }
81        return mKeyboard;
82    }
83
84    public boolean alwaysAllowsSlidingInput() {
85        return false;
86    }
87
88    /**
89     * Detect the key whose hitbox the touch point is in.
90     *
91     * @param x The x-coordinate of a touch point
92     * @param y The y-coordinate of a touch point
93     * @return the key that the touch point hits.
94     */
95    public Key detectHitKey(int x, int y) {
96        final int touchX = getTouchX(x);
97        final int touchY = getTouchY(y);
98
99        int minDistance = Integer.MAX_VALUE;
100        Key primaryKey = null;
101        for (final Key key: mKeyboard.getNearestKeys(touchX, touchY)) {
102            // An edge key always has its enlarged hitbox to respond to an event that occurred in
103            // the empty area around the key. (@see Key#markAsLeftEdge(KeyboardParams)} etc.)
104            if (!key.isOnKey(touchX, touchY)) {
105                continue;
106            }
107            final int distance = key.squaredDistanceToEdge(touchX, touchY);
108            if (distance > minDistance) {
109                continue;
110            }
111            // To take care of hitbox overlaps, we compare key's code here too.
112            if (primaryKey == null || distance < minDistance
113                    || key.getCode() > primaryKey.getCode()) {
114                minDistance = distance;
115                primaryKey = key;
116            }
117        }
118        return primaryKey;
119    }
120
121    public static String printableCode(Key key) {
122        return key != null ? Constants.printableCode(key.getCode()) : "none";
123    }
124
125    public static String printableCodes(int[] codes) {
126        final StringBuilder sb = new StringBuilder();
127        boolean addDelimiter = false;
128        for (final int code : codes) {
129            if (code == Constants.NOT_A_CODE) break;
130            if (addDelimiter) sb.append(", ");
131            sb.append(Constants.printableCode(code));
132            addDelimiter = true;
133        }
134        return "[" + sb + "]";
135    }
136}
137