NumberKeyListener.java revision 3dec7d563a2f3e1eb967ce2054a00b6620e3558c 
1/*
2 * Copyright (C) 2006 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 android.text.method;
18
19import android.view.KeyEvent;
20import android.view.View;
21import android.text.Editable;
22import android.text.InputFilter;
23import android.text.Selection;
24import android.text.Spannable;
25import android.text.SpannableStringBuilder;
26import android.text.Spanned;
27
28/**
29 * For numeric text entry
30 */
31public abstract class NumberKeyListener extends BaseKeyListener
32    implements InputFilter
33{
34    /**
35     * You can say which characters you can accept.
36     */
37    protected abstract char[] getAcceptedChars();
38
39    protected int lookup(KeyEvent event, Spannable content) {
40        return event.getMatch(getAcceptedChars(), getMetaState(content));
41    }
42
43    public CharSequence filter(CharSequence source, int start, int end,
44                               Spanned dest, int dstart, int dend) {
45        char[] accept = getAcceptedChars();
46        boolean filter = false;
47
48        int i;
49        for (i = start; i < end; i++) {
50            if (!ok(accept, source.charAt(i))) {
51                break;
52            }
53        }
54
55        if (i == end) {
56            // It was all OK.
57            return null;
58        }
59
60        if (end - start == 1) {
61            // It was not OK, and there is only one char, so nothing remains.
62            return "";
63        }
64
65        SpannableStringBuilder filtered =
66            new SpannableStringBuilder(source, start, end);
67        i -= start;
68        end -= start;
69
70        int len = end - start;
71        // Only count down to i because the chars before that were all OK.
72        for (int j = end - 1; j >= i; j--) {
73            if (!ok(accept, source.charAt(j))) {
74                filtered.delete(j, j + 1);
75            }
76        }
77
78        return filtered;
79    }
80
81    protected static boolean ok(char[] accept, char c) {
82        for (int i = accept.length - 1; i >= 0; i--) {
83            if (accept[i] == c) {
84                return true;
85            }
86        }
87
88        return false;
89    }
90
91    @Override
92    public boolean onKeyDown(View view, Editable content,
93                             int keyCode, KeyEvent event) {
94        int selStart, selEnd;
95
96        {
97            int a = Selection.getSelectionStart(content);
98            int b = Selection.getSelectionEnd(content);
99
100            selStart = Math.min(a, b);
101            selEnd = Math.max(a, b);
102        }
103
104        if (selStart < 0 || selEnd < 0) {
105            selStart = selEnd = 0;
106            Selection.setSelection(content, 0);
107        }
108
109        int i = event != null ? lookup(event, content) : 0;
110        int repeatCount = event != null ? event.getRepeatCount() : 0;
111        if (repeatCount == 0) {
112            if (i != 0) {
113                if (selStart != selEnd) {
114                    Selection.setSelection(content, selEnd);
115                }
116
117                content.replace(selStart, selEnd, String.valueOf((char) i));
118
119                adjustMetaAfterKeypress(content);
120                return true;
121            }
122        } else if (i == '0' && repeatCount == 1) {
123            // Pretty hackish, it replaces the 0 with the +
124
125            if (selStart == selEnd && selEnd > 0 &&
126                    content.charAt(selStart - 1) == '0') {
127                content.replace(selStart - 1, selEnd, String.valueOf('+'));
128                adjustMetaAfterKeypress(content);
129                return true;
130            }
131        }
132
133        adjustMetaAfterKeypress(content);
134        return super.onKeyDown(view, content, keyCode, event);
135    }
136}
137