BaseKeyListener.java revision 54b6cfa9a9e5b861a9930af873580d6dc20f773c 
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.os.Message;
22import android.util.Log;
23import android.text.*;
24import android.widget.TextView;
25
26public abstract class BaseKeyListener
27extends MetaKeyKeyListener
28implements KeyListener {
29    /* package */ static final Object OLD_SEL_START = new Object();
30
31    /**
32     * Performs the action that happens when you press the DEL key in
33     * a TextView.  If there is a selection, deletes the selection;
34     * otherwise, DEL alone deletes the character before the cursor,
35     * if any;
36     * ALT+DEL deletes everything on the line the cursor is on.
37     *
38     * @return true if anything was deleted; false otherwise.
39     */
40    public boolean backspace(View view, Editable content, int keyCode,
41                             KeyEvent event) {
42        int selStart, selEnd;
43        boolean result = true;
44
45        {
46            int a = Selection.getSelectionStart(content);
47            int b = Selection.getSelectionEnd(content);
48
49            selStart = Math.min(a, b);
50            selEnd = Math.max(a, b);
51        }
52
53        if (selStart != selEnd) {
54            content.delete(selStart, selEnd);
55        } else if (altBackspace(view, content, keyCode, event)) {
56            result = true;
57        } else {
58            int to = TextUtils.getOffsetBefore(content, selEnd);
59
60            if (to != selEnd) {
61                content.delete(Math.min(to, selEnd), Math.max(to, selEnd));
62            }
63            else {
64                result = false;
65            }
66        }
67
68        if (result)
69            adjustMetaAfterKeypress(content);
70
71        return result;
72    }
73
74    private boolean altBackspace(View view, Editable content, int keyCode,
75                                 KeyEvent event) {
76        if (getMetaState(content, META_ALT_ON) != 1) {
77            return false;
78        }
79
80        if (!(view instanceof TextView)) {
81            return false;
82        }
83
84        Layout layout = ((TextView) view).getLayout();
85
86        if (layout == null) {
87            return false;
88        }
89
90        int l = layout.getLineForOffset(Selection.getSelectionStart(content));
91        int start = layout.getLineStart(l);
92        int end = layout.getLineEnd(l);
93
94        if (end == start) {
95            return false;
96        }
97
98        content.delete(start, end);
99        return true;
100    }
101
102    public boolean onKeyDown(View view, Editable content,
103                             int keyCode, KeyEvent event) {
104        if (keyCode == KeyEvent.KEYCODE_DEL) {
105            backspace(view, content, keyCode, event);
106            return true;
107        }
108
109        return super.onKeyDown(view, content, keyCode, event);
110    }
111}
112
113