1/*
2 * Copyright (C) 2011 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.contacts.format;
18
19import android.text.SpannableString;
20import android.text.style.CharacterStyle;
21import android.text.style.StyleSpan;
22import android.widget.TextView;
23
24/**
25 * Highlights the text in a text field.
26 */
27public class TextHighlighter {
28    private final String TAG = TextHighlighter.class.getSimpleName();
29    private final static boolean DEBUG = false;
30
31    private int mTextStyle;
32
33    private CharacterStyle mTextStyleSpan;
34
35    public TextHighlighter(int textStyle) {
36        mTextStyle = textStyle;
37        mTextStyleSpan = getStyleSpan();
38    }
39
40    /**
41     * Sets the text on the given text view, highlighting the word that matches the given prefix.
42     *
43     * @param view the view on which to set the text
44     * @param text the string to use as the text
45     * @param prefix the prefix to look for
46     */
47    public void setPrefixText(TextView view, String text, String prefix) {
48        view.setText(applyPrefixHighlight(text, prefix));
49    }
50
51    private CharacterStyle getStyleSpan() {
52        return new StyleSpan(mTextStyle);
53    }
54
55    /**
56     * Applies highlight span to the text.
57     * @param text Text sequence to be highlighted.
58     * @param start Start position of the highlight sequence.
59     * @param end End position of the highlight sequence.
60     */
61    public void applyMaskingHighlight(SpannableString text, int start, int end) {
62        /** Sets text color of the masked locations to be highlighted. */
63        text.setSpan(getStyleSpan(), start, end, 0);
64    }
65
66    /**
67     * Returns a CharSequence which highlights the given prefix if found in the given text.
68     *
69     * @param text the text to which to apply the highlight
70     * @param prefix the prefix to look for
71     */
72    public CharSequence applyPrefixHighlight(CharSequence text, String prefix) {
73        if (prefix == null) {
74            return text;
75        }
76
77        // Skip non-word characters at the beginning of prefix.
78        int prefixStart = 0;
79        while (prefixStart < prefix.length() &&
80                !Character.isLetterOrDigit(prefix.charAt(prefixStart))) {
81            prefixStart++;
82        }
83        final String trimmedPrefix = prefix.substring(prefixStart);
84
85        int index = FormatUtils.indexOfWordPrefix(text, trimmedPrefix);
86        if (index != -1) {
87            final SpannableString result = new SpannableString(text);
88            result.setSpan(mTextStyleSpan, index, index + trimmedPrefix.length(), 0 /* flags */);
89            return result;
90        } else {
91            return text;
92        }
93    }
94}
95