EmailHtmlUtil.java revision 21ace307e07cb4c363c4183f4d62f4049f5d92fd 
1/*
2 * Copyright (C) 2008 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.email.mail.internet;
18
19import com.android.email.mail.MessagingException;
20import com.android.email.mail.Multipart;
21import com.android.email.mail.Part;
22import com.android.email.mail.store.LocalStore.LocalAttachmentBodyPart;
23import com.android.email.provider.AttachmentProvider;
24import com.android.email.provider.EmailContent;
25
26import android.content.ContentResolver;
27import android.net.Uri;
28
29import java.util.regex.Matcher;
30import java.util.regex.Pattern;
31
32public class EmailHtmlUtil {
33
34    // Regex that matches characters that have special meaning in HTML. '<', '>', '&' and
35    // multiple continuous spaces.
36    private static final Pattern PLAIN_TEXT_TO_ESCAPE = Pattern.compile("[<>&]| {2,}|\r?\n");
37
38    //TODO: make resolveInlineImage() work in the new content provider model.
39    /**
40     * Resolve content-id reference in src attribute of img tag to AttachmentProvider's
41     * content uri.  This method calls itself recursively at most the number of
42     * LocalAttachmentPart that mime type is image and has content id.
43     * The attribute src="cid:content_id" is resolved as src="content://...".
44     * This method is package scope for testing purpose.
45     *
46     * @param text html email text
47     * @param part mime part which may contain inline image
48     * @return html text in which src attribute of img tag may be replaced with content uri
49     */
50    public static String resolveInlineImage(
51            ContentResolver resolver, EmailContent.Account account, String text, Part part, int depth)
52        throws MessagingException {
53        // avoid too deep recursive call.
54        if (depth >= 10 || text == null) {
55            return text;
56        }
57        String contentType = MimeUtility.unfoldAndDecode(part.getContentType());
58        String contentId = part.getContentId();
59        if (contentType.startsWith("image/") &&
60            contentId != null &&
61            part instanceof LocalAttachmentBodyPart) {
62            LocalAttachmentBodyPart attachment = (LocalAttachmentBodyPart)part;
63            Uri contentUri = AttachmentProvider.resolveAttachmentIdToContentUri(
64                    resolver, AttachmentProvider.getAttachmentUri(account, attachment.getAttachmentId()));
65            // Regexp which matches ' src="cid:contentId"'.
66            String contentIdRe = "\\s+(?i)src=\"cid(?-i):\\Q" + contentId + "\\E\"";
67            // Replace all occurrences of src attribute with ' src="content://contentUri"'.
68            text = text.replaceAll(contentIdRe, " src=\"" + contentUri + "\"");
69        }
70
71        if (part.getBody() instanceof Multipart) {
72            Multipart mp = (Multipart)part.getBody();
73            for (int i = 0; i < mp.getCount(); i++) {
74                text = resolveInlineImage(resolver, account, text, mp.getBodyPart(i), depth + 1);
75            }
76        }
77
78        return text;
79    }
80
81    /**
82     * Escape some special character as HTML escape sequence.
83     *
84     * @param text Text to be displayed using WebView.
85     * @return Text correctly escaped.
86     */
87    public static String escapeCharacterToDisplay(String text) {
88        Pattern pattern = PLAIN_TEXT_TO_ESCAPE;
89        Matcher match = pattern.matcher(text);
90
91        if (match.find()) {
92            StringBuilder out = new StringBuilder();
93            int end = 0;
94            do {
95                int start = match.start();
96                out.append(text.substring(end, start));
97                end = match.end();
98                int c = text.codePointAt(start);
99                if (c == ' ') {
100                    // Escape successive spaces into series of "&nbsp;".
101                    for (int i = 1, n = end - start; i < n; ++i) {
102                        out.append("&nbsp;");
103                    }
104                    out.append(' ');
105                } else if (c == '\r' || c == '\n') {
106                    out.append("<br>");
107                } else if (c == '<') {
108                    out.append("&lt;");
109                } else if (c == '>') {
110                    out.append("&gt;");
111                } else if (c == '&') {
112                    out.append("&amp;");
113                }
114            } while (match.find());
115            out.append(text.substring(end));
116            text = out.toString();
117        }
118        return text;
119    }
120}
121