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.htmlviewer;
18
19import android.app.Activity;
20import android.content.ActivityNotFoundException;
21import android.content.ContentResolver;
22import android.content.Intent;
23import android.content.pm.PackageManager;
24import android.Manifest;
25import android.net.Uri;
26import android.os.Bundle;
27import android.util.Log;
28import android.view.View;
29import android.webkit.WebChromeClient;
30import android.webkit.WebResourceRequest;
31import android.webkit.WebResourceResponse;
32import android.webkit.WebSettings;
33import android.webkit.WebView;
34import android.webkit.WebViewClient;
35import android.widget.Toast;
36
37import java.io.IOException;
38import java.io.InputStream;
39import java.net.URISyntaxException;
40import java.util.zip.GZIPInputStream;
41
42/**
43 * Simple activity that shows the requested HTML page. This utility is
44 * purposefully very limited in what it supports, including no network or
45 * JavaScript.
46 */
47public class HTMLViewerActivity extends Activity {
48    private static final String TAG = "HTMLViewer";
49
50    private WebView mWebView;
51    private View mLoading;
52    private Intent mIntent;
53
54    @Override
55    protected void onCreate(Bundle savedInstanceState) {
56        super.onCreate(savedInstanceState);
57
58        setContentView(R.layout.main);
59
60        mWebView = (WebView) findViewById(R.id.webview);
61        mLoading = findViewById(R.id.loading);
62
63        mWebView.setWebChromeClient(new ChromeClient());
64        mWebView.setWebViewClient(new ViewClient());
65
66        WebSettings s = mWebView.getSettings();
67        s.setUseWideViewPort(true);
68        s.setSupportZoom(true);
69        s.setBuiltInZoomControls(true);
70        s.setDisplayZoomControls(false);
71        s.setSavePassword(false);
72        s.setSaveFormData(false);
73        s.setBlockNetworkLoads(true);
74
75        // Javascript is purposely disabled, so that nothing can be
76        // automatically run.
77        s.setJavaScriptEnabled(false);
78        s.setDefaultTextEncodingName("utf-8");
79
80        mIntent = getIntent();
81        requestPermissionAndLoad();
82    }
83
84    private void loadUrl() {
85        if (mIntent.hasExtra(Intent.EXTRA_TITLE)) {
86            setTitle(mIntent.getStringExtra(Intent.EXTRA_TITLE));
87        }
88        mWebView.loadUrl(String.valueOf(mIntent.getData()));
89    }
90
91    private void requestPermissionAndLoad() {
92        Uri destination = mIntent.getData();
93        if (destination != null) {
94            // Is this a local file?
95            if ("file".equals(destination.getScheme())
96                        && PackageManager.PERMISSION_DENIED ==
97                                checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE)) {
98                requestPermissions(new String[] {Manifest.permission.READ_EXTERNAL_STORAGE}, 0);
99            } else {
100                loadUrl();
101            }
102        }
103    }
104
105    @Override
106    public void onRequestPermissionsResult(int requestCode,
107            String permissions[], int[] grantResults) {
108        // We only ever request 1 permission, so these arguments should always have the same form.
109        assert permissions.length == 1;
110        assert Manifest.permission.READ_EXTERNAL_STORAGE.equals(permissions[0]);
111
112        if (grantResults.length == 1 && PackageManager.PERMISSION_GRANTED == grantResults[0]) {
113            // Try again now that we have the permission.
114            loadUrl();
115        } else {
116            Toast.makeText(HTMLViewerActivity.this,
117                    R.string.turn_on_storage_permission, Toast.LENGTH_SHORT).show();
118            finish();
119        }
120    }
121
122    @Override
123    protected void onDestroy() {
124        super.onDestroy();
125        mWebView.destroy();
126    }
127
128    private class ChromeClient extends WebChromeClient {
129        @Override
130        public void onReceivedTitle(WebView view, String title) {
131            if (!getIntent().hasExtra(Intent.EXTRA_TITLE)) {
132                HTMLViewerActivity.this.setTitle(title);
133            }
134        }
135    }
136
137    private class ViewClient extends WebViewClient {
138        @Override
139        public void onPageFinished(WebView view, String url) {
140            mLoading.setVisibility(View.GONE);
141        }
142
143        @Override
144        public boolean shouldOverrideUrlLoading(WebView view, String url) {
145            Intent intent;
146            // Perform generic parsing of the URI to turn it into an Intent.
147            try {
148                intent = Intent.parseUri(url, Intent.URI_INTENT_SCHEME);
149            } catch (URISyntaxException ex) {
150                Log.w(TAG, "Bad URI " + url + ": " + ex.getMessage());
151                Toast.makeText(HTMLViewerActivity.this,
152                        R.string.cannot_open_link, Toast.LENGTH_SHORT).show();
153                return true;
154            }
155            // Sanitize the Intent, ensuring web pages can not bypass browser
156            // security (only access to BROWSABLE activities).
157            intent.addCategory(Intent.CATEGORY_BROWSABLE);
158            intent.setComponent(null);
159            Intent selector = intent.getSelector();
160            if (selector != null) {
161                selector.addCategory(Intent.CATEGORY_BROWSABLE);
162                selector.setComponent(null);
163            }
164
165            try {
166                view.getContext().startActivity(intent);
167            } catch (ActivityNotFoundException ex) {
168                Log.w(TAG, "No application can handle " + url);
169                Toast.makeText(HTMLViewerActivity.this,
170                        R.string.cannot_open_link, Toast.LENGTH_SHORT).show();
171            }
172            return true;
173        }
174
175        @Override
176        public WebResourceResponse shouldInterceptRequest(WebView view,
177                WebResourceRequest request) {
178            final Uri uri = request.getUrl();
179            if (ContentResolver.SCHEME_FILE.equals(uri.getScheme())
180                    && uri.getPath().endsWith(".gz")) {
181                Log.d(TAG, "Trying to decompress " + uri + " on the fly");
182                try {
183                    final InputStream in = new GZIPInputStream(
184                            getContentResolver().openInputStream(uri));
185                    final WebResourceResponse resp = new WebResourceResponse(
186                            getIntent().getType(), "utf-8", in);
187                    resp.setStatusCodeAndReasonPhrase(200, "OK");
188                    return resp;
189                } catch (IOException e) {
190                    Log.w(TAG, "Failed to decompress; falling back", e);
191                }
192            }
193            return null;
194        }
195    }
196}
197