app/src/main/java/com/stoutner/privacybrowser/fragments/AboutTabFragment.java

   1 /*
   2  * Copyright © 2016-2018 Soren Stoutner <soren@stoutner.com>.
   3  *
   4  * This file is part of Privacy Browser <https://www.stoutner.com/privacy-browser>.
   5  *
   6  * Privacy Browser is free software: you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * Privacy Browser is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with Privacy Browser.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 package com.stoutner.privacybrowser.fragments;
  21
  22 import android.annotation.SuppressLint;
  23 import android.content.pm.PackageManager;
  24 import android.content.pm.Signature;
  25 import android.os.Build;
  26 import android.os.Bundle;
  27 import android.support.annotation.NonNull;
  28 import android.support.v4.app.Fragment;
  29 import android.text.SpannableStringBuilder;
  30 import android.text.Spanned;
  31 import android.text.style.ForegroundColorSpan;
  32 import android.view.LayoutInflater;
  33 import android.view.View;
  34 import android.view.ViewGroup;
  35 import android.webkit.WebView;
  36 import android.widget.TextView;
  37
  38 import com.stoutner.privacybrowser.BuildConfig;
  39 import com.stoutner.privacybrowser.R;
  40 import com.stoutner.privacybrowser.activities.MainWebViewActivity;
  41
  42 import java.io.ByteArrayInputStream;
  43 import java.io.InputStream;
  44 import java.math.BigInteger;
  45 import java.security.Principal;
  46 import java.security.cert.CertificateException;
  47 import java.security.cert.CertificateFactory;
  48 import java.security.cert.X509Certificate;
  49 import java.text.DateFormat;
  50 import java.util.Date;
  51
  52 public class AboutTabFragment extends Fragment {
  53     private int tabNumber;
  54
  55     // Store the tab number in the arguments bundle.
  56     public static AboutTabFragment createTab(int tab) {
  57         // Create a bundle.
  58         Bundle bundle = new Bundle();
  59
  60         // Store the tab number in the bundle.
  61         bundle.putInt("Tab", tab);
  62
  63         // Add the bundle to the fragment.
  64         AboutTabFragment aboutTabFragment = new AboutTabFragment();
  65         aboutTabFragment.setArguments(bundle);
  66
  67         // Return the new fragment.
  68         return aboutTabFragment;
  69     }
  70
  71     @Override
  72     public void onCreate(Bundle savedInstanceState) {
  73         // Run the default commands.
  74         super.onCreate(savedInstanceState);
  75
  76         // Remove the lint warning that `getArguments()` might be null.
  77         assert getArguments() != null;
  78
  79         // Store the tab number in a class variable.
  80         tabNumber = getArguments().getInt("Tab");
  81     }
  82
  83     @Override
  84     public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
  85         View tabLayout;
  86
  87         // Load the tabs.  Tab numbers start at 0.
  88         if (tabNumber == 0) {  // Load the about tab.
  89             // Setting false at the end of inflater.inflate does not attach the inflated layout as a child of container.  The fragment will take care of attaching the root automatically.
  90             tabLayout = inflater.inflate(R.layout.about_tab_version, container, false);
  91
  92             // Get handles for the `TextViews`.
  93             TextView versionNumberTextView = tabLayout.findViewById(R.id.about_version_number);
  94             TextView versionBrandTextView = tabLayout.findViewById(R.id.about_version_brand);
  95             TextView versionManufacturerTextView = tabLayout.findViewById(R.id.about_version_manufacturer);
  96             TextView versionModelTextView = tabLayout.findViewById(R.id.about_version_model);
  97             TextView versionDeviceTextView = tabLayout.findViewById(R.id.about_version_device);
  98             TextView versionBootloaderTextView = tabLayout.findViewById(R.id.about_version_bootloader);
  99             TextView versionRadioTextView = tabLayout.findViewById(R.id.about_version_radio);
 100             TextView versionAndroidTextView = tabLayout.findViewById(R.id.about_version_android);
 101             TextView versionSecurityPatchTextView = tabLayout.findViewById(R.id.about_version_securitypatch);
 102             TextView versionBuildTextView = tabLayout.findViewById(R.id.about_version_build);
 103             TextView versionWebKitTextView = tabLayout.findViewById(R.id.about_version_webkit);
 104             TextView versionChromeTextView = tabLayout.findViewById(R.id.about_version_chrome);
 105             TextView versionOrbotTextView = tabLayout.findViewById(R.id.about_version_orbot);
 106             TextView versionEasyListTextView = tabLayout.findViewById(R.id.about_version_easylist);
 107             TextView versionEasyPrivacyTextView = tabLayout.findViewById(R.id.about_version_easyprivacy);
 108             TextView versionFanboyAnnoyanceTextView = tabLayout.findViewById(R.id.about_version_fanboy_annoyance);
 109             TextView versionFanboySocialTextView = tabLayout.findViewById(R.id.about_version_fanboy_social);
 110             TextView versionUltraPrivacyTextView = tabLayout.findViewById(R.id.about_version_ultraprivacy);
 111             TextView certificateIssuerDNTextView = tabLayout.findViewById(R.id.about_version_certificate_issuer_dn);
 112             TextView certificateSubjectDNTextView = tabLayout.findViewById(R.id.about_version_certificate_subject_dn);
 113             TextView certificateStartDateTextView = tabLayout.findViewById(R.id.about_version_certificate_start_date);
 114             TextView certificateEndDateTextView = tabLayout.findViewById(R.id.about_version_certificate_end_date);
 115             TextView certificateVersionTextView = tabLayout.findViewById(R.id.about_version_certificate_version);
 116             TextView certificateSerialNumberTextView = tabLayout.findViewById(R.id.about_version_certificate_serial_number);
 117             TextView certificateSignatureAlgorithmTextView = tabLayout.findViewById(R.id.about_version_certificate_signature_algorithm);
 118
 119             // Setup the labels.
 120             String version = getString(R.string.version) + " " + BuildConfig.VERSION_NAME + " (" + getString(R.string.version_code) + " " + Integer.toString(BuildConfig.VERSION_CODE) + ")";
 121             String brandLabel = getString(R.string.brand) + "  ";
 122             String manufacturerLabel = getString(R.string.manufacturer) + "  ";
 123             String modelLabel = getString(R.string.model) + "  ";
 124             String deviceLabel = getString(R.string.device) + "  ";
 125             String bootloaderLabel = getString(R.string.bootloader) + "  ";
 126             String androidLabel = getString(R.string.android) + "  ";
 127             String buildLabel = getString(R.string.build) + "  ";
 128             String webKitLabel = getString(R.string.webkit) + "  ";
 129             String chromeLabel = getString(R.string.chrome) + "  ";
 130             String easyListLabel = getString(R.string.easylist_label) + "  ";
 131             String easyPrivacyLabel = getString(R.string.easyprivacy_label) + "  ";
 132             String fanboyAnnoyanceLabel = getString(R.string.fanboy_annoyance_label) + "  ";
 133             String fanboySocialLabel = getString(R.string.fanboy_social_label) + "  ";
 134             String ultraPrivacyLabel = getString(R.string.ultraprivacy_label) + "  ";
 135             String issuerDNLabel = getString(R.string.issuer_dn) + "  ";
 136             String subjectDNLabel = getString(R.string.subject_dn) + "  ";
 137             String startDateLabel = getString(R.string.start_date) + "  ";
 138             String endDateLabel = getString(R.string.end_date) + "  ";
 139             String certificateVersionLabel = getString(R.string.certificate_version) + "  ";
 140             String serialNumberLabel = getString(R.string.serial_number) + "  ";
 141             String signatureAlgorithmLabel = getString(R.string.signature_algorithm) + "  ";
 142
 143             // `webViewLayout` is only used to get the default user agent from `bare_webview`.  It is not used to render content on the screen.
 144             View webViewLayout = inflater.inflate(R.layout.bare_webview, container, false);
 145             WebView tabLayoutWebView = webViewLayout.findViewById(R.id.bare_webview);
 146             String userAgentString =  tabLayoutWebView.getSettings().getUserAgentString();
 147
 148             // Get the device's information and store it in strings.
 149             String brand = Build.BRAND;
 150             String manufacturer = Build.MANUFACTURER;
 151             String model = Build.MODEL;
 152             String device = Build.DEVICE;
 153             String bootloader = Build.BOOTLOADER;
 154             String radio = Build.getRadioVersion();
 155             String android = Build.VERSION.RELEASE + " (" + getString(R.string.api) + " " + Integer.toString(Build.VERSION.SDK_INT) + ")";
 156             String build = Build.DISPLAY;
 157             // Select the substring that begins after "Safari/" and goes to the end of the string.
 158             String webKit = userAgentString.substring(userAgentString.indexOf("Safari/") + 7);
 159             // Select the substring that begins after "Chrome/" and goes until the next " ".
 160             String chrome = userAgentString.substring(userAgentString.indexOf("Chrome/") + 7, userAgentString.indexOf(" ", userAgentString.indexOf("Chrome/")));
 161
 162             // Get the Orbot version name if Orbot is installed.
 163             String orbot;
 164             try {
 165                 // Remove the lint warning that `getContext()` might be null.
 166                 assert getContext() != null;
 167
 168                 // Store the version name.
 169                 orbot = getContext().getPackageManager().getPackageInfo("org.torproject.android", PackageManager.GET_CONFIGURATIONS).versionName;
 170             } catch (PackageManager.NameNotFoundException e) {  // Orbot is not installed.
 171                 orbot = "";
 172             }
 173
 174             // Create a `SpannableStringBuilder` for the hardware and software `TextViews` that needs multiple colors of text.
 175             SpannableStringBuilder brandStringBuilder = new SpannableStringBuilder(brandLabel + brand);
 176             SpannableStringBuilder manufacturerStringBuilder = new SpannableStringBuilder(manufacturerLabel + manufacturer);
 177             SpannableStringBuilder modelStringBuilder = new SpannableStringBuilder(modelLabel + model);
 178             SpannableStringBuilder deviceStringBuilder = new SpannableStringBuilder(deviceLabel + device);
 179             SpannableStringBuilder bootloaderStringBuilder = new SpannableStringBuilder(bootloaderLabel + bootloader);
 180             SpannableStringBuilder androidStringBuilder = new SpannableStringBuilder(androidLabel + android);
 181             SpannableStringBuilder buildStringBuilder = new SpannableStringBuilder(buildLabel + build);
 182             SpannableStringBuilder webKitStringBuilder = new SpannableStringBuilder(webKitLabel + webKit);
 183             SpannableStringBuilder chromeStringBuilder = new SpannableStringBuilder(chromeLabel + chrome);
 184             SpannableStringBuilder easyListStringBuilder = new SpannableStringBuilder(easyListLabel + MainWebViewActivity.easyListVersion);
 185             SpannableStringBuilder easyPrivacyStringBuilder = new SpannableStringBuilder(easyPrivacyLabel + MainWebViewActivity.easyPrivacyVersion);
 186             SpannableStringBuilder fanboyAnnoyanceStringBuilder = new SpannableStringBuilder(fanboyAnnoyanceLabel + MainWebViewActivity.fanboysAnnoyanceVersion);
 187             SpannableStringBuilder fanboySocialStringBuilder = new SpannableStringBuilder(fanboySocialLabel + MainWebViewActivity.fanboysSocialVersion);
 188             SpannableStringBuilder ultraPrivacyStringBuilder = new SpannableStringBuilder(ultraPrivacyLabel + MainWebViewActivity.ultraPrivacyVersion);
 189
 190             // Create the `blueColorSpan` variable.
 191             ForegroundColorSpan blueColorSpan;
 192
 193             // Set `blueColorSpan` according to the theme.  We have to use the deprecated `getColor()` until API >= 23.
 194             if (MainWebViewActivity.darkTheme) {
 195                 //noinspection deprecation
 196                 blueColorSpan = new ForegroundColorSpan(getResources().getColor(R.color.blue_400));
 197             } else {
 198                 //noinspection deprecation
 199                 blueColorSpan = new ForegroundColorSpan(getResources().getColor(R.color.blue_700));
 200             }
 201
 202             // Setup the spans to display the device information in blue.  `SPAN_INCLUSIVE_INCLUSIVE` allows the span to grow in either direction.
 203             brandStringBuilder.setSpan(blueColorSpan, brandLabel.length(), brandStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 204             manufacturerStringBuilder.setSpan(blueColorSpan, manufacturerLabel.length(), manufacturerStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 205             modelStringBuilder.setSpan(blueColorSpan, modelLabel.length(), modelStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 206             deviceStringBuilder.setSpan(blueColorSpan, deviceLabel.length(), deviceStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 207             bootloaderStringBuilder.setSpan(blueColorSpan, bootloaderLabel.length(), bootloaderStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 208             androidStringBuilder.setSpan(blueColorSpan, androidLabel.length(), androidStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 209             buildStringBuilder.setSpan(blueColorSpan, buildLabel.length(), buildStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 210             webKitStringBuilder.setSpan(blueColorSpan, webKitLabel.length(), webKitStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 211             chromeStringBuilder.setSpan(blueColorSpan, chromeLabel.length(), chromeStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 212             easyListStringBuilder.setSpan(blueColorSpan, easyListLabel.length(), easyListStringBuilder.length(), Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
 213             easyPrivacyStringBuilder.setSpan(blueColorSpan, easyPrivacyLabel.length(), easyPrivacyStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 214             fanboyAnnoyanceStringBuilder.setSpan(blueColorSpan, fanboyAnnoyanceLabel.length(), fanboyAnnoyanceStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 215             fanboySocialStringBuilder.setSpan(blueColorSpan, fanboySocialLabel.length(), fanboySocialStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 216             ultraPrivacyStringBuilder.setSpan(blueColorSpan, ultraPrivacyLabel.length(), ultraPrivacyStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 217
 218             // Display the strings in the text boxes.
 219             versionNumberTextView.setText(version);
 220             versionBrandTextView.setText(brandStringBuilder);
 221             versionManufacturerTextView.setText(manufacturerStringBuilder);
 222             versionModelTextView.setText(modelStringBuilder);
 223             versionDeviceTextView.setText(deviceStringBuilder);
 224             versionBootloaderTextView.setText(bootloaderStringBuilder);
 225             versionAndroidTextView.setText(androidStringBuilder);
 226             versionBuildTextView.setText(buildStringBuilder);
 227             versionWebKitTextView.setText(webKitStringBuilder);
 228             versionChromeTextView.setText(chromeStringBuilder);
 229             versionEasyListTextView.setText(easyListStringBuilder);
 230             versionEasyPrivacyTextView.setText(easyPrivacyStringBuilder);
 231             versionFanboyAnnoyanceTextView.setText(fanboyAnnoyanceStringBuilder);
 232             versionFanboySocialTextView.setText(fanboySocialStringBuilder);
 233             versionUltraPrivacyTextView.setText(ultraPrivacyStringBuilder);
 234
 235             // Build.VERSION.SECURITY_PATCH is only available for SDK_INT >= 23.
 236             if (Build.VERSION.SDK_INT >= 23) {
 237                 String securityPatchLabel = getString(R.string.security_patch) + "  ";
 238                 String securityPatch = Build.VERSION.SECURITY_PATCH;
 239                 SpannableStringBuilder securityPatchStringBuilder = new SpannableStringBuilder(securityPatchLabel + securityPatch);
 240                 securityPatchStringBuilder.setSpan(blueColorSpan, securityPatchLabel.length(), securityPatchStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 241                 versionSecurityPatchTextView.setText(securityPatchStringBuilder);
 242             } else {  // SDK_INT < 23, so `versionSecurityPatchTextView` should be hidden.
 243                 versionSecurityPatchTextView.setVisibility(View.GONE);
 244             }
 245
 246             // Only populate `versionRadioTextView` if there is a radio in the device.
 247             if (!radio.equals("")) {
 248                 String radioLabel = getString(R.string.radio) + "  ";
 249                 SpannableStringBuilder radioStringBuilder = new SpannableStringBuilder(radioLabel + radio);
 250                 radioStringBuilder.setSpan(blueColorSpan, radioLabel.length(), radioStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 251                 versionRadioTextView.setText(radioStringBuilder);
 252             } else {  // This device does not have a radio, so `versionRadioTextView` should be hidden.
 253                 versionRadioTextView.setVisibility(View.GONE);
 254             }
 255
 256             // Only populate `versionOrbotTextView` if Orbot is installed.
 257             if (!orbot.equals("")) {
 258                 String orbotLabel = getString(R.string.orbot) + "  ";
 259                 SpannableStringBuilder orbotStringBuilder = new SpannableStringBuilder(orbotLabel + orbot);
 260                 orbotStringBuilder.setSpan(blueColorSpan, orbotLabel.length(), orbotStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 261                 versionOrbotTextView.setText(orbotStringBuilder);
 262             } else {  // Orbot is not installed, so the `versionOrbotTextView` should be hidden.
 263                 versionOrbotTextView.setVisibility(View.GONE);
 264             }
 265
 266             // Display the package signature.
 267             try {
 268                 // Get the first package signature.  Suppress the lint warning about the need to be careful in implementing comparison of certificates for security purposes.
 269                 @SuppressLint("PackageManagerGetSignatures") Signature packageSignature = getContext().getPackageManager().getPackageInfo(getContext().getPackageName(), PackageManager.GET_SIGNATURES).signatures[0];
 270
 271                 // Convert the signature to a `byte[]` `InputStream`.
 272                 InputStream certificateByteArrayInputStream = new ByteArrayInputStream(packageSignature.toByteArray());
 273
 274                 // Display the certificate information on the screen.
 275                 try {
 276                     // Instantiate a `CertificateFactory`.
 277                     CertificateFactory certificateFactory = CertificateFactory.getInstance("X509");
 278
 279                     // Generate an `X509Certificate`.
 280                     X509Certificate x509Certificate = (X509Certificate) certificateFactory.generateCertificate(certificateByteArrayInputStream);
 281
 282                     // Store the individual sections of the certificate that we are interested in.
 283                     Principal issuerDNPrincipal = x509Certificate.getIssuerDN();
 284                     Principal subjectDNPrincipal = x509Certificate.getSubjectDN();
 285                     Date startDate = x509Certificate.getNotBefore();
 286                     Date endDate = x509Certificate.getNotAfter();
 287                     int certificateVersion = x509Certificate.getVersion();
 288                     BigInteger serialNumberBigInteger = x509Certificate.getSerialNumber();
 289                     String signatureAlgorithmNameString = x509Certificate.getSigAlgName();
 290
 291                     // Create a `SpannableStringBuilder` for each `TextView` that needs multiple colors of text.
 292                     SpannableStringBuilder issuerDNStringBuilder = new SpannableStringBuilder(issuerDNLabel + issuerDNPrincipal.toString());
 293                     SpannableStringBuilder subjectDNStringBuilder = new SpannableStringBuilder(subjectDNLabel + subjectDNPrincipal.toString());
 294                     SpannableStringBuilder startDateStringBuilder = new SpannableStringBuilder(startDateLabel + DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.LONG).format(startDate));
 295                     SpannableStringBuilder endDataStringBuilder = new SpannableStringBuilder(endDateLabel + DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.LONG).format(endDate));
 296                     SpannableStringBuilder certificateVersionStringBuilder = new SpannableStringBuilder(certificateVersionLabel + certificateVersion);
 297                     SpannableStringBuilder serialNumberStringBuilder = new SpannableStringBuilder(serialNumberLabel + serialNumberBigInteger);
 298                     SpannableStringBuilder signatureAlgorithmStringBuilder = new SpannableStringBuilder(signatureAlgorithmLabel + signatureAlgorithmNameString);
 299
 300                     // Setup the spans to display the device information in blue.  `SPAN_INCLUSIVE_INCLUSIVE` allows the span to grow in either direction.
 301                     issuerDNStringBuilder.setSpan(blueColorSpan, issuerDNLabel.length(), issuerDNStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 302                     subjectDNStringBuilder.setSpan(blueColorSpan, subjectDNLabel.length(), subjectDNStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 303                     startDateStringBuilder.setSpan(blueColorSpan, startDateLabel.length(), startDateStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 304                     endDataStringBuilder.setSpan(blueColorSpan, endDateLabel.length(), endDataStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 305                     certificateVersionStringBuilder.setSpan(blueColorSpan, certificateVersionLabel.length(), certificateVersionStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 306                     serialNumberStringBuilder.setSpan(blueColorSpan, serialNumberLabel.length(), serialNumberStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 307                     signatureAlgorithmStringBuilder.setSpan(blueColorSpan, signatureAlgorithmLabel.length(), signatureAlgorithmStringBuilder.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
 308
 309                     // Display the strings in the text boxes.
 310                     certificateIssuerDNTextView.setText(issuerDNStringBuilder);
 311                     certificateSubjectDNTextView.setText(subjectDNStringBuilder);
 312                     certificateStartDateTextView.setText(startDateStringBuilder);
 313                     certificateEndDateTextView.setText(endDataStringBuilder);
 314                     certificateVersionTextView.setText(certificateVersionStringBuilder);
 315                     certificateSerialNumberTextView.setText(serialNumberStringBuilder);
 316                     certificateSignatureAlgorithmTextView.setText(signatureAlgorithmStringBuilder);
 317                 } catch (CertificateException e) {
 318                     // Do nothing if there is a certificate error.
 319                 }
 320             } catch (PackageManager.NameNotFoundException e) {
 321                 // Do nothing if `PackageManager` says Privacy Browser isn't installed.
 322             }
 323         } else { // load a `WebView` for all the other tabs.  Tab numbers start at 0.
 324             // Setting false at the end of inflater.inflate does not attach the inflated layout as a child of container.  The fragment will take care of attaching the root automatically.
 325             tabLayout = inflater.inflate(R.layout.bare_webview, container, false);
 326
 327             // Get a handle for `tabWebView`.
 328             WebView tabWebView = (WebView) tabLayout;
 329
 330             // Load the tabs according to the theme.
 331             if (MainWebViewActivity.darkTheme) {  // The dark theme is applied.
 332                 // Set the background color.  We have to use the deprecated `.getColor()` until API >= 23.
 333                 //noinspection deprecation
 334                 tabWebView.setBackgroundColor(getResources().getColor(R.color.gray_850));
 335
 336                 switch (tabNumber) {
 337                     case 1:
 338                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_permissions_dark.html");
 339                         break;
 340
 341                     case 2:
 342                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_privacy_policy_dark.html");
 343                         break;
 344
 345                     case 3:
 346                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_changelog_dark.html");
 347                         break;
 348
 349                     case 4:
 350                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_licenses_dark.html");
 351                         break;
 352
 353                     case 5:
 354                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_contributors_dark.html");
 355                         break;
 356
 357                     case 6:
 358                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_links_dark.html");
 359                         break;
 360                 }
 361             } else {  // The light theme is applied.
 362                 switch (tabNumber) {
 363                     case 1:
 364                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_permissions_light.html");
 365                         break;
 366
 367                     case 2:
 368                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_privacy_policy_light.html");
 369                         break;
 370
 371                     case 3:
 372                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_changelog_light.html");
 373                         break;
 374
 375                     case 4:
 376                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_licenses_light.html");
 377                         break;
 378
 379                     case 5:
 380                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_contributors_light.html");
 381                         break;
 382
 383                     case 6:
 384                         tabWebView.loadUrl("file:///android_asset/" + getString(R.string.android_asset_path) + "/about_links_light.html");
 385                         break;
 386                 }
 387             }
 388         }
 389
 390         // Return the formatted `tabLayout`.
 391         return tabLayout;
 392     }
 393 }