Use custom tabs to open links in original message

app/src/main/java/eu/faircode/email/FragmentWebView.java

@@ -19,7 +19,10 @@ package eu.faircode.email;
     Copyright 2018 by Marcel Bokhorst (M66B)
 */
 
+import android.content.SharedPreferences;
+import android.net.Uri;
 import android.os.Bundle;
+import android.preference.PreferenceManager;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -31,6 +34,7 @@ import android.widget.ProgressBar;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.browser.customtabs.CustomTabsIntent;
 
 // https://developer.android.com/reference/android/webkit/WebView
 
@@ -50,11 +54,22 @@ public class FragmentWebView extends FragmentEx {
         settings.setJavaScriptEnabled(true);
         settings.setMixedContentMode(WebSettings.MIXED_CONTENT_ALWAYS_ALLOW);
 
+        final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
+
         webview.setWebViewClient(new WebViewClient() {
             public boolean shouldOverrideUrlLoading(WebView view, String url) {
-                view.loadUrl(url);
-                setSubtitle(url);
-                return false;
+                if (prefs.getBoolean("webview", false)) {
+                    view.loadUrl(url);
+                    setSubtitle(url);
+                    return false;
+                } else {
+                    CustomTabsIntent.Builder builder = new CustomTabsIntent.Builder();
+                    builder.setToolbarColor(Helper.resolveColor(getContext(), R.attr.colorPrimary));
+
+                    CustomTabsIntent customTabsIntent = builder.build();
+                    customTabsIntent.launchUrl(getContext(), Uri.parse(url));
+                    return true;
+                }
             }
         });