Animated GIF's now animate when viewed in fullscreen.

app/src/main/java/com/keylesspalace/tusky/SFragment.java

@@ -18,6 +18,7 @@ package com.keylesspalace.tusky;
 import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
+import android.media.ImageReader;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.support.v4.app.Fragment;
@@ -36,6 +37,7 @@ import com.android.volley.toolbox.JsonObjectRequest;
 
 import org.json.JSONObject;
 
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -203,10 +205,26 @@ public class SFragment extends Fragment {
         popup.show();
     }
 
+    private boolean fileExtensionMatches(String url, String extension) {
+        extension = "." + extension;
+        int parametersStart = url.indexOf('?');
+        if (parametersStart == -1) {
+            return url.toLowerCase().endsWith(extension);
+        } else {
+            int start = parametersStart - extension.length();
+            return start > 0 && url.substring(start, parametersStart).equals(extension);
+        }
+    }
+
     protected void viewMedia(String url, Status.MediaAttachment.Type type) {
         switch (type) {
             case IMAGE: {
-                Fragment newFragment = ViewMediaFragment.newInstance(url);
+                Fragment newFragment;
+                if (fileExtensionMatches(url, "gif")) {
+                    newFragment = ViewGifFragment.newInstance(url);
+                } else {
+                    newFragment = ViewMediaFragment.newInstance(url);
+                }
                 FragmentManager manager = getFragmentManager();
                 manager.beginTransaction()
                         .add(R.id.overlay_fragment_container, newFragment)

app/src/main/java/com/keylesspalace/tusky/ViewGifFragment.java

@@ -0,0 +1,58 @@
+/* Copyright 2017 Andrew Dawson
+ *
+ * This file is part of Tusky.
+ *
+ * Tusky is free software: you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License as published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Tusky. If not, see
+ * <http://www.gnu.org/licenses/>. */
+
+package com.keylesspalace.tusky;
+
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.v4.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.webkit.WebView;
+
+public class ViewGifFragment extends Fragment {
+    public static ViewGifFragment newInstance(String url) {
+        Bundle arguments = new Bundle();
+        ViewGifFragment fragment = new ViewGifFragment();
+        arguments.putString("url", url);
+        fragment.setArguments(arguments);
+        return fragment;
+    }
+
+    @Nullable
+    @Override
+    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
+            @Nullable Bundle savedInstanceState) {
+        View rootView = inflater.inflate(R.layout.fragment_view_gif, container, false);
+
+        String url = getArguments().getString("url");
+        WebView gifView = (WebView) rootView.findViewById(R.id.gif_view);
+        gifView.loadUrl(url);
+
+        rootView.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                dismiss();
+            }
+        });
+
+        return rootView;
+    }
+
+    private void dismiss() {
+        getFragmentManager().popBackStack();
+    }
+}

app/src/main/res/layout/fragment_view_gif.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="#60000000">
+
+    <WebView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:id="@+id/gif_view"
+        android:layout_centerInParent="true" />
+
+</RelativeLayout>