show conversation media in contact/conference details

18 files changed, 537 insertions, 116 deletions

diff --git a/src/main/java/de/pixart/messenger/persistance/DatabaseBackend.java b/src/main/java/de/pixart/messenger/persistance/DatabaseBackend.java
index 94710b86e..54d99ec43 100644
--- a/src/main/java/de/pixart/messenger/persistance/DatabaseBackend.java
+++ b/src/main/java/de/pixart/messenger/persistance/DatabaseBackend.java
@@ -35,6 +35,7 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.UUID;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 import de.pixart.messenger.Config;
@@ -787,6 +788,29 @@ public class DatabaseBackend extends SQLiteOpenHelper {
         };
     }
 
+    public List<FilePath> getRelativeFilePaths(Account account, Jid jid, int limit) {
+        SQLiteDatabase db = this.getReadableDatabase();
+        final String SQL = "select uuid,relativeFilePath from messages where type in (1,2) and conversationUuid=(select uuid from conversations where accountUuid=? and (contactJid=? or contactJid like ?)) order by timeSent desc";
+        final String[] args = {account.getUuid(), jid.asBareJid().toEscapedString(), jid.asBareJid().toEscapedString() + "/%"};
+        Cursor cursor = db.rawQuery(SQL + (limit > 0 ? " limit " + String.valueOf(limit) : ""), args);
+        List<FilePath> filesPaths = new ArrayList<>();
+        while (cursor.moveToNext()) {
+            filesPaths.add(new FilePath(cursor.getString(0), cursor.getString(1)));
+        }
+        cursor.close();
+        return filesPaths;
+    }
+
+    public static class FilePath {
+        public final UUID uuid;
+        public final String path;
+
+        private FilePath(String uuid, String path) {
+            this.uuid = UUID.fromString(uuid);
+            this.path = path;
+        }
+    }
+
     public Conversation findConversation(final Account account, final Jid contactJid) {
         SQLiteDatabase db = this.getReadableDatabase();
         String[] selectionArgs = {account.getUuid(),
diff --git a/src/main/java/de/pixart/messenger/persistance/FileBackend.java b/src/main/java/de/pixart/messenger/persistance/FileBackend.java
index 35967e624..92bb84e33 100644
--- a/src/main/java/de/pixart/messenger/persistance/FileBackend.java
+++ b/src/main/java/de/pixart/messenger/persistance/FileBackend.java
@@ -46,6 +46,7 @@ import java.security.DigestOutputStream;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.text.SimpleDateFormat;
+import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
 import java.util.Locale;
@@ -81,8 +82,8 @@ public class FileBackend {
     }
 
     private void createNoMedia() {
-        final File nomedia_files = new File(getConversationsDirectory("Files", true) + ".nomedia");
-        final File nomedia_audios = new File(getConversationsDirectory("Audios", true) + ".nomedia");
+        final File nomedia_files = new File(getConversationsDirectory("Files") + ".nomedia");
+        final File nomedia_audios = new File(getConversationsDirectory("Audios") + ".nomedia");
         if (!nomedia_files.exists()) {
             try {
                 nomedia_files.createNewFile();
@@ -100,8 +101,8 @@ public class FileBackend {
     }
 
     public void updateMediaScanner(File file) {
-        if (file.getAbsolutePath().startsWith(getConversationsDirectory("Images", true))
-                || file.getAbsolutePath().startsWith(getConversationsDirectory("Videos", true))) {
+        if (file.getAbsolutePath().startsWith(getConversationsDirectory("Images"))
+                || file.getAbsolutePath().startsWith(getConversationsDirectory("Videos"))) {
             Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
             intent.setData(Uri.fromFile(file));
             mXmppConnectionService.sendBroadcast(intent);
@@ -130,13 +131,13 @@ public class FileBackend {
             file = new DownloadableFile(path);
         } else {
             if (mime != null && mime.startsWith("image")) {
-                file = new DownloadableFile(getConversationsDirectory("Images", true) + path);
+                file = new DownloadableFile(getConversationsDirectory("Images") + path);
             } else if (mime != null && mime.startsWith("video")) {
-                file = new DownloadableFile(getConversationsDirectory("Videos", true) + path);
+                file = new DownloadableFile(getConversationsDirectory("Videos") + path);
             } else if (mime != null && mime.startsWith("audio")) {
-                file = new DownloadableFile(getConversationsDirectory("Audios", true) + path);
+                file = new DownloadableFile(getConversationsDirectory("Audios") + path);
             } else {
-                file = new DownloadableFile(getConversationsDirectory("Files", true) + path);
+                file = new DownloadableFile(getConversationsDirectory("Files") + path);
             }
         }
         return file;
@@ -152,7 +153,7 @@ public class FileBackend {
         }
         final DownloadableFile file = getFileForPath(path, message.getMimeType());
         if (encrypted) {
-            return new DownloadableFile(getConversationsDirectory("Files", true) + file.getName() + ".pgp");
+            return new DownloadableFile(getConversationsDirectory("Files") + file.getName() + ".pgp");
         } else {
             return file;
         }
@@ -202,31 +203,43 @@ public class FileBackend {
         return true;
     }
 
-    public static String getDirectoryName(final String type, final boolean isMedia) {
-        String media = "";
-        if (isMedia) {
-        		media = "Media/Pix-Art Messenger ";
+    public List<Attachment> convertToAttachments(List<DatabaseBackend.FilePath> relativeFilePaths) {
+        List<Attachment> attachments = new ArrayList<>();
+        for (DatabaseBackend.FilePath relativeFilePath : relativeFilePaths) {
+            final String mime = MimeUtils.guessMimeTypeFromExtension(MimeUtils.extractRelevantExtension(relativeFilePath.path));
+            Log.d(Config.LOGTAG, "mime=" + mime);
+            File file = getFileForPath(relativeFilePath.path, mime);
+            if (file.exists()) {
+                attachments.add(Attachment.of(relativeFilePath.uuid, file, mime));
+            } else {
+                Log.d(Config.LOGTAG, "file " + file.getAbsolutePath() + " doesn't exist");
+            }
         }
-        if (type == "null" || type == null) {
-            return "/Pix-Art Messenger/";
+        return attachments;
+    }
+
+    public static String getConversationsDirectory(final String type) {
+        if (type.equalsIgnoreCase("null") || type == null) {
+            return getAppMediaDirectory() + "Pix-Art Messenger" + "/";
         } else {
-            return "/Pix-Art Messenger" + "/" + media + type + "/";
+            return getAppMediaDirectory() + "Pix-Art Messenger" + " " + type + "/";
         }
     }
 
-    public static String getConversationsDirectory(final String type, final boolean isMedia) {
-        String DirName = null;
-        if (type != "null" || type != null) {
-            DirName = type;
-        }
-        String path = Environment.getExternalStorageDirectory().getAbsolutePath() + getDirectoryName(DirName, isMedia);
-        File createFolders = new File(path);
-        if (!createFolders.exists()) {
-            Log.d(Config.LOGTAG, "creating directory " + createFolders);
-            createFolders.mkdirs();
-        }
-        return path;
+    public static String getAppMediaDirectory() {
+        return Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + "Pix-Art Messenger" + "/Media/";
+    }
+
+    public static String getBackupDirectory() {
+        return Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + "Pix-Art Messenger" + "/Database/";
+    }
+
+    public static String getAppLogsDirectory() {
+        return Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + "Pix-Art Messenger" + "/Chats/";
+    }
 
+    public static String getAppUpdateDirectory() {
+        return Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + "Pix-Art Messenger" + "/Update/";
     }
 
     private Bitmap resize(final Bitmap originalBitmap, int size) throws IOException {
@@ -298,7 +311,7 @@ public class FileBackend {
             Log.d(Config.LOGTAG, "File path = null");
             return false;
         }
-        if (path.contains(getDirectoryName("null", true))) {
+        if (path.contains(getConversationsDirectory("null"))) {
             Log.d(Config.LOGTAG, "File " + path + " is in our directory");
             return true;
         }
@@ -1061,12 +1074,12 @@ public class FileBackend {
     }
 
     public Bitmap getPreviewForUri(Attachment attachment, int size, boolean cacheOnly) {
+        final String key = "attachment_" + attachment.getUuid().toString() + "_" + String.valueOf(size);
         final LruCache<String, Bitmap> cache = mXmppConnectionService.getBitmapCache();
-        Bitmap bitmap = cache.get(attachment.getUuid().toString());
+        Bitmap bitmap = cache.get(key);
         if (bitmap != null || cacheOnly) {
             return bitmap;
         }
-        Log.d(Config.LOGTAG, "attachment mime=" + attachment.getMime());
         if (attachment.getMime() != null && attachment.getMime().startsWith("video/")) {
             bitmap = cropCenterSquareVideo(attachment.getUri(), size);
             drawOverlay(bitmap, R.drawable.play_video, 0.75f);
@@ -1079,7 +1092,7 @@ public class FileBackend {
                 bitmap = withGifOverlay;
             }
         }
-        cache.put(attachment.getUuid().toString(), bitmap);
+        cache.put(key, bitmap);
         return bitmap;
     }
 
diff --git a/src/main/java/de/pixart/messenger/services/ExportLogsService.java b/src/main/java/de/pixart/messenger/services/ExportLogsService.java
index b0da108ba..e66873acc 100644
--- a/src/main/java/de/pixart/messenger/services/ExportLogsService.java
+++ b/src/main/java/de/pixart/messenger/services/ExportLogsService.java
@@ -41,7 +41,7 @@ import static de.pixart.messenger.ui.SettingsActivity.USE_MULTI_ACCOUNTS;
 public class ExportLogsService extends XmppConnectionService {
 
     private static final SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
-    private static final String DIRECTORY_STRING_FORMAT = FileBackend.getConversationsDirectory("Chats", false) + "%s";
+    private static final String DIRECTORY_STRING_FORMAT = FileBackend.getAppLogsDirectory() + "%s";
     private static final String MESSAGE_STRING_FORMAT = "(%s) %s: %s\n";
     private static AtomicBoolean running = new AtomicBoolean(false);
     boolean ReadableLogsEnabled = false;
@@ -171,7 +171,7 @@ public class ExportLogsService extends XmppConnectionService {
         // Get hold of the db:
         FileInputStream InputFile = new FileInputStream(this.getDatabasePath(DatabaseBackend.DATABASE_NAME));
         // Set the output folder on the SDcard
-        File directory = new File(FileBackend.getConversationsDirectory("Database", false));
+        File directory = new File(FileBackend.getBackupDirectory());
         // Create the folder if it doesn't exist:
         if (!directory.exists()) {
             boolean directory_created = directory.mkdirs();
diff --git a/src/main/java/de/pixart/messenger/services/XmppConnectionService.java b/src/main/java/de/pixart/messenger/services/XmppConnectionService.java
index 25d4fb2b8..cd35198dc 100644
--- a/src/main/java/de/pixart/messenger/services/XmppConnectionService.java
+++ b/src/main/java/de/pixart/messenger/services/XmppConnectionService.java
@@ -116,6 +116,7 @@ import de.pixart.messenger.persistance.FileBackend;
 import de.pixart.messenger.ui.SettingsActivity;
 import de.pixart.messenger.ui.UiCallback;
 import de.pixart.messenger.ui.interfaces.OnAvatarPublication;
+import de.pixart.messenger.ui.interfaces.OnMediaLoaded;
 import de.pixart.messenger.ui.interfaces.OnSearchResultsAvailable;
 import de.pixart.messenger.utils.Compatibility;
 import de.pixart.messenger.utils.ConversationsFileObserver;
@@ -2681,6 +2682,14 @@ public class XmppConnectionService extends Service {
         return false;
     }
 
+    public void getAttachments(final Conversation conversation, int limit, final OnMediaLoaded onMediaLoaded) {
+        getAttachments(conversation.getAccount(), conversation.getJid().asBareJid(), limit, onMediaLoaded);
+    }
+
+    public void getAttachments(final Account account, final Jid jid, final int limit, final OnMediaLoaded onMediaLoaded) {
+        new Thread(() -> onMediaLoaded.onMediaLoaded(fileBackend.convertToAttachments(databaseBackend.getRelativeFilePaths(account, jid, limit)))).start();
+    }
+
     public void persistSelfNick(MucOptions.User self) {
         final Conversation conversation = self.getConversation();
         Jid full = self.getFullJid();
diff --git a/src/main/java/de/pixart/messenger/ui/ConferenceDetailsActivity.java b/src/main/java/de/pixart/messenger/ui/ConferenceDetailsActivity.java
index 38479b459..fd7c66c18 100644
--- a/src/main/java/de/pixart/messenger/ui/ConferenceDetailsActivity.java
+++ b/src/main/java/de/pixart/messenger/ui/ConferenceDetailsActivity.java
@@ -32,6 +32,7 @@ import org.openintents.openpgp.util.OpenPgpUtils;
 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -49,6 +50,10 @@ import de.pixart.messenger.entities.MucOptions.User;
 import de.pixart.messenger.services.XmppConnectionService;
 import de.pixart.messenger.services.XmppConnectionService.OnConversationUpdate;
 import de.pixart.messenger.services.XmppConnectionService.OnMucRosterUpdate;
+import de.pixart.messenger.ui.adapter.MediaAdapter;
+import de.pixart.messenger.ui.interfaces.OnMediaLoaded;
+import de.pixart.messenger.ui.util.Attachment;
+import de.pixart.messenger.ui.util.GridManager;
 import de.pixart.messenger.ui.util.MucDetailsContextMenuHelper;
 import de.pixart.messenger.ui.util.MyLinkify;
 import de.pixart.messenger.ui.util.SoftKeyboardUtils;
@@ -64,7 +69,7 @@ import rocks.xmpp.addr.Jid;
 import static de.pixart.messenger.entities.Bookmark.printableValue;
 import static de.pixart.messenger.utils.StringUtils.changed;
 
-public class ConferenceDetailsActivity extends XmppActivity implements OnConversationUpdate, OnMucRosterUpdate, XmppConnectionService.OnAffiliationChanged, XmppConnectionService.OnRoleChanged, XmppConnectionService.OnConfigurationPushed, TextWatcher {
+public class ConferenceDetailsActivity extends XmppActivity implements OnConversationUpdate, OnMucRosterUpdate, XmppConnectionService.OnAffiliationChanged, XmppConnectionService.OnRoleChanged, XmppConnectionService.OnConfigurationPushed, TextWatcher, OnMediaLoaded {
     public static final String ACTION_VIEW_MUC = "view_muc";
     private static final float INACTIVE_ALPHA = 0.4684f; //compromise between dark and light theme
     private Conversation mConversation;
@@ -96,6 +101,7 @@ public class ConferenceDetailsActivity extends XmppActivity implements OnConvers
         }
     };
     private ActivityMucDetailsBinding binding;
+    private MediaAdapter mMediaAdapter;
     private String uuid = null;
     private User mSelectedUser = null;
 
@@ -319,6 +325,9 @@ public class ConferenceDetailsActivity extends XmppActivity implements OnConvers
         this.binding.mucEditTitle.addTextChangedListener(this);
         this.binding.mucEditSubject.addTextChangedListener(this);
         this.binding.mucEditSubject.addTextChangedListener(new StylingHelper.MessageEditorStyler(this.binding.mucEditSubject));
+        mMediaAdapter = new MediaAdapter(this, R.dimen.media_size);
+        this.binding.media.setAdapter(mMediaAdapter);
+        GridManager.setupLayoutManager(this, this.binding.media, R.dimen.media_size);
     }
 
     @Override
@@ -475,6 +484,15 @@ public class ConferenceDetailsActivity extends XmppActivity implements OnConvers
         return true;
     }
 
+    @Override
+    public void onMediaLoaded(List<Attachment> attachments) {
+        runOnUiThread(() -> {
+            int limit = GridManager.getCurrentColumnCount(binding.media);
+            mMediaAdapter.setAttachments(attachments.subList(0, Math.min(limit, attachments.size())));
+            binding.mediaWrapper.setVisibility(attachments.size() > 0 ? View.VISIBLE : View.GONE);
+        });
+    }
+
     protected void saveAsBookmark() {
         xmppConnectionService.saveConversationAsBookmark(mConversation, mConversation.getMucOptions().getName());
         updateView();
@@ -503,6 +521,8 @@ public class ConferenceDetailsActivity extends XmppActivity implements OnConvers
         if (uuid != null) {
             this.mConversation = xmppConnectionService.findConversationByUuid(uuid);
             if (this.mConversation != null) {
+                final int limit = GridManager.getCurrentColumnCount(this.binding.media);
+                xmppConnectionService.getAttachments(this.mConversation, limit, this);
                 updateView();
             }
         }
diff --git a/src/main/java/de/pixart/messenger/ui/ContactDetailsActivity.java b/src/main/java/de/pixart/messenger/ui/ContactDetailsActivity.java
index 5dce3fca2..d488419d2 100644
--- a/src/main/java/de/pixart/messenger/ui/ContactDetailsActivity.java
+++ b/src/main/java/de/pixart/messenger/ui/ContactDetailsActivity.java
@@ -30,6 +30,7 @@ import android.widget.Toast;
 
 import org.openintents.openpgp.util.OpenPgpUtils;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -45,6 +46,10 @@ import de.pixart.messenger.entities.Conversation;
 import de.pixart.messenger.entities.ListItem;
 import de.pixart.messenger.services.XmppConnectionService.OnAccountUpdate;
 import de.pixart.messenger.services.XmppConnectionService.OnRosterUpdate;
+import de.pixart.messenger.ui.adapter.MediaAdapter;
+import de.pixart.messenger.ui.interfaces.OnMediaLoaded;
+import de.pixart.messenger.ui.util.Attachment;
+import de.pixart.messenger.ui.util.GridManager;
 import de.pixart.messenger.utils.CryptoHelper;
 import de.pixart.messenger.utils.IrregularUnicodeDetector;
 import de.pixart.messenger.utils.MenuDoubleTabUtil;
@@ -57,12 +62,13 @@ import de.pixart.messenger.xmpp.OnUpdateBlocklist;
 import de.pixart.messenger.xmpp.XmppConnection;
 import rocks.xmpp.addr.Jid;
 
-public class ContactDetailsActivity extends OmemoActivity implements OnAccountUpdate, OnRosterUpdate, OnUpdateBlocklist, OnKeyStatusUpdated {
+public class ContactDetailsActivity extends OmemoActivity implements OnAccountUpdate, OnRosterUpdate, OnUpdateBlocklist, OnKeyStatusUpdated, OnMediaLoaded {
     public static final String ACTION_VIEW_CONTACT = "view_contact";
 
     private Contact contact;
     private Conversation mConversation;
     ActivityContactDetailsBinding binding;
+    private MediaAdapter mMediaAdapter;
     private DialogInterface.OnClickListener removeFromRoster = new DialogInterface.OnClickListener() {
 
         @Override
@@ -260,6 +266,9 @@ public class ContactDetailsActivity extends OmemoActivity implements OnAccountUp
         this.mNotifyStatusButton = findViewById(R.id.notification_status_button);
         this.mNotifyStatusButton.setOnClickListener(this.mNotifyStatusClickListener);
         this.mNotifyStatusText = findViewById(R.id.notification_status_text);
+        mMediaAdapter = new MediaAdapter(this, R.dimen.media_size);
+        this.binding.media.setAdapter(mMediaAdapter);
+        GridManager.setupLayoutManager(this, this.binding.media, R.dimen.media_size);
     }
 
     @Override
@@ -279,6 +288,7 @@ public class ContactDetailsActivity extends OmemoActivity implements OnAccountUp
             this.showDynamicTags = preferences.getBoolean(SettingsActivity.SHOW_DYNAMIC_TAGS, false);
             this.showLastSeen = preferences.getBoolean("last_activity", false);
         }
+        mMediaAdapter.setAttachments(Collections.emptyList());
     }
 
     @Override
@@ -657,6 +667,8 @@ public class ContactDetailsActivity extends OmemoActivity implements OnAccountUp
                 processFingerprintVerification(mPendingFingerprintVerificationUri);
                 mPendingFingerprintVerificationUri = null;
             }
+            final int limit = GridManager.getCurrentColumnCount(this.binding.media);
+            xmppConnectionService.getAttachments(account, contact.getJid().asBareJid(), limit, this);
             populateView();
         }
     }
@@ -676,4 +688,13 @@ public class ContactDetailsActivity extends OmemoActivity implements OnAccountUp
             Toast.makeText(this, R.string.invalid_barcode, Toast.LENGTH_SHORT).show();
         }
     }
+
+    @Override
+    public void onMediaLoaded(List<Attachment> attachments) {
+        runOnUiThread(() -> {
+            int limit = GridManager.getCurrentColumnCount(binding.media);
+            mMediaAdapter.setAttachments(attachments.subList(0, Math.min(limit, attachments.size())));
+            binding.mediaWrapper.setVisibility(attachments.size() > 0 ? View.VISIBLE : View.GONE);
+        });
+    }
 }
diff --git a/src/main/java/de/pixart/messenger/ui/ConversationFragment.java b/src/main/java/de/pixart/messenger/ui/ConversationFragment.java
index 9961e014b..c2e2902ac 100644
--- a/src/main/java/de/pixart/messenger/ui/ConversationFragment.java
+++ b/src/main/java/de/pixart/messenger/ui/ConversationFragment.java
@@ -1375,7 +1375,7 @@ public class ConversationFragment extends XmppFragment implements EditMessage.Ke
             if (m.isFileOrImage() && !deleted) {
                 String path = m.getRelativeFilePath();
                 Log.d(Config.LOGTAG, "Path = " + path);
-                if (path == null || !path.startsWith("/") || path.contains(FileBackend.getConversationsDirectory("null", false))) {
+                if (path == null || !path.startsWith("/") || path.contains(FileBackend.getConversationsDirectory("null"))) {
                     deleteFile.setVisible(true);
                     deleteFile.setTitle(activity.getString(R.string.delete_x_file, UIHelper.getFileDescriptionString(activity, m)));
                 }
diff --git a/src/main/java/de/pixart/messenger/ui/RecordingActivity.java b/src/main/java/de/pixart/messenger/ui/RecordingActivity.java
index 455bbf3c3..31dc1681a 100644
--- a/src/main/java/de/pixart/messenger/ui/RecordingActivity.java
+++ b/src/main/java/de/pixart/messenger/ui/RecordingActivity.java
@@ -127,7 +127,7 @@ public class RecordingActivity extends Activity implements View.OnClickListener
 
     private static File generateOutputFilename(Context context) {
         SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd_HHmmssSSS", Locale.US);
-        return new File(FileBackend.getConversationsDirectory("Audios", true) + "/"
+        return new File(FileBackend.getConversationsDirectory("Audios")
                 + dateFormat.format(new Date())
                 + ".m4a");
     }
diff --git a/src/main/java/de/pixart/messenger/ui/UpdaterActivity.java b/src/main/java/de/pixart/messenger/ui/UpdaterActivity.java
index 959060101..9e35d7ebf 100644
--- a/src/main/java/de/pixart/messenger/ui/UpdaterActivity.java
+++ b/src/main/java/de/pixart/messenger/ui/UpdaterActivity.java
@@ -114,7 +114,7 @@ public class UpdaterActivity extends XmppActivity {
                 store = null;
             }
             //delete old downloaded localVersion files
-            File dir = new File(FileBackend.getConversationsDirectory("Update", false));
+            File dir = new File(FileBackend.getAppUpdateDirectory());
             if (dir.isDirectory()) {
                 String[] children = dir.list();
                 for (String aChildren : children) {
@@ -291,7 +291,7 @@ public class UpdaterActivity extends XmppActivity {
 
     private class DownloadTask extends AsyncTask<String, Integer, String> {
 
-        File dir = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + FileBackend.getDirectoryName("Update", false));
+        File dir = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + FileBackend.getAppUpdateDirectory());
         File file = new File(dir, FileName);
         private Context context;
         private PowerManager.WakeLock mWakeLock;
diff --git a/src/main/java/de/pixart/messenger/ui/WelcomeActivity.java b/src/main/java/de/pixart/messenger/ui/WelcomeActivity.java
index 9d5b76c1c..e2bf9d8e9 100644
--- a/src/main/java/de/pixart/messenger/ui/WelcomeActivity.java
+++ b/src/main/java/de/pixart/messenger/ui/WelcomeActivity.java
@@ -193,7 +193,7 @@ public class WelcomeActivity extends XmppActivity {
 
     private boolean BackupAvailable() {
         // Set the folder on the SDcard
-        File filePath = new File(FileBackend.getConversationsDirectory("Database", false) + "database.db.crypt");
+        File filePath = new File(FileBackend.getBackupDirectory() + "database.db.crypt");
         Log.d(Config.LOGTAG, "DB Path: " + filePath.toString());
         if (filePath.exists()) {
             Log.d(Config.LOGTAG, "DB Path existing");
@@ -206,11 +206,11 @@ public class WelcomeActivity extends XmppActivity {
 
     private void checkDatabase(String DecryptionKey) throws IOException {
         // Set the folder on the SDcard
-        File directory = new File(FileBackend.getConversationsDirectory("Database", false));
+        File directory = new File(FileBackend.getBackupDirectory());
         // Set the input file stream up:
-        FileInputStream InputFile = new FileInputStream(directory.getPath() + "/database.db.crypt");
+        FileInputStream InputFile = new FileInputStream(directory.getPath() + "database.db.crypt");
         // Temp output for DB checks
-        File TempFile = new File(directory.getPath() + "/database.bak");
+        File TempFile = new File(directory.getPath() + "database.bak");
         FileOutputStream OutputTemp = new FileOutputStream(TempFile);
 
         try {
@@ -286,11 +286,11 @@ public class WelcomeActivity extends XmppActivity {
         // Set location for the db:
         final OutputStream OutputFile = new FileOutputStream(this.getDatabasePath(DatabaseBackend.DATABASE_NAME));
         // Set the folder on the SDcard
-        File directory = new File(FileBackend.getConversationsDirectory("Database", false));
+        File directory = new File(FileBackend.getBackupDirectory());
         // Set the input file stream up:
-        final InputStream InputFile = new FileInputStream(directory.getPath() + "/database.bak");
+        final InputStream InputFile = new FileInputStream(directory.getPath() + "database.bak");
         //set temp file
-        File TempFile = new File(directory.getPath() + "/database.bak");
+        File TempFile = new File(directory.getPath() + "database.bak");
 
         // Transfer bytes from the input file to the output file
         byte[] buffer = new byte[1024];
diff --git a/src/main/java/de/pixart/messenger/ui/adapter/MediaAdapter.java b/src/main/java/de/pixart/messenger/ui/adapter/MediaAdapter.java
new file mode 100644
index 000000000..0472c6d11
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/ui/adapter/MediaAdapter.java
@@ -0,0 +1,226 @@
+package de.pixart.messenger.ui.adapter;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.databinding.DataBindingUtil;
+import android.graphics.Bitmap;
+import android.graphics.drawable.BitmapDrawable;
+import android.graphics.drawable.Drawable;
+import android.os.AsyncTask;
+import android.support.annotation.AttrRes;
+import android.support.annotation.DimenRes;
+import android.support.annotation.NonNull;
+import android.support.v7.widget.RecyclerView;
+import android.view.LayoutInflater;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.RejectedExecutionException;
+
+import de.pixart.messenger.R;
+import de.pixart.messenger.databinding.MediaBinding;
+import de.pixart.messenger.ui.XmppActivity;
+import de.pixart.messenger.ui.util.Attachment;
+import de.pixart.messenger.ui.util.StyledAttributes;
+import de.pixart.messenger.ui.util.ViewUtil;
+
+public class MediaAdapter extends RecyclerView.Adapter<MediaAdapter.MediaViewHolder> {
+
+    private static final List<String> DOCUMENT_MIMES = Arrays.asList(
+            "application/pdf",
+            "application/vnd.oasis.opendocument.text",
+            "application/msword",
+            "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+            "text/x-tex",
+            "text/plain"
+    );
+
+    private final ArrayList<Attachment> attachments = new ArrayList<>();
+
+    private final XmppActivity activity;
+
+    private int mediaSize = 0;
+
+    public MediaAdapter(XmppActivity activity, @DimenRes int mediaSize) {
+        this.activity = activity;
+        this.mediaSize = Math.round(activity.getResources().getDimension(mediaSize));
+    }
+
+    public static void setMediaSize(RecyclerView recyclerView, int mediaSize) {
+        RecyclerView.Adapter adapter = recyclerView.getAdapter();
+        if (adapter instanceof MediaAdapter) {
+            ((MediaAdapter) adapter).setMediaSize(mediaSize);
+        }
+    }
+
+    private static @AttrRes
+    int getImageAttr(Attachment attachment) {
+        final @AttrRes int attr;
+        if (attachment.getType() == Attachment.Type.LOCATION) {
+            attr = R.attr.media_preview_location;
+        } else if (attachment.getType() == Attachment.Type.RECORDING) {
+            attr = R.attr.media_preview_recording;
+        } else {
+            final String mime = attachment.getMime();
+            if (mime == null) {
+                attr = R.attr.media_preview_unknown;
+            } else if (mime.startsWith("audio/")) {
+                attr = R.attr.media_preview_audio;
+            } else if (mime.equals("text/calendar") || (mime.equals("text/x-vcalendar"))) {
+                attr = R.attr.media_preview_calendar;
+            } else if (mime.equals("text/x-vcard")) {
+                attr = R.attr.media_preview_contact;
+            } else if (mime.equals("application/vnd.android.package-archive")) {
+                attr = R.attr.media_preview_app;
+            } else if (mime.equals("application/zip") || mime.equals("application/rar")) {
+                attr = R.attr.media_preview_archive;
+            } else if (DOCUMENT_MIMES.contains(mime)) {
+                attr = R.attr.media_preview_document;
+            } else {
+                attr = R.attr.media_preview_unknown;
+            }
+        }
+        return attr;
+    }
+
+    public static void renderPreview(Context context, Attachment attachment, ImageView imageView) {
+        imageView.setBackgroundColor(StyledAttributes.getColor(context, R.attr.color_background_tertiary));
+        imageView.setImageAlpha(Math.round(StyledAttributes.getFloat(context, R.attr.icon_alpha) * 255));
+        imageView.setImageDrawable(StyledAttributes.getDrawable(context, getImageAttr(attachment)));
+    }
+
+    private static boolean cancelPotentialWork(Attachment attachment, ImageView imageView) {
+        final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView);
+
+        if (bitmapWorkerTask != null) {
+            final Attachment oldAttachment = bitmapWorkerTask.attachment;
+            if (oldAttachment == null || !oldAttachment.equals(attachment)) {
+                bitmapWorkerTask.cancel(true);
+            } else {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private static BitmapWorkerTask getBitmapWorkerTask(ImageView imageView) {
+        if (imageView != null) {
+            final Drawable drawable = imageView.getDrawable();
+            if (drawable instanceof AsyncDrawable) {
+                final AsyncDrawable asyncDrawable = (AsyncDrawable) drawable;
+                return asyncDrawable.getBitmapWorkerTask();
+            }
+        }
+        return null;
+    }
+
+    @NonNull
+    @Override
+    public MediaViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
+        MediaBinding binding = DataBindingUtil.inflate(layoutInflater, R.layout.media, parent, false);
+        return new MediaViewHolder(binding);
+    }
+
+    @Override
+    public void onBindViewHolder(@NonNull MediaViewHolder holder, int position) {
+        final Attachment attachment = attachments.get(position);
+        if (attachment.renderThumbnail()) {
+            holder.binding.media.setImageAlpha(255);
+            loadPreview(attachment, holder.binding.media);
+        } else {
+            cancelPotentialWork(attachment, holder.binding.media);
+            renderPreview(activity, attachment, holder.binding.media);
+        }
+        holder.binding.media.setOnClickListener(v -> ViewUtil.view(activity, attachment));
+    }
+
+    public void setAttachments(List<Attachment> attachments) {
+        this.attachments.clear();
+        this.attachments.addAll(attachments);
+        notifyDataSetChanged();
+    }
+
+    private void setMediaSize(int mediaSize) {
+        this.mediaSize = mediaSize;
+    }
+
+    private void loadPreview(Attachment attachment, ImageView imageView) {
+        if (cancelPotentialWork(attachment, imageView)) {
+            final Bitmap bm = activity.xmppConnectionService.getFileBackend().getPreviewForUri(attachment, mediaSize, true);
+            if (bm != null) {
+                cancelPotentialWork(attachment, imageView);
+                imageView.setImageBitmap(bm);
+                imageView.setBackgroundColor(0x00000000);
+            } else {
+                imageView.setBackgroundColor(0xff333333);
+                imageView.setImageDrawable(null);
+                final BitmapWorkerTask task = new BitmapWorkerTask(imageView);
+                final AsyncDrawable asyncDrawable = new AsyncDrawable(activity.getResources(), null, task);
+                imageView.setImageDrawable(asyncDrawable);
+                try {
+                    task.execute(attachment);
+                } catch (final RejectedExecutionException ignored) {
+                }
+            }
+        }
+    }
+
+    @Override
+    public int getItemCount() {
+        return attachments.size();
+    }
+
+    static class AsyncDrawable extends BitmapDrawable {
+        private final WeakReference<BitmapWorkerTask> bitmapWorkerTaskReference;
+
+        AsyncDrawable(Resources res, Bitmap bitmap, BitmapWorkerTask bitmapWorkerTask) {
+            super(res, bitmap);
+            bitmapWorkerTaskReference = new WeakReference<>(bitmapWorkerTask);
+        }
+
+        BitmapWorkerTask getBitmapWorkerTask() {
+            return bitmapWorkerTaskReference.get();
+        }
+    }
+
+    class MediaViewHolder extends RecyclerView.ViewHolder {
+
+        private final MediaBinding binding;
+
+        MediaViewHolder(MediaBinding binding) {
+            super(binding.getRoot());
+            this.binding = binding;
+        }
+    }
+
+    class BitmapWorkerTask extends AsyncTask<Attachment, Void, Bitmap> {
+        private final WeakReference<ImageView> imageViewReference;
+        private Attachment attachment = null;
+
+        BitmapWorkerTask(ImageView imageView) {
+            imageViewReference = new WeakReference<>(imageView);
+        }
+
+        @Override
+        protected Bitmap doInBackground(Attachment... params) {
+            this.attachment = params[0];
+            return activity.xmppConnectionService.getFileBackend().getPreviewForUri(this.attachment, mediaSize, false);
+        }
+
+        @Override
+        protected void onPostExecute(Bitmap bitmap) {
+            if (bitmap != null && !isCancelled()) {
+                final ImageView imageView = imageViewReference.get();
+                if (imageView != null) {
+                    imageView.setImageBitmap(bitmap);
+                    imageView.setBackgroundColor(0x00000000);
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/ui/adapter/MediaPreviewAdapter.java b/src/main/java/de/pixart/messenger/ui/adapter/MediaPreviewAdapter.java
index 9192c6555..ae4c42816 100644
--- a/src/main/java/de/pixart/messenger/ui/adapter/MediaPreviewAdapter.java
+++ b/src/main/java/de/pixart/messenger/ui/adapter/MediaPreviewAdapter.java
@@ -8,7 +8,6 @@ import android.graphics.Bitmap;
 import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
 import android.os.AsyncTask;
-import android.support.annotation.AttrRes;
 import android.support.annotation.NonNull;
 import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
@@ -17,7 +16,6 @@ import android.widget.ImageView;
 
 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.RejectedExecutionException;
 
@@ -26,19 +24,9 @@ import de.pixart.messenger.databinding.MediaPreviewBinding;
 import de.pixart.messenger.ui.ConversationFragment;
 import de.pixart.messenger.ui.XmppActivity;
 import de.pixart.messenger.ui.util.Attachment;
-import de.pixart.messenger.ui.util.StyledAttributes;
 
 public class MediaPreviewAdapter extends RecyclerView.Adapter<MediaPreviewAdapter.MediaPreviewViewHolder> {
 
-    private static final List<String> DOCUMENT_MIMES = Arrays.asList(
-            "application/pdf",
-            "application/vnd.oasis.opendocument.text",
-            "application/msword",
-            "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
-            "text/x-tex",
-            "text/plain"
-    );
-
     private final ArrayList<Attachment> mediaPreviews = new ArrayList<>();
 
     private final ConversationFragment conversationFragment;
@@ -89,34 +77,7 @@ public class MediaPreviewAdapter extends RecyclerView.Adapter<MediaPreviewAdapte
             loadPreview(attachment, holder.binding.mediaPreview);
         } else {
             cancelPotentialWork(attachment, holder.binding.mediaPreview);
-            holder.binding.mediaPreview.setBackgroundColor(StyledAttributes.getColor(context, R.attr.color_background_tertiary));
-            holder.binding.mediaPreview.setImageAlpha(Math.round(StyledAttributes.getFloat(context, R.attr.icon_alpha) * 255));
-            final @AttrRes int attr;
-            if (attachment.getType() == Attachment.Type.LOCATION) {
-                attr = R.attr.media_preview_location;
-            } else if (attachment.getType() == Attachment.Type.RECORDING) {
-                attr = R.attr.media_preview_recording;
-            } else {
-                final String mime = attachment.getMime();
-                if (mime == null) {
-                    attr = R.attr.media_preview_unknown;
-                } else if (mime.startsWith("audio/")) {
-                    attr = R.attr.media_preview_audio;
-                } else if (mime.equals("text/calendar") || (mime.equals("text/x-vcalendar"))) {
-                    attr = R.attr.media_preview_calendar;
-                } else if (mime.equals("text/x-vcard")) {
-                    attr = R.attr.media_preview_contact;
-                } else if (mime.equals("application/vnd.android.package-archive")) {
-                    attr = R.attr.media_preview_app;
-                } else if (mime.equals("application/zip") || mime.equals("application/rar")) {
-                    attr = R.attr.media_preview_archive;
-                } else if (DOCUMENT_MIMES.contains(mime)) {
-                    attr = R.attr.media_preview_document;
-                } else {
-                    attr = R.attr.media_preview_unknown;
-                }
-            }
-            holder.binding.mediaPreview.setImageDrawable(StyledAttributes.getDrawable(context, attr));
+            MediaAdapter.renderPreview(context, attachment, holder.binding.mediaPreview);
         }
         holder.binding.deleteButton.setOnClickListener(v -> {
             int pos = mediaPreviews.indexOf(attachment);
@@ -166,6 +127,10 @@ public class MediaPreviewAdapter extends RecyclerView.Adapter<MediaPreviewAdapte
         return mediaPreviews;
     }
 
+    public void clearPreviews() {
+        this.mediaPreviews.clear();
+    }
+
     static class AsyncDrawable extends BitmapDrawable {
         private final WeakReference<BitmapWorkerTask> bitmapWorkerTaskReference;
 
@@ -179,11 +144,6 @@ public class MediaPreviewAdapter extends RecyclerView.Adapter<MediaPreviewAdapte
         }
     }
 
-    public void clearPreviews() {
-        this.mediaPreviews.clear();
-    }
-
-
     class MediaPreviewViewHolder extends RecyclerView.ViewHolder {
 
         private final MediaPreviewBinding binding;
diff --git a/src/main/java/de/pixart/messenger/ui/adapter/MessageAdapter.java b/src/main/java/de/pixart/messenger/ui/adapter/MessageAdapter.java
index efd3b8842..ae124e950 100644
--- a/src/main/java/de/pixart/messenger/ui/adapter/MessageAdapter.java
+++ b/src/main/java/de/pixart/messenger/ui/adapter/MessageAdapter.java
@@ -6,7 +6,6 @@ import android.content.ActivityNotFoundException;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
-import android.content.pm.ResolveInfo;
 import android.content.res.Resources;
 import android.graphics.Bitmap;
 import android.graphics.Color;
@@ -29,7 +28,6 @@ import android.text.style.RelativeSizeSpan;
 import android.text.style.StyleSpan;
 import android.util.Base64;
 import android.util.DisplayMetrics;
-import android.util.Log;
 import android.view.ActionMode;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -77,6 +75,7 @@ import de.pixart.messenger.ui.XmppActivity;
 import de.pixart.messenger.ui.text.DividerSpan;
 import de.pixart.messenger.ui.text.QuoteSpan;
 import de.pixart.messenger.ui.util.MyLinkify;
+import de.pixart.messenger.ui.util.ViewUtil;
 import de.pixart.messenger.ui.widget.ClickableMovementMethod;
 import de.pixart.messenger.ui.widget.CopyTextView;
 import de.pixart.messenger.ui.widget.ListSelectionManager;
@@ -1068,31 +1067,10 @@ public class MessageAdapter extends ArrayAdapter<Message> implements CopyTextVie
                 //ignored
             }
         }
-        Intent openIntent = new Intent(Intent.ACTION_VIEW);
         if (mime == null) {
             mime = "*/*";
         }
-        Uri uri;
-        try {
-            uri = FileBackend.getUriForFile(activity, file);
-        } catch (SecurityException e) {
-            Log.d(Config.LOGTAG, "No permission to access " + file.getAbsolutePath(), e);
-            Toast.makeText(activity, activity.getString(R.string.no_permission_to_access_x, file.getAbsolutePath()), Toast.LENGTH_SHORT).show();
-            return;
-        }
-        openIntent.setDataAndType(uri, mime);
-        openIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
-        PackageManager manager = activity.getPackageManager();
-        List<ResolveInfo> info = manager.queryIntentActivities(openIntent, 0);
-        if (info.size() == 0) {
-            openIntent.setDataAndType(uri,"*/*");
-        }
-        try {
-            getContext().startActivity(openIntent);
-            activity.overridePendingTransition(R.animator.fade_in, R.animator.fade_out);
-        } catch (ActivityNotFoundException e) {
-            Toast.makeText(activity, R.string.no_application_found_to_open_file, Toast.LENGTH_SHORT).show();
-        }
+        ViewUtil.view(activity, file, mime);
     }
 
     public void showLocation(Message message) {
diff --git a/src/main/java/de/pixart/messenger/ui/interfaces/OnMediaLoaded.java b/src/main/java/de/pixart/messenger/ui/interfaces/OnMediaLoaded.java
new file mode 100644
index 000000000..0441be96d
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/ui/interfaces/OnMediaLoaded.java
@@ -0,0 +1,10 @@
+package de.pixart.messenger.ui.interfaces;
+
+import java.util.List;
+
+import de.pixart.messenger.ui.util.Attachment;
+
+public interface OnMediaLoaded {
+
+    void onMediaLoaded(List<Attachment> attachments);
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/ui/util/Attachment.java b/src/main/java/de/pixart/messenger/ui/util/Attachment.java
index f11efd0d1..96159c1bd 100644
--- a/src/main/java/de/pixart/messenger/ui/util/Attachment.java
+++ b/src/main/java/de/pixart/messenger/ui/util/Attachment.java
@@ -37,6 +37,7 @@ import android.os.Parcel;
 import android.os.Parcelable;
 import android.util.Log;
 
+import java.io.File;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -61,12 +62,21 @@ public class Attachment implements Parcelable {
     private final Type type;
     private final UUID uuid;
     private final String mime;
+
     Attachment(Parcel in) {
         uri = in.readParcelable(Uri.class.getClassLoader());
         mime = in.readString();
         uuid = UUID.fromString(in.readString());
         type = Type.valueOf(in.readString());
     }
+
+    private Attachment(UUID uuid, Uri uri, Type type, String mime) {
+        this.uri = uri;
+        this.type = type;
+        this.mime = mime;
+        this.uuid = uuid;
+    }
+
     private Attachment(Uri uri, Type type, String mime) {
         this.uri = uri;
         this.type = type;
@@ -88,6 +98,10 @@ public class Attachment implements Parcelable {
         return attachments;
     }
 
+    public static Attachment of(UUID uuid, final File file, String mime) {
+        return new Attachment(uuid, Uri.fromFile(file), mime != null && (mime.startsWith("image/") || mime.startsWith("video/")) ? Type.IMAGE : Type.FILE, mime);
+    }
+
     public static List<Attachment> extractAttachments(final Context context, final Intent intent, Type type) {
         List<Attachment> uris = new ArrayList<>();
         if (intent == null) {
diff --git a/src/main/java/de/pixart/messenger/ui/util/GridManager.java b/src/main/java/de/pixart/messenger/ui/util/GridManager.java
new file mode 100644
index 000000000..717fef526
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/ui/util/GridManager.java
@@ -0,0 +1,71 @@
+package de.pixart.messenger.ui.util;
+
+import android.content.Context;
+import android.support.annotation.DimenRes;
+import android.support.v7.widget.GridLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.util.Log;
+import android.view.ViewTreeObserver;
+
+import de.pixart.messenger.Config;
+import de.pixart.messenger.ui.adapter.MediaAdapter;
+
+public class GridManager {
+
+    public static void setupLayoutManager(final Context context, RecyclerView recyclerView, @DimenRes int desiredSize) {
+        int maxWidth = context.getResources().getDisplayMetrics().widthPixels;
+        ColumnInfo columnInfo = calculateColumnCount(context, maxWidth, desiredSize);
+        Log.d(Config.LOGTAG, "preliminary count=" + columnInfo.count);
+        MediaAdapter.setMediaSize(recyclerView, columnInfo.width);
+        recyclerView.setLayoutManager(new GridLayoutManager(context, columnInfo.count));
+        recyclerView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
+            @Override
+            public void onGlobalLayout() {
+                recyclerView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
+                final ColumnInfo columnInfo = calculateColumnCount(context, recyclerView.getMeasuredWidth(), desiredSize);
+                Log.d(Config.LOGTAG, "final count " + columnInfo.count);
+                if (recyclerView.getAdapter().getItemCount() != 0) {
+                    Log.e(Config.LOGTAG, "adapter already has items; just go with it now");
+                    return;
+                }
+                setupLayoutManagerInternal(recyclerView, columnInfo);
+                MediaAdapter.setMediaSize(recyclerView, columnInfo.width);
+            }
+        });
+    }
+
+    private static void setupLayoutManagerInternal(RecyclerView recyclerView, final ColumnInfo columnInfo) {
+        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
+        if (layoutManager instanceof GridLayoutManager) {
+            ((GridLayoutManager) layoutManager).setSpanCount(columnInfo.count);
+        }
+    }
+
+    private static ColumnInfo calculateColumnCount(Context context, int availableWidth, @DimenRes int desiredSize) {
+        final float desiredWidth = context.getResources().getDimension(desiredSize);
+        final int columns = Math.round(availableWidth / desiredWidth);
+        final int realWidth = availableWidth / columns;
+        Log.d(Config.LOGTAG, "desired=" + desiredWidth + " real=" + realWidth);
+        return new ColumnInfo(columns, realWidth);
+    }
+
+    public static int getCurrentColumnCount(RecyclerView recyclerView) {
+        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
+        if (layoutManager instanceof GridLayoutManager) {
+            return ((GridLayoutManager) layoutManager).getSpanCount();
+        } else {
+            return 0;
+        }
+    }
+
+    public static class ColumnInfo {
+        private final int count;
+        private final int width;
+
+        private ColumnInfo(int count, int width) {
+            this.count = count;
+            this.width = width;
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/ui/util/ViewUtil.java b/src/main/java/de/pixart/messenger/ui/util/ViewUtil.java
new file mode 100644
index 000000000..2442df8dc
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/ui/util/ViewUtil.java
@@ -0,0 +1,50 @@
+package de.pixart.messenger.ui.util;
+
+import android.content.ActivityNotFoundException;
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.content.pm.ResolveInfo;
+import android.net.Uri;
+import android.util.Log;
+import android.widget.Toast;
+
+import java.io.File;
+import java.util.List;
+
+import de.pixart.messenger.Config;
+import de.pixart.messenger.R;
+import de.pixart.messenger.persistance.FileBackend;
+
+public class ViewUtil {
+
+    public static void view(Context context, Attachment attachment) {
+        File file = new File(attachment.getUri().getPath());
+        final String mime = attachment.getMime() == null ? "*/*" : attachment.getMime();
+        view(context, file, mime);
+    }
+
+    public static void view(Context context, File file, String mime) {
+        Intent openIntent = new Intent(Intent.ACTION_VIEW);
+        Uri uri;
+        try {
+            uri = FileBackend.getUriForFile(context, file);
+        } catch (SecurityException e) {
+            Log.d(Config.LOGTAG, "No permission to access " + file.getAbsolutePath(), e);
+            Toast.makeText(context, context.getString(R.string.no_permission_to_access_x, file.getAbsolutePath()), Toast.LENGTH_SHORT).show();
+            return;
+        }
+        openIntent.setDataAndType(uri, mime);
+        openIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
+        PackageManager manager = context.getPackageManager();
+        List<ResolveInfo> info = manager.queryIntentActivities(openIntent, 0);
+        if (info.size() == 0) {
+            openIntent.setDataAndType(uri, "*/*");
+        }
+        try {
+            context.startActivity(openIntent);
+        } catch (ActivityNotFoundException e) {
+            Toast.makeText(context, R.string.no_application_found_to_open_file, Toast.LENGTH_SHORT).show();
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/ui/widget/SquareFrameLayout.java b/src/main/java/de/pixart/messenger/ui/widget/SquareFrameLayout.java
new file mode 100644
index 000000000..4d2fcf92d
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/ui/widget/SquareFrameLayout.java
@@ -0,0 +1,25 @@
+package de.pixart.messenger.ui.widget;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.widget.FrameLayout;
+
+public class SquareFrameLayout extends FrameLayout {
+    public SquareFrameLayout(Context context) {
+        super(context);
+    }
+
+    public SquareFrameLayout(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public SquareFrameLayout(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+    }
+
+    @Override
+    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        //noinspection SuspiciousNameCombination
+        super.onMeasure(widthMeasureSpec, widthMeasureSpec);
+    }
+}
\ No newline at end of file