Retain TextView selection after list updating

src/main/java/eu/siacs/conversations/ui/ConversationFragment.java

@@ -12,8 +12,6 @@ import android.content.IntentSender.SendIntentException;
 import android.os.Bundle;
 import android.os.Handler;
 import android.text.InputType;
-import android.text.Selection;
-import android.text.Spannable;
 import android.util.Log;
 import android.util.Pair;
 import android.view.ContextMenu;
@@ -40,8 +38,6 @@ import android.widget.Toast;
 
 import net.java.otr4j.session.SessionStatus;
 
-import java.lang.reflect.Field;
-import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -66,6 +62,7 @@ import eu.siacs.conversations.ui.XmppActivity.OnValueEdited;
 import eu.siacs.conversations.ui.adapter.MessageAdapter;
 import eu.siacs.conversations.ui.adapter.MessageAdapter.OnContactPictureClicked;
 import eu.siacs.conversations.ui.adapter.MessageAdapter.OnContactPictureLongClicked;
+import eu.siacs.conversations.ui.widget.ListSelectionManager;
 import eu.siacs.conversations.utils.GeoHelper;
 import eu.siacs.conversations.utils.UIHelper;
 import eu.siacs.conversations.xmpp.XmppConnection;
@@ -553,7 +550,7 @@ public class ConversationFragment extends Fragment implements EditMessage.Keyboa
 					&& !GeoHelper.isGeoUri(m.getBody())
 					&& m.treatAsDownloadable() != Message.Decision.MUST) {
 				copyText.setVisible(true);
-				selectText.setVisible(METHOD_START_SELECTION != null);
+				selectText.setVisible(ListSelectionManager.isSupported());
 			}
 			if (m.getEncryption() == Message.ENCRYPTION_DECRYPTION_FAILED) {
 				retryDecryption.setVisible(true);
@@ -677,13 +674,7 @@ public class ConversationFragment extends Fragment implements EditMessage.Keyboa
 				final View view = this.messagesView.getChildAt(index - first);
 				final TextView messageBody = this.messageListAdapter.getMessageBody(view);
 				if (messageBody != null) {
-					final Spannable text = (Spannable) messageBody.getText();
+					ListSelectionManager.startSelection(messageBody);
-					Selection.setSelection(text, 0, text.length());
-					try {
-						Object editor = FIELD_EDITOR != null ? FIELD_EDITOR.get(messageBody) : messageBody;
-						METHOD_START_SELECTION.invoke(editor);
-					} catch (Exception e) {
-					}
 				}
 			}
 		}
@@ -1463,31 +1454,4 @@ public class ConversationFragment extends Fragment implements EditMessage.Keyboa
 		}
 	}
 
-	private static final Field FIELD_EDITOR;
-	private static final Method METHOD_START_SELECTION;
-
-	static {
-		Field editor;
-		try {
-			editor = TextView.class.getDeclaredField("mEditor");
-			editor.setAccessible(true);
-		} catch (Exception e) {
-			editor = null;
-		}
-		FIELD_EDITOR = editor;
-		Class<?> editorClass = editor != null ? editor.getType() : TextView.class;
-		String[] startSelectionNames = {"startSelectionActionMode", "startSelectionActionModeWithSelection"};
-		Method startSelection = null;
-		for (String startSelectionName : startSelectionNames) {
-			try {
-				startSelection = editorClass.getDeclaredMethod(startSelectionName);
-				startSelection.setAccessible(true);
-				break;
-			} catch (Exception e) {
-				startSelection = null;
-			}
-		}
-		METHOD_START_SELECTION = startSelection;
-	}
-
 }

src/main/java/eu/siacs/conversations/ui/adapter/MessageAdapter.java

@@ -53,6 +53,7 @@ import eu.siacs.conversations.entities.Message.FileParams;
 import eu.siacs.conversations.entities.Transferable;
 import eu.siacs.conversations.ui.ConversationActivity;
 import eu.siacs.conversations.ui.widget.ClickableMovementMethod;
+import eu.siacs.conversations.ui.widget.ListSelectionManager;
 import eu.siacs.conversations.utils.CryptoHelper;
 import eu.siacs.conversations.utils.GeoHelper;
 import eu.siacs.conversations.utils.UIHelper;
@@ -86,6 +87,8 @@ public class MessageAdapter extends ArrayAdapter<Message> {
 	private boolean mIndicateReceived = false;
 	private boolean mUseGreenBackground = false;
 
+	private final ListSelectionManager listSelectionManager = new ListSelectionManager();
+
 	public MessageAdapter(ConversationActivity activity, List<Message> messages) {
 		super(activity, 0, messages);
 		this.activity = activity;
@@ -361,6 +364,7 @@ public class MessageAdapter extends ArrayAdapter<Message> {
 			viewHolder.messageBody.setText(formattedBody);
 			viewHolder.messageBody.setTextIsSelectable(true);
 			viewHolder.messageBody.setMovementMethod(ClickableMovementMethod.getInstance());
+			listSelectionManager.onUpdate(viewHolder.messageBody, message);
 		} else {
 			viewHolder.messageBody.setText("");
 			viewHolder.messageBody.setTextIsSelectable(false);
@@ -534,6 +538,7 @@ public class MessageAdapter extends ArrayAdapter<Message> {
 					viewHolder = null;
 					break;
 			}
+			if (viewHolder.messageBody != null) listSelectionManager.onCreate(viewHolder.messageBody);
 			view.setTag(viewHolder);
 		} else {
 			viewHolder = (ViewHolder) view.getTag();
@@ -684,6 +689,13 @@ public class MessageAdapter extends ArrayAdapter<Message> {
 		return view;
 	}
 
+	@Override
+	public void notifyDataSetChanged() {
+		listSelectionManager.onBeforeNotifyDataSetChanged();
+		super.notifyDataSetChanged();
+		listSelectionManager.onAfterNotifyDataSetChanged();
+	}
+
 	public void openDownloadable(Message message) {
 		DownloadableFile file = activity.xmppConnectionService.getFileBackend().getFile(message);
 		if (!file.exists()) {

src/main/java/eu/siacs/conversations/ui/widget/ListSelectionManager.java

@@ -0,0 +1,201 @@
+package eu.siacs.conversations.ui.widget;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+import android.text.Selection;
+import android.text.Spannable;
+import android.view.ActionMode;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.widget.TextView;
+
+public class ListSelectionManager {
+
+	private static final int MESSAGE_SEND_RESET = 1;
+	private static final int MESSAGE_RESET = 2;
+	private static final int MESSAGE_START_SELECTION = 3;
+
+	private static final Handler HANDLER = new Handler(Looper.getMainLooper(), new Handler.Callback() {
+
+		@Override
+		public boolean handleMessage(Message msg) {
+			switch (msg.what) {
+				case MESSAGE_SEND_RESET: {
+					// Skip one more message queue loop
+					HANDLER.obtainMessage(MESSAGE_RESET, msg.obj).sendToTarget();
+					return true;
+				}
+				case MESSAGE_RESET: {
+					final ListSelectionManager listSelectionManager = (ListSelectionManager) msg.obj;
+					listSelectionManager.futureSelectionIdentifier = null;
+					return true;
+				}
+				case MESSAGE_START_SELECTION: {
+					final StartSelectionHolder holder = (StartSelectionHolder) msg.obj;
+					holder.listSelectionManager.futureSelectionIdentifier = null;
+					startSelection(holder.textView, holder.start, holder.end);
+					return true;
+				}
+			}
+			return false;
+		}
+	});
+
+	private static class StartSelectionHolder {
+
+		public final ListSelectionManager listSelectionManager;
+		public final TextView textView;
+		public final int start;
+		public final int end;
+
+		public StartSelectionHolder(ListSelectionManager listSelectionManager, TextView textView,
+				int start, int end) {
+			this.listSelectionManager = listSelectionManager;
+			this.textView = textView;
+			this.start = start;
+			this.end = end;
+		}
+	}
+
+	private ActionMode selectionActionMode;
+	private Object selectionIdentifier;
+	private TextView selectionTextView;
+
+	private Object futureSelectionIdentifier;
+	private int futureSelectionStart;
+	private int futureSelectionEnd;
+
+	public void onCreate(TextView textView) {
+		final CustomCallback callback = new CustomCallback(textView);
+		textView.setCustomSelectionActionModeCallback(callback);
+	}
+
+	public void onUpdate(TextView textView, Object identifier) {
+		if (SUPPORTED) {
+			CustomCallback callback = (CustomCallback) textView.getCustomSelectionActionModeCallback();
+			callback.identifier = identifier;
+			if (futureSelectionIdentifier == identifier) {
+				HANDLER.obtainMessage(MESSAGE_START_SELECTION, new StartSelectionHolder(this,
+						textView, futureSelectionStart, futureSelectionEnd)).sendToTarget();
+			}
+		}
+	}
+
+	public void onBeforeNotifyDataSetChanged() {
+		if (SUPPORTED) {
+			HANDLER.removeMessages(MESSAGE_SEND_RESET);
+			HANDLER.removeMessages(MESSAGE_RESET);
+			HANDLER.removeMessages(MESSAGE_START_SELECTION);
+			if (selectionActionMode != null) {
+				final CharSequence text = selectionTextView.getText();
+				futureSelectionIdentifier = selectionIdentifier;
+				futureSelectionStart = Selection.getSelectionStart(text);
+				futureSelectionEnd = Selection.getSelectionEnd(text);
+				selectionActionMode.finish();
+				selectionActionMode = null;
+				selectionIdentifier = null;
+				selectionTextView = null;
+			}
+		}
+	}
+
+	public void onAfterNotifyDataSetChanged() {
+		if (SUPPORTED && futureSelectionIdentifier != null) {
+			HANDLER.obtainMessage(MESSAGE_SEND_RESET, this).sendToTarget();
+		}
+	}
+
+	private class CustomCallback implements ActionMode.Callback {
+
+		private final TextView textView;
+		public Object identifier;
+
+		public CustomCallback(TextView textView) {
+			this.textView = textView;
+		}
+
+		@Override
+		public boolean onCreateActionMode(ActionMode mode, Menu menu) {
+			selectionActionMode = mode;
+			selectionIdentifier = identifier;
+			selectionTextView = textView;
+			return true;
+		}
+
+		@Override
+		public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
+			return true;
+		}
+
+		@Override
+		public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
+			return false;
+		}
+
+		@Override
+		public void onDestroyActionMode(ActionMode mode) {
+			if (selectionActionMode == mode) {
+				selectionActionMode = null;
+				selectionIdentifier = null;
+				selectionTextView = null;
+			}
+		}
+	}
+
+	private static final Field FIELD_EDITOR;
+	private static final Method METHOD_START_SELECTION;
+	private static final boolean SUPPORTED;
+
+	static {
+		Field editor;
+		try {
+			editor = TextView.class.getDeclaredField("mEditor");
+			editor.setAccessible(true);
+		} catch (Exception e) {
+			editor = null;
+		}
+		FIELD_EDITOR = editor;
+		Method startSelection = null;
+		if (editor != null) {
+			String[] startSelectionNames = {"startSelectionActionMode", "startSelectionActionModeWithSelection"};
+			for (String startSelectionName : startSelectionNames) {
+				try {
+					startSelection = editor.getType().getDeclaredMethod(startSelectionName);
+					startSelection.setAccessible(true);
+					break;
+				} catch (Exception e) {
+					startSelection = null;
+				}
+			}
+		}
+		METHOD_START_SELECTION = startSelection;
+		SUPPORTED = FIELD_EDITOR != null && METHOD_START_SELECTION != null;
+	}
+
+	public static boolean isSupported() {
+		return SUPPORTED;
+	}
+
+	public static void startSelection(TextView textView) {
+		startSelection(textView, 0, textView.getText().length());
+	}
+
+	public static void startSelection(TextView textView, int start, int end) {
+		final CharSequence text = textView.getText();
+		if (SUPPORTED && start >= 0 && end > start && textView.isTextSelectable() && text instanceof Spannable) {
+			final Spannable spannable = (Spannable) text;
+			start = Math.min(start, spannable.length());
+			end = Math.min(end, spannable.length());
+			Selection.setSelection(spannable, start, end);
+			try {
+				final Object editor = FIELD_EDITOR != null ? FIELD_EDITOR.get(textView) : textView;
+				METHOD_START_SELECTION.invoke(editor);
+			} catch (Exception e) {
+			}
+		}
+	}
+}