feat: Implement partial text selection in chat messages

src/main/java/org/thoughtcrime/securesms/ConversationItem.java

@@ -80,6 +80,8 @@
 import org.thoughtcrime.securesms.util.LongClickMovementMethod;
 import org.thoughtcrime.securesms.util.MarkdownUtil;
 import org.thoughtcrime.securesms.util.MediaUtil;
+import org.thoughtcrime.securesms.util.Prefs;
+import org.thoughtcrime.securesms.util.TextSelectionActionModeCallback;
 import org.thoughtcrime.securesms.util.Util;
 import org.thoughtcrime.securesms.util.ViewUtil;
 import org.thoughtcrime.securesms.util.views.Stub;

src/main/java/org/thoughtcrime/securesms/util/Prefs.java

@@ -42,6 +42,7 @@ public class Prefs {
   private static final String CHAT_RINGTONE = "pref_chat_ringtone_"; // followed by chat-id
   public static final String SCREEN_SECURITY_PREF = "pref_screen_security";
   private static final String ENTER_SENDS_PREF = "pref_enter_sends";
+  private static final String TEXT_SELECTION_PREF = "pref_text_selection";
   private static final String PROMPTED_DOZE_MSG_ID_PREF = "pref_prompted_doze_msg_id";
   private static final String STATS_DEVICE_MSG_ID_PREF = "pref_stats_device_msg_id";
   private static final String UPDATE_MSG_PREF = "pref_update_msg";
@@ -142,6 +143,10 @@ public static boolean isEnterSendsEnabled(Context context) {
     return getBooleanPreference(context, ENTER_SENDS_PREF, false);
   }
 
+  public static boolean isTextSelectionEnabled(Context context) {
+    return getBooleanPreference(context, TEXT_SELECTION_PREF, false);
+  }
+
   public static boolean isPasswordDisabled(Context context) {
     return getBooleanPreference(context, DISABLE_PASSPHRASE_PREF, false);
   }

src/main/java/org/thoughtcrime/securesms/util/TextSelectionActionModeCallback.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2026 ArcaneChat contributors
+ *
+ * This program 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.
+ */
+package org.thoughtcrime.securesms.util;
+
+import android.content.Context;
+import android.content.Intent;
+import android.view.ActionMode;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.widget.TextView;
+import android.widget.Toast;
+import androidx.annotation.NonNull;
+import org.thoughtcrime.securesms.R;
+
+/**
+ * Custom ActionMode callback shown when the user selects part of a message's text.
+ *
+ * <p>It exposes "Copy", "Select all" and "Share" actions for the currently selected text,
+ * and shows a confirmation toast when text is copied to the clipboard.
+ */
+public class TextSelectionActionModeCallback implements ActionMode.Callback {
+
+  private final Context context;
+  private final TextView textView;
+
+  public TextSelectionActionModeCallback(@NonNull Context context, @NonNull TextView textView) {
+    this.context = context;
+    this.textView = textView;
+  }
+
+  @Override
+  public boolean onCreateActionMode(ActionMode mode, Menu menu) {
+    mode.getMenuInflater().inflate(R.menu.text_selection_context, menu);
+    return true;
+  }
+
+  @Override
+  public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
+    return false;
+  }
+
+  @Override
+  public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
+    int id = item.getItemId();
+    if (id == R.id.menu_context_copy) {
+      CharSequence selected = textView.getText().subSequence(
+          textView.getSelectionStart(), textView.getSelectionEnd());
+      Util.writeTextToClipboard(context, selected.toString());
+      Toast.makeText(
+              context,
+              R.string.copied_to_clipboard,
+              Toast.LENGTH_SHORT)
+          .show();
+      mode.finish();
+      return true;
+    } else if (id == R.id.menu_context_select_all) {
+      textView.selectAll();
+      return true;
+    } else if (id == R.id.menu_context_share_text) {
+      CharSequence selected = textView.getText().subSequence(
+          textView.getSelectionStart(), textView.getSelectionEnd());
+      shareText(selected.toString());
+      mode.finish();
+      return true;
+    }
+    return false;
+  }
+
+  @Override
+  public void onDestroyActionMode(ActionMode mode) {}
+
+  private void shareText(@NonNull String text) {
+    Intent sendIntent = new Intent(Intent.ACTION_SEND);
+    sendIntent.setType("text/plain");
+    sendIntent.putExtra(Intent.EXTRA_TEXT, text);
+    context.startActivity(Intent.createChooser(sendIntent, context.getString(R.string.share_via)));
+  }
+}

src/main/res/menu/text_selection_context.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item
+        android:title="@string/menu_copy_text_to_clipboard"
+        android:id="@+id/menu_context_copy"
+        android:icon="?menu_copy_icon"
+        app:showAsAction="ifRoom" />
+
+    <item
+        android:title="@string/menu_select_all"
+        android:id="@+id/menu_context_select_all"
+        app:showAsAction="never" />
+
+    <item
+        android:title="@string/menu_share"
+        android:id="@+id/menu_context_share_text"
+        android:icon="@drawable/ic_share_white_24dp"
+        app:showAsAction="ifRoom" />
+</menu>

src/main/res/values/strings.xml

@@ -789,6 +789,8 @@
     <!-- Option name for changing behaviour of the "Enter key" to sending out a message directly (instead of adding new line). If in doubt, please refer to a similar option in other messengers. -->
     <string name="pref_enter_sends">Enter Key Sends</string>
     <string name="pref_enter_sends_explain">Pressing the Enter key will send text messages</string>
+    <string name="pref_text_selection">Text selection in messages</string>
+    <string name="pref_text_selection_explain">Select and copy parts of message text instead of entire messages only</string>
     <string name="pref_outgoing_media_quality">Outgoing Media Quality</string>
     <string name="pref_outgoing_media_quality_hint">To send original quality, attach media as a \"File\". This uses significantly more data for you and your recipients.</string>
     <string name="pref_outgoing_balanced">Balanced</string>

src/main/res/xml/preferences_chats.xml

@@ -8,6 +8,12 @@
         android:summary="@string/pref_enter_sends_explain"
         android:title="@string/pref_enter_sends" />
 
+    <org.thoughtcrime.securesms.components.SwitchPreferenceCompat
+        android:defaultValue="false"
+        android:key="pref_text_selection"
+        android:summary="@string/pref_text_selection_explain"
+        android:title="@string/pref_text_selection" />
+
     <ListPreference
         android:key="pref_compression"
         android:title="@string/pref_outgoing_media_quality"