From 12c4283c306974b1deb7239156b33f321c268280 Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Thu, 17 Oct 2019 22:23:27 -0400
Subject: [PATCH] Conditionally show a toolbar shadow in the conversation list.

---
 res/drawable/toolbar_shadow.xml               |  8 +++++++
 res/layout/conversation_list_activity.xml     |  9 +++++++-
 .../securesms/ConversationListActivity.java   | 20 +++++++++++++++++-
 .../ConversationListArchiveActivity.java      | 11 +++++++++-
 .../securesms/ConversationListFragment.java   | 21 +++++++++++++++----
 5 files changed, 62 insertions(+), 7 deletions(-)
 create mode 100644 res/drawable/toolbar_shadow.xml

diff --git a/res/drawable/toolbar_shadow.xml b/res/drawable/toolbar_shadow.xml
new file mode 100644
index 0000000000..af128ceb1f
--- /dev/null
+++ b/res/drawable/toolbar_shadow.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <gradient
+        android:angle="90"
+        android:dither="true"
+        android:startColor="@android:color/transparent"
+        android:endColor="@color/conversation_compose_divider" />
+</shape>
diff --git a/res/layout/conversation_list_activity.xml b/res/layout/conversation_list_activity.xml
index 4a58843c05..2a14ae7704 100644
--- a/res/layout/conversation_list_activity.xml
+++ b/res/layout/conversation_list_activity.xml
@@ -14,7 +14,6 @@
             android:layout_height="?attr/actionBarSize"
             android:minHeight="?attr/actionBarSize"
             android:background="?attr/conversation_list_toolbar_background"
-            android:elevation="4dp"
             android:theme="?attr/actionBarStyle">
 
         <androidx.constraintlayout.widget.ConstraintLayout
@@ -64,6 +63,14 @@
 
     </androidx.appcompat.widget.Toolbar>
 
+    <ImageView
+        android:id="@+id/conversation_list_toolbar_shadow"
+        android:layout_width="match_parent"
+        android:layout_height="4dp"
+        android:layout_below="@id/toolbar"
+        android:src="@drawable/toolbar_shadow"
+        android:visibility="gone" />
+
     <FrameLayout android:id="@+id/fragment_container"
                  android:layout_below="@id/toolbar"
                  android:layout_width="match_parent"
diff --git a/src/org/thoughtcrime/securesms/ConversationListActivity.java b/src/org/thoughtcrime/securesms/ConversationListActivity.java
index 76a61a9c2b..e35f6425b8 100644
--- a/src/org/thoughtcrime/securesms/ConversationListActivity.java
+++ b/src/org/thoughtcrime/securesms/ConversationListActivity.java
@@ -33,6 +33,7 @@ import android.text.TextUtils;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
+import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ImageView;
 import android.widget.Toast;
@@ -60,13 +61,14 @@ import org.thoughtcrime.securesms.util.DynamicLanguage;
 import org.thoughtcrime.securesms.util.DynamicNoActionBarTheme;
 import org.thoughtcrime.securesms.util.DynamicTheme;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
+import org.thoughtcrime.securesms.util.ViewUtil;
 import org.thoughtcrime.securesms.util.concurrent.SimpleTask;
 import org.whispersystems.libsignal.util.guava.Optional;
 
 import java.util.List;
 
 public class ConversationListActivity extends PassphraseRequiredActionBarActivity
-    implements ConversationListFragment.ConversationSelectedListener
+    implements ConversationListFragment.Controller
 {
   @SuppressWarnings("unused")
   private static final String TAG = ConversationListActivity.class.getSimpleName();
@@ -79,6 +81,7 @@ public class ConversationListActivity extends PassphraseRequiredActionBarActivit
   private SearchToolbar            searchToolbar;
   private ImageView                searchAction;
   private ViewGroup                fragmentContainer;
+  private View                     toolbarShadow;
 
   @Override
   protected void onPreCreate() {
@@ -96,6 +99,7 @@ public class ConversationListActivity extends PassphraseRequiredActionBarActivit
     searchToolbar            = findViewById(R.id.search_toolbar);
     searchAction             = findViewById(R.id.search_action);
     fragmentContainer        = findViewById(R.id.fragment_container);
+    toolbarShadow            = findViewById(R.id.conversation_list_toolbar_shadow);
     conversationListFragment = initFragment(R.id.fragment_container, new ConversationListFragment(), dynamicLanguage.getCurrentLocale());
 
     initializeSearchListener();
@@ -246,6 +250,20 @@ public class ConversationListActivity extends PassphraseRequiredActionBarActivit
     else                           super.onBackPressed();
   }
 
+  @Override
+  public void onListScrolledToTop() {
+    if (toolbarShadow.getVisibility() != View.GONE) {
+      ViewUtil.fadeOut(toolbarShadow, 250);
+    }
+  }
+
+  @Override
+  public void onListScrolledAwayFromTop() {
+    if (toolbarShadow.getVisibility() != View.VISIBLE) {
+      ViewUtil.fadeIn(toolbarShadow, 250);
+    }
+  }
+
   private void createGroup() {
     Intent intent = new Intent(this, GroupCreateActivity.class);
     startActivity(intent);
diff --git a/src/org/thoughtcrime/securesms/ConversationListArchiveActivity.java b/src/org/thoughtcrime/securesms/ConversationListArchiveActivity.java
index dcfeffb411..3aa7da6444 100644
--- a/src/org/thoughtcrime/securesms/ConversationListArchiveActivity.java
+++ b/src/org/thoughtcrime/securesms/ConversationListArchiveActivity.java
@@ -10,7 +10,7 @@ import org.thoughtcrime.securesms.util.DynamicLanguage;
 import org.thoughtcrime.securesms.util.DynamicTheme;
 
 public class ConversationListArchiveActivity extends PassphraseRequiredActionBarActivity
-    implements ConversationListFragment.ConversationSelectedListener
+    implements ConversationListFragment.Controller
 {
 
   private final DynamicTheme    dynamicTheme    = new DynamicTheme();
@@ -69,4 +69,13 @@ public class ConversationListArchiveActivity extends PassphraseRequiredActionBar
     throw new AssertionError();
   }
 
+  @Override
+  public void onListScrolledToTop() {
+
+  }
+
+  @Override
+  public void onListScrolledAwayFromTop() {
+
+  }
 }
diff --git a/src/org/thoughtcrime/securesms/ConversationListFragment.java b/src/org/thoughtcrime/securesms/ConversationListFragment.java
index 626c32a896..ecf651c631 100644
--- a/src/org/thoughtcrime/securesms/ConversationListFragment.java
+++ b/src/org/thoughtcrime/securesms/ConversationListFragment.java
@@ -34,7 +34,6 @@ import android.os.Bundle;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
-import com.google.android.material.floatingactionbutton.FloatingActionButton;
 import com.google.android.material.snackbar.Snackbar;
 import androidx.fragment.app.Fragment;
 import androidx.loader.app.LoaderManager;
@@ -155,6 +154,7 @@ public class ConversationListFragment extends Fragment
     list.setHasFixedSize(true);
     list.setLayoutManager(new LinearLayoutManager(getActivity()));
     list.setItemAnimator(new DeleteItemAnimator());
+    list.addOnScrollListener(new ScrollListener());
 
     new ItemTouchHelper(new ArchiveListenerCallback()).attachToRecyclerView(list);
 
@@ -373,7 +373,7 @@ public class ConversationListFragment extends Fragment
   }
 
   private void handleCreateConversation(long threadId, Recipient recipient, int distributionType, long lastSeen) {
-    ((ConversationSelectedListener)getActivity()).onCreateConversation(threadId, recipient, distributionType, lastSeen);
+    ((Controller)getActivity()).onCreateConversation(threadId, recipient, distributionType, lastSeen);
   }
 
   @Override
@@ -441,12 +441,14 @@ public class ConversationListFragment extends Fragment
 
   @Override
   public void onSwitchToArchive() {
-    ((ConversationSelectedListener)getActivity()).onSwitchToArchive();
+    ((Controller)getActivity()).onSwitchToArchive();
   }
 
-  public interface ConversationSelectedListener {
+  public interface Controller {
     void onCreateConversation(long threadId, Recipient recipient, int distributionType, long lastSeen);
     void onSwitchToArchive();
+    void onListScrolledToTop();
+    void onListScrolledAwayFromTop();
 }
 
   @Override
@@ -628,6 +630,17 @@ public class ConversationListFragment extends Fragment
       }
     }
   }
+
+  private class ScrollListener extends RecyclerView.OnScrollListener {
+    @Override
+    public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
+      if (recyclerView.canScrollVertically(-1)) {
+        ((Controller) getActivity()).onListScrolledAwayFromTop();
+      } else {
+        ((Controller) getActivity()).onListScrolledToTop();
+      }
+    }
+  }
 }