first implementation of sticky header logic.

Signed-off-by: alex <alex.plutta@googlemail.com>
Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

Author: AlexNi245

src/main/java/com/owncloud/android/ui/activities/ActivityListItemDecoration.java

@@ -1,28 +1,38 @@
 package com.owncloud.android.ui.activities;
 
+import android.app.Activity;
 import android.content.Context;
 import android.graphics.Canvas;
 import android.util.Log;
 import android.view.View;
 
+import com.owncloud.android.ui.adapter.ActivityListAdapter;
+
 import androidx.annotation.NonNull;
 import androidx.recyclerview.widget.RecyclerView;
 
 public class ActivityListItemDecoration extends RecyclerView.ItemDecoration {
     private final String TAG = this.getClass().getSimpleName();
+    private View currentHeader;
+
     @Override
     public void onDrawOver(@NonNull Canvas c, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {
         super.onDrawOver(c, parent, state);
 
-        View topChild = parent.getChildAt(0);
-        View currentHeader = topChild;
 
+        View topChild = parent.getChildAt(0);
+        int topChildPosition = parent.getChildAdapterPosition(topChild);
+        if (topChildPosition == -1) {
+            return;
+        }
+        ActivityListAdapter adapter = (ActivityListAdapter) parent.getAdapter();
 
+        Object topElement = adapter.getActivityAtByPosition(topChildPosition);
 
-        if (currentHeader != null) {
-            drawHeader(c, currentHeader);
-            Log.d(TAG,"Attach new Header" );
+        if (topElement instanceof ActivityListHeader) {
+            currentHeader = parent.getChildAt(0);
         }
+        drawHeader(c, currentHeader);
     }
 
     private void drawHeader(Canvas c, View header) {

src/main/java/com/owncloud/android/ui/adapter/ActivityListAdapter.java

@@ -243,6 +243,11 @@ public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int positi
         }
     }
 
+    public Object getActivityAtByPosition(int pos) {
+        return values.get(pos);
+
+    }
+
     private ImageView createThumbnailNew(PreviewObject previewObject) {
         LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(px, px);
         params.setMargins(10, 10, 10, 10);