Auto hide answer for web view scrolling

app/src/main/java/eu/faircode/email/AdapterMessage.java

@@ -2839,8 +2839,8 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
                                 }
 
                                 @Override
-                                public void onScrollChange(int scrollX, int scrollY) {
+                                public void onScrollChange(int dx, int dy, int scrollX, int scrollY) {
-                                    properties.setPosition(message.id, new Pair<Integer, Integer>(scrollX, scrollY));
+                                    properties.setPosition(message.id, new Pair<>(dx, dy), new Pair<>(scrollX, scrollY));
                                 }
 
                                 @Override
@@ -4500,7 +4500,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
 
                             properties.setSize(message.id, null);
                             properties.setHeight(message.id, null);
-                            properties.setPosition(message.id, null);
+                            properties.setPosition(message.id, null, null);
 
                             if (itemId == R.string.title_fit_width && wvBody instanceof WebView)
                                 ((WebView) wvBody).getSettings().setLoadWithOverviewMode(enabled);
@@ -5371,7 +5371,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
 
             properties.setSize(message.id, null);
             properties.setHeight(message.id, null);
-            properties.setPosition(message.id, null);
+            properties.setPosition(message.id, null, null);
 
             if (full)
                 setupTools(message, false, false);
@@ -6589,7 +6589,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
                         public boolean onMenuItemClick(MenuItem item) {
                             properties.setSize(message.id, null);
                             properties.setHeight(message.id, null);
-                            properties.setPosition(message.id, null);
+                            properties.setPosition(message.id, null, null);
 
                             args.putString("charset", item.getIntent().getStringExtra("charset"));
 
@@ -6642,7 +6642,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
         private void onMenuAlt(TupleMessageEx message) {
             properties.setSize(message.id, null);
             properties.setHeight(message.id, null);
-            properties.setPosition(message.id, null);
+            properties.setPosition(message.id, null, null);
 
             Bundle args = new Bundle();
             args.putLong("id", message.id);
@@ -8571,7 +8571,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
 
         int getHeight(long id, int defaultHeight);
 
-        void setPosition(long id, Pair<Integer, Integer> position);
+        void setPosition(long id, Pair<Integer, Integer> delta, Pair<Integer, Integer> position);
 
         Pair<Integer, Integer> getPosition(long id);
 

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -26,6 +26,8 @@ import static android.text.format.DateUtils.FORMAT_SHOW_DATE;
 import static android.text.format.DateUtils.FORMAT_SHOW_WEEKDAY;
 import static android.view.KeyEvent.ACTION_DOWN;
 import static android.view.KeyEvent.ACTION_UP;
+import static android.view.View.GONE;
+import static android.view.View.VISIBLE;
 import static androidx.recyclerview.widget.RecyclerView.NO_POSITION;
 import static org.openintents.openpgp.OpenPgpSignatureResult.RESULT_KEY_MISSING;
 import static org.openintents.openpgp.OpenPgpSignatureResult.RESULT_NO_SIGNATURE;
@@ -2480,7 +2482,16 @@ public class FragmentMessages extends FragmentBase
         }
 
         @Override
-        public void setPosition(long id, Pair<Integer, Integer> position) {
+        public void setPosition(long id, Pair<Integer, Integer> delta, Pair<Integer, Integer> position) {
+            if (delta != null && delta.second != 0) {
+                boolean down = (delta.second > 0);
+                if (scrolling != down) {
+                    scrolling = down;
+                    updateCompose();
+                    updateExpanded();
+                }
+            }
+
             if (position == null)
                 positions.remove(id);
             else

app/src/main/java/eu/faircode/email/WebViewEx.java

@@ -188,7 +188,7 @@ public class WebViewEx extends WebView implements DownloadListener, View.OnLongC
                 @Override
                 public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
                     Log.i("Scroll (x,y)=" + scrollX + "," + scrollY);
-                    intf.onScrollChange(scrollX, scrollY);
+                    intf.onScrollChange(scrollX - oldScrollX, scrollY - oldScrollY, scrollX, scrollY);
                 }
             });
     }
@@ -412,7 +412,7 @@ public class WebViewEx extends WebView implements DownloadListener, View.OnLongC
 
         void onScaleChanged(float newScale);
 
-        void onScrollChange(int scrollX, int scrollY);
+        void onScrollChange(int dx, int dy, int scrollX, int scrollY);
 
         boolean onOpenLink(String url);
     }