fab: move in direct ratio to scroll

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/fragment/TunnelListFragment.java

@@ -27,8 +27,6 @@ import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
-import android.view.animation.AccelerateInterpolator;
-import android.view.animation.DecelerateInterpolator;
 
 import com.wireguard.android.Application;
 import com.wireguard.android.R;
@@ -38,7 +36,7 @@ import com.wireguard.android.databinding.TunnelListFragmentBinding;
 import com.wireguard.android.databinding.TunnelListItemBinding;
 import com.wireguard.android.model.Tunnel;
 import com.wireguard.android.util.ExceptionLoggers;
-import com.wireguard.android.widget.CustomRecyclerViewScrollListener;
+import com.wireguard.android.widget.fab.FloatingActionsMenuRecyclerViewScrollListener;
 import com.wireguard.config.Config;
 
 import java.io.BufferedReader;
@@ -62,8 +60,6 @@ import java9.util.stream.StreamSupport;
 public class TunnelListFragment extends BaseFragment {
     private static final int REQUEST_IMPORT = 1;
     private static final String TAG = "WireGuard/" + TunnelListFragment.class.getSimpleName();
-    private static final TimeInterpolator FAB_SHOW_ANIMATION = new DecelerateInterpolator(2);
-    private static final TimeInterpolator FAB_HIDE_ANIMATION = new AccelerateInterpolator(2);
 
     private final ActionModeListener actionModeListener = new ActionModeListener();
     @Nullable private ActionMode actionMode;
@@ -196,23 +192,7 @@ public class TunnelListFragment extends BaseFragment {
             }
             return false;
         });
-        binding.tunnelList.setOnScrollListener(new CustomRecyclerViewScrollListener() {
+        binding.tunnelList.setOnScrollListener(new FloatingActionsMenuRecyclerViewScrollListener(binding.createMenu));
-            @Override
-            public void show() {
-                binding.createMenu.animate()
-                        .translationY(0)
-                        .setInterpolator(FAB_SHOW_ANIMATION)
-                        .start();
-            }
-
-            @Override
-            public void hide() {
-                binding.createMenu.animate()
-                        .translationY(binding.createMenu.getHeight() + getResources().getDimension(R.dimen.fab_margin))
-                        .setInterpolator(FAB_HIDE_ANIMATION)
-                        .start();
-            }
-        });
         binding.executePendingBindings();
         return binding.getRoot();
     }

app/src/main/java/com/wireguard/android/widget/CustomRecyclerViewScrollListener.java

@@ -1,43 +0,0 @@
-/*
- * Copyright © 2018 Harsh Shandilya <msfjarvis@gmail.com>
- * Copyright © 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.wireguard.android.widget;
-
-import android.support.v7.widget.RecyclerView;
-
-import com.wireguard.android.R;
-
-public abstract class CustomRecyclerViewScrollListener extends RecyclerView.OnScrollListener {
-
-    private int scrollDist;
-    private boolean isVisible = true;
-    private static int flingThreshold;
-
-    @Override
-    public void onScrolled(final RecyclerView recyclerView, final int dx, final int dy) {
-        super.onScrolled(recyclerView, dx, dy);
-
-        if (flingThreshold == 0)
-            flingThreshold = recyclerView.getResources().getDimensionPixelSize(R.dimen.design_fab_size_normal) / 2;
-
-        if (isVisible && scrollDist >= flingThreshold) {
-            hide();
-            scrollDist = 0;
-            isVisible = false;
-        } else if (!isVisible && scrollDist <= -flingThreshold) {
-            show();
-            scrollDist = 0;
-            isVisible = true;
-        }
-
-        if (isVisible ? dy > 0 : dy < 0) {
-            scrollDist += dy;
-        }
-    }
-
-    public abstract void show();
-    public abstract void hide();
-}

app/src/main/java/com/wireguard/android/widget/fab/FloatingActionButtonBehavior.java

@@ -25,8 +25,7 @@ public class FloatingActionButtonBehavior extends CoordinatorLayout.Behavior<Flo
     @Override
     public boolean onDependentViewChanged(final CoordinatorLayout parent, final FloatingActionsMenu child,
                                           final View dependency) {
-        final float translationY = Math.min(0, dependency.getTranslationY() - dependency.getHeight());
+        child.setBehaviorYTranslation(Math.min(0, dependency.getTranslationY() - dependency.getMeasuredHeight()));
-        child.setTranslationY(translationY);
         return true;
     }
 }

app/src/main/java/com/wireguard/android/widget/fab/FloatingActionsMenu.java

@@ -67,6 +67,8 @@ public class FloatingActionsMenu extends ViewGroup {
     @Nullable private TouchDelegateGroup mTouchDelegateGroup;
     @Nullable private OnFloatingActionsMenuUpdateListener mListener;
     private final Rect touchArea = new Rect(0, 0, 0, 0);
+    private float scrollYTranslation;
+    private float behaviorYTranslation;
 
     public FloatingActionsMenu(final Context context) {
         this(context, null);
@@ -103,6 +105,24 @@ public class FloatingActionsMenu extends ViewGroup {
         createAddButton(context);
     }
 
+    public float getScrollYTranslation() {
+        return scrollYTranslation;
+    }
+
+    public void setScrollYTranslation(final float scrollYTranslation) {
+        this.scrollYTranslation = scrollYTranslation;
+        setTranslationY(behaviorYTranslation + scrollYTranslation);
+    }
+
+    public float getBehaviorYTranslation() {
+        return behaviorYTranslation;
+    }
+
+    public void setBehaviorYTranslation(final float behaviorYTranslation) {
+        this.behaviorYTranslation = behaviorYTranslation;
+        setTranslationY(behaviorYTranslation + scrollYTranslation);
+    }
+
     public void setOnFloatingActionsMenuUpdateListener(final OnFloatingActionsMenuUpdateListener listener) {
         mListener = listener;
     }

app/src/main/java/com/wireguard/android/widget/fab/FloatingActionsMenuRecyclerViewScrollListener.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright © 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.wireguard.android.widget.fab;
+
+import android.support.v7.widget.RecyclerView;
+
+import com.wireguard.android.R;
+
+public class FloatingActionsMenuRecyclerViewScrollListener extends RecyclerView.OnScrollListener {
+    private static final float SCALE_FACTOR = 1.5f;
+    private final FloatingActionsMenu menu;
+
+    public FloatingActionsMenuRecyclerViewScrollListener(final FloatingActionsMenu menu) {
+        this.menu = menu;
+    }
+
+    private static float bound(float min, float proposal, float max) {
+        return Math.min(max, Math.max(min, proposal));
+    }
+
+    @Override
+    public void onScrolled(final RecyclerView recyclerView, final int dx, final int dy) {
+        super.onScrolled(recyclerView, dx, dy);
+        menu.setScrollYTranslation(bound(0, menu.getScrollYTranslation() + dy * SCALE_FACTOR, menu.getMeasuredHeight() - menu.getTranslationY()));
+    }
+}

app/src/main/res/layout/tunnel_list_fragment.xml

@@ -30,7 +30,7 @@
             android:id="@+id/tunnel_list"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
-            android:paddingBottom="@dimen/design_fab_size_normal"
+            android:paddingBottom="@{@dimen/design_fab_size_normal * 1.1f}"
             android:clipToPadding="false"
             android:choiceMode="multipleChoiceModal"
             app:items="@{tunnels}"