fab: make fab respond to recyclerview scroll events

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

1 files changed, 38 insertions, 0 deletions

diff --git a/app/src/main/java/com/wireguard/android/widget/CustomRecyclerViewScrollListener.java b/app/src/main/java/com/wireguard/android/widget/CustomRecyclerViewScrollListener.java
new file mode 100644
index 00000000..2660179f
--- /dev/null
+++ b/app/src/main/java/com/wireguard/android/widget/CustomRecyclerViewScrollListener.java
@@ -0,0 +1,38 @@
+/*
+ * 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;
+
+public abstract class CustomRecyclerViewScrollListener extends RecyclerView.OnScrollListener {
+
+    private int scrollDist;
+    private boolean isVisible = true;
+    private static final float FLING_THRESHOLD = 25;
+
+    @Override
+    public void onScrolled(final RecyclerView recyclerView, final int dx, final int dy) {
+        super.onScrolled(recyclerView, dx, dy);
+
+        if (isVisible && scrollDist > FLING_THRESHOLD) {
+            hide();
+            scrollDist = 0;
+            isVisible = false;
+        } else if (!isVisible && scrollDist < -FLING_THRESHOLD) {
+            show();
+            scrollDist = 0;
+            isVisible = true;
+        }
+
+        if (isVisible ? dy > 0 : dy < 0) {
+            scrollDist += dy;
+        }
+    }
+
+    public abstract void show();
+    public abstract void hide();
+}