1 files changed, 69 insertions, 0 deletions
diff --git a/mobile/android/base/java/org/mozilla/gecko/tabs/TabsTouchHelperCallback.java b/mobile/android/base/java/org/mozilla/gecko/tabs/TabsTouchHelperCallback.java
new file mode 100644
index 000000000..36e9e4739
--- /dev/null
+++ b/mobile/android/base/java/org/mozilla/gecko/tabs/TabsTouchHelperCallback.java
@@ -0,0 +1,69 @@
+/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.tabs;
+
+import android.graphics.Canvas;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.helper.ItemTouchHelper;
+import android.view.View;
+
+class TabsTouchHelperCallback extends ItemTouchHelper.Callback {
+    private final DismissListener dismissListener;
+
+    interface DismissListener {
+        void onItemDismiss(View view);
+    }
+
+    public TabsTouchHelperCallback(DismissListener dismissListener) {
+        this.dismissListener = dismissListener;
+    }
+
+    @Override
+    public boolean isItemViewSwipeEnabled() {
+        return true;
+    }
+
+    @Override
+    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
+        return makeFlag(ItemTouchHelper.ACTION_STATE_SWIPE, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT);
+    }
+
+    @Override
+    public void onSwiped(RecyclerView.ViewHolder viewHolder, int i) {
+        dismissListener.onItemDismiss(viewHolder.itemView);
+    }
+
+    @Override
+    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,
+                          RecyclerView.ViewHolder target) {
+        return false;
+    }
+
+    // Alpha on an itemView being swiped should decrease to a min over a distance equal to the
+    // width of the item being swiped.
+    @Override
+    public void onChildDraw(Canvas c,
+                            RecyclerView recyclerView,
+                            RecyclerView.ViewHolder viewHolder,
+                            float dX,
+                            float dY,
+                            int actionState,
+                            boolean isCurrentlyActive) {
+        if (actionState != ItemTouchHelper.ACTION_STATE_SWIPE) {
+            return;
+        }
+
+        super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
+
+        viewHolder.itemView.setAlpha(Math.max(0.1f,
+                Math.min(1f, 1f - 2f * Math.abs(dX) / viewHolder.itemView.getWidth())));
+    }
+
+    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
+        super.clearView(recyclerView, viewHolder);
+        viewHolder.itemView.setAlpha(1);
+    }
+}