INFRA: Set Up Project.

lib/widget/story_view/utils.dart

@@ -0,0 +1,25 @@
+enum LoadState { loading, success, failure }
+
+enum Direction { up, down, left, right }
+
+class VerticalDragInfo {
+  bool cancel = false;
+
+  Direction? direction;
+
+  void update(double primaryDelta) {
+    Direction tmpDirection;
+
+    if (primaryDelta > 0) {
+      tmpDirection = Direction.down;
+    } else {
+      tmpDirection = Direction.up;
+    }
+
+    if (direction != null && tmpDirection != direction) {
+      cancel = true;
+    }
+
+    direction = tmpDirection;
+  }
+}