mash: Move ShelfWindowTargeter out of shelf_widget.cc

ash/shelf/shelf_window_targeter.cc

Index: ash/shelf/shelf_window_targeter.cc
diff --git a/ash/shelf/shelf_window_targeter.cc b/ash/shelf/shelf_window_targeter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b368f4ad181aac271a10ff923c80d968463cc6e7
--- /dev/null
+++ b/ash/shelf/shelf_window_targeter.cc
@@ -0,0 +1,68 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ash/shelf/shelf_window_targeter.h"
+
+#include "ash/aura/wm_window_aura.h"
+#include "ash/common/shelf/shelf_constants.h"
+#include "ash/common/shelf/shelf_types.h"
+#include "ash/common/shelf/wm_shelf.h"
+#include "ash/common/wm_window.h"
+
+namespace ash {
+
+namespace {
+
+gfx::Insets GetInsetsForAlignment(int distance, ShelfAlignment alignment) {
+  if (alignment == SHELF_ALIGNMENT_LEFT)
+    return gfx::Insets(0, 0, 0, distance);
+  if (alignment == SHELF_ALIGNMENT_RIGHT)
+    return gfx::Insets(0, distance, 0, 0);
+  return gfx::Insets(distance, 0, 0, 0);
+}
+
+}  // namespace
+
+ShelfWindowTargeter::ShelfWindowTargeter(WmWindow* container, WmShelf* shelf)
+    : ::wm::EasyResizeWindowTargeter(WmWindowAura::GetAuraWindow(container),
+                                     gfx::Insets(),
+                                     gfx::Insets()),
+      shelf_(shelf) {
+  WillChangeVisibilityState(shelf_->GetVisibilityState());
+  container->AddObserver(this);
+  shelf_->AddObserver(this);
+}
+
+ShelfWindowTargeter::~ShelfWindowTargeter() {
+  // Ensure that the observers were removed and the shelf pointer was cleared.
+  DCHECK(!shelf_);
+}
+
+void ShelfWindowTargeter::OnWindowDestroying(WmWindow* window) {
+  window->RemoveObserver(this);
+  shelf_->RemoveObserver(this);
+  shelf_ = nullptr;
+}
+
+void ShelfWindowTargeter::WillChangeVisibilityState(
+    ShelfVisibilityState new_state) {
+  gfx::Insets mouse_insets;
+  gfx::Insets touch_insets;
+  if (new_state == SHELF_VISIBLE) {
+    // Let clicks at the very top of the shelf through so windows can be
+    // resized with the bottom-right corner and bottom edge.
+    mouse_insets = GetInsetsForAlignment(kWorkspaceAreaVisibleInset,
+                                         shelf_->GetAlignment());
+  } else if (new_state == SHELF_AUTO_HIDE) {
+    // Extend the touch hit target out a bit to allow users to drag shelf out
+    // while hidden.
+    touch_insets = GetInsetsForAlignment(-kWorkspaceAreaAutoHideInset,
+                                         shelf_->GetAlignment());
+  }
+
+  set_mouse_extend(mouse_insets);
+  set_touch_extend(touch_insets);
+}
+
+}  // namespace ash