Enable keyboard accelerators while a menu is open

ui/views/controls/menu/menu_event_filter.cc

Index: ui/views/controls/menu/menu_event_filter.cc
diff --git a/ui/views/controls/menu/menu_event_filter.cc b/ui/views/controls/menu/menu_event_filter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..377ba7f1a48e192972c036397bbe9857bd2fcf91
--- /dev/null
+++ b/ui/views/controls/menu/menu_event_filter.cc
@@ -0,0 +1,162 @@
+// Copyright 2015 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 "ui/views/controls/menu/menu_event_filter.h"
+
+#include "ui/aura/window.h"
+#include "ui/aura/window_property.h"
+#include "ui/base/accelerators/accelerator.h"
+#include "ui/events/keycodes/keyboard_code_conversion.h"
+#include "ui/views/controls/menu/menu_controller.h"
+
+DECLARE_WINDOW_PROPERTY_TYPE(views::MenuEventFilter::Delegate*);
+
+DEFINE_LOCAL_WINDOW_PROPERTY_KEY(views::MenuEventFilter::Delegate*,
+                                 kMenuEventFilterDelegateKey,
+                                 nullptr);
+
+namespace views {
+
+namespace {
+
+const int kKeyFlagsMask = ui::EF_CONTROL_DOWN | ui::EF_ALT_DOWN |
+                          ui::EF_COMMAND_DOWN;
+
+// Defines a NULL-Object delegate for non-ash platforms.
+class DefaultMenuDelegate : public MenuEventFilter::Delegate {
+ public:
+  DefaultMenuDelegate() {}
+  ~DefaultMenuDelegate() override {}
+
+  // MenuEventFilter::Delegate:
+  void StoreInHistory(const ui::Accelerator& accelerator) override {}
+  bool ShouldCloseMenuAndRepostAccelerator(
+      const ui::Accelerator& accelerator) const override {
+    return false;
+  }
+  void ProcessAcceleratorNow(const ui::Accelerator& accelerator) override {
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DefaultMenuDelegate);
+};
+
+// Reposts the |accelerator| to be processed later.
+void RepostAccelerator(const ui::Accelerator& accelerator,
+                       MenuEventFilter::Delegate* delegate) {
+  base::MessageLoopForUI::current()->PostTask(
+      FROM_HERE,
+      base::Bind(&MenuEventFilter::Delegate::ProcessAcceleratorNow,
+                 base::Unretained(delegate),
+                 accelerator));
+}
+
+}  // namespace
+
+MenuEventFilter::MenuEventFilter()
+    : default_delegate_(new DefaultMenuDelegate),
+      filter_delegate_(nullptr) {
+}
+
+MenuEventFilter::~MenuEventFilter() {
+}
+
+// static
+void MenuEventFilter::SetMenuEventFilterDelegate(
+    aura::Window* root_window,
+    MenuEventFilter::Delegate* delegate) {
+  DCHECK(root_window);
+  DCHECK(delegate);
+  DCHECK_EQ(root_window->GetRootWindow(), root_window);
+  root_window->SetProperty(kMenuEventFilterDelegateKey, delegate);
+}
+
+// static
+MenuEventFilter::Delegate* MenuEventFilter::GetMenuEventFilterDelegate(
+    aura::Window* root_window) {
+  DCHECK(root_window);
+  DCHECK_EQ(root_window->GetRootWindow(), root_window);
+  return root_window->GetProperty(kMenuEventFilterDelegateKey);
+}
+
+void MenuEventFilter::OnKeyEvent(ui::KeyEvent* event) {
+  DCHECK(event);
+
+  MenuEventFilter::Delegate* delegate =
+      filter_delegate_ ? filter_delegate_ : default_delegate_.get();
+  DCHECK(delegate);
+
+  // First record the current accelerator (this is normally done by the
+  // AcceleratorFilter, but since the MenuEventFilter will precede the
+  // AcceleratorFilter in the pre-target handlers list, we have to do it here).
+  ui::Accelerator accelerator(*event);
+  delegate->StoreInHistory(accelerator);
+
+  MenuController* menu_controller = MenuController::GetActiveInstance();

[pkotwicz, 2015/08/27 17:19:55]

Nit: Can you pass in the active menu controller in the constructor?

[afakhry, 2015/08/28 01:24:41]

Great idea! And it opened the path to create the event filter on the stack
inside MenuMessageLoopAura::Run() which is perfect for nested run loops with
nested menus. Now I don't event need MenuEventFilter::GetCurrentDelegate() so I
removed it.

+  CHECK(menu_controller);
+
+  bool should_close_and_repost_accelerator = false;
+
+  if (menu_controller->exit_type() == MenuController::EXIT_ALL ||
+      menu_controller->exit_type() == MenuController::EXIT_DESTROYED) {
+    // If the event has arrived after the menu's exit type had changed but
+    // before its message loop terminated, the accelerator should be reposted
+    // after the message loop terminates.
+    should_close_and_repost_accelerator = true;

[pkotwicz, 2015/08/27 17:19:55]

Can we just drop the accelerator in this case? Note that the behavior in this
scenario with the CL applied is different than the behavior without the CL
applied.

[afakhry, 2015/08/28 01:24:41]

Done.

+  } else {
+    if (event->type() == ui::ET_KEY_PRESSED) {
+      menu_controller->OnKeyDown(event->key_code());
+
+      const int flags = event->flags();
+      if (menu_controller->exit_type() == MenuController::EXIT_NONE &&
+          (flags & kKeyFlagsMask) == 0) {

[pkotwicz, 2015/08/27 17:19:55]

menu_event_dispatcher.cc still runs MenuController::SelectByChar() even if the
EF_COMMAND_DOWN modifier is present. Can we get the same behavior here too?

[afakhry, 2015/08/28 01:24:41]

I know but isn't that something we want to prevent? See
https://code.google.com/p/chromium/issues/detail?id=471488#c12 It's a different
bug but it looks like we want to treat the Search key on CrOs as a modifier like
Ctrl & Alt.

That being said, I removed this change in this CL. We can add it later if we
need to.
Done.

+        // Only check mnemonics if the menu hasn't exited as a result from
+        // MenuController::OnKeyDown() and no modifiers are pressed.
+        char c = ui::GetCharacterFromKeyCode(event->key_code(), flags);
+        menu_controller->SelectByChar(c);
+      }
+    }
+  }
+
+  if (menu_controller->exit_type() == MenuController::EXIT_NONE) {
+    should_close_and_repost_accelerator =
+        delegate->ShouldCloseMenuAndRepostAccelerator(accelerator);
+  } else {
+    menu_controller->TerminateNestedMessageLoop();
+  }
+
+  // The event's propagation will always be stopped.
+  event->StopPropagation();
+
+  if (should_close_and_repost_accelerator) {
+    menu_controller->CancelAll();
+    RepostAccelerator(accelerator, delegate);
+  } else {
+    delegate->ProcessAcceleratorNow(accelerator);
+  }
+}
+
+void MenuEventFilter::OnTouchEvent(ui::TouchEvent* event) {
+  if (event->type() == ui::ET_TOUCH_RELEASED ||
+      event->type() == ui::ET_TOUCH_CANCELLED) {
+    // Don't allow the event copy to clear the native touch id
+    // mapping, or we'll lose the mapping before the initial event
+    // has finished being dispatched.
+    event->set_should_remove_native_touch_id_mapping(false);
+  }
+}
+
+void MenuEventFilter::SetDelegate(MenuEventFilter::Delegate* delegate) {
+  filter_delegate_ = delegate;
+}
+
+void MenuEventFilter::ClearDelegate() {
+  filter_delegate_ = nullptr;
+}
+
+MenuEventFilter::Delegate* MenuEventFilter::GetCurrentDelegate() const {
+  return filter_delegate_;
+}
+
+}  // namespace views