Widget::GetCurrentEvent() to get hold of the current input event being processed.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/7144001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@89074 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 55 insertions, 1 deletions

diff --git a/views/widget/widget.cc b/views/widget/widget.cc
index f282823..ec971f6 100644
--- a/views/widget/widget.cc
+++ b/views/widget/widget.cc
@@ -26,6 +26,36 @@ namespace {
 bool use_pure_views = false;
 }
 
+// This class is used to keep track of the event a Widget is processing, and
+// restore any previously active event afterwards.
+class ScopedEvent {
+ public:
+  ScopedEvent(Widget* widget, const Event& event)
+      : widget_(widget),
+        event_(&event) {
+    widget->event_stack_.push(this);
+  }
+
+  ~ScopedEvent() {
+    if (widget_)
+      widget_->event_stack_.pop();
+  }
+
+  void reset() {
+    widget_ = NULL;
+  }
+
+  const Event* event() {
+    return event_;
+  }
+
+ private:
+  Widget* widget_;
+  const Event* event_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedEvent);
+};
+
 // A default implementation of WidgetDelegate, used by Widget when no
 // WidgetDelegate is supplied.
 class DefaultWidgetDelegate : public WidgetDelegate {
@@ -96,6 +126,7 @@ Widget::Widget()
       widget_delegate_(NULL),
       non_client_view_(NULL),
       dragged_view_(NULL),
+      event_stack_(),
       ownership_(InitParams::NATIVE_WIDGET_OWNS_WIDGET),
       is_secondary_widget_(true),
       frame_type_(FRAME_TYPE_DEFAULT),
@@ -106,6 +137,11 @@ Widget::Widget()
 }
 
 Widget::~Widget() {
+  while (!event_stack_.empty()) {
+    event_stack_.top()->reset();
+    event_stack_.pop();
+  }
+
   DestroyRootView();
 
   if (ownership_ == InitParams::WIDGET_OWNS_NATIVE_WIDGET)
@@ -573,6 +609,10 @@ void Widget::NotifyAccessibilityEvent(
     native_widget_->SendNativeAccessibilityEvent(view, event_type);
 }
 
+const Event* Widget::GetCurrentEvent() {
+  return event_stack_.empty() ? NULL : event_stack_.top()->event();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Widget, NativeWidgetDelegate implementation:
 
@@ -686,10 +726,12 @@ int Widget::GetNonClientComponent(const gfx::Point& point) {
 }
 
 bool Widget::OnKeyEvent(const KeyEvent& event) {
+  ScopedEvent scoped(this, event);
   return static_cast<internal::RootView*>(GetRootView())->OnKeyEvent(event);
 }
 
 bool Widget::OnMouseEvent(const MouseEvent& event) {
+  ScopedEvent scoped(this, event);
   switch (event.type()) {
     case ui::ET_MOUSE_PRESSED:
       last_mouse_event_was_move_ = false;
diff --git a/views/widget/widget.h b/views/widget/widget.h
index 42866f6..437ca35 100644
--- a/views/widget/widget.h
+++ b/views/widget/widget.h
@@ -6,7 +6,7 @@
 #define VIEWS_WIDGET_WIDGET_H_
 #pragma once
 
-#include <vector>
+#include <stack>
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ -52,6 +52,7 @@ class DefaultThemeProvider;
 class InputMethod;
 class NativeWidget;
 class NonClientFrameView;
+class ScopedEvent;
 class TooltipManager;
 class View;
 class WidgetDelegate;
@@ -461,6 +462,12 @@ class Widget : public internal::NativeWidgetDelegate,
   const NativeWidget* native_widget() const { return native_widget_; }
   NativeWidget* native_widget() { return native_widget_; }
 
+  // Returns the current event being processed. If there are multiple events
+  // being processed at the same time (e.g. one event triggers another event),
+  // then the most recent event is returned. Returns NULL if no event is being
+  // processed.
+  const Event* GetCurrentEvent();
+
   // Overridden from NativeWidgetDelegate:
   virtual bool IsModal() const OVERRIDE;
   virtual bool IsDialogBox() const OVERRIDE;
@@ -525,6 +532,8 @@ class Widget : public internal::NativeWidgetDelegate,
   gfx::Point last_mouse_event_position_;
 
  private:
+  friend class ScopedEvent;
+
   // Try to create a compositor if one hasn't been created yet.
   void EnsureCompositor();
 
@@ -568,6 +577,9 @@ class Widget : public internal::NativeWidgetDelegate,
   // started from.
   View* dragged_view_;
 
+  // The event stack.
+  std::stack<ScopedEvent*> event_stack_;
+
   // The compositor for accelerated drawing.
   scoped_refptr<ui::Compositor> compositor_;