ui/base/win/hidden_window.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ui/base/win/hidden_window.h"
   6
   7 #include "ui/gfx/win/window_impl.h"
   8
   9 namespace ui {
  10
  11 namespace {
  12
  13 // We need to have a parent window for the compositing code to work correctly.
  14 //
  15 // A tab will not have a parent HWND whenever it is not active in its
  16 // host window - for example at creation time and when it's in the
  17 // background, so we provide a default widget to host them.
  18 //
  19 // It may be tempting to use GetDesktopWindow() instead, but this is
  20 // problematic as the shell sends messages to children of the desktop
  21 // window that interact poorly with us.
  22 //
  23 // See: http://crbug.com/16476
  24 class TempParent : public gfx::WindowImpl {
  25  public:
  26   static TempParent* Get() {
  27     static TempParent* g_temp_parent;
  28     if (!g_temp_parent) {
  29       g_temp_parent = new TempParent();
  30
  31       g_temp_parent->set_window_style(WS_POPUP);
  32       g_temp_parent->set_window_ex_style(WS_EX_TOOLWINDOW);
  33       g_temp_parent->Init(GetDesktopWindow(), gfx::Rect());
  34       EnableWindow(g_temp_parent->hwnd(), FALSE);
  35     }
  36     return g_temp_parent;
  37   }
  38
  39  private:
  40   // Explicitly do nothing in Close. We do this as some external apps may get a
  41   // handle to this window and attempt to close it.
  42   void OnClose() {
  43   }
  44
  45   CR_BEGIN_MSG_MAP_EX(WebContentsViewWin)
  46     CR_MSG_WM_CLOSE(OnClose)
  47   CR_END_MSG_MAP()
  48 };
  49
  50 }  // namespace
  51
  52 HWND GetHiddenWindow() {
  53   return TempParent::Get()->hwnd();
  54 }
  55
  56 }  // namespace ui