root/content/browser/renderer_host/legacy_render_widget_host_win.cc

DEFINITIONS

1. Create
2. UpdateParent
3. GetParent
4. OnManagerDeleted
5. Show
6. Hide
7. SetBounds
8. OnFinalMessage
9. mouse_tracking_enabled_
10. Init
11. GetWindowEventTarget
12. OnEraseBkGnd
13. OnGetObject
14. OnKeyboardRange
15. OnMouseRange
16. OnMouseLeave
17. OnMouseActivate
18. OnTouch
19. OnScroll
20. OnNCHitTest
21. OnNCPaint
22. OnPaint
23. OnSetCursor
24. OnNCCalcSize
25. OnSize

// Copyright (c) 2014 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 "content/browser/renderer_host/legacy_render_widget_host_win.h"

#include "base/command_line.h"
#include "base/memory/scoped_ptr.h"
#include "base/win/windows_version.h"
#include "content/browser/accessibility/browser_accessibility_manager_win.h"
#include "content/browser/accessibility/browser_accessibility_win.h"
#include "content/public/common/content_switches.h"
#include "ui/base/touch/touch_enabled.h"
#include "ui/base/view_prop.h"
#include "ui/base/win/internal_constants.h"
#include "ui/base/win/window_event_target.h"
#include "ui/gfx/geometry/rect.h"

namespace content {

LegacyRenderWidgetHostHWND::~LegacyRenderWidgetHostHWND() {
  ::DestroyWindow(hwnd());
}

// static
scoped_ptr<LegacyRenderWidgetHostHWND> LegacyRenderWidgetHostHWND::Create(
    HWND parent) {
  // content_unittests passes in the desktop window as the parent. We allow
  // the LegacyRenderWidgetHostHWND instance to be created in this case for
  // these tests to pass.
  if (CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kDisableLegacyIntermediateWindow) ||
      (!GetWindowEventTarget(parent) && parent != ::GetDesktopWindow()))
    return scoped_ptr<LegacyRenderWidgetHostHWND>();

  scoped_ptr<LegacyRenderWidgetHostHWND> legacy_window_instance;
  legacy_window_instance.reset(new LegacyRenderWidgetHostHWND(parent));
  // If we failed to create the child, or if the switch to disable the legacy
  // window is passed in, then return NULL.
  if (!::IsWindow(legacy_window_instance->hwnd()))
    return scoped_ptr<LegacyRenderWidgetHostHWND>();

  legacy_window_instance->Init();
  return legacy_window_instance.Pass();
}

void LegacyRenderWidgetHostHWND::UpdateParent(HWND parent) {
  ::SetParent(hwnd(), parent);
  // If the new parent is the desktop Window, then we disable the child window
  // to ensure that it does not receive any input events. It should not because
  // of WS_EX_TRANSPARENT. This is only for safety.
  if (parent == ::GetDesktopWindow()) {
    ::EnableWindow(hwnd(), FALSE);
  } else {
    ::EnableWindow(hwnd(), TRUE);
  }
}

HWND LegacyRenderWidgetHostHWND::GetParent() {
  return ::GetParent(hwnd());
}

void LegacyRenderWidgetHostHWND::OnManagerDeleted() {
  manager_ = NULL;
}

void LegacyRenderWidgetHostHWND::Show() {
  ::ShowWindow(hwnd(), SW_SHOW);
}

void LegacyRenderWidgetHostHWND::Hide() {
  ::ShowWindow(hwnd(), SW_HIDE);
}

void LegacyRenderWidgetHostHWND::SetBounds(const gfx::Rect& bounds) {
  ::SetWindowPos(hwnd(), NULL, bounds.x(), bounds.y(), bounds.width(),
                  bounds.height(), 0);
}

void LegacyRenderWidgetHostHWND::OnFinalMessage(HWND hwnd) {
  if (manager_)
    manager_->OnAccessibleHwndDeleted();
}

LegacyRenderWidgetHostHWND::LegacyRenderWidgetHostHWND(HWND parent)
    : manager_(NULL),
      mouse_tracking_enabled_(false) {
  RECT rect = {0};
  Base::Create(parent, rect, L"Chrome Legacy Window",
               WS_CHILDWINDOW | WS_CLIPCHILDREN | WS_CLIPSIBLINGS,
               WS_EX_TRANSPARENT);
}

bool LegacyRenderWidgetHostHWND::Init() {
  if (base::win::GetVersion() >= base::win::VERSION_WIN7 &&
      ui::AreTouchEventsEnabled())
    RegisterTouchWindow(hwnd(), TWF_WANTPALM);

  HRESULT hr = ::CreateStdAccessibleObject(
      hwnd(), OBJID_WINDOW, IID_IAccessible,
      reinterpret_cast<void **>(window_accessible_.Receive()));
  DCHECK(SUCCEEDED(hr));
  return !!SUCCEEDED(hr);
}

// static
ui::WindowEventTarget* LegacyRenderWidgetHostHWND::GetWindowEventTarget(
    HWND parent) {
  return reinterpret_cast<ui::WindowEventTarget*>(ui::ViewProp::GetValue(
      parent, ui::WindowEventTarget::kWin32InputEventTarget));
}

LRESULT LegacyRenderWidgetHostHWND::OnEraseBkGnd(UINT message,
                                                 WPARAM w_param,
                                                 LPARAM l_param) {
  return 1;
}

LRESULT LegacyRenderWidgetHostHWND::OnGetObject(UINT message,
                                                WPARAM w_param,
                                                LPARAM l_param) {
  if (OBJID_CLIENT != l_param || !manager_)
    return static_cast<LRESULT>(0L);

  base::win::ScopedComPtr<IAccessible> root(
      manager_->GetRoot()->ToBrowserAccessibilityWin());
  return LresultFromObject(IID_IAccessible, w_param,
      static_cast<IAccessible*>(root.Detach()));
}

// We send keyboard/mouse/touch messages to the parent window via SendMessage.
// While this works, this has the side effect of converting input messages into
// sent messages which changes their priority and could technically result
// in these messages starving other messages in the queue. Additionally
// keyboard/mouse hooks would not see these messages. The alternative approach
// is to set and release capture as needed on the parent to ensure that it
// receives all mouse events. However that was shelved due to possible issues
// with capture changes.
LRESULT LegacyRenderWidgetHostHWND::OnKeyboardRange(UINT message,
                                                    WPARAM w_param,
                                                    LPARAM l_param,
                                                    BOOL& handled) {
  if (GetWindowEventTarget(GetParent())) {
    return GetWindowEventTarget(GetParent())->HandleKeyboardMessage(
        message, w_param, l_param);
  }
  return 0;
}

LRESULT LegacyRenderWidgetHostHWND::OnMouseRange(UINT message,
                                                 WPARAM w_param,
                                                 LPARAM l_param,
                                                 BOOL& handled) {
  if (message == WM_MOUSEMOVE) {
    if (!mouse_tracking_enabled_) {
      mouse_tracking_enabled_ = true;
      TRACKMOUSEEVENT tme;
      tme.cbSize = sizeof(tme);
      tme.dwFlags = TME_LEAVE;
      tme.hwndTrack = hwnd();
      tme.dwHoverTime = 0;
      TrackMouseEvent(&tme);
    }
  }
  // The offsets for WM_NCXXX and WM_MOUSEWHEEL and WM_MOUSEHWHEEL messages are
  // in screen coordinates. We should not be converting them to parent
  // coordinates.
  if ((message >= WM_MOUSEFIRST && message <= WM_MOUSELAST) &&
      (message != WM_MOUSEWHEEL && message != WM_MOUSEHWHEEL)) {
    POINT mouse_coords;
    mouse_coords.x = GET_X_LPARAM(l_param);
    mouse_coords.y = GET_Y_LPARAM(l_param);
    ::MapWindowPoints(hwnd(), GetParent(), &mouse_coords, 1);
    l_param = MAKELPARAM(mouse_coords.x, mouse_coords.y);
  }
  if (GetWindowEventTarget(GetParent())) {
    return GetWindowEventTarget(GetParent())->HandleMouseMessage(
        message, w_param, l_param);
  }
  return 0;
}

LRESULT LegacyRenderWidgetHostHWND::OnMouseLeave(UINT message,
                                                 WPARAM w_param,
                                                 LPARAM l_param) {
  mouse_tracking_enabled_ = false;
  if ((::GetCapture() != GetParent()) && GetWindowEventTarget(GetParent())) {
    // We should send a WM_MOUSELEAVE to the parent window only if the mouse
    // has moved outside the bounds of the parent.
    POINT cursor_pos;
    ::GetCursorPos(&cursor_pos);
    if (::WindowFromPoint(cursor_pos) != GetParent()) {
      return GetWindowEventTarget(GetParent())->HandleMouseMessage(
          message, w_param, l_param);
    }
  }
  return 0;
}

LRESULT LegacyRenderWidgetHostHWND::OnMouseActivate(UINT message,
                                                    WPARAM w_param,
                                                    LPARAM l_param) {
  // Don't pass this to DefWindowProc. That results in the WM_MOUSEACTIVATE
  // message going all the way to the parent which then messes up state
  // related to focused views, etc. This is because it treats this as if
  // it lost activation.
  // Our dummy window should not interfere with focus and activation in
  // the parent. Return MA_ACTIVATE here ensures that focus state in the parent
  // is preserved. The only exception is if the parent was created with the
  // WS_EX_NOACTIVATE style.
  if (::GetWindowLong(GetParent(), GWL_EXSTYLE) & WS_EX_NOACTIVATE)
    return MA_NOACTIVATE;
  // On Windows, if we select the menu item by touch and if the window at the
  // location is another window on the same thread, that window gets a
  // WM_MOUSEACTIVATE message and ends up activating itself, which is not
  // correct. We workaround this by setting a property on the window at the
  // current cursor location. We check for this property in our
  // WM_MOUSEACTIVATE handler and don't activate the window if the property is
  // set.
  if (::GetProp(hwnd(), ui::kIgnoreTouchMouseActivateForWindow)) {
    ::RemoveProp(hwnd(), ui::kIgnoreTouchMouseActivateForWindow);
    return MA_NOACTIVATE;
  }
  return MA_ACTIVATE;
}

LRESULT LegacyRenderWidgetHostHWND::OnTouch(UINT message,
                                            WPARAM w_param,
                                            LPARAM l_param) {
  if (GetWindowEventTarget(GetParent())) {
    return GetWindowEventTarget(GetParent())->HandleTouchMessage(
        message, w_param, l_param);
  }
  return 0;
}

LRESULT LegacyRenderWidgetHostHWND::OnScroll(UINT message,
                                             WPARAM w_param,
                                             LPARAM l_param) {
  if (GetWindowEventTarget(GetParent())) {
    return GetWindowEventTarget(GetParent())->HandleScrollMessage(
        message, w_param, l_param);
  }
  return 0;
}

LRESULT LegacyRenderWidgetHostHWND::OnNCHitTest(UINT message,
                                                WPARAM w_param,
                                                LPARAM l_param) {
  if (GetWindowEventTarget(GetParent())) {
    LRESULT hit_test = GetWindowEventTarget(
        GetParent())->HandleNcHitTestMessage(message, w_param, l_param);
    // If the parent returns HTNOWHERE which can happen for popup windows, etc
    // we return HTCLIENT.
    if (hit_test == HTNOWHERE)
      hit_test = HTCLIENT;
    return hit_test;
  }
  return HTNOWHERE;
}

LRESULT LegacyRenderWidgetHostHWND::OnNCPaint(UINT message,
                                              WPARAM w_param,
                                              LPARAM l_param) {
  return 0;
}

LRESULT LegacyRenderWidgetHostHWND::OnPaint(UINT message,
                                            WPARAM w_param,
                                            LPARAM l_param) {
  PAINTSTRUCT ps = {0};
  ::BeginPaint(hwnd(), &ps);
  ::EndPaint(hwnd(), &ps);
  return 0;
}

LRESULT LegacyRenderWidgetHostHWND::OnSetCursor(UINT message,
                                                WPARAM w_param,
                                                LPARAM l_param) {
  return 0;
}

LRESULT LegacyRenderWidgetHostHWND::OnNCCalcSize(UINT message,
                                                 WPARAM w_param,
                                                 LPARAM l_param) {
  // Prevent scrollbars, etc from drawing.
  return 0;
}

LRESULT LegacyRenderWidgetHostHWND::OnSize(UINT message,
                                           WPARAM w_param,
                                           LPARAM l_param) {
  // Certain trackpad drivers on Windows have bugs where in they don't generate
  // WM_MOUSEWHEEL messages for the trackpoint and trackpad scrolling gestures
  // unless there is an entry for Chrome with the class name of the Window.
  // Additionally others check if the window WS_VSCROLL/WS_HSCROLL styles and
  // generate the legacy WM_VSCROLL/WM_HSCROLL messages.
  // We add these styles to ensure that trackpad/trackpoint scrolling
  // work.
  long current_style = ::GetWindowLong(hwnd(), GWL_STYLE);
  ::SetWindowLong(hwnd(), GWL_STYLE,
                  current_style | WS_VSCROLL | WS_HSCROLL);
  return 0;
}