gecko/widget/windows/WinMouseScrollHandler.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifdef MOZ_LOGGING
#define FORCE_PR_LOG /* Allow logging in the release build */
#endif // MOZ_LOGGING
#include "prlog.h"

#include "WinMouseScrollHandler.h"
#include "nsWindow.h"
#include "WinUtils.h"

namespace mozilla {
namespace widget {

#ifdef PR_LOGGING
PRLogModuleInfo* gMouseScrollLog = nsnull;
#endif

MouseScrollHandler* MouseScrollHandler::sInstance = nsnull;


/******************************************************************************
 *
 * MouseScrollHandler
 *
 ******************************************************************************/

/* static */
void
MouseScrollHandler::Initialize()
{
#ifdef PR_LOGGING
  if (!gMouseScrollLog) {
    gMouseScrollLog = PR_NewLogModule("MouseScrollHandlerWidgets");
  }
#endif
}

/* static */
void
MouseScrollHandler::Shutdown()
{
  delete sInstance;
  sInstance = nsnull;
}

/* static */
MouseScrollHandler*
MouseScrollHandler::GetInstance()
{
  if (!sInstance) {
    sInstance = new MouseScrollHandler();
  }
  return sInstance;
}

MouseScrollHandler::MouseScrollHandler()
{
  PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
    ("MouseScroll: Creating an instance, this=%p, sInstance=%p",
     this, sInstance));
}

MouseScrollHandler::~MouseScrollHandler()
{
  PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
    ("MouseScroll: Destroying an instance, this=%p, sInstance=%p",
     this, sInstance));
}

/* static */
bool
MouseScrollHandler::ProcessMessage(nsWindow* aWindow, UINT msg,
                                   WPARAM wParam, LPARAM lParam,
                                   LRESULT *aRetValue, bool &aEatMessage)
{
  switch (msg) {
    case WM_SETTINGCHANGE:
      if (!sInstance) {
        return false;
      }
      if (wParam == SPI_SETWHEELSCROLLLINES ||
          wParam == SPI_SETWHEELSCROLLCHARS) {
        sInstance->mSystemSettings.MarkDirty();
      }
      return false;
    default:
      return false;
  }
}

/******************************************************************************
 *
 * SystemSettings
 *
 ******************************************************************************/

void
MouseScrollHandler::SystemSettings::Init()
{
  if (mInitialized) {
    return;
  }

  mInitialized = true;

  if (!::SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0, &mScrollLines, 0)) {
    PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
      ("MouseScroll::SystemSettings::Init(): ::SystemParametersInfo("
         "SPI_GETWHEELSCROLLLINES) failed"));
    mScrollLines = 3;
  } else if (mScrollLines > WHEEL_DELTA) {
    PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
      ("MouseScroll::SystemSettings::Init(): the result of "
         "::SystemParametersInfo(SPI_GETWHEELSCROLLLINES) is too large: %d",
       mScrollLines));
    // sScrollLines usually equals 3 or 0 (for no scrolling)
    // However, if sScrollLines > WHEEL_DELTA, we assume that
    // the mouse driver wants a page scroll.  The docs state that
    // sScrollLines should explicitly equal WHEEL_PAGESCROLL, but
    // since some mouse drivers use an arbitrary large number instead,
    // we have to handle that as well.
    mScrollLines = WHEEL_PAGESCROLL;
  }

  if (!::SystemParametersInfo(SPI_GETWHEELSCROLLCHARS, 0, &mScrollChars, 0)) {
    PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
      ("MouseScroll::SystemSettings::Init(): ::SystemParametersInfo("
         "SPI_GETWHEELSCROLLCHARS) failed, %s",
       WinUtils::GetWindowsVersion() >= WinUtils::VISTA_VERSION ?
         "this is unexpected on Vista or later" :
         "but on XP or earlier, this is not a problem"));
    mScrollChars = 1;
  } else if (mScrollChars > WHEEL_DELTA) {
    PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
      ("MouseScroll::SystemSettings::Init(): the result of "
         "::SystemParametersInfo(SPI_GETWHEELSCROLLCHARS) is too large: %d",
       mScrollChars));
    // See the comments for the case mScrollLines > WHEEL_DELTA.
    mScrollChars = WHEEL_PAGESCROLL;
  }

  PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
    ("MouseScroll::SystemSettings::Init(): initialized, "
       "mScrollLines=%d, mScrollChars=%d",
     mScrollLines, mScrollChars));
}

void
MouseScrollHandler::SystemSettings::MarkDirty()
{
  PR_LOG(gMouseScrollLog, PR_LOG_ALWAYS,
    ("MouseScrollHandler::SystemSettings::MarkDirty(): "
       "Marking SystemSettings dirty"));
  mInitialized = false;
}

} // namespace widget
} // namespace mozilla