gecko-dev/widget/windows/ScreenHelperWin.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=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/. */

#include "ScreenHelperWin.h"

#include "mozilla/Logging.h"
#include "nsTArray.h"
#include "WinUtils.h"

static mozilla::LazyLogModule sScreenLog("WidgetScreen");

namespace mozilla {
namespace widget {

BOOL CALLBACK CollectMonitors(HMONITOR aMon, HDC, LPRECT, LPARAM ioParam) {
  auto screens = reinterpret_cast<nsTArray<RefPtr<Screen>>*>(ioParam);
  BOOL success = FALSE;
  MONITORINFOEX info;
  info.cbSize = sizeof(MONITORINFOEX);
  success = ::GetMonitorInfoW(aMon, &info);
  if (!success) {
    MOZ_LOG(sScreenLog, LogLevel::Error, ("GetMonitorInfoW failed"));
    return TRUE;  // continue the enumeration
  }

  double scale = WinUtils::LogToPhysFactor(aMon);
  DesktopToLayoutDeviceScale contentsScaleFactor;
  if (WinUtils::IsPerMonitorDPIAware()) {
    contentsScaleFactor.scale = 1.0;
  } else {
    contentsScaleFactor.scale = scale;
  }
  CSSToLayoutDeviceScale defaultCssScaleFactor(scale);
  LayoutDeviceIntRect rect(info.rcMonitor.left, info.rcMonitor.top,
                           info.rcMonitor.right - info.rcMonitor.left,
                           info.rcMonitor.bottom - info.rcMonitor.top);
  LayoutDeviceIntRect availRect(info.rcWork.left, info.rcWork.top,
                                info.rcWork.right - info.rcWork.left,
                                info.rcWork.bottom - info.rcWork.top);

  HDC hDC = CreateDC(nullptr, info.szDevice, nullptr, nullptr);
  if (!hDC) {
    MOZ_LOG(sScreenLog, LogLevel::Error, ("CollectMonitors CreateDC failed"));
    return TRUE;
  }
  uint32_t pixelDepth = ::GetDeviceCaps(hDC, BITSPIXEL);
  DeleteDC(hDC);
  if (pixelDepth == 32) {
    // If a device uses 32 bits per pixel, it's still only using 8 bits
    // per color component, which is what our callers want to know.
    // (Some devices report 32 and some devices report 24.)
    pixelDepth = 24;
  }

  float dpi = WinUtils::MonitorDPI(aMon);
  MOZ_LOG(sScreenLog, LogLevel::Debug,
          ("New screen [%d %d %d %d (%d %d %d %d) %d %f %f %f]", rect.X(),
           rect.Y(), rect.Width(), rect.Height(), availRect.X(), availRect.Y(),
           availRect.Width(), availRect.Height(), pixelDepth,
           contentsScaleFactor.scale, defaultCssScaleFactor.scale, dpi));
  auto screen = new Screen(rect, availRect, pixelDepth, pixelDepth,
                           contentsScaleFactor, defaultCssScaleFactor, dpi);
  if (info.dwFlags & MONITORINFOF_PRIMARY) {
    // The primary monitor must be the first element of the screen list.
    screens->InsertElementAt(0, std::move(screen));
  } else {
    screens->AppendElement(std::move(screen));
  }
  return TRUE;
}

void ScreenHelperWin::RefreshScreens() {
  MOZ_LOG(sScreenLog, LogLevel::Debug, ("Refreshing screens"));

  AutoTArray<RefPtr<Screen>, 4> screens;
  BOOL result = ::EnumDisplayMonitors(
      nullptr, nullptr, (MONITORENUMPROC)CollectMonitors, (LPARAM)&screens);
  if (!result) {
    NS_WARNING("Unable to EnumDisplayMonitors");
  }
  ScreenManager& screenManager = ScreenManager::GetSingleton();
  screenManager.Refresh(std::move(screens));
}

}  // namespace widget
}  // namespace mozilla