remoting/host/desktop_resizer_win.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 "remoting/host/desktop_resizer.h"
   6
   7 #include <map>
   8 #include <windows.h>
   9
  10 #include "base/logging.h"
  11
  12 namespace {
  13 // TODO(jamiewalch): Use the correct DPI for the mode: http://crbug.com/172405.
  14 const int kDefaultDPI = 96;
  15 }  // namespace
  16
  17 namespace remoting {
  18
  19 // Provide comparison operation for ScreenResolution so we can use it in
  20 // std::map.
  21 static inline bool operator <(const ScreenResolution& a,
  22                               const ScreenResolution& b) {
  23   if (a.dimensions().width() != b.dimensions().width())
  24     return a.dimensions().width() < b.dimensions().width();
  25   if (a.dimensions().height() != b.dimensions().height())
  26     return a.dimensions().height() < b.dimensions().height();
  27   if (a.dpi().x() != b.dpi().x())
  28     return a.dpi().x() < b.dpi().x();
  29   return a.dpi().y() < b.dpi().y();
  30 }
  31
  32 class DesktopResizerWin : public DesktopResizer {
  33  public:
  34   DesktopResizerWin();
  35   ~DesktopResizerWin() override;
  36
  37   // DesktopResizer interface.
  38   ScreenResolution GetCurrentResolution() override;
  39   std::list<ScreenResolution> GetSupportedResolutions(
  40       const ScreenResolution& preferred) override;
  41   void SetResolution(const ScreenResolution& resolution) override;
  42   void RestoreResolution(const ScreenResolution& original) override;
  43
  44  private:
  45   static bool IsResizeSupported();
  46
  47   // Calls EnumDisplaySettingsEx() for the primary monitor.
  48   // Returns false if |mode_number| does not exist.
  49   static bool GetPrimaryDisplayMode(
  50       DWORD mode_number, DWORD flags, DEVMODE* mode);
  51
  52   // Returns true if the mode has width, height, bits-per-pixel, frequency
  53   // and orientation fields.
  54   static bool IsModeValid(const DEVMODE& mode);
  55
  56   // Returns the width & height of |mode|, or 0x0 if they are missing.
  57   static ScreenResolution GetModeResolution(const DEVMODE& mode);
  58
  59   std::map<ScreenResolution, DEVMODE> best_mode_for_resolution_;
  60
  61   DISALLOW_COPY_AND_ASSIGN(DesktopResizerWin);
  62 };
  63
  64 DesktopResizerWin::DesktopResizerWin() {
  65 }
  66
  67 DesktopResizerWin::~DesktopResizerWin() {
  68 }
  69
  70 ScreenResolution DesktopResizerWin::GetCurrentResolution() {
  71   DEVMODE current_mode;
  72   if (GetPrimaryDisplayMode(ENUM_CURRENT_SETTINGS, 0, &current_mode) &&
  73       IsModeValid(current_mode))
  74     return GetModeResolution(current_mode);
  75   return ScreenResolution();
  76 }
  77
  78 std::list<ScreenResolution> DesktopResizerWin::GetSupportedResolutions(
  79     const ScreenResolution& preferred) {
  80   if (!IsResizeSupported())
  81     return std::list<ScreenResolution>();
  82
  83   // Enumerate the resolutions to return, and where there are multiple modes of
  84   // the same resolution, store the one most closely matching the current mode
  85   // in |best_mode_for_resolution_|.
  86   DEVMODE current_mode;
  87   if (!GetPrimaryDisplayMode(ENUM_CURRENT_SETTINGS, 0, &current_mode) ||
  88       !IsModeValid(current_mode))
  89     return std::list<ScreenResolution>();
  90
  91   std::list<ScreenResolution> resolutions;
  92   best_mode_for_resolution_.clear();
  93   for (DWORD i = 0; ; ++i) {
  94     DEVMODE candidate_mode;
  95     if (!GetPrimaryDisplayMode(i, EDS_ROTATEDMODE, &candidate_mode))
  96       break;
  97
  98     // Ignore modes missing the fields that we expect.
  99     if (!IsModeValid(candidate_mode))
 100       continue;
 101
 102     // Ignore modes with differing bits-per-pixel.
 103     if (candidate_mode.dmBitsPerPel != current_mode.dmBitsPerPel)
 104       continue;
 105
 106     // If there are multiple modes with the same dimensions:
 107     // - Prefer the modes which match the current rotation.
 108     // - Among those, prefer modes which match the current frequency.
 109     // - Otherwise, prefer modes with a higher frequency.
 110     ScreenResolution candidate_resolution = GetModeResolution(candidate_mode);
 111     if (best_mode_for_resolution_.count(candidate_resolution) != 0) {
 112       DEVMODE best_mode = best_mode_for_resolution_[candidate_resolution];
 113
 114       if ((candidate_mode.dmDisplayOrientation !=
 115            current_mode.dmDisplayOrientation) &&
 116           (best_mode.dmDisplayOrientation ==
 117            current_mode.dmDisplayOrientation)) {
 118         continue;
 119       }
 120
 121       if ((candidate_mode.dmDisplayFrequency !=
 122            current_mode.dmDisplayFrequency) &&
 123           (best_mode.dmDisplayFrequency >=
 124            candidate_mode.dmDisplayFrequency)) {
 125         continue;
 126       }
 127     } else {
 128       // If we haven't seen this resolution before, add it to those we return.
 129       resolutions.push_back(candidate_resolution);
 130     }
 131
 132     best_mode_for_resolution_[candidate_resolution] = candidate_mode;
 133   }
 134
 135   return resolutions;
 136 }
 137
 138 void DesktopResizerWin::SetResolution(const ScreenResolution& resolution) {
 139   if (best_mode_for_resolution_.count(resolution) == 0)
 140     return;
 141
 142   DEVMODE new_mode = best_mode_for_resolution_[resolution];
 143   DWORD result = ChangeDisplaySettings(&new_mode, CDS_FULLSCREEN);
 144   if (result != DISP_CHANGE_SUCCESSFUL)
 145     LOG(ERROR) << "SetResolution failed: " << result;
 146 }
 147
 148 void DesktopResizerWin::RestoreResolution(const ScreenResolution& original) {
 149   // Restore the display mode based on the registry configuration.
 150   DWORD result = ChangeDisplaySettings(nullptr, 0);
 151   if (result != DISP_CHANGE_SUCCESSFUL)
 152     LOG(ERROR) << "RestoreResolution failed: " << result;
 153 }
 154
 155 // static
 156 bool DesktopResizerWin::IsResizeSupported() {
 157   // Resize is supported only on single-monitor systems.
 158   return GetSystemMetrics(SM_CMONITORS) == 1;
 159 }
 160
 161 // static
 162 bool DesktopResizerWin::GetPrimaryDisplayMode(
 163     DWORD mode_number, DWORD flags, DEVMODE* mode) {
 164  memset(mode, 0, sizeof(DEVMODE));
 165  mode->dmSize = sizeof(DEVMODE);
 166  if (!EnumDisplaySettingsEx(nullptr, mode_number, mode, flags))
 167    return false;
 168  return true;
 169 }
 170
 171 // static
 172 bool DesktopResizerWin::IsModeValid(const DEVMODE& mode) {
 173   const DWORD kRequiredFields =
 174       DM_PELSWIDTH | DM_PELSHEIGHT | DM_BITSPERPEL |
 175       DM_DISPLAYFREQUENCY | DM_DISPLAYORIENTATION;
 176   return (mode.dmFields & kRequiredFields) == kRequiredFields;
 177 }
 178
 179 // static
 180 ScreenResolution DesktopResizerWin::GetModeResolution(const DEVMODE& mode) {
 181   DCHECK(IsModeValid(mode));
 182   return ScreenResolution(
 183       webrtc::DesktopSize(mode.dmPelsWidth, mode.dmPelsHeight),
 184       webrtc::DesktopVector(kDefaultDPI, kDefaultDPI));
 185 }
 186
 187 scoped_ptr<DesktopResizer> DesktopResizer::Create() {
 188   return make_scoped_ptr(new DesktopResizerWin);
 189 }
 190
 191 }  // namespace remoting