src/third_party/webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.cc

   1 /*
   2  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11 #include "webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.h"
  12
  13 #include "webrtc/modules/desktop_capture/desktop_capture_options.h"
  14 #include "webrtc/modules/desktop_capture/desktop_frame.h"
  15 #include "webrtc/modules/desktop_capture/desktop_frame_win.h"
  16 #include "webrtc/modules/desktop_capture/desktop_region.h"
  17 #include "webrtc/modules/desktop_capture/differ.h"
  18 #include "webrtc/modules/desktop_capture/mouse_cursor.h"
  19 #include "webrtc/modules/desktop_capture/win/cursor.h"
  20 #include "webrtc/modules/desktop_capture/win/desktop.h"
  21 #include "webrtc/modules/desktop_capture/win/screen_capture_utils.h"
  22 #include "webrtc/system_wrappers/interface/logging.h"
  23 #include "webrtc/system_wrappers/interface/tick_util.h"
  24
  25 namespace webrtc {
  26
  27 namespace {
  28
  29 // Constants from dwmapi.h.
  30 const UINT DWM_EC_DISABLECOMPOSITION = 0;
  31 const UINT DWM_EC_ENABLECOMPOSITION = 1;
  32
  33 const wchar_t kDwmapiLibraryName[] = L"dwmapi.dll";
  34
  35 }  // namespace
  36
  37 ScreenCapturerWinGdi::ScreenCapturerWinGdi(const DesktopCaptureOptions& options)
  38     : callback_(NULL),
  39       mouse_shape_observer_(NULL),
  40       current_screen_id_(kFullDesktopScreenId),
  41       desktop_dc_(NULL),
  42       memory_dc_(NULL),
  43       dwmapi_library_(NULL),
  44       composition_func_(NULL),
  45       set_thread_execution_state_failed_(false) {
  46   if (options.disable_effects()) {
  47     // Load dwmapi.dll dynamically since it is not available on XP.
  48     if (!dwmapi_library_)
  49       dwmapi_library_ = LoadLibrary(kDwmapiLibraryName);
  50
  51     if (dwmapi_library_) {
  52       composition_func_ = reinterpret_cast<DwmEnableCompositionFunc>(
  53           GetProcAddress(dwmapi_library_, "DwmEnableComposition"));
  54     }
  55   }
  56 }
  57
  58 ScreenCapturerWinGdi::~ScreenCapturerWinGdi() {
  59   if (desktop_dc_)
  60     ReleaseDC(NULL, desktop_dc_);
  61   if (memory_dc_)
  62     DeleteDC(memory_dc_);
  63
  64   // Restore Aero.
  65   if (composition_func_)
  66     (*composition_func_)(DWM_EC_ENABLECOMPOSITION);
  67
  68   if (dwmapi_library_)
  69     FreeLibrary(dwmapi_library_);
  70 }
  71
  72 void ScreenCapturerWinGdi::Capture(const DesktopRegion& region) {
  73   TickTime capture_start_time = TickTime::Now();
  74
  75   queue_.MoveToNextFrame();
  76
  77   // Request that the system not power-down the system, or the display hardware.
  78   if (!SetThreadExecutionState(ES_DISPLAY_REQUIRED | ES_SYSTEM_REQUIRED)) {
  79     if (!set_thread_execution_state_failed_) {
  80       set_thread_execution_state_failed_ = true;
  81       LOG_F(LS_WARNING) << "Failed to make system & display power assertion: "
  82                         << GetLastError();
  83     }
  84   }
  85
  86   // Make sure the GDI capture resources are up-to-date.
  87   PrepareCaptureResources();
  88
  89   if (!CaptureImage()) {
  90     callback_->OnCaptureCompleted(NULL);
  91     return;
  92   }
  93
  94   const DesktopFrame* current_frame = queue_.current_frame();
  95   const DesktopFrame* last_frame = queue_.previous_frame();
  96   if (last_frame && last_frame->size().equals(current_frame->size())) {
  97     // Make sure the differencer is set up correctly for these previous and
  98     // current screens.
  99     if (!differ_.get() ||
 100         (differ_->width() != current_frame->size().width()) ||
 101         (differ_->height() != current_frame->size().height()) ||
 102         (differ_->bytes_per_row() != current_frame->stride())) {
 103       differ_.reset(new Differ(current_frame->size().width(),
 104                                current_frame->size().height(),
 105                                DesktopFrame::kBytesPerPixel,
 106                                current_frame->stride()));
 107     }
 108
 109     // Calculate difference between the two last captured frames.
 110     DesktopRegion region;
 111     differ_->CalcDirtyRegion(last_frame->data(), current_frame->data(),
 112                              &region);
 113     helper_.InvalidateRegion(region);
 114   } else {
 115     // No previous frame is available, or the screen is resized. Invalidate the
 116     // whole screen.
 117     helper_.InvalidateScreen(current_frame->size());
 118   }
 119
 120   helper_.set_size_most_recent(current_frame->size());
 121
 122   // Emit the current frame.
 123   DesktopFrame* frame = queue_.current_frame()->Share();
 124   frame->set_dpi(DesktopVector(
 125       GetDeviceCaps(desktop_dc_, LOGPIXELSX),
 126       GetDeviceCaps(desktop_dc_, LOGPIXELSY)));
 127   frame->mutable_updated_region()->Clear();
 128   helper_.TakeInvalidRegion(frame->mutable_updated_region());
 129   frame->set_capture_time_ms(
 130       (TickTime::Now() - capture_start_time).Milliseconds());
 131   callback_->OnCaptureCompleted(frame);
 132
 133   // Check for cursor shape update.
 134   CaptureCursor();
 135 }
 136
 137 void ScreenCapturerWinGdi::SetMouseShapeObserver(
 138     MouseShapeObserver* mouse_shape_observer) {
 139   assert(!mouse_shape_observer_);
 140   assert(mouse_shape_observer);
 141
 142   mouse_shape_observer_ = mouse_shape_observer;
 143 }
 144
 145 bool ScreenCapturerWinGdi::GetScreenList(ScreenList* screens) {
 146   return webrtc::GetScreenList(screens);
 147 }
 148
 149 bool ScreenCapturerWinGdi::SelectScreen(ScreenId id) {
 150   bool valid = IsScreenValid(id, &current_device_key_);
 151   if (valid)
 152     current_screen_id_ = id;
 153   return valid;
 154 }
 155
 156 void ScreenCapturerWinGdi::Start(Callback* callback) {
 157   assert(!callback_);
 158   assert(callback);
 159
 160   callback_ = callback;
 161
 162   // Vote to disable Aero composited desktop effects while capturing. Windows
 163   // will restore Aero automatically if the process exits. This has no effect
 164   // under Windows 8 or higher.  See crbug.com/124018.
 165   if (composition_func_)
 166     (*composition_func_)(DWM_EC_DISABLECOMPOSITION);
 167 }
 168
 169 void ScreenCapturerWinGdi::PrepareCaptureResources() {
 170   // Switch to the desktop receiving user input if different from the current
 171   // one.
 172   scoped_ptr<Desktop> input_desktop(Desktop::GetInputDesktop());
 173   if (input_desktop.get() != NULL && !desktop_.IsSame(*input_desktop)) {
 174     // Release GDI resources otherwise SetThreadDesktop will fail.
 175     if (desktop_dc_) {
 176       ReleaseDC(NULL, desktop_dc_);
 177       desktop_dc_ = NULL;
 178     }
 179
 180     if (memory_dc_) {
 181       DeleteDC(memory_dc_);
 182       memory_dc_ = NULL;
 183     }
 184
 185     // If SetThreadDesktop() fails, the thread is still assigned a desktop.
 186     // So we can continue capture screen bits, just from the wrong desktop.
 187     desktop_.SetThreadDesktop(input_desktop.release());
 188
 189     // Re-assert our vote to disable Aero.
 190     // See crbug.com/124018 and crbug.com/129906.
 191     if (composition_func_ != NULL) {
 192       (*composition_func_)(DWM_EC_DISABLECOMPOSITION);
 193     }
 194   }
 195
 196   // If the display bounds have changed then recreate GDI resources.
 197   // TODO(wez): Also check for pixel format changes.
 198   DesktopRect screen_rect(DesktopRect::MakeXYWH(
 199       GetSystemMetrics(SM_XVIRTUALSCREEN),
 200       GetSystemMetrics(SM_YVIRTUALSCREEN),
 201       GetSystemMetrics(SM_CXVIRTUALSCREEN),
 202       GetSystemMetrics(SM_CYVIRTUALSCREEN)));
 203   if (!screen_rect.equals(desktop_dc_rect_)) {
 204     if (desktop_dc_) {
 205       ReleaseDC(NULL, desktop_dc_);
 206       desktop_dc_ = NULL;
 207     }
 208     if (memory_dc_) {
 209       DeleteDC(memory_dc_);
 210       memory_dc_ = NULL;
 211     }
 212     desktop_dc_rect_ = DesktopRect();
 213   }
 214
 215   if (desktop_dc_ == NULL) {
 216     assert(memory_dc_ == NULL);
 217
 218     // Create GDI device contexts to capture from the desktop into memory.
 219     desktop_dc_ = GetDC(NULL);
 220     if (!desktop_dc_)
 221       abort();
 222     memory_dc_ = CreateCompatibleDC(desktop_dc_);
 223     if (!memory_dc_)
 224       abort();
 225
 226     desktop_dc_rect_ = screen_rect;
 227
 228     // Make sure the frame buffers will be reallocated.
 229     queue_.Reset();
 230
 231     helper_.ClearInvalidRegion();
 232   }
 233 }
 234
 235 bool ScreenCapturerWinGdi::CaptureImage() {
 236   DesktopRect screen_rect =
 237       GetScreenRect(current_screen_id_, current_device_key_);
 238   if (screen_rect.is_empty())
 239     return false;
 240
 241   DesktopSize size = screen_rect.size();
 242   // If the current buffer is from an older generation then allocate a new one.
 243   // Note that we can't reallocate other buffers at this point, since the caller
 244   // may still be reading from them.
 245   if (!queue_.current_frame() ||
 246       !queue_.current_frame()->size().equals(screen_rect.size())) {
 247     assert(desktop_dc_ != NULL);
 248     assert(memory_dc_ != NULL);
 249
 250     size_t buffer_size = size.width() * size.height() *
 251         DesktopFrame::kBytesPerPixel;
 252     SharedMemory* shared_memory = callback_->CreateSharedMemory(buffer_size);
 253
 254     scoped_ptr<DesktopFrame> buffer;
 255     buffer.reset(
 256         DesktopFrameWin::Create(size, shared_memory, desktop_dc_));
 257     queue_.ReplaceCurrentFrame(buffer.release());
 258   }
 259
 260   // Select the target bitmap into the memory dc and copy the rect from desktop
 261   // to memory.
 262   DesktopFrameWin* current = static_cast<DesktopFrameWin*>(
 263       queue_.current_frame()->GetUnderlyingFrame());
 264   HGDIOBJ previous_object = SelectObject(memory_dc_, current->bitmap());
 265   if (previous_object != NULL) {
 266     BitBlt(memory_dc_,
 267            0, 0, screen_rect.width(), screen_rect.height(),
 268            desktop_dc_,
 269            screen_rect.left(), screen_rect.top(),
 270            SRCCOPY | CAPTUREBLT);
 271
 272     // Select back the previously selected object to that the device contect
 273     // could be destroyed independently of the bitmap if needed.
 274     SelectObject(memory_dc_, previous_object);
 275   }
 276   return true;
 277 }
 278
 279 void ScreenCapturerWinGdi::CaptureCursor() {
 280   CURSORINFO cursor_info;
 281   cursor_info.cbSize = sizeof(CURSORINFO);
 282   if (!GetCursorInfo(&cursor_info)) {
 283     LOG_F(LS_ERROR) << "Unable to get cursor info. Error = " << GetLastError();
 284     return;
 285   }
 286
 287   // Note that |cursor_info.hCursor| does not need to be freed.
 288   scoped_ptr<MouseCursor> cursor_image(
 289       CreateMouseCursorFromHCursor(desktop_dc_, cursor_info.hCursor));
 290   if (!cursor_image.get())
 291     return;
 292
 293   scoped_ptr<MouseCursorShape> cursor(new MouseCursorShape);
 294   cursor->hotspot = cursor_image->hotspot();
 295   cursor->size = cursor_image->image()->size();
 296   uint8_t* current_row = cursor_image->image()->data();
 297   for (int y = 0; y < cursor_image->image()->size().height(); ++y) {
 298     cursor->data.append(current_row,
 299                         current_row + cursor_image->image()->size().width() *
 300                                         DesktopFrame::kBytesPerPixel);
 301     current_row += cursor_image->image()->stride();
 302   }
 303
 304   // Compare the current cursor with the last one we sent to the client. If
 305   // they're the same, then don't bother sending the cursor again.
 306   if (last_cursor_.size.equals(cursor->size) &&
 307       last_cursor_.hotspot.equals(cursor->hotspot) &&
 308       last_cursor_.data == cursor->data) {
 309     return;
 310   }
 311
 312   LOG(LS_VERBOSE) << "Sending updated cursor: " << cursor->size.width() << "x"
 313                   << cursor->size.height();
 314
 315   // Record the last cursor image that we sent to the client.
 316   last_cursor_ = *cursor;
 317
 318   if (mouse_shape_observer_)
 319     mouse_shape_observer_->OnCursorShapeChanged(cursor.release());
 320 }
 321
 322 }  // namespace webrtc