modules/desktop_capture/cropping_window_capturer.cc

/*
 *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "modules/desktop_capture/cropping_window_capturer.h"

#include <cstddef>
#include <memory>
#include <utility>

#include "modules/desktop_capture/cropped_desktop_frame.h"
#include "modules/desktop_capture/desktop_capture_options.h"
#include "modules/desktop_capture/desktop_capture_types.h"
#include "modules/desktop_capture/desktop_capturer.h"
#include "modules/desktop_capture/desktop_frame.h"
#include "modules/desktop_capture/desktop_geometry.h"
#include "modules/desktop_capture/shared_memory.h"
#include "rtc_base/logging.h"

namespace webrtc {

CroppingWindowCapturer::CroppingWindowCapturer(
    const DesktopCaptureOptions& options)
    : options_(options),
      callback_(nullptr),
      window_capturer_(DesktopCapturer::CreateRawWindowCapturer(options)),
      selected_window_(kNullWindowId),
      excluded_window_(kNullWindowId) {}

CroppingWindowCapturer::~CroppingWindowCapturer() {}

void CroppingWindowCapturer::Start(DesktopCapturer::Callback* callback) {
  callback_ = callback;
  window_capturer_->Start(callback);
}

void CroppingWindowCapturer::SetSharedMemoryFactory(
    std::unique_ptr<SharedMemoryFactory> shared_memory_factory) {
  window_capturer_->SetSharedMemoryFactory(std::move(shared_memory_factory));
}

void CroppingWindowCapturer::EnsureScreenCapturer() {
  if (screen_capturer_) {
    return;
  }

  screen_capturer_ = DesktopCapturer::CreateRawScreenCapturer(options_);
  if (excluded_window_) {
    screen_capturer_->SetExcludedWindow(excluded_window_);
  }
  screen_capturer_->Start(this);
}

void CroppingWindowCapturer::CaptureFrame() {
  if (ShouldUseScreenCapturer()) {
    // If the window has moved from the last time that we started a capture,
    // there is a possibility that DWM hasn't actually updated it's location
    // yet, as that can happen asynchronously compared to this bounds update.
    // To ensure that we don't accidentally capture a location the window isn't
    // at, try to fall back to *solely* a Window Capturer if the window has
    // recently moved.
    // Note that last_window_rect_ is also stored to validate that the window
    // doesn't move during the capture.
    // Note that `ShouldUseScreenCapturer` computes the updated window rect, so
    // we must query this after that has run.
    const auto current_rect = GetWindowRectInVirtualScreen();
    const bool has_moved = !last_window_rect_.equals(current_rect);
    last_window_rect_ = current_rect;

    if (!has_moved) {
      EnsureScreenCapturer();
      screen_capturer_->CaptureFrame();
      return;
    }
  }

  window_capturer_->CaptureFrame();
}

void CroppingWindowCapturer::SetExcludedWindow(WindowId window) {
  excluded_window_ = window;
  if (screen_capturer_) {
    screen_capturer_->SetExcludedWindow(window);
  }
}

bool CroppingWindowCapturer::GetSourceList(SourceList* sources) {
  return window_capturer_->GetSourceList(sources);
}

bool CroppingWindowCapturer::SelectSource(SourceId id) {
  if (window_capturer_->SelectSource(id)) {
    selected_window_ = id;
    last_window_rect_ = {};
    return true;
  }
  return false;
}

bool CroppingWindowCapturer::FocusOnSelectedSource() {
  return window_capturer_->FocusOnSelectedSource();
}

void CroppingWindowCapturer::OnCaptureResult(
    DesktopCapturer::Result result,
    std::unique_ptr<DesktopFrame> screen_frame) {
  if (!ShouldUseScreenCapturer()) {
    RTC_LOG(LS_INFO) << "Window no longer on top when ScreenCapturer finishes";
    window_capturer_->CaptureFrame();
    return;
  }

  // We don't know when capture has occurred, so if the window moved we can't
  // assert which pixels we should capture. Capture again and we'll return a
  // frame once the window is stationary between the two calls.
  DesktopRect current_window_rect = GetWindowRectInVirtualScreen();
  if (!current_window_rect.equals(last_window_rect_)) {
    RTC_LOG(LS_INFO) << "Window moved during capture";
    window_capturer_->CaptureFrame();
    return;
  }

  if (result != Result::SUCCESS) {
    RTC_LOG(LS_WARNING) << "ScreenCapturer failed to capture a frame";
    callback_->OnCaptureResult(result, nullptr);
    return;
  }

  if (last_window_rect_.is_empty()) {
    RTC_LOG(LS_WARNING) << "Window rect is empty";
    callback_->OnCaptureResult(Result::ERROR_TEMPORARY, nullptr);
    return;
  }

  std::unique_ptr<DesktopFrame> cropped_frame =
      CreateCroppedDesktopFrame(std::move(screen_frame), last_window_rect_);

  if (!cropped_frame) {
    RTC_LOG(LS_WARNING) << "Window is outside of the captured display";
    callback_->OnCaptureResult(Result::ERROR_TEMPORARY, nullptr);
    return;
  }

  callback_->OnCaptureResult(Result::SUCCESS, std::move(cropped_frame));
}

bool CroppingWindowCapturer::IsOccluded(const DesktopVector& pos) {
  // Returns true if either capturer returns true.
  if (window_capturer_->IsOccluded(pos)) {
    return true;
  }
  if (screen_capturer_ != nullptr && screen_capturer_->IsOccluded(pos)) {
    return true;
  }
  return false;
}

#if !defined(WEBRTC_WIN)
// CroppingWindowCapturer is implemented only for windows. On other platforms
// the regular window capturer is used.
// static
std::unique_ptr<DesktopCapturer> CroppingWindowCapturer::CreateCapturer(
    const DesktopCaptureOptions& options) {
  return DesktopCapturer::CreateWindowCapturer(options);
}
#endif

}  // namespace webrtc