modules/desktop_capture/linux/x11/shared_x_display.cc

/*
 *  Copyright (c) 2013 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/linux/x11/shared_x_display.h"

#include <X11/Xlib.h>
#include <X11/extensions/XTest.h>

#include <algorithm>
#include <cstddef>
#include <string>
#include <vector>

#include "absl/strings/string_view.h"
#include "api/scoped_refptr.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/synchronization/mutex.h"

namespace webrtc {

SharedXDisplay::SharedXDisplay(Display* display) : display_(display) {
  RTC_DCHECK(display_);
}

SharedXDisplay::~SharedXDisplay() {
  RTC_DCHECK(event_handlers_.empty());
  XCloseDisplay(display_);
}

// static
scoped_refptr<SharedXDisplay> SharedXDisplay::Create(
    absl::string_view display_name) {
  Display* display = XOpenDisplay(
      display_name.empty() ? nullptr : std::string(display_name).c_str());
  if (!display) {
    RTC_LOG(LS_ERROR) << "Unable to open display";
    return nullptr;
  }
  return scoped_refptr<SharedXDisplay>(new SharedXDisplay(display));
}

// static
scoped_refptr<SharedXDisplay> SharedXDisplay::CreateDefault() {
  return Create(std::string());
}

void SharedXDisplay::AddEventHandler(int type, XEventHandler* handler) {
  MutexLock lock(&mutex_);
  event_handlers_[type].push_back(handler);
}

void SharedXDisplay::RemoveEventHandler(int type, XEventHandler* handler) {
  MutexLock lock(&mutex_);
  EventHandlersMap::iterator handlers = event_handlers_.find(type);
  if (handlers == event_handlers_.end())
    return;

  std::erase(handlers->second, handler);

  // Check if no handlers left for this event.
  if (handlers->second.empty())
    event_handlers_.erase(handlers);
}

void SharedXDisplay::ProcessPendingXEvents() {
  // Hold reference to `this` to prevent it from being destroyed while
  // processing events.
  scoped_refptr<SharedXDisplay> self(this);

  // Protect access to `event_handlers_` after incrementing the refcount for
  // `this` to ensure the instance is still valid when the lock is acquired.
  MutexLock lock(&mutex_);

  // Find the number of events that are outstanding "now."  We don't just loop
  // on XPending because we want to guarantee this terminates.
  int events_to_process = XPending(display());
  XEvent e;

  for (int i = 0; i < events_to_process; i++) {
    XNextEvent(display(), &e);
    EventHandlersMap::iterator handlers = event_handlers_.find(e.type);
    if (handlers == event_handlers_.end())
      continue;
    for (std::vector<XEventHandler*>::iterator it = handlers->second.begin();
         it != handlers->second.end(); ++it) {
      if ((*it)->HandleXEvent(e))
        break;
    }
  }
}

void SharedXDisplay::IgnoreXServerGrabs() {
  int test_event_base = 0;
  int test_error_base = 0;
  int major = 0;
  int minor = 0;
  if (XTestQueryExtension(display(), &test_event_base, &test_error_base, &major,
                          &minor)) {
    XTestGrabControl(display(), true);
  }
}

}  // namespace webrtc