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/*
* 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/win/screen_capture_utils.h"
#include <shellscalingapi.h>
#include <windows.h>
#include <string>
#include <vector>
#include "modules/desktop_capture/desktop_capturer.h"
#include "modules/desktop_capture/desktop_geometry.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/string_utils.h"
#include "rtc_base/win32.h"
namespace webrtc {
bool HasActiveDisplay() {
DesktopCapturer::SourceList screens;
return GetScreenList(&screens) && !screens.empty();
}
bool GetScreenList(DesktopCapturer::SourceList* screens,
std::vector<std::string>* device_names /* = nullptr */) {
RTC_DCHECK(screens->empty());
RTC_DCHECK(!device_names || device_names->empty());
BOOL enum_result = TRUE;
for (int device_index = 0;; ++device_index) {
DISPLAY_DEVICEW device;
device.cb = sizeof(device);
enum_result = EnumDisplayDevicesW(NULL, device_index, &device, 0);
// `enum_result` is 0 if we have enumerated all devices.
if (!enum_result) {
break;
}
// We only care about active displays.
if (!(device.StateFlags & DISPLAY_DEVICE_ACTIVE)) {
continue;
}
screens->push_back({device_index, 0, std::string()});
if (device_names) {
device_names->push_back(rtc::ToUtf8(device.DeviceName));
}
}
return true;
}
bool GetHmonitorFromDeviceIndex(const DesktopCapturer::SourceId device_index,
HMONITOR* hmonitor) {
// A device index of `kFullDesktopScreenId` or -1 represents all screens, an
// HMONITOR of 0 indicates the same.
if (device_index == kFullDesktopScreenId) {
*hmonitor = 0;
return true;
}
std::wstring device_key;
if (!IsScreenValid(device_index, &device_key)) {
return false;
}
DesktopRect screen_rect = GetScreenRect(device_index, device_key);
if (screen_rect.is_empty()) {
return false;
}
RECT rect = {screen_rect.left(), screen_rect.top(), screen_rect.right(),
screen_rect.bottom()};
HMONITOR monitor = MonitorFromRect(&rect, MONITOR_DEFAULTTONULL);
if (monitor == NULL) {
RTC_LOG(LS_WARNING) << "No HMONITOR found for supplied device index.";
return false;
}
*hmonitor = monitor;
return true;
}
bool IsMonitorValid(const HMONITOR monitor) {
// An HMONITOR of 0 refers to a virtual monitor that spans all physical
// monitors.
if (monitor == 0) {
// There is a bug in a Windows OS API that causes a crash when capturing if
// there are no active displays. We must ensure there is an active display
// before returning true.
if (!HasActiveDisplay())
return false;
return true;
}
MONITORINFO monitor_info;
monitor_info.cbSize = sizeof(MONITORINFO);
return GetMonitorInfoA(monitor, &monitor_info);
}
DesktopRect GetMonitorRect(const HMONITOR monitor) {
MONITORINFO monitor_info;
monitor_info.cbSize = sizeof(MONITORINFO);
if (!GetMonitorInfoA(monitor, &monitor_info)) {
return DesktopRect();
}
return DesktopRect::MakeLTRB(
monitor_info.rcMonitor.left, monitor_info.rcMonitor.top,
monitor_info.rcMonitor.right, monitor_info.rcMonitor.bottom);
}
bool IsScreenValid(const DesktopCapturer::SourceId screen,
std::wstring* device_key) {
if (screen == kFullDesktopScreenId) {
*device_key = L"";
return true;
}
DISPLAY_DEVICEW device;
device.cb = sizeof(device);
BOOL enum_result = EnumDisplayDevicesW(NULL, screen, &device, 0);
if (enum_result) {
*device_key = device.DeviceKey;
}
return !!enum_result;
}
DesktopRect GetFullscreenRect() {
return DesktopRect::MakeXYWH(GetSystemMetrics(SM_XVIRTUALSCREEN),
GetSystemMetrics(SM_YVIRTUALSCREEN),
GetSystemMetrics(SM_CXVIRTUALSCREEN),
GetSystemMetrics(SM_CYVIRTUALSCREEN));
}
DesktopVector GetDpiForMonitor(HMONITOR monitor) {
UINT dpi_x, dpi_y;
// MDT_EFFECTIVE_DPI includes the scale factor as well as the system DPI.
HRESULT hr = ::GetDpiForMonitor(monitor, MDT_EFFECTIVE_DPI, &dpi_x, &dpi_y);
if (SUCCEEDED(hr)) {
return {static_cast<INT>(dpi_x), static_cast<INT>(dpi_y)};
}
RTC_LOG_GLE_EX(LS_WARNING, hr) << "GetDpiForMonitor() failed";
// If we can't get the per-monitor DPI, then return the system DPI.
HDC hdc = GetDC(nullptr);
if (hdc) {
DesktopVector dpi{GetDeviceCaps(hdc, LOGPIXELSX),
GetDeviceCaps(hdc, LOGPIXELSY)};
ReleaseDC(nullptr, hdc);
return dpi;
}
// If everything fails, then return the default DPI for Windows.
return {96, 96};
}
DesktopRect GetScreenRect(const DesktopCapturer::SourceId screen,
const std::wstring& device_key) {
if (screen == kFullDesktopScreenId) {
return GetFullscreenRect();
}
DISPLAY_DEVICEW device;
device.cb = sizeof(device);
BOOL result = EnumDisplayDevicesW(NULL, screen, &device, 0);
if (!result) {
return DesktopRect();
}
// Verifies the device index still maps to the same display device, to make
// sure we are capturing the same device when devices are added or removed.
// DeviceKey is documented as reserved, but it actually contains the registry
// key for the device and is unique for each monitor, while DeviceID is not.
if (device_key != device.DeviceKey) {
return DesktopRect();
}
DEVMODEW device_mode;
device_mode.dmSize = sizeof(device_mode);
device_mode.dmDriverExtra = 0;
result = EnumDisplaySettingsExW(device.DeviceName, ENUM_CURRENT_SETTINGS,
&device_mode, 0);
if (!result) {
return DesktopRect();
}
return DesktopRect::MakeXYWH(
device_mode.dmPosition.x, device_mode.dmPosition.y,
device_mode.dmPelsWidth, device_mode.dmPelsHeight);
}
} // namespace webrtc