blob: edde01c7ba6acd7d6fb34806b102ae0e3951659e [file] [log] [blame]
* 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 <memory>
#include "webrtc/modules/desktop_capture/mouse_cursor_monitor.h"
#include <X11/extensions/Xfixes.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include "webrtc/modules/desktop_capture/desktop_capture_options.h"
#include "webrtc/modules/desktop_capture/desktop_capture_types.h"
#include "webrtc/modules/desktop_capture/desktop_frame.h"
#include "webrtc/modules/desktop_capture/mouse_cursor.h"
#include "webrtc/modules/desktop_capture/x11/x_error_trap.h"
#include "webrtc/rtc_base/logging.h"
namespace {
// WindowCapturer returns window IDs of X11 windows with WM_STATE attribute.
// These windows may not be immediate children of the root window, because
// window managers may re-parent them to add decorations. However,
// XQueryPointer() expects to be passed children of the root. This function
// searches up the list of the windows to find the root child that corresponds
// to |window|.
Window GetTopLevelWindow(Display* display, Window window) {
while (true) {
// If the window is in WithdrawnState then look at all of its children.
::Window root, parent;
::Window *children;
unsigned int num_children;
if (!XQueryTree(display, window, &root, &parent, &children,
&num_children)) {
LOG(LS_ERROR) << "Failed to query for child windows although window"
<< "does not have a valid WM_STATE.";
return None;
if (children)
if (parent == root)
window = parent;
return window;
} // namespace
namespace webrtc {
class MouseCursorMonitorX11 : public MouseCursorMonitor,
public SharedXDisplay::XEventHandler {
MouseCursorMonitorX11(const DesktopCaptureOptions& options, Window window);
~MouseCursorMonitorX11() override;
void Init(Callback* callback, Mode mode) override;
void Capture() override;
// SharedXDisplay::XEventHandler interface.
bool HandleXEvent(const XEvent& event) override;
Display* display() { return x_display_->display(); }
// Captures current cursor shape and stores it in |cursor_shape_|.
void CaptureCursor();
rtc::scoped_refptr<SharedXDisplay> x_display_;
Callback* callback_;
Mode mode_;
Window window_;
bool have_xfixes_;
int xfixes_event_base_;
int xfixes_error_base_;
std::unique_ptr<MouseCursor> cursor_shape_;
const DesktopCaptureOptions& options,
Window window)
: x_display_(options.x_display()),
xfixes_error_base_(-1) {
// Set a default initial cursor shape in case XFixes is not present.
const int kSize = 5;
std::unique_ptr<DesktopFrame> default_cursor(
new BasicDesktopFrame(DesktopSize(kSize, kSize)));
const uint8_t pixels[kSize * kSize] = {
0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0xff, 0xff, 0xff, 0x00,
0x00, 0xff, 0xff, 0xff, 0x00,
0x00, 0xff, 0xff, 0xff, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00
uint8_t* ptr = default_cursor->data();
for (int y = 0; y < kSize; ++y) {
for (int x = 0; x < kSize; ++x) {
*ptr++ = pixels[kSize * y + x];
*ptr++ = pixels[kSize * y + x];
*ptr++ = pixels[kSize * y + x];
*ptr++ = 0xff;
DesktopVector hotspot(2, 2);
cursor_shape_.reset(new MouseCursor(default_cursor.release(), hotspot));
MouseCursorMonitorX11::~MouseCursorMonitorX11() {
if (have_xfixes_) {
x_display_->RemoveEventHandler(xfixes_event_base_ + XFixesCursorNotify,
void MouseCursorMonitorX11::Init(Callback* callback, Mode mode) {
// Init can be called only once per instance of MouseCursorMonitor.
callback_ = callback;
mode_ = mode;
have_xfixes_ =
XFixesQueryExtension(display(), &xfixes_event_base_, &xfixes_error_base_);
if (have_xfixes_) {
// Register for changes to the cursor shape.
XFixesSelectCursorInput(display(), window_, XFixesDisplayCursorNotifyMask);
x_display_->AddEventHandler(xfixes_event_base_ + XFixesCursorNotify, this);
} else {
LOG(LS_INFO) << "X server does not support XFixes.";
void MouseCursorMonitorX11::Capture() {
// Process X11 events in case XFixes has sent cursor notification.
// cursor_shape_| is set only if we were notified of a cursor shape change.
if (cursor_shape_.get())
// Get cursor position if necessary.
if (mode_ == SHAPE_AND_POSITION) {
int root_x;
int root_y;
int win_x;
int win_y;
Window root_window;
Window child_window;
unsigned int mask;
XErrorTrap error_trap(display());
Bool result = XQueryPointer(display(), window_, &root_window, &child_window,
&root_x, &root_y, &win_x, &win_y, &mask);
CursorState state;
if (!result || error_trap.GetLastErrorAndDisable() != 0) {
state = OUTSIDE;
} else {
// In screen mode (window_ == root_window) the mouse is always inside.
// XQueryPointer() sets |child_window| to None if the cursor is outside
// |window_|.
state =
(window_ == root_window || child_window != None) ? INSIDE : OUTSIDE;
// As the comments to GetTopLevelWindow() above indicate, in window capture,
// the cursor position capture happens in |window_|, while the frame catpure
// happens in |child_window|. These two windows are not alwyas same, as
// window manager may add some decorations to the |window_|. So translate
// the coordinate in |window_| to the coordinate space of |child_window|.
if (window_ != root_window && state == INSIDE) {
int translated_x, translated_y;
Window unused;
if (XTranslateCoordinates(display(), window_, child_window, win_x, win_y,
&translated_x, &translated_y, &unused)) {
win_x = translated_x;
win_y = translated_y;
const DesktopVector position(win_x, win_y);
// TODO(zijiehe): Remove this overload.
callback_->OnMouseCursorPosition(state, position);
// X11 always starts the coordinate from (0, 0), so we do not need to
// translate here.
bool MouseCursorMonitorX11::HandleXEvent(const XEvent& event) {
if (have_xfixes_ && event.type == xfixes_event_base_ + XFixesCursorNotify) {
const XFixesCursorNotifyEvent* cursor_event =
reinterpret_cast<const XFixesCursorNotifyEvent*>(&event);
if (cursor_event->subtype == XFixesDisplayCursorNotify) {
// Return false, even if the event has been handled, because there might be
// other listeners for cursor notifications.
return false;
void MouseCursorMonitorX11::CaptureCursor() {
XFixesCursorImage* img;
XErrorTrap error_trap(display());
img = XFixesGetCursorImage(display());
if (!img || error_trap.GetLastErrorAndDisable() != 0)
std::unique_ptr<DesktopFrame> image(
new BasicDesktopFrame(DesktopSize(img->width, img->height)));
// Xlib stores 32-bit data in longs, even if longs are 64-bits long.
unsigned long* src = img->pixels;
uint32_t* dst = reinterpret_cast<uint32_t*>(image->data());
uint32_t* dst_end = dst + (img->width * img->height);
while (dst < dst_end) {
*dst++ = static_cast<uint32_t>(*src++);
DesktopVector hotspot(std::min(img->width, img->xhot),
std::min(img->height, img->yhot));
cursor_shape_.reset(new MouseCursor(image.release(), hotspot));
// static
MouseCursorMonitor* MouseCursorMonitor::CreateForWindow(
const DesktopCaptureOptions& options, WindowId window) {
if (!options.x_display())
return NULL;
window = GetTopLevelWindow(options.x_display()->display(), window);
if (window == None)
return NULL;
return new MouseCursorMonitorX11(options, window);
MouseCursorMonitor* MouseCursorMonitor::CreateForScreen(
const DesktopCaptureOptions& options,
ScreenId screen) {
if (!options.x_display())
return NULL;
return new MouseCursorMonitorX11(
options, DefaultRootWindow(options.x_display()->display()));
std::unique_ptr<MouseCursorMonitor> MouseCursorMonitor::Create(
const DesktopCaptureOptions& options) {
return std::unique_ptr<MouseCursorMonitor>(
CreateForScreen(options, kFullDesktopScreenId));
} // namespace webrtc