tor-browser

screen_drawer_win.cc (5797B)

---

/*
*  Copyright (c) 2016 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 <windows.h>

#include <cstddef>
#include <memory>

#include "modules/desktop_capture/desktop_capture_types.h"
#include "modules/desktop_capture/desktop_geometry.h"
#include "modules/desktop_capture/rgba_color.h"
#include "modules/desktop_capture/screen_drawer.h"
#include "rtc_base/thread.h"

namespace webrtc {

namespace {

static constexpr TCHAR kMutexName[] =
   TEXT("Local\\ScreenDrawerWin-da834f82-8044-11e6-ac81-73dcdd1c1869");

class ScreenDrawerLockWin : public ScreenDrawerLock {
public:
 ScreenDrawerLockWin();
 ~ScreenDrawerLockWin() override;

private:
 HANDLE mutex_;
};

ScreenDrawerLockWin::ScreenDrawerLockWin() {
 while (true) {
   mutex_ = CreateMutex(NULL, FALSE, kMutexName);
   if (GetLastError() != ERROR_ALREADY_EXISTS && mutex_ != NULL) {
     break;
   } else {
     if (mutex_) {
       CloseHandle(mutex_);
     }
     Thread::SleepMs(1000);
   }
 }
}

ScreenDrawerLockWin::~ScreenDrawerLockWin() {
 CloseHandle(mutex_);
}

DesktopRect GetScreenRect() {
 HDC hdc = GetDC(NULL);
 DesktopRect rect = DesktopRect::MakeWH(GetDeviceCaps(hdc, HORZRES),
                                        GetDeviceCaps(hdc, VERTRES));
 ReleaseDC(NULL, hdc);
 return rect;
}

HWND CreateDrawerWindow(DesktopRect rect) {
 HWND hwnd = CreateWindowA(
     "STATIC", "DrawerWindow", WS_POPUPWINDOW | WS_VISIBLE, rect.left(),
     rect.top(), rect.width(), rect.height(), NULL, NULL, NULL, NULL);
 SetForegroundWindow(hwnd);
 return hwnd;
}

COLORREF ColorToRef(RgbaColor color) {
 // Windows device context does not support alpha.
 return RGB(color.red, color.green, color.blue);
}

// A ScreenDrawer implementation for Windows.
class ScreenDrawerWin : public ScreenDrawer {
public:
 ScreenDrawerWin();
 ~ScreenDrawerWin() override;

 // ScreenDrawer interface.
 DesktopRect DrawableRegion() override;
 void DrawRectangle(DesktopRect rect, RgbaColor color) override;
 void Clear() override;
 void WaitForPendingDraws() override;
 bool MayDrawIncompleteShapes() override;
 WindowId window_id() const override;

private:
 // Bring the window to the front, this can help to avoid the impact from other
 // windows or shadow effects.
 void BringToFront();

 // Draw a line with `color`.
 void DrawLine(DesktopVector start, DesktopVector end, RgbaColor color);

 // Draw a dot with `color`.
 void DrawDot(DesktopVector vect, RgbaColor color);

 const DesktopRect rect_;
 HWND window_;
 HDC hdc_;
};

ScreenDrawerWin::ScreenDrawerWin()
   : ScreenDrawer(),
     rect_(GetScreenRect()),
     window_(CreateDrawerWindow(rect_)),
     hdc_(GetWindowDC(window_)) {
 // We do not need to handle any messages for the `window_`, so disable Windows
 // from processing windows ghosting feature.
 DisableProcessWindowsGhosting();

 // Always use stock pen (DC_PEN) and brush (DC_BRUSH).
 SelectObject(hdc_, GetStockObject(DC_PEN));
 SelectObject(hdc_, GetStockObject(DC_BRUSH));
 BringToFront();
}

ScreenDrawerWin::~ScreenDrawerWin() {
 ReleaseDC(NULL, hdc_);
 DestroyWindow(window_);
 // Unfortunately there is no EnableProcessWindowsGhosting() API.
}

DesktopRect ScreenDrawerWin::DrawableRegion() {
 return rect_;
}

void ScreenDrawerWin::DrawRectangle(DesktopRect rect, RgbaColor color) {
 if (rect.width() == 1 && rect.height() == 1) {
   // Rectangle function cannot draw a 1 pixel rectangle.
   DrawDot(rect.top_left(), color);
   return;
 }

 if (rect.width() == 1 || rect.height() == 1) {
   // Rectangle function cannot draw a 1 pixel rectangle.
   DrawLine(rect.top_left(), DesktopVector(rect.right(), rect.bottom()),
            color);
   return;
 }

 SetDCBrushColor(hdc_, ColorToRef(color));
 SetDCPenColor(hdc_, ColorToRef(color));
 Rectangle(hdc_, rect.left(), rect.top(), rect.right(), rect.bottom());
}

void ScreenDrawerWin::Clear() {
 DrawRectangle(rect_, RgbaColor(0, 0, 0));
}

// TODO(zijiehe): Find the right signal to indicate the finish of all pending
// paintings.
void ScreenDrawerWin::WaitForPendingDraws() {
 BringToFront();
 Thread::SleepMs(50);
}

bool ScreenDrawerWin::MayDrawIncompleteShapes() {
 return true;
}

WindowId ScreenDrawerWin::window_id() const {
 return reinterpret_cast<WindowId>(window_);
}

void ScreenDrawerWin::DrawLine(DesktopVector start,
                              DesktopVector end,
                              RgbaColor color) {
 POINT points[2];
 points[0].x = start.x();
 points[0].y = start.y();
 points[1].x = end.x();
 points[1].y = end.y();
 SetDCPenColor(hdc_, ColorToRef(color));
 Polyline(hdc_, points, 2);
}

void ScreenDrawerWin::DrawDot(DesktopVector vect, RgbaColor color) {
 SetPixel(hdc_, vect.x(), vect.y(), ColorToRef(color));
}

void ScreenDrawerWin::BringToFront() {
 if (SetWindowPos(window_, HWND_TOPMOST, 0, 0, 0, 0,
                  SWP_NOMOVE | SWP_NOSIZE) != FALSE) {
   return;
 }

 long ex_style = GetWindowLong(window_, GWL_EXSTYLE);
 ex_style |= WS_EX_TOPMOST;
 if (SetWindowLong(window_, GWL_EXSTYLE, ex_style) != 0) {
   return;
 }

 BringWindowToTop(window_);
}

}  // namespace

// static
std::unique_ptr<ScreenDrawerLock> ScreenDrawerLock::Create() {
 return std::unique_ptr<ScreenDrawerLock>(new ScreenDrawerLockWin());
}

// static
std::unique_ptr<ScreenDrawer> ScreenDrawer::Create() {
 return std::unique_ptr<ScreenDrawer>(new ScreenDrawerWin());
}

}  // namespace webrtc