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++ // Copyright (C) 2023 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
++
++ #include "qgdiwindowcapture_p.h"
++
++ #include "qvideoframe.h"
++ #include <QtMultimedia/private/qsurfacecapturegrabber_p.h>
++ #include "private/qcapturablewindow_p.h"
++ #include "private/qmemoryvideobuffer_p.h"
++ #include "private/qvideoframe_p.h"
++
++ #include <qt_windows.h>
++ #include <QtCore/qloggingcategory.h>
++
++ Q_STATIC_LOGGING_CATEGORY(qLcGdiWindowCapture, "qt.multimedia.ffmpeg.gdiwindowcapture");
++
++ QT_BEGIN_NAMESPACE
++
++ class QGdiWindowCapture::Grabber : public QSurfaceCaptureGrabber
++ {
++ public:
++ static std::unique_ptr<Grabber> create(QGdiWindowCapture &capture, HWND hWnd)
++ {
++ auto hdcWindow = GetDC(hWnd);
++ if (!hdcWindow) {
++ capture.updateError(QPlatformSurfaceCapture::Error::CaptureFailed,
++ QLatin1String("Cannot create a window drawing context"));
++ return nullptr;
++ }
++
++ auto hdcMem = CreateCompatibleDC(hdcWindow);
++
++ if (!hdcMem) {
++ capture.updateError(QPlatformSurfaceCapture::Error::CaptureFailed,
++ QLatin1String("Cannot create a compatible drawing context"));
++ return nullptr;
++ }
++
++ std::unique_ptr<Grabber> result(new Grabber(capture, hWnd, hdcWindow, hdcMem));
++ if (!result->update())
++ return nullptr;
++
++ result->start();
++ return result;
++ }
++
++ ~Grabber() override
++ {
++ stop();
++
++ if (m_hBitmap)
++ DeleteObject(m_hBitmap);
++
++ if (m_hdcMem)
++ DeleteDC(m_hdcMem);
++
++ if (m_hdcWindow)
++ ReleaseDC(m_hwnd, m_hdcWindow);
++ }
++
++ QVideoFrameFormat format() const { return m_format; }
++
++ private:
++ Grabber(QGdiWindowCapture &capture, HWND hWnd, HDC hdcWindow, HDC hdcMem)
++ : QSurfaceCaptureGrabber(),
++ m_hwnd(hWnd),
++ m_hdcWindow(hdcWindow),
++ m_hdcMem(hdcMem)
++ {
++ addFrameCallback(&capture, &QGdiWindowCapture::newVideoFrame);
++ connect(this, &Grabber::errorUpdated, &capture, &QGdiWindowCapture::updateError);
++
++ const auto vrefresh = GetDeviceCaps(hdcWindow, VREFRESH);
++ const auto defaultRate = vrefresh > 0
++ ? qMin(static_cast<qreal>(vrefresh), DefaultScreenCaptureFrameRate)
++ : DefaultScreenCaptureFrameRate;
++ setFrameRate(capture.frameRate().value_or(defaultRate));
++ }
++
++ bool update()
++ {
++ RECT windowRect{};
++ if (!GetWindowRect(m_hwnd, &windowRect)) {
++ updateError(QPlatformSurfaceCapture::Error::CaptureFailed,
++ QLatin1String("Cannot get window size"));
++ return false;
++ }
++
++ const QSize size{ windowRect.right - windowRect.left, windowRect.bottom - windowRect.top };
++
++ if (m_format.isValid() && size == m_format.frameSize() && m_hBitmap)
++ return true;
++
++ if (m_hBitmap)
++ DeleteObject(std::exchange(m_hBitmap, nullptr));
++
++ if (size.isEmpty()) {
++ m_format = {};
++ updateError(QPlatformSurfaceCapture::Error::CaptureFailed,
++ QLatin1String("Invalid window size"));
++ return false;
++ }
++
++ m_hBitmap = CreateCompatibleBitmap(m_hdcWindow, size.width(), size.height());
++
++ if (!m_hBitmap) {
++ m_format = {};
++ updateError(QPlatformSurfaceCapture::Error::CaptureFailed,
++ QLatin1String("Cannot create a compatible bitmap"));
++ return false;
++ }
++
++ QVideoFrameFormat format(size, QVideoFrameFormat::Format_BGRX8888);
++ format.setStreamFrameRate(activeFrameRate());
++ m_format = format;
++ return true;
++ }
++
++ QVideoFrame grabFrame() override
++ {
++ if (!update())
++ return {};
++
++ const auto oldBitmap = SelectObject(m_hdcMem, m_hBitmap);
++ auto deselect = qScopeGuard([&]() { SelectObject(m_hdcMem, oldBitmap); });
++
++ const auto size = m_format.frameSize();
++
++ if (!BitBlt(m_hdcMem, 0, 0, size.width(), size.height(), m_hdcWindow, 0, 0, SRCCOPY)) {
++ updateError(QPlatformSurfaceCapture::Error::CaptureFailed,
++ QLatin1String("Cannot copy image to the compatible DC"));
++ return {};
++ }
++
++ BITMAPINFO info{};
++ auto &header = info.bmiHeader;
++ header.biSize = sizeof(BITMAPINFOHEADER);
++ header.biWidth = size.width();
++ header.biHeight = -size.height(); // negative height to ensure top-down orientation
++ header.biPlanes = 1;
++ header.biBitCount = 32;
++ header.biCompression = BI_RGB;
++
++ const auto bytesPerLine = size.width() * 4;
++
++ QByteArray array(size.height() * bytesPerLine, Qt::Uninitialized);
++
++ const auto copiedHeight = GetDIBits(m_hdcMem, m_hBitmap, 0, size.height(), array.data(), &info, DIB_RGB_COLORS);
++ if (copiedHeight != size.height()) {
++ qCWarning(qLcGdiWindowCapture) << copiedHeight << "lines have been copied, expected:" << size.height();
++ // In practice, it might fail randomly first time after start. So we don't consider it as an error.
++ // TODO: investigate reasons and properly handle the error
++ // updateError(QPlatformSurfaceCapture::CaptureFailed,
++ // QLatin1String("Cannot get raw image data"));
++ return {};
++ }
++
++ if (header.biWidth != size.width() || header.biHeight != -size.height()
++ || header.biPlanes != 1 || header.biBitCount != 32 || header.biCompression != BI_RGB) {
++ updateError(QPlatformSurfaceCapture::Error::CaptureFailed,
++ QLatin1String("Output bitmap info is unexpected"));
++ return {};
++ }
++
++ return QVideoFramePrivate::createFrame(
++ std::make_unique<QMemoryVideoBuffer>(std::move(array), bytesPerLine), m_format);
++ }
++
++ private:
++ HWND m_hwnd = {};
++ QVideoFrameFormat m_format;
++ HDC m_hdcWindow = {};
++ HDC m_hdcMem = {};
++ HBITMAP m_hBitmap = {};
++ };
++
++ QGdiWindowCapture::QGdiWindowCapture() : QPlatformSurfaceCapture(WindowSource{}) { }
++
++ QGdiWindowCapture::~QGdiWindowCapture() = default;
++
++ QVideoFrameFormat QGdiWindowCapture::frameFormat() const
++ {
++ return m_grabber ? m_grabber->format() : QVideoFrameFormat();
++ }
++
++ bool QGdiWindowCapture::setActiveInternal(bool active)
++ {
++ if (active == static_cast<bool>(m_grabber))
++ return true;
++
++ if (m_grabber) {
++ m_grabber.reset();
++ } else {
++ auto window = source<WindowSource>();
++ auto handle = QCapturableWindowPrivate::handle(window);
++
++ m_grabber = Grabber::create(*this, reinterpret_cast<HWND>(handle ? handle->id : 0));
++ }
++
++ return static_cast<bool>(m_grabber) == active;
++ }
++
++ QT_END_NAMESPACE