Add empty eglfs screen capture

We need custom eglfs screen capture implementation as
common QScreen::grabWindow implementation has valuable overhead.

The patch adds matching classes and methods,
implementation is supposed to go in next commits.

Pick-to: 6.6 6.5
Change-Id: I40a605f3bd3651de51c75732041ffe28e385db91
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>
Reviewed-by: Mikko Hallamaa <mikko.hallamaa@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
(cherry picked from commit 8c814014c4131ca1193c443714e2d2756e4f7e58)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

4 files changed, 120 insertions, 0 deletions

diff --git a/src/plugins/multimedia/ffmpeg/CMakeLists.txt b/src/plugins/multimedia/ffmpeg/CMakeLists.txt
index 806d31635..8ba9a9264 100644
--- a/src/plugins/multimedia/ffmpeg/CMakeLists.txt
+++ b/src/plugins/multimedia/ffmpeg/CMakeLists.txt
@@ -195,6 +195,11 @@ qt_internal_extend_target(QFFmpegMediaPlugin CONDITION QT_FEATURE_xlib
         Xext
 )
 
+qt_internal_extend_target(QFFmpegMediaPlugin CONDITION QT_FEATURE_eglfs
+    SOURCES
+        qeglfsscreencapture.cpp qeglfsscreencapture_p.h
+)
+
 set_source_files_properties(qx11surfacecapture.cpp qx11capturablewindows.cpp # X headers
                             PROPERTIES SKIP_UNITY_BUILD_INCLUSION ON)
 
diff --git a/src/plugins/multimedia/ffmpeg/qeglfsscreencapture.cpp b/src/plugins/multimedia/ffmpeg/qeglfsscreencapture.cpp
new file mode 100644
index 000000000..1837c3c57
--- /dev/null
+++ b/src/plugins/multimedia/ffmpeg/qeglfsscreencapture.cpp
@@ -0,0 +1,61 @@
+// 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 "qeglfsscreencapture_p.h"
+#include "qffmpegsurfacecapturegrabber_p.h"
+#include "qguiapplication.h"
+
+QT_BEGIN_NAMESPACE
+
+class QEglfsScreenCapture::Grabber : public QFFmpegSurfaceCaptureGrabber
+{
+public:
+    Grabber(QEglfsScreenCapture &screenCapture, QScreen *screen)
+        : QFFmpegSurfaceCaptureGrabber(false)
+    {
+        setFrameRate(screen->refreshRate());
+        addFrameCallback(screenCapture, &QEglfsScreenCapture::newVideoFrame);
+        connect(this, &Grabber::errorUpdated, &screenCapture, &QEglfsScreenCapture::updateError);
+    }
+
+    ~Grabber() override { stop(); }
+
+    QVideoFrameFormat format() { return m_format; }
+
+    QVideoFrame grabFrame() override
+    {
+        // To be implemented: take a frame and updare m_format
+        return {};
+    }
+
+private:
+    QVideoFrameFormat m_format;
+};
+
+QEglfsScreenCapture::QEglfsScreenCapture() : QPlatformSurfaceCapture(ScreenSource{}) { }
+
+QEglfsScreenCapture::~QEglfsScreenCapture() = default;
+
+QVideoFrameFormat QEglfsScreenCapture::frameFormat() const
+{
+    return m_grabber ? m_grabber->format() : QVideoFrameFormat();
+}
+
+bool QEglfsScreenCapture::setActiveInternal(bool active)
+{
+    if (m_grabber)
+        m_grabber.reset();
+    else if (auto screen = source<ScreenSource>(); checkScreenWithError(screen))
+        m_grabber = std::make_unique<Grabber>(*this, screen);
+
+    return static_cast<bool>(m_grabber) == active;
+}
+
+bool QEglfsScreenCapture::isSupported()
+{
+    // return QGuiApplication::platformName() == QLatin1String("eglfs"))
+    return false;
+}
+
+QT_END_NAMESPACE
diff --git a/src/plugins/multimedia/ffmpeg/qeglfsscreencapture_p.h b/src/plugins/multimedia/ffmpeg/qeglfsscreencapture_p.h
new file mode 100644
index 000000000..bbef78428
--- /dev/null
+++ b/src/plugins/multimedia/ffmpeg/qeglfsscreencapture_p.h
@@ -0,0 +1,45 @@
+// 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
+
+#ifndef QEGLFSSCREENCAPTURE_H
+#define QEGLFSSCREENCAPTURE_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API. It exists purely as an
+// implementation detail. This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <private/qplatformsurfacecapture_p.h>
+#include <memory>
+
+QT_BEGIN_NAMESPACE
+
+class QEglfsScreenCapture : public QPlatformSurfaceCapture
+{
+public:
+    QEglfsScreenCapture();
+
+    ~QEglfsScreenCapture() override;
+
+    QVideoFrameFormat frameFormat() const override;
+
+    static bool isSupported();
+
+private:
+    bool setActiveInternal(bool active) override;
+
+private:
+    class Grabber;
+    std::unique_ptr<Grabber> m_grabber;
+};
+
+QT_END_NAMESPACE
+
+#endif // QEGLFSSCREENCAPTURE_H
diff --git a/src/plugins/multimedia/ffmpeg/qffmpegmediaintegration.cpp b/src/plugins/multimedia/ffmpeg/qffmpegmediaintegration.cpp
index 5c97e66b8..7d8859ebc 100644
--- a/src/plugins/multimedia/ffmpeg/qffmpegmediaintegration.cpp
+++ b/src/plugins/multimedia/ffmpeg/qffmpegmediaintegration.cpp
@@ -59,6 +59,10 @@ extern "C" {
 #include "qx11capturablewindows_p.h"
 #endif
 
+#if QT_CONFIG(eglfs)
+#include "qeglfsscreencapture_p.h"
+#endif
+
 QT_BEGIN_NAMESPACE
 
 class QFFmpegMediaPlugin : public QPlatformMediaPlugin
@@ -213,6 +217,11 @@ QPlatformSurfaceCapture *QFFmpegMediaIntegration::createScreenCapture(QScreenCap
         return new QX11SurfaceCapture(QPlatformSurfaceCapture::ScreenSource{});
 #endif
 
+#if QT_CONFIG(eglfs)
+    if (QEglfsScreenCapture::isSupported())
+        return new QEglfsScreenCapture;
+#endif
+
 #if defined(Q_OS_WINDOWS)
     return new QFFmpegScreenCaptureDxgi;
 #elif defined(Q_OS_MACOS) // TODO: probably use it for iOS as well