Add implementation to EGLFS screen capture

Implementation for EGLFS screen capture added in change
codereview.qt-project.org/c/qt/qtmultimedia/+/527432. This allows for
optimizations as well as handling platform-specific conditions.

Task-number: QTBUG-117746
Pick-to: 6.6 6.5
Change-Id: Iadffba1c93bd3bc62c267a096d4ac23f1fedf4fd
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>
(cherry picked from commit 0fd782d27e7732040c755a1bf22cc56198d64cac)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 53 insertions, 6 deletions

diff --git a/src/plugins/multimedia/ffmpeg/CMakeLists.txt b/src/plugins/multimedia/ffmpeg/CMakeLists.txt
index 8ba9a9264..0b3005a4d 100644
--- a/src/plugins/multimedia/ffmpeg/CMakeLists.txt
+++ b/src/plugins/multimedia/ffmpeg/CMakeLists.txt
@@ -198,6 +198,8 @@ qt_internal_extend_target(QFFmpegMediaPlugin CONDITION QT_FEATURE_xlib
 qt_internal_extend_target(QFFmpegMediaPlugin CONDITION QT_FEATURE_eglfs
     SOURCES
         qeglfsscreencapture.cpp qeglfsscreencapture_p.h
+    LIBRARIES
+        Qt::OpenGLPrivate
 )
 
 set_source_files_properties(qx11surfacecapture.cpp qx11capturablewindows.cpp # X headers
diff --git a/src/plugins/multimedia/ffmpeg/qeglfsscreencapture.cpp b/src/plugins/multimedia/ffmpeg/qeglfsscreencapture.cpp
index 1837c3c57..2f9ad1add 100644
--- a/src/plugins/multimedia/ffmpeg/qeglfsscreencapture.cpp
+++ b/src/plugins/multimedia/ffmpeg/qeglfsscreencapture.cpp
@@ -6,6 +6,10 @@
 #include "qffmpegsurfacecapturegrabber_p.h"
 #include "qguiapplication.h"
 
+#include "private/qimagevideobuffer_p.h"
+
+#include <QtOpenGL/private/qopenglcompositor_p.h>
+
 QT_BEGIN_NAMESPACE
 
 class QEglfsScreenCapture::Grabber : public QFFmpegSurfaceCaptureGrabber
@@ -14,9 +18,11 @@ public:
     Grabber(QEglfsScreenCapture &screenCapture, QScreen *screen)
         : QFFmpegSurfaceCaptureGrabber(false)
     {
-        setFrameRate(screen->refreshRate());
         addFrameCallback(screenCapture, &QEglfsScreenCapture::newVideoFrame);
         connect(this, &Grabber::errorUpdated, &screenCapture, &QEglfsScreenCapture::updateError);
+        // Limit frame rate to 30 fps for performance reasons, to be reviewed at the next optimization round
+        setFrameRate(std::min(screen->refreshRate(), 30.0));
+        start();
     }
 
     ~Grabber() override { stop(); }
@@ -25,8 +31,25 @@ public:
 
     QVideoFrame grabFrame() override
     {
-        // To be implemented: take a frame and updare m_format
-        return {};
+        QOpenGLCompositor *compositor = QOpenGLCompositor::instance();
+        QImage img = compositor->grab();
+
+        if (img.isNull()) {
+            updateError(Error::InternalError, QLatin1String("Null image captured"));
+            return {};
+        }
+
+        if (!m_format.isValid()) {
+            // This is a hack to use RGBX8888 video frame format for RGBA8888_Premultiplied image format,
+            // due to the lack of QVideoFrameFormat::Format_RGBA8888_Premultiplied
+            auto videoFrameFormat = img.format() == QImage::Format_RGBA8888_Premultiplied
+                    ? QVideoFrameFormat::Format_RGBX8888
+                    : QVideoFrameFormat::pixelFormatFromImageFormat(img.format());
+            m_format = { img.size(), videoFrameFormat };
+            m_format.setFrameRate(frameRate());
+        }
+
+        return QVideoFrame(new QImageVideoBuffer(std::move(img)), m_format);
     }
 
 private:
@@ -44,18 +67,40 @@ QVideoFrameFormat QEglfsScreenCapture::frameFormat() const
 
 bool QEglfsScreenCapture::setActiveInternal(bool active)
 {
+    if (static_cast<bool>(m_grabber) == active)
+        return true;
+
     if (m_grabber)
         m_grabber.reset();
-    else if (auto screen = source<ScreenSource>(); checkScreenWithError(screen))
+    else {
+        auto screen = source<ScreenSource>();
+        if (!checkScreenWithError(screen))
+            return false;
+
+        QOpenGLCompositor *compositor = QOpenGLCompositor::instance();
+        if (!compositor->context()) {
+            updateError(Error::CaptureFailed, QLatin1String("OpenGL context is not found"));
+            return false;
+        }
+
+        if (!compositor->targetWindow()) {
+            updateError(Error::CaptureFailed, QLatin1String("Target window is not set for OpenGL compositor"));
+            return false;
+        }
+
+        // TODO Add check to differentiate between uninitialized UI and QML
+        // If UI not started, wait and try again, and then give error if still not started.
+        // If QML, give not supported error for now.
+
         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;
+    return QGuiApplication::platformName() == QLatin1String("eglfs");
 }
 
 QT_END_NAMESPACE