Android: Fix fetching video frame data from the GUI thread5.13

If QAbstractVideoSurface is not used on rendering thread
added a way to pass shared opengl context via GLContext surface property.

Camera and media players that are created in Qt Quick will usually have
their rendering done on the render thread, but the callback for custom video
surface(s) (or probes) will usually be handle on the GUI thread, so to
make it convenient to for the user to access the frame data, which is rendered
on request, we now set-up context sharing and render to a fbo on the calling
thread, if needed.

Task-number: QTBUG-69333
Change-Id: I4cc5c1f741c82376f1402a047b946b59281c9a4c
Reviewed-by: Christian Strømme <christian.stromme@qt.io>

2 files changed, 38 insertions, 0 deletions

diff --git a/src/plugins/android/src/common/qandroidvideooutput.cpp b/src/plugins/android/src/common/qandroidvideooutput.cpp
index 083ceff24..a4f4dbd5d 100644
--- a/src/plugins/android/src/common/qandroidvideooutput.cpp
+++ b/src/plugins/android/src/common/qandroidvideooutput.cpp
@@ -49,6 +49,8 @@
 #include <qopenglshaderprogram.h>
 #include <qopenglframebufferobject.h>
 #include <QtCore/private/qjnihelpers_p.h>
+#include <QtGui/QWindow>
+#include <QtGui/QOffscreenSurface>
 
 QT_BEGIN_NAMESPACE
 
@@ -182,6 +184,8 @@ QAndroidTextureVideoOutput::QAndroidTextureVideoOutput(QObject *parent)
 
 QAndroidTextureVideoOutput::~QAndroidTextureVideoOutput()
 {
+    delete m_offscreenSurface;
+    delete m_glContext;
     clearSurfaceTexture();
 
     if (m_glDeleter) { // Make sure all of these are deleted on the render thread.
@@ -345,6 +349,35 @@ bool QAndroidTextureVideoOutput::renderFrameToFbo()
     if (!m_nativeSize.isValid() || !m_surfaceTexture)
         return false;
 
+    // Make sure we have an OpenGL context to make current.
+    if (!QOpenGLContext::currentContext() && !m_glContext) {
+        // Create Hidden QWindow surface to create context in this thread.
+        m_offscreenSurface = new QWindow();
+        m_offscreenSurface->setSurfaceType(QWindow::OpenGLSurface);
+        // Needs geometry to be a valid surface, but size is not important.
+        m_offscreenSurface->setGeometry(0, 0, 1, 1);
+        m_offscreenSurface->create();
+
+        // Create OpenGL context and set share context from surface.
+        m_glContext = new QOpenGLContext();
+        m_glContext->setFormat(m_offscreenSurface->requestedFormat());
+
+        auto surface = qobject_cast<QAbstractVideoSurface *>(m_surface->property("videoSurface").value<QObject *>());
+        if (!surface)
+            surface = m_surface;
+        auto shareContext = qobject_cast<QOpenGLContext *>(surface->property("GLContext").value<QObject *>());
+        if (shareContext)
+            m_glContext->setShareContext(shareContext);
+
+        if (!m_glContext->create()) {
+            qWarning("Failed to create QOpenGLContext");
+            return false;
+        }
+    }
+
+    if (m_glContext)
+        m_glContext->makeCurrent(m_offscreenSurface);
+
     createGLResources();
 
     m_surfaceTexture->updateTexImage();
diff --git a/src/plugins/android/src/common/qandroidvideooutput.h b/src/plugins/android/src/common/qandroidvideooutput.h
index 2a35247e9..456fe8e22 100644
--- a/src/plugins/android/src/common/qandroidvideooutput.h
+++ b/src/plugins/android/src/common/qandroidvideooutput.h
@@ -51,6 +51,8 @@ class AndroidSurfaceHolder;
 class QOpenGLFramebufferObject;
 class QOpenGLShaderProgram;
 class QAbstractVideoSurface;
+class QWindow;
+class QOpenGLContext;
 
 class QAndroidVideoOutput : public QObject
 {
@@ -132,6 +134,9 @@ private:
 
     bool m_surfaceTextureCanAttachToContext;
 
+    QWindow *m_offscreenSurface = nullptr;
+    QOpenGLContext *m_glContext = nullptr;
+
     friend class AndroidTextureVideoBuffer;
 };