qt: allow per feature registration

Split plugin into features including
dynamic types which can be indiviually
registered during a static build.

More details here:

https://gitlab.freedesktop.org/gstreamer/gst-build/-/merge_requests/199
https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/661

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/merge_requests/876>

ext/qt/gstplugin.cc

@@ -22,32 +22,22 @@
 #include "config.h"
 #endif
 
-#include "gstqtoverlay.h"
-#include "gstqtsink.h"
-#include "gstqtsrc.h"
+#include "gstqtelements.h"
+#include "qtitem.h"
 #include <QtQml/QQmlApplicationEngine>
 
 static gboolean
 plugin_init (GstPlugin * plugin)
 {
-  if (!gst_element_register (plugin, "qmlglsink",
-          GST_RANK_NONE, GST_TYPE_QT_SINK)) {
-    return FALSE;
-  }
+  gboolean ret = FALSE;
 
-  if (!gst_element_register (plugin, "qmlglsrc",
-          GST_RANK_NONE, GST_TYPE_QT_SRC)) {
-    return FALSE;
-  }
+  ret |= GST_ELEMENT_REGISTER (qmlglsink, plugin);
 
-  if (!gst_element_register (plugin, "qmlgloverlay",
-          GST_RANK_NONE, GST_TYPE_QT_OVERLAY)) {
-    return FALSE;
-  }
-  /* this means the plugin must be loaded before the qml engine is loaded */
-  qmlRegisterType<QtGLVideoItem> ("org.freedesktop.gstreamer.GLVideoItem", 1, 0, "GstGLVideoItem");
+  ret |= GST_ELEMENT_REGISTER (qmlglsrc, plugin);
 
-  return TRUE;
+  ret |= GST_ELEMENT_REGISTER (qmlgloverlay, plugin);
+
+  return ret;
 }
 
 #ifndef GST_PACKAGE_NAME

ext/qt/gstqtelement.cc

@@ -0,0 +1,39 @@
+/*
+ * GStreamer
+ * Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstqtelements.h"
+#include "qtitem.h"
+#include <QtQml/QQmlApplicationEngine>
+
+gboolean
+qt5_element_init (GstPlugin * plugin)
+{
+  static gsize res = FALSE;
+  if (g_once_init_enter (&res)) {
+    /* this means the plugin must be loaded before the qml engine is loaded */
+    qmlRegisterType<QtGLVideoItem> ("org.freedesktop.gstreamer.GLVideoItem", 1, 0, "GstGLVideoItem");
+    g_once_init_leave (&res, TRUE);
+  }
+  return res;
+}

ext/qt/gstqtelements.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2020 Huawei Technologies Co., Ltd.
+ *   @Author: Julian Bouzas <julian.bouzas@collabora.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __GST_QT_ELEMENTS_H__
+#define __GST_QT_ELEMENTS_H__
+
+#include <gst/gst.h>
+
+G_BEGIN_DECLS
+
+gboolean qt5_element_init (GstPlugin * plugin);
+
+GST_ELEMENT_REGISTER_DECLARE (qmlglsink);
+GST_ELEMENT_REGISTER_DECLARE (qmlglsrc);
+GST_ELEMENT_REGISTER_DECLARE (qmlgloverlay);
+
+G_END_DECLS
+
+#endif /* __GST_QT_ELEMENTS_H__ */

ext/qt/gstqtoverlay.cc

@@ -79,6 +79,7 @@
 #include "config.h"
 #endif
 
+#include "gstqtelements.h"
 #include "gstqtoverlay.h"
 #include "qtglrenderer.h"
 #include "gstqtglutility.h"
@@ -131,6 +132,10 @@ static guint gst_qt_overlay_signals[LAST_SIGNAL] = { 0 };
 G_DEFINE_TYPE_WITH_CODE (GstQtOverlay, gst_qt_overlay,
     GST_TYPE_GL_FILTER, GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT,
         "qtoverlay", 0, "Qt Video Overlay"));
+#define _do_init \
+    ret |= qt5_element_init (plugin);
+GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (qmlgloverlay, "qmlgloverlay",
+    GST_RANK_NONE, GST_TYPE_QT_OVERLAY, _do_init);
 
 static void
 gst_qt_overlay_class_init (GstQtOverlayClass * klass)

ext/qt/gstqtsink.cc

@@ -72,6 +72,7 @@
 #include "config.h"
 #endif
 
+#include "gstqtelements.h"
 #include "gstqtsink.h"
 #include <QtGui/QGuiApplication>
 
@@ -134,6 +135,10 @@ enum
 G_DEFINE_TYPE_WITH_CODE (GstQtSink, gst_qt_sink,
     GST_TYPE_VIDEO_SINK, GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT,
         "qtsink", 0, "Qt Video Sink"));
+#define _do_init \
+    ret |= qt5_element_init (plugin);
+GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (qmlglsink, "qmlglsink",
+    GST_RANK_NONE, GST_TYPE_QT_SINK, _do_init);
 
 static void
 gst_qt_sink_class_init (GstQtSinkClass * klass)

ext/qt/gstqtsrc.cc

@@ -27,6 +27,7 @@
 #include "config.h"
 #endif
 
+#include "gstqtelements.h"
 #include "gstqtsrc.h"
 #include <QtGui/QGuiApplication>
 
@@ -76,6 +77,10 @@ enum
 G_DEFINE_TYPE_WITH_CODE (GstQtSrc, gst_qt_src,
     GST_TYPE_PUSH_SRC, GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT,
         "qtsrc", 0, "Qt Video Src"));
+#define _do_init \
+    ret |= qt5_element_init (plugin);
+GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (qmlglsrc, "qmlglsrc",
+    GST_RANK_NONE, GST_TYPE_QT_SRC, _do_init);
 
 static const gfloat vertical_flip_matrix[] = {
   1.0f, 0.0f, 0.0f, 0.0f,

ext/qt/meson.build

@@ -1,5 +1,6 @@
 sources = [
   'gstplugin.cc',
+  'gstqtelement.cc',
   'gstqsgtexture.cc',
   'gstqtglutility.cc',
   'gstqtoverlay.cc',

ext/qt/qtplugin.pro

@@ -79,6 +79,7 @@ versionAtLeast(QT_VERSION, "5.5") {
 
 SOURCES += \
     gstplugin.cc \
+    gstqtelement.cc \
     gstqtglutility.cc \
     gstqsgtexture.cc \
     gstqtoverlay.cc \
@@ -89,6 +90,7 @@ SOURCES += \
     qtitem.cc
 
 HEADERS += \
+	gstqtelements.h \
     gstqsgtexture.h \
     gstqtgl.h \
     gstqtglutility.h \