gstqmlgl: build on Windows with qmake without pkgconfig; update instructions on building for Windows

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/merge_requests/591>

ext/qt/README.md

@@ -48,3 +48,52 @@ make
 
 Copy the built plugin to your $GSTREAMER_ROOT/lib/gstreamer-1.0 or link to it
 directly if it is compiled statically
+
+# Building for Windows using pre-built gstreamer development package and Qt Creator 
+
+## Step 1
+
+Open `qtplugin.pro` in Qt Creator as project and configure it as usual. 
+
+## Step 2
+
+Open `qtplugin.pro` in the editor and make sure `GSTREAMER_PATH` 
+variable in `qmlplugin.pro` is set to the path of your gstreamer SDK installation. This directory 
+should contain subdirectories `bin`, `include`, `lib` etc. Pay attention to the correct choice 
+of x86 or x86_64 platform. 
+
+## Step 3
+
+Build the project as usual.
+
+## Step 3 
+
+Copy the built plugin to your $GSTREAMER_ROOT/lib/gstreamer-1.0 or link to it
+directly if it is compiled statically.
+
+# Building for Windows using pre-built gstreamer development package and Qt on MinGW command line 
+
+## Step 1 
+
+Launch Qt developer command line from the Start menu.
+
+## Step 2 
+
+cd to the directory of the gstqmlgl plugin and make sure `GSTREAMER_PATH` 
+variable in `qmlplugin.pro` is set to the path of your gstreamer SDK installation. This directory 
+should contain subdirectories `bin`, `include`, `lib` etc. Pay attention to the correct choice 
+of x86 or x86_64 platform. 
+
+## Step 3
+
+Run the following commands in the gstqmlgl plugin directory:
+
+```
+qmake 
+mingw32-make
+```
+
+## Step 4
+
+Copy the built plugin to your $GSTREAMER_ROOT/lib/gstreamer-1.0 or link to it
+directly if it is compiled statically.

ext/qt/qtplugin.pro

@@ -4,12 +4,63 @@ TARGET = gstqmlgl
 
 QT += qml quick gui
 
+win32:!defined(packagesExist, test) {
+    # Change this to your gstreamer SDK installation path
+    GSTREAMER_PATH=C:/gstreamer/1.0/x86
+
+    # pkgconfig dependencies: gstreamer-1.0, gstreamer-video-1.0, gstreamer-gl-1.0
+    
+    GSTREAMER_1_0_INCLUDEPATH = $${GSTREAMER_PATH}/include/gstreamer-1.0   
+    win32-g++:GSTREAMER_1_0_LIBS = -L$${GSTREAMER_PATH}/lib -lgstreamer-1.0
+    win32-msvc:GSTREAMER_1_0_LIBS = /LIBPATH:$${GSTREAMER_PATH}/lib gstreamer-1.0.lib
+    
+    GSTREAMER_VIDEO_1_0_INCLUDEPATH = $${GSTREAMER_PATH}/include/gstreamer-1.0
+    win32-g++:GSTREAMER_VIDEO_1_0_LIBS = -L$${GSTREAMER_PATH}/lib -lgstvideo-1.0
+    win32-msvc:GSTREAMER_VIDEO_1_0_LIBS = /LIBPATH:$${GSTREAMER_PATH}/lib gstvideo-1.0.lib
+
+    GSTREAMER_GL_1_0_INCLUDEPATH = $${GSTREAMER_PATH}/include \
+                                   $${GSTREAMER_PATH}/lib/gstreamer-1.0/include 
+    win32-g++:GSTREAMER_GL_1_0_LIBS = -L$${GSTREAMER_PATH}/lib -lgstgl-1.0
+    win32-msvc:GSTREAMER_GL_1_0_LIBS = /LIBPATH:$${GSTREAMER_PATH}/lib gstgl-1.0.lib
+    
+    # Extra dependencies: 
+    # glib-2.0, gobject-2.0 (required by gstreamer-1.0)
+    # gstreamer-base-1.0 (required by gstreamer-video-1.0)   
+    
+    GLIB_2_0_INCLUDEPATH = $${GSTREAMER_PATH}/include/glib-2.0 \
+                           $${GSTREAMER_PATH}/lib/glib-2.0/include
+    win32-g++:GLIB_2_0_LIBS = -L$${GSTREAMER_PATH}/lib -lglib-2.0 -lintl    
+    win32-msvc:GLIB_2_0_LIBS = /LIBPATH:$${GSTREAMER_PATH}/lib glib-2.0.lib intl.lib
+        
+    GOBJECT_2_0_INCLUDEPATH = $${GSTREAMER_PATH}/include
+    win32-g++:GOBJECT_2_0_LIBS = -L$${GSTREAMER_PATH}/lib -lgobject-2.0
+    win32-msvc:GOBJECT_2_0_LIBS = /LIBPATH:$${GSTREAMER_PATH}/lib gobject-2.0.lib
+    
+    GSTREAMER_BASE_1_0_INCLUDEPATH = $${GSTREAMER_PATH}/include/gstreamer-1.0
+    win32-g++:GSTREAMER_BASE_1_0_LIBS = -L$${GSTREAMER_PATH}/lib -lgstbase-1.0
+    win32-msvc:GSTREAMER_BASE_1_0_LIBS = /LIBPATH:$${GSTREAMER_PATH}/lib gstbase-1.0.lib
+    
+    INCLUDEPATH += $${GSTREAMER_1_0_INCLUDEPATH} \
+                   $${GSTREAMER_VIDEO_1_0_INCLUDEPATH} \
+                   $${GSTREAMER_GL_1_0_INCLUDEPATH} \
+                   $${GLIB_2_0_INCLUDEPATH} \
+                   $${GOBJECT_2_0_INCLUDEPATH} \
+                   $${GSTREAMER_BASE_1_0_INCLUDEPATH}
+    
+    LIBS += $${GSTREAMER_1_0_LIBS} \
+            $${GSTREAMER_VIDEO_1_0_LIBS} \
+            $${GSTREAMER_GL_1_0_LIBS} \
+            $${GLIB_2_0_LIBS} \
+            $${GOBJECT_2_0_LIBS} \
+            $${GSTREAMER_BASE_1_0_LIBS}
+} else {
     QT_CONFIG -= no-pkg-config
     CONFIG += link_pkgconfig debug
     PKGCONFIG = \
         gstreamer-1.0 \
         gstreamer-video-1.0 \
         gstreamer-gl-1.0
+}
 
 android {
     CONFIG += static
@@ -30,8 +81,10 @@ SOURCES += \
     gstplugin.cc \
     gstqtglutility.cc \
     gstqsgtexture.cc \
+    gstqtoverlay.cc \
     gstqtsink.cc \
     gstqtsrc.cc \
+    qtglrenderer.cc \
     qtwindow.cc \
     qtitem.cc
 
@@ -39,7 +92,9 @@ HEADERS += \
     gstqsgtexture.h \
     gstqtgl.h \
     gstqtglutility.h \
+    gstqtoverlay.h \
     gstqtsink.h \
     gstqtsrc.h \
+    qtglrenderer.h \
     qtwindow.h \
     qtitem.h