QInteropWindow with QPA

[Meteorhead]

Quite a while ago I created a class called QInteropWindow which was inspired by QOpenGLWindow, but the class takes care of setting up OpenCL-GL interop. Because it has a few extra behaviors QOpenGLWindow does not, it inherits from QWindow.

class InteropWindow : public QWindow
{
    Q_OBJECT

public:

#ifdef _WIN32
    typedef QPair<HDC, HGLRC> gl_device;           // Windows-specific OpenGL device handles
#endif
#ifdef __linux__
    typedef QPair<Display*, GLXContext> gl_device; // Linux-specific OpenGL device handles
#endif

   ...
};

This is how the class starts because, I will need these two handles so I can pass them over to OpenCL when I create the context.

QVector<cl_context_properties> InteropWindow::interopCLcontextProps(const cl::Platform& plat)
{
    QVector<cl_context_properties> result;

    result.append(CL_CONTEXT_PLATFORM);
    result.append(reinterpret_cast<cl_context_properties>(plat()));
#ifdef _WIN32
    result.append(CL_WGL_HDC_KHR);
    result.append(reinterpret_cast<cl_context_properties>(m_gl_device.first));
    result.append(CL_GL_CONTEXT_KHR);
    result.append(reinterpret_cast<cl_context_properties>(m_gl_device.second));
#endif
#ifdef __linux__
    result.append(CL_GLX_DISPLAY_KHR);
    result.append(reinterpret_cast<cl_context_properties>(m_gl_device.first));
    result.append(CL_GL_CONTEXT_KHR);
    result.append(reinterpret_cast<cl_context_properties>(m_gl_device.second));
#endif
    result.append(0);

   return result;
}

My questions are:

• How can I get the include files for QPlatformOpenGLContext that does not have the Qt version in its path? It is really annoying to have to update the source files when I revisit a project with a different Qt version.

// Qt5 includes
#include <QtGui>
#include <QtGui/5.7.0/QtGui/qpa/qplatformnativeinterface.h>
#include <QtGui/5.7.0/QtGui/qpa/qplatformopenglcontext.h>

• How can I omit the platform native handle types? This would be the very reason I am using Qt in the first place? Ultimately I saw that Qt does not provide any typedefs for these entities. Is there a solution other than me doing it by hand?

• Can QPA provide the implementations to all of its internals? What module do I have to use? QPA is highly underdocumented. I get linker errors like the following when linking against Qt libs only. If even in the build scripts I have to take of platform specific linkage, plus have to take care of platform specific OpenGL usage, what is the purpose of QPlatformOpenGLContext really?

InteropWindow.cpp.obj : error LNK2019: unresolved external symbol __imp_wglGetCurrentContext referenced in function "private: struct QPair<struct HDC__ *,struct HGLRC__ *> __cdecl InteropWindow::nativeGLdevice(void)" (?nativeGLdevice@InteropWindow@@AEAA?AU?$QPair@PEAUHDC__@@PEAUHGLRC__@@@@XZ)
InteropWindow.cpp.obj : error LNK2019: unresolved external symbol __imp_wglGetCurrentDC referenced in function "private: struct QPair<struct HDC__ *,struct HGLRC__ *> __cdecl InteropWindow::nativeGLdevice(void)" (?nativeGLdevice@InteropWindow@@AEAA?AU?$QPair@PEAUHDC__@@PEAUHGLRC__@@@@XZ)

This is how my build script currently looks like:

cmake_minimum_required (VERSION 3.1)

project (Interop)

set (CMAKE_CXX_STANDARD 11)
set (CMAKE_AUTOMOC ON)

find_package (Qt5 5.7 CONFIG REQUIRED Gui OpenGL)
find_package (OpenCL 1.2 REQUIRED)

set (Sources)
set (Headers)
set (Kernels)
set (Shaders)

list (APPEND Sources src/Application.cpp src/InteropWindow.cpp)
list (APPEND Headers inc/Application.hpp inc/InteropWindow.hpp)
list (APPEND Kernels src/Interop_kernel.cl)
list (APPEND Shaders src/Interop_vertex.glsl src/Interop_fragment.glsl)

add_executable(${PROJECT_NAME} ${Sources} ${Headers} ${Kernels} ${Shaders})

target_include_directories (${PROJECT_NAME} PUBLIC ${PROJECT_SOURCE_DIR}/inc)
target_include_directories (${PROJECT_NAME} PUBLIC ${OpenCL_INCLUDE_DIRS})

target_link_libraries (${PROJECT_NAME} ${OpenCL_LIBRARIES})

qt5_use_modules (${PROJECT_NAME} Gui)
qt5_use_modules (${PROJECT_NAME} OpenGL)

if (CMAKE_CXX_COMPILER_ID MATCHES "MSVC")

#  target_compile_definitions (${PROJECT_NAME} PUBLIC "/EHsc")

  set (MSVC_CXX_COMPILER_FLAGS)
  set (MSVC_CXX_LINKER_FLAGS)
  
    # Enable C++ exception handler unwind semantics
    set (MSVC_CXX_COMPILER_FLAGS "${MSVC_CXX_COMPILER_FLAGS} /EHsc")
    # Disable warnings of having to use dllspec(__import) when using user libraries
    set (MSVC_CXX_COMPILER_FLAGS "${MSVC_CXX_COMPILER_FLAGS} /wd4251")
    # Disable warnings of cl.hpp for finding deprecated OpenCL 1.1 functions, even though they are never used
    set (MSVC_CXX_COMPILER_FLAGS "${MSVC_CXX_COMPILER_FLAGS} /wd4996")
  
    # Disable incremental linking and manifest files for annoying command line errors
    set (MSVC_CXX_LINKER_FLAGS " /INCREMENTAL:NO /MANIFEST:NO /NOLOGO ")
  
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${MSVC_CXX_COMPILER_FLAGS}")
	
  endif (CMAKE_CXX_COMPILER_ID MATCHES "MSVC")

[SGaist]

Hi,

I don't know if there are cmake files for that but IIRC qmake provides the private-qtmodulename to use private headers.

Note that I'm not sure that the qpa headers are provided through them.

Hope it helps