Introduce platform API abstraction for QOpenGLContext

The API is available by including qopenglcontext.h as usual,
but scoped in the QPlatformInterface namespace. The namespace
exposes platform specific type-safe interfaces that provide:

 a) Factory functions for adopting native contexts, e.g.

    QCocoaGLContext::fromNative(nsContext, shareContext);

 b) Access to underlying native handles, e.g.

    openGLContext->platformInterface<QCocoaGLContext>->nativeContext()

 c) Platform specific functionality, e.g.

    static QWGLContext::openGLModuleHandle()

    openGLContext->platformInterface<QEGLContext>->doSomething();

The platform interfaces live close to the classes they extend,
removing the need for complex indirection and plumbing, and
avoids kitchen-sink modules and APIs such as the extras modules,
QPlatformFunctions, or QPlatformNativeInterface.

In the case of QOpenGLContext these platform APIs are backed
by the platform plugin, so dynamic_cast is used to ensure the
platform plugin supports the requested interface, but this is
and implementation detail. The interface APIs are agnostic
to where the implementation lives, while still being available
to the user as part of the APIs they extend/augment.

The documentation will be restored when the dust settles.

Task-number: QTBUG-80233
Change-Id: Iac612403383991c4b24064332542a6e4bcbb3293
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 5 insertions, 2 deletions

diff --git a/src/plugins/platforms/windows/qwindowsglcontext.h b/src/plugins/platforms/windows/qwindowsglcontext.h
index 608cc9cfea..2970f3d333 100644
--- a/src/plugins/platforms/windows/qwindowsglcontext.h
+++ b/src/plugins/platforms/windows/qwindowsglcontext.h
@@ -174,6 +174,7 @@ public:
     static QByteArray getGlString(unsigned int which);
 
     QWindowsOpenGLContext *createContext(QOpenGLContext *context) override;
+    QWindowsOpenGLContext *createContext(HGLRC context, HWND window) override;
     void *moduleHandle() const override { return opengl32.moduleHandle(); }
     QOpenGLContext::OpenGLModuleType moduleType() const override
     { return QOpenGLContext::LibGL; }
@@ -199,10 +200,12 @@ public:
     static QWindowsOpengl32DLL opengl32;
 };
 
-class QWindowsGLContext : public QWindowsOpenGLContext
+class QWindowsGLContext : public QWindowsOpenGLContext, public QPlatformInterface::QWGLContext
 {
 public:
     explicit QWindowsGLContext(QOpenGLStaticContext *staticContext, QOpenGLContext *context);
+    explicit QWindowsGLContext(QOpenGLStaticContext *staticContext, HGLRC context, HWND window);
+
     ~QWindowsGLContext() override;
     bool isSharing() const override { return context()->shareHandle(); }
     bool isValid() const override { return m_renderingContext && !m_lost; }
@@ -219,7 +222,7 @@ public:
 
     HGLRC renderingContext() const { return m_renderingContext; }
 
-    void *nativeContext() const override { return m_renderingContext; }
+    HGLRC nativeContext() const override { return m_renderingContext; }
 
 private:
     typedef GLenum (APIENTRY *GlGetGraphicsResetStatusArbType)();