glContext.h

//
// Copyright 2016 Pixar
//
// Licensed under the terms set forth in the LICENSE.txt file available at
// https://openusd.org/license.
//
#ifndef PXR_IMAGING_GLF_GL_CONTEXT_H
#define PXR_IMAGING_GLF_GL_CONTEXT_H
 
#include "pxr/pxr.h"
#include "pxr/imaging/glf/api.h"
#include "pxr/base/arch/threads.h"
 
#include <memory>
 
PXR_NAMESPACE_OPEN_SCOPE
 
 
typedef std::shared_ptr<class GlfGLContext> GlfGLContextSharedPtr;
 
class GlfGLContext
{
public:
    GLF_API
    virtual ~GlfGLContext();
 
    // Disallow copies
    GlfGLContext(const GlfGLContext&) = delete;
    GlfGLContext& operator=(const GlfGLContext&) = delete;
 
    GLF_API
    static GlfGLContextSharedPtr GetCurrentGLContext();
 
    GLF_API
    static GlfGLContextSharedPtr GetSharedGLContext();
 
    GLF_API
    static void MakeCurrent(const GlfGLContextSharedPtr& context);
 
    GLF_API
    static bool AreSharing(GlfGLContextSharedPtr const & context1,
                           GlfGLContextSharedPtr const & context2);
 
    GLF_API
    static bool IsInitialized();
 
    GLF_API
    bool IsCurrent() const;
 
private:
    void MakeCurrent();
 
public:
    GLF_API
    static void DoneCurrent();
 
    GLF_API
    bool IsSharing(GlfGLContextSharedPtr const & otherContext);
 
    virtual bool IsValid() const = 0;
 
    virtual GlfGLContextSharedPtr CreateSharingContext() {return nullptr;}
 
protected:
    GLF_API
    GlfGLContext();
 
    virtual void _MakeCurrent() = 0;
 
    virtual bool _IsSharing(const GlfGLContextSharedPtr& rhs) const = 0;
 
    virtual bool _IsEqual(const GlfGLContextSharedPtr& rhs) const = 0;
};
 
class GlfGLContextScopeHolder
{
public:
    GLF_API
    explicit GlfGLContextScopeHolder(const GlfGLContextSharedPtr& newContext);
 
    GLF_API
    ~GlfGLContextScopeHolder();
 
    GlfGLContextScopeHolder(const GlfGLContextScopeHolder&) = delete;
    GlfGLContextScopeHolder& operator=(const GlfGLContextScopeHolder) = delete;
 
protected:
    GLF_API
    void _MakeNewContextCurrent();
    GLF_API
    void _RestoreOldContext();
 
private:
    GlfGLContextSharedPtr _newContext;
    GlfGLContextSharedPtr _oldContext;
};
 
class GlfSharedGLContextScopeHolder final : private GlfGLContextScopeHolder
{
public:
    GlfSharedGLContextScopeHolder() :
        GlfGLContextScopeHolder(_GetSharedContext())
    {
        // Do nothing
    }
 
private:
    static GlfGLContextSharedPtr _GetSharedContext()
    {
        if (GlfGLContext::IsInitialized() && ArchIsMainThread()) {
            return GlfGLContext::GetSharedGLContext();
        }
        return GlfGLContextSharedPtr();
    }
};
 
#define API_GLF_HAS_ANY_GL_CONTEXT_SCOPE_HOLDER 1
 
class GlfAnyGLContextScopeHolder final : private GlfGLContextScopeHolder
{
public:
    GlfAnyGLContextScopeHolder() :
        GlfGLContextScopeHolder(_GetAnyContext())
    {
        // Do nothing
    }
 
private:
    static GlfGLContextSharedPtr _GetAnyContext()
    {
        if (GlfGLContext::IsInitialized() && ArchIsMainThread()) {
            GlfGLContextSharedPtr const current =
                GlfGLContext::GetCurrentGLContext();
            if (!(current &&
                  current->IsValid() &&
                  current->IsSharing(GlfGLContext::GetSharedGLContext()))) {
                return GlfGLContext::GetSharedGLContext();
            }
        }
        return GlfGLContextSharedPtr();
    }
};
 
class GlfGLContextRegistrationInterface
{
public:
    GLF_API
    virtual ~GlfGLContextRegistrationInterface();
 
    // Disallow copies
    GlfGLContextRegistrationInterface(
        const GlfGLContextRegistrationInterface&) = delete;
    GlfGLContextRegistrationInterface& operator=(
        const GlfGLContextRegistrationInterface&) = delete;
 
    virtual GlfGLContextSharedPtr GetShared() = 0;
 
    virtual GlfGLContextSharedPtr GetCurrent() = 0;
 
protected:
    GLF_API
    GlfGLContextRegistrationInterface();
};
 
 
PXR_NAMESPACE_CLOSE_SCOPE
 
#endif