glContext.h

//
// Copyright 2016 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache 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