renderer_backend.hpp

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#pragma once
 
#include <mbgl/util/util.hpp>
 
#include <memory>
#include <mutex>
 
namespace mbgl {
namespace gfx {
 
class Context;
class Renderable;
class BackendScope;
 
// We can make some optimizations if we know that the drawing context is not shared with other code.
enum class ContextMode : bool {
    Unique,
    Shared,
};
 
class RendererBackend {
protected:
    explicit RendererBackend(ContextMode);
 
public:
    virtual ~RendererBackend();
    RendererBackend(const RendererBackend&) = delete;
    RendererBackend& operator=(const RendererBackend&) = delete;
 
    Context& getContext();
 
    template <typename T>
    T& getContext() {
        return static_cast<T&>(getContext());
    }
 
    bool contextIsShared() const {
        return contextMode == ContextMode::Shared;
    }
 
    virtual Renderable& getDefaultRenderable() = 0;
 
protected:
    virtual std::unique_ptr<Context> createContext() = 0;
 
    virtual void activate() = 0;
    virtual void deactivate() = 0;
 
protected:
    std::unique_ptr<Context> context;
    const ContextMode contextMode;
    std::once_flag initialized;
 
    friend class BackendScope;
};
 
MBGL_CONSTEXPR bool operator==(const RendererBackend& a, const RendererBackend& b) {
    return &a == &b;
}
 
} // namespace gfx
} // namespace mbgl