099fcc3b3c
Use a host interface for CustomLayer instead of function pointers Co-authored-by: Julian Rex <julian.rex@mapbox.com>
93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
#pragma once
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#include <mbgl/renderer/backend_scope.hpp>
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#include <mbgl/util/image.hpp>
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#include <mbgl/util/size.hpp>
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#include <mbgl/util/util.hpp>
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#include <memory>
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#include <mutex>
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namespace mbgl {
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namespace gl {
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class Context;
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using ProcAddress = void (*)();
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using FramebufferID = uint32_t;
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} // namespace gl
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// The RendererBackend is used by the Renderer to facilitate
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// the actual rendering.
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class RendererBackend {
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public:
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RendererBackend();
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virtual ~RendererBackend();
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// Returns the backend's context which manages OpenGL state.
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gl::Context& getContext();
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// Called prior to rendering to update the internally assumed OpenGL state.
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virtual void updateAssumedState() = 0;
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// Called when this backend is used for rendering. Implementations should ensure that a renderable
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// object is bound and glClear/glDraw* calls can be done. They should also make sure that
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// calling .bind() repeatedly is a no-op and that the appropriate gl::Context values are
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// set to the current state.
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virtual void bind() = 0;
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virtual Size getFramebufferSize() const = 0;
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protected:
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// Called with the name of an OpenGL extension that should be loaded. RendererBackend implementations
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// must call the API-specific version that obtains the function pointer for this function,
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// or a null pointer if unsupported/unavailable.
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virtual gl::ProcAddress getExtensionFunctionPointer(const char*) = 0;
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// Called when the backend's GL context needs to be made active or inactive. These are called,
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// as a matched pair, exclusively through BackendScope, in two situations:
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//
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// 1. When releasing GL resources during Renderer destruction
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// (Including calling CustomLayerHost::deinitialize during RenderCustomLayer destruction)
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// 2. When renderering through Renderer::render()
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// (Including calling CustomLayerHost::initialize for newly added custom layers and
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// CustomLayerHost::deinitialize on layer removal)
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virtual void activate() = 0;
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virtual void deactivate() = 0;
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// Reads the color pixel data from the currently bound framebuffer.
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PremultipliedImage readFramebuffer(const Size&) const;
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// A constant to signal that a framebuffer is bound, but with an unknown ID.
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static constexpr const gl::FramebufferID ImplicitFramebufferBinding =
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std::numeric_limits<gl::FramebufferID>::max();
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// Tells the renderer that OpenGL state has already been set by the windowing toolkit.
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// It sets the internal assumed state to the supplied values.
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void assumeFramebufferBinding(gl::FramebufferID fbo);
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void assumeViewport(int32_t x, int32_t y, const Size&);
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void assumeScissorTest(bool);
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// Returns true when assumed framebuffer binding hasn't changed from the implicit binding.
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bool implicitFramebufferBound();
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// Triggers an OpenGL state update if the internal assumed state doesn't match the
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// supplied values.
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void setFramebufferBinding(gl::FramebufferID fbo);
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void setViewport(int32_t x, int32_t y, const Size&);
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void setScissorTest(bool);
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protected:
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std::unique_ptr<gl::Context> context;
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private:
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std::once_flag initialized;
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friend class BackendScope;
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};
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MBGL_CONSTEXPR bool operator==(const RendererBackend& a, const RendererBackend& b) {
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return &a == &b;
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}
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} // namespace mbgl
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