65 lines
1.6 KiB
C++
65 lines
1.6 KiB
C++
#pragma once
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#include <mbgl/map/change.hpp>
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#include <memory>
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namespace mbgl {
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namespace gl {
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class Context;
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} // namespace gl
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class BackendScope;
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class Backend {
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public:
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Backend();
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virtual ~Backend();
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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 when the map needs to be rendered; the backend should call Map::render() at some point
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// in the near future. (Not called for Map::renderStill() mode.)
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virtual void invalidate() = 0;
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// Notifies a watcher of map x/y/scale/rotation changes.
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virtual void notifyMapChange(MapChange change);
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protected:
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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, in four situations:
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//
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// 1. When releasing GL resources during Map destruction
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// 2. When calling a CustomLayerInitializeFunction, during Map::addLayer
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// 3. When calling a CustomLayerDeinitializeFunction, during Map::removeLayer
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// 4. When rendering for Map::renderStill
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//
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// They are *not* called for Map::render; it is assumed that the correct context is already
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// activated prior to calling Map::render.
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virtual void activate() = 0;
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virtual void deactivate() = 0;
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private:
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const std::unique_ptr<gl::Context> context;
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friend class BackendScope;
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};
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class BackendScope {
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public:
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BackendScope(Backend& backend_) : backend(backend_) {
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backend.activate();
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}
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~BackendScope() {
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backend.deactivate();
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}
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private:
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Backend& backend;
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};
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} // namespace mbgl
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