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#pragma once
#include <mbgl/util/noncopyable.hpp>
#include <mbgl/util/any.hpp>
#include <mbgl/util/immutable.hpp>
#include <mbgl/style/layer_type.hpp>
#include <mbgl/style/types.hpp>
#include <cassert>
#include <memory>
#include <string>
#include <stdexcept>
namespace mbgl {
namespace style {
class FillLayer;
class LineLayer;
class CircleLayer;
class SymbolLayer;
class RasterLayer;
class BackgroundLayer;
class CustomLayer;
class FillExtrusionLayer;
class LayerObserver;
/**
* The runtime representation of a [layer](https://www.mapbox.com/mapbox-gl-style-spec/#layers) from the Mapbox Style
* Specification.
*
* `Layer` is an abstract base class; concrete derived classes are provided for each layer type. `Layer` contains
* functionality that is common to all layer types:
*
* * Runtime type information: type predicates and casting
* * Accessors for properties common to all layer types: ID, visibility, etc.
* * Cloning and copying
*
* All other functionality lives in the derived classes. To instantiate a layer, create an instance of the desired
* type, passing the ID:
*
* auto circleLayer = std::make_unique<CircleLayer>("my-circle-layer");
*/
class Layer : public mbgl::util::noncopyable {
public:
virtual ~Layer();
// Check whether this layer is of the given subtype.
template <class T>
bool is() const;
// Dynamically cast this layer to the given subtype.
template <class T>
T* as() {
return is<T>() ? reinterpret_cast<T*>(this) : nullptr;
}
template <class T>
const T* as() const {
return is<T>() ? reinterpret_cast<const T*>(this) : nullptr;
}
// Convenience method for dynamic dispatch on the concrete layer type. Using
// method overloading, this allows consolidation of logic common to vector-based
// layers (Fill, FillExtrusion, Line, Circle, or Symbol). For example:
//
// struct Visitor {
// void operator()(CustomLayer&) { ... }
// void operator()(RasterLayer&) { ... }
// void operator()(BackgroundLayer&) { ... }
// template <class VectorLayer>
// void operator()(VectorLayer&) { ... }
// };
//
template <class V>
auto accept(V&& visitor) {
switch (getType()) {
case LayerType::Fill:
return std::forward<V>(visitor)(*as<FillLayer>());
case LayerType::Line:
return std::forward<V>(visitor)(*as<LineLayer>());
case LayerType::Circle:
return std::forward<V>(visitor)(*as<CircleLayer>());
case LayerType::Symbol:
return std::forward<V>(visitor)(*as<SymbolLayer>());
case LayerType::Raster:
return std::forward<V>(visitor)(*as<RasterLayer>());
case LayerType::Background:
return std::forward<V>(visitor)(*as<BackgroundLayer>());
case LayerType::Custom:
return std::forward<V>(visitor)(*as<CustomLayer>());
case LayerType::FillExtrusion:
return std::forward<V>(visitor)(*as<FillExtrusionLayer>());
}
// Not reachable, but placate GCC.
assert(false);
throw new std::runtime_error("unknown layer type");
}
LayerType getType() const;
std::string getID() const;
// Visibility
VisibilityType getVisibility() const;
virtual void setVisibility(VisibilityType) = 0;
// Zoom range
float getMinZoom() const;
float getMaxZoom() const;
virtual void setMinZoom(float) = 0;
virtual void setMaxZoom(float) = 0;
// Private implementation
class Impl;
Immutable<Impl> baseImpl;
Layer(Immutable<Impl>);
// Create a layer, copying all properties except id and paint properties from this layer.
virtual std::unique_ptr<Layer> cloneRef(const std::string& id) const = 0;
LayerObserver* observer = nullptr;
void setObserver(LayerObserver*);
// For use in SDK bindings, which store a reference to a platform-native peer
// object here, so that separately-obtained references to this object share
// identical platform-native peers.
any peer;
};
} // namespace style
} // namespace mbgl
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