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#pragma once
#include <mbgl/style/expression/expression.hpp>
#include <mbgl/style/expression/interpolate.hpp>
#include <mbgl/style/expression/step.hpp>
#include <mbgl/style/expression/find_zoom_curve.hpp>
#include <mbgl/style/expression/value.hpp>
#include <mbgl/style/expression/is_constant.hpp>
#include <mbgl/style/function/convert.hpp>
#include <mbgl/style/function/exponential_stops.hpp>
#include <mbgl/style/function/interval_stops.hpp>
#include <mbgl/util/interpolate.hpp>
#include <mbgl/util/variant.hpp>
namespace mbgl {
namespace style {
template <class T>
class CameraFunction {
public:
using Stops = std::conditional_t<
util::Interpolatable<T>::value,
variant<
ExponentialStops<T>,
IntervalStops<T>>,
variant<
IntervalStops<T>>>;
CameraFunction(std::unique_ptr<expression::Expression> expression_)
: expression(std::move(expression_)),
zoomCurve(expression::findZoomCurveChecked(expression.get()))
{
assert(!expression::isZoomConstant(*expression));
assert(expression::isFeatureConstant(*expression));
}
CameraFunction(Stops stops_)
: stops(std::move(stops_)),
expression(stops.match([&] (const auto& s) {
return expression::Convert::toExpression(s);
})),
zoomCurve(expression::findZoomCurveChecked(expression.get()))
{}
T evaluate(float zoom) const {
const expression::EvaluationResult result = expression->evaluate(expression::EvaluationContext(zoom, nullptr));
if (result) {
const optional<T> typed = expression::fromExpressionValue<T>(*result);
return typed ? *typed : T();
}
return T();
}
float interpolationFactor(const Range<float>& inputLevels, const float inputValue) const {
return zoomCurve.match(
[&](const expression::InterpolateBase* z) {
return z->interpolationFactor(Range<double> { inputLevels.min, inputLevels.max }, inputValue);
},
[&](const expression::Step*) { return 0.0f; }
);
}
Range<float> getCoveringStops(const float lower, const float upper) const {
return zoomCurve.match(
[&](auto z) { return z->getCoveringStops(lower, upper); }
);
}
friend bool operator==(const CameraFunction& lhs,
const CameraFunction& rhs) {
return *lhs.expression == *rhs.expression;
}
bool useIntegerZoom = false;
// retained for compatibility with pre-expression function API
Stops stops;
private:
std::shared_ptr<expression::Expression> expression;
const variant<const expression::InterpolateBase*, const expression::Step*> zoomCurve;
};
} // namespace style
} // namespace mbgl
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