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Diffstat (limited to 'src/mbgl/style/expression/interpolate.cpp')
| -rw-r--r-- | src/mbgl/style/expression/interpolate.cpp | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/src/mbgl/style/expression/interpolate.cpp b/src/mbgl/style/expression/interpolate.cpp new file mode 100644 index 0000000000..5ddfca8e9f --- /dev/null +++ b/src/mbgl/style/expression/interpolate.cpp @@ -0,0 +1,211 @@ +#include <mbgl/style/expression/interpolate.hpp> +#include <mbgl/util/string.hpp> + +namespace mbgl { +namespace style { +namespace expression { + +using Interpolator = variant<ExponentialInterpolator, + CubicBezierInterpolator>; + +using namespace mbgl::style::conversion; + +ParseResult parseInterpolate(const Convertible& value, ParsingContext& ctx) { + assert(isArray(value)); + + auto length = arrayLength(value); + + if (length < 2) { + ctx.error("Expected an interpolation type expression."); + return ParseResult(); + } + + const Convertible& interp = arrayMember(value, 1); + if (!isArray(interp) || arrayLength(interp) == 0) { + ctx.error("Expected an interpolation type expression."); + return ParseResult(); + } + + optional<Interpolator> interpolator; + + const optional<std::string> interpName = toString(arrayMember(interp, 0)); + if (interpName && *interpName == "linear") { + interpolator = {ExponentialInterpolator(1.0)}; + } else if (interpName && *interpName == "exponential") { + optional<double> base; + if (arrayLength(interp) == 2) { + base = toDouble(arrayMember(interp, 1)); + } + if (!base) { + ctx.error("Exponential interpolation requires a numeric base.", 1, 1); + return ParseResult(); + } + interpolator = {ExponentialInterpolator(*base)}; + } else if (interpName && *interpName == "cubic-bezier") { + optional<double> x1; + optional<double> y1; + optional<double> x2; + optional<double> y2; + if (arrayLength(interp) == 5) { + x1 = toDouble(arrayMember(interp, 1)); + y1 = toDouble(arrayMember(interp, 2)); + x2 = toDouble(arrayMember(interp, 3)); + y2 = toDouble(arrayMember(interp, 4)); + } + if ( + !x1 || !y1 || !x2 || !y2 || + *x1 < 0 || *x1 > 1 || + *y1 < 0 || *y1 > 1 || + *x2 < 0 || *x2 > 1 || + *y2 < 0 || *y2 > 1 + ) { + ctx.error("Cubic bezier interpolation requires four numeric arguments with values between 0 and 1.", 1); + return ParseResult(); + + } + interpolator = {CubicBezierInterpolator(*x1, *y1, *x2, *y2)}; + } + + if (!interpolator) { + ctx.error("Unknown interpolation type " + (interpName ? *interpName : ""), 1, 0); + return ParseResult(); + } + + std::size_t minArgs = 4; + if (length - 1 < minArgs) { + ctx.error("Expected at least 4 arguments, but found only " + util::toString(length - 1) + "."); + return ParseResult(); + } + + // [interpolation, interp_type, input, 2 * (n pairs)...] + if ((length - 1) % 2 != 0) { + ctx.error("Expected an even number of arguments."); + return ParseResult(); + } + + ParseResult input = ctx.parse(arrayMember(value, 2), 2, {type::Number}); + if (!input) { + return input; + } + + std::map<double, std::unique_ptr<Expression>> stops; + optional<type::Type> outputType; + if (ctx.getExpected() && *ctx.getExpected() != type::Value) { + outputType = ctx.getExpected(); + } + + double previous = - std::numeric_limits<double>::infinity(); + + for (std::size_t i = 3; i + 1 < length; i += 2) { + const optional<mbgl::Value> labelValue = toValue(arrayMember(value, i)); + optional<double> label; + optional<std::string> labelError; + if (labelValue) { + labelValue->match( + [&](uint64_t n) { + if (n > std::numeric_limits<double>::max()) { + label = {std::numeric_limits<double>::infinity()}; + } else { + label = {static_cast<double>(n)}; + } + }, + [&](int64_t n) { + if (n > std::numeric_limits<double>::max()) { + label = {std::numeric_limits<double>::infinity()}; + } else { + label = {static_cast<double>(n)}; + } + }, + [&](double n) { + if (n > std::numeric_limits<double>::max()) { + label = {std::numeric_limits<double>::infinity()}; + } else { + label = {static_cast<double>(n)}; + } + }, + [&](const auto&) {} + ); + } + if (!label) { + ctx.error(labelError ? *labelError : + R"(Input/output pairs for "interpolate" expressions must be defined using literal numeric values (not computed expressions) for the input values.)", + i); + return ParseResult(); + } + + if (*label <= previous) { + ctx.error( + R"(Input/output pairs for "interpolate" expressions must be arranged with input values in strictly ascending order.)", + i + ); + return ParseResult(); + } + previous = *label; + + auto output = ctx.parse(arrayMember(value, i + 1), i + 1, outputType); + if (!output) { + return ParseResult(); + } + if (!outputType) { + outputType = (*output)->getType(); + } + + stops.emplace(*label, std::move(*output)); + } + + assert(outputType); + + if ( + *outputType != type::Number && + *outputType != type::Color && + !( + outputType->is<type::Array>() && + outputType->get<type::Array>().itemType == type::Number && + outputType->get<type::Array>().N + ) + ) + { + ctx.error("Type " + toString(*outputType) + " is not interpolatable."); + return ParseResult(); + } + + return outputType->match( + [&](const type::NumberType&) -> ParseResult { + return interpolator->match([&](const auto& interpolator_) { + return ParseResult(std::make_unique<Interpolate<double>>( + *outputType, interpolator_, std::move(*input), std::move(stops) + )); + }); + }, + [&](const type::ColorType&) -> ParseResult { + return interpolator->match([&](const auto& interpolator_) { + return ParseResult(std::make_unique<Interpolate<Color>>( + *outputType, interpolator_, std::move(*input), std::move(stops) + )); + }); + }, + [&](const type::Array& arrayType) -> ParseResult { + return interpolator->match( + [&](const auto& continuousInterpolator) { + if (arrayType.itemType != type::Number || !arrayType.N) { + assert(false); // interpolability already checked above. + return ParseResult(); + } + return ParseResult(std::make_unique<Interpolate<std::vector<Value>>>( + *outputType, continuousInterpolator, std::move(*input), std::move(stops) + )); + } + ); + }, + [&](const auto&) { + // unreachable: Null, Boolean, String, Object, Value output types + // are not interpolatable, and interpolability was already checked above + assert(false); + return ParseResult(); + } + ); +} + +} // namespace expression +} // namespace style +} // namespace mbgl |