[Qt] Added conversion functions for the runtime style API

platform/qt/src/qmapboxgl.cpp

@@ -1,5 +1,7 @@
 #include "qmapboxgl_p.hpp"
 
+#include "qt_conversion.hpp"
+
 #include <mbgl/annotation/annotation.hpp>
 #include <mbgl/gl/gl.hpp>
 #include <mbgl/map/camera.hpp>

platform/qt/src/qt_conversion.hpp

@@ -0,0 +1,106 @@
+#pragma once
+
+#include <mbgl/style/conversion.hpp>
+#include <mbgl/util/feature.hpp>
+#include <mbgl/util/optional.hpp>
+
+#include <QColor>
+#include <QVariant>
+
+namespace mbgl {
+namespace style {
+namespace conversion {
+
+inline bool isUndefined(const QVariant& value) {
+    return value.isNull() || !value.isValid();
+}
+
+inline bool isArray(const QVariant& value) {
+    return value.canConvert(QVariant::List);
+}
+
+inline std::size_t arrayLength(const QVariant& value) {
+    return value.toList().size();
+}
+
+inline QVariant arrayMember(const QVariant& value, std::size_t i) {
+    return value.toList()[i];
+}
+
+inline bool isObject(const QVariant& value) {
+    return value.canConvert(QVariant::Map);
+}
+
+inline optional<QVariant> objectMember(const QVariant& value, const char* key) {
+    auto map = value.toMap();
+    auto iter = map.constFind(key);
+
+    if (iter != map.constEnd()) {
+        return iter.value();
+    } else {
+        return {};
+    }
+}
+
+template <class Fn>
+optional<Error> eachMember(const QVariant& value, Fn&& fn) {
+    auto map = value.toMap();
+    auto iter = map.constBegin();
+
+    while (iter != map.constEnd()) {
+        optional<Error> result = fn(iter.key().toStdString(), iter.value());
+        if (result) {
+            return result;
+        }
+
+        ++iter;
+    }
+
+    return {};
+}
+
+inline optional<bool> toBool(const QVariant& value) {
+    if (value.type() == QVariant::Bool) {
+        return value.toBool();
+    } else {
+        return {};
+    }
+}
+
+inline optional<float> toNumber(const QVariant& value) {
+    if (value.type() == QVariant::Double) {
+        return value.toFloat();
+    } else {
+        return {};
+    }
+}
+
+inline optional<std::string> toString(const QVariant& value) {
+    if (value.type() == QVariant::String) {
+        return value.toString().toStdString();
+    } else if (value.type() == QVariant::Color) {
+        return value.value<QColor>().name().toStdString();
+    } else {
+        return {};
+    }
+}
+
+inline optional<Value> toValue(const QVariant& value) {
+    if (value.type() == QVariant::Bool) {
+        return { value.toBool() };
+    } else if (value.type() == QVariant::String) {
+        return { value.toString().toStdString() };
+    } else if (value.type() == QVariant::Color) {
+        return { value.value<QColor>().name().toStdString() };
+    } else if (value.type() == QVariant::Int) {
+        return { value.toInt() };
+    } else if (value.canConvert(QVariant::Double)) {
+        return { value.toFloat() };
+    } else {
+        return {};
+    }
+}
+
+} // namespace conversion
+} // namespace style
+} // namespace mbgl