From 0b201f75a75b26516e3c12d38ab72b75de2ef830 Mon Sep 17 00:00:00 2001
From: Asheem Mamoowala <asheem.mamoowala@mapbox.com>
Date: Tue, 26 Jun 2018 15:51:49 -0700
Subject: init

---
 platform/qt/include/qmapboxgl.hpp |  2 +-
 platform/qt/src/qmapboxgl.cpp     | 75 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/platform/qt/include/qmapboxgl.hpp b/platform/qt/include/qmapboxgl.hpp
index ac143066e3..a699b77cec 100644
--- a/platform/qt/include/qmapboxgl.hpp
+++ b/platform/qt/include/qmapboxgl.hpp
@@ -239,7 +239,7 @@ public:
     QList<QString> layerIds() const;
 
     void setFilter(const QString &layer, const QVariant &filter);
-
+    QVariant getFilter(const QString &layer) const;
     // When rendering on a different thread,
     // should be called on the render thread.
     void createRenderer();
diff --git a/platform/qt/src/qmapboxgl.cpp b/platform/qt/src/qmapboxgl.cpp
index 581a1c4111..c15d8654b5 100644
--- a/platform/qt/src/qmapboxgl.cpp
+++ b/platform/qt/src/qmapboxgl.cpp
@@ -55,6 +55,10 @@
 #include <QString>
 #include <QStringList>
 #include <QThreadStorage>
+#include <QVariant>
+#include <QVariantList>
+#include <QVariantMap>
+#include <QColor>
 
 #include <memory>
 
@@ -1572,6 +1576,77 @@ void QMapboxGL::setFilter(const QString& layer, const QVariant& filter)
     qWarning() << "Layer doesn't support filters";
 }
 
+QVariant QVariantFromValue(const mbgl::Value &value) {
+    return value.match(
+        [](const mbgl::NullValue) {
+            return QVariant();
+        }, [](const bool value) {
+            return QVariant(value);
+        }, [](const float value) {
+            return QVariant(value);
+        }, [](const int64_t value) {
+            return QVariant(value);
+        }, [](const double value) {
+            return QVariant(value);
+        }, [](const std::string &value) {
+           return QVariant(value.c_str());
+        }, [](const mbgl::Color &value) {
+            return QColor(value.r, value.g, value.b, value.a);
+        }, [&](const std::vector<mbgl::Value> &vector) {
+            QVariantList list;
+            list.reserve(vector.size());
+            for (auto &value : vector) {
+                list.append(QVariantFromValue(value));
+            }
+            return list;
+        }, [&](const std::unordered_map<std::string, mbgl::Value> &map) {
+            QVariantMap varMap;
+            for (auto &item : map) {
+                varMap.insert(item.first.c_str(), QVariantFromValue(item.second));
+            }
+            return varMap;
+        }, [](const auto &) {
+            return QVariant();
+        });
+}
+
+QVariant QMapboxGL::getFilter(const QString &layer)  const {
+    using namespace mbgl::style;
+    using namespace mbgl::style::conversion;
+
+    Layer* layer_ = d_ptr->mapObj->getStyle().getLayer(layer.toStdString());
+    if (!layer_) {
+        qWarning() << "Layer not found:" << layer;
+        return QVariant();
+    }
+
+    Filter filter_;
+
+    if (layer_->is<FillLayer>()) {
+        filter_ = layer_->as<FillLayer>()->getFilter();
+    } else if (layer_->is<LineLayer>()) {
+        filter_ = layer_->as<LineLayer>()->getFilter();
+    } else if (layer_->is<SymbolLayer>()) {
+        filter_ = layer_->as<SymbolLayer>()->getFilter();
+    } else if (layer_->is<CircleLayer>()) {
+        filter_ = layer_->as<CircleLayer>()->getFilter();
+    } else if (layer_->is<FillExtrusionLayer>()) {
+        filter_ = layer_->as<FillExtrusionLayer>()->getFilter();
+    } else {
+        qWarning() << "Layer doesn't support filters";
+        return QVariant();
+    }
+
+    if (!filter_.expression) {
+        qWarning() << "getFilter only supports expression-based filters";
+        return QVariant();
+    }
+
+    auto serialized = (**filter_.expression).serialize();
+    return QVariantFromValue(serialized);
+
+
+}
 /*!
     Creates the infrastructure needed for rendering the map. It
     should be called before any call to render().
-- 
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