[glfw] Add feature state support

platform/glfw/glfw_view.cpp

@@ -6,10 +6,12 @@
 #include <mbgl/annotation/annotation.hpp>
 #include <mbgl/style/style.hpp>
 #include <mbgl/style/sources/custom_geometry_source.hpp>
+#include <mbgl/style/sources/geojson_source.hpp>
 #include <mbgl/style/image.hpp>
 #include <mbgl/style/transition_options.hpp>
 #include <mbgl/style/layers/fill_extrusion_layer.hpp>
 #include <mbgl/style/layers/line_layer.hpp>
+#include <mbgl/style/layers/fill_layer.hpp>
 #include <mbgl/style/expression/dsl.hpp>
 #include <mbgl/util/logging.hpp>
 #include <mbgl/util/platform.hpp>
@@ -323,6 +325,48 @@ void GLFWView::onKey(GLFWwindow *window, int key, int /*scancode*/, int action,
         case GLFW_KEY_T:
             view->toggleCustomSource();
             break;
+        case GLFW_KEY_F: {
+            using namespace mbgl;
+            using namespace mbgl::style;
+            using namespace mbgl::style::expression::dsl;
+
+            auto& style = view->map->getStyle();
+            if (!style.getSource("states")) {
+                std::string url = "https://docs.mapbox.com/mapbox-gl-js/assets/us_states.geojson";
+                auto source = std::make_unique<GeoJSONSource>("states");
+                source->setURL(url);
+                style.addSource(std::move(source));
+
+                mbgl::CameraOptions cameraOptions;
+                cameraOptions.center = mbgl::LatLng { 42.619626, -103.523181 };
+                cameraOptions.zoom = 3;
+                cameraOptions.pitch = 0;
+                cameraOptions.bearing = 0;
+                view->map->jumpTo(cameraOptions);
+            }
+
+            auto layer = style.getLayer("state-fills");
+            if (!layer) {
+                auto fillLayer = std::make_unique<FillLayer>("state-fills", "states");
+                fillLayer->setFillColor(mbgl::Color{ 0.0, 0.0, 1.0, 0.5 });
+                fillLayer->setFillOpacity(PropertyExpression<float>(createExpression(R"(["case", ["boolean", ["feature-state", "hover"], false], 1, 0.5])")));
+                style.addLayer(std::move(fillLayer));
+            } else {
+                layer->setVisibility(layer->getVisibility() == mbgl::style::VisibilityType::Visible ?
+                                     mbgl::style::VisibilityType::None : mbgl::style::VisibilityType::Visible);
+            }
+
+            layer = style.getLayer("state-borders");
+            if (!layer) {
+                auto borderLayer = std::make_unique<LineLayer>("state-borders", "states");
+                borderLayer->setLineColor(mbgl::Color{ 0.0, 0.0, 1.0, 1.0 });
+                borderLayer->setLineWidth(PropertyExpression<float>(createExpression(R"(["case", ["boolean", ["feature-state", "hover"], false], 2, 1])")));
+                style.addLayer(std::move(borderLayer));
+            } else {
+                layer->setVisibility(layer->getVisibility() == mbgl::style::VisibilityType::Visible ?
+                                     mbgl::style::VisibilityType::None : mbgl::style::VisibilityType::Visible);
+            }
+        } break;
         }
     }
 
@@ -537,6 +581,7 @@ void GLFWView::onMouseClick(GLFWwindow *window, int button, int action, int modi
             }
             view->lastClick = now;
         }
+
     }
 }
 
@@ -558,6 +603,41 @@ void GLFWView::onMouseMove(GLFWwindow *window, double x, double y) {
     }
     view->lastX = x;
     view->lastY = y;
+
+    auto& style = view->map->getStyle();
+    if (style.getLayer("state-fills")) {
+        auto screenCoordinate = mbgl::ScreenCoordinate { view->lastX, view->lastY };
+        const mbgl::RenderedQueryOptions queryOptions({{{ "state-fills" }}, {}});
+        auto result = view->rendererFrontend->getRenderer()->queryRenderedFeatures(screenCoordinate, queryOptions);
+        using namespace mbgl;
+        FeatureState newState;
+
+        if (result.size() > 0) {
+            FeatureIdentifier id = result[0].id;
+            optional<std::string> idStr = featureIDtoString(id);
+
+            if (idStr) {
+                if (view->featureID && (*view->featureID != *idStr)) {
+                    newState["hover"] = false;
+                    view->rendererFrontend->getRenderer()->setFeatureState("states", { }, *view->featureID, newState);
+                    view->featureID = nullopt;
+                }
+
+                if (!view->featureID) {
+                    newState["hover"] = true;
+                    view->featureID = featureIDtoString(id);
+                    view->rendererFrontend->getRenderer()->setFeatureState("states", { }, *view->featureID, newState);
+                }
+            }
+        } else {
+            if (view->featureID) {
+                newState["hover"] = false;
+                view->rendererFrontend->getRenderer()->setFeatureState("states", { }, *view->featureID, newState);
+                view->featureID = nullopt;
+            }
+        }
+        view->invalidate();
+    }
 }
 
 void GLFWView::onWindowFocus(GLFWwindow *window, int focused) {

platform/glfw/glfw_view.hpp

@@ -4,6 +4,7 @@
 #include <mbgl/util/run_loop.hpp>
 #include <mbgl/util/timer.hpp>
 #include <mbgl/util/geometry.hpp>
+#include <mbgl/util/optional.hpp>
 
 struct GLFWwindow;
 class GLFWBackend;
@@ -134,4 +135,5 @@ private:
 
     GLFWwindow *window = nullptr;
     bool dirty = false;
+    mbgl::optional<std::string> featureID;
 };