From 87b735aaf71557b157a092a8025e6126ed2d8611 Mon Sep 17 00:00:00 2001
From: Ivo van Dongen <info@ivovandongen.nl>
Date: Mon, 9 Oct 2017 16:49:29 +0300
Subject: [default] map snapshotter - add function to get screen coordinate
 from latlng for snapshot

- Wraps the TransformState for the snapshot so that the snapshotter itself is free to be re-used or destroyed
---
 platform/default/mbgl/map/map_snapshotter.cpp | 21 ++++++++++++++++++++-
 platform/default/mbgl/map/map_snapshotter.hpp |  4 +++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/platform/default/mbgl/map/map_snapshotter.cpp b/platform/default/mbgl/map/map_snapshotter.cpp
index e542e2fb54..3e930c31f1 100644
--- a/platform/default/mbgl/map/map_snapshotter.cpp
+++ b/platform/default/mbgl/map/map_snapshotter.cpp
@@ -3,9 +3,11 @@
 #include <mbgl/actor/actor_ref.hpp>
 #include <mbgl/gl/headless_frontend.hpp>
 #include <mbgl/map/map.hpp>
+#include <mbgl/map/transform_state.hpp>
 #include <mbgl/storage/file_source.hpp>
 #include <mbgl/style/style.hpp>
 #include <mbgl/util/event.hpp>
+#include <mbgl/map/transform.hpp>
 
 namespace mbgl {
 
@@ -62,7 +64,24 @@ MapSnapshotter::Impl::Impl(FileSource& fileSource,
 
 void MapSnapshotter::Impl::snapshot(ActorRef<MapSnapshotter::Callback> callback) {
     map.renderStill([this, callback = std::move(callback)] (std::exception_ptr error) mutable {
-        callback.invoke(&MapSnapshotter::Callback::operator(), error, error ? PremultipliedImage() : frontend.readStillImage());
+
+        // Create lambda that captures the current transform state
+        // and can be used to translate for geographic to screen
+        // coordinates
+        assert (frontend.getTransformState());
+        PointForFn pointForFn { [=, center=map.getLatLng(), transformState = *frontend.getTransformState()] (const LatLng& latLng) {
+            LatLng unwrappedLatLng = latLng.wrapped();
+            unwrappedLatLng.unwrapForShortestPath(center);
+            Transform transform { transformState };
+            return transform.latLngToScreenCoordinate(unwrappedLatLng);
+        }};
+
+        callback.invoke(
+                &MapSnapshotter::Callback::operator(),
+                error,
+                error ? PremultipliedImage() : frontend.readStillImage(),
+                std::move(pointForFn)
+        );
     });
 }
 
diff --git a/platform/default/mbgl/map/map_snapshotter.hpp b/platform/default/mbgl/map/map_snapshotter.hpp
index 2450fa7612..b3cfb3058f 100644
--- a/platform/default/mbgl/map/map_snapshotter.hpp
+++ b/platform/default/mbgl/map/map_snapshotter.hpp
@@ -3,6 +3,7 @@
 #include <mbgl/util/image.hpp>
 #include <mbgl/util/thread.hpp>
 #include <mbgl/util/optional.hpp>
+#include <mbgl/util/geo.hpp>
 
 #include <exception>
 #include <memory>
@@ -46,7 +47,8 @@ public:
     void setRegion(const LatLngBounds&);
     LatLngBounds getRegion() const;
 
-    using Callback = std::function<void (std::exception_ptr, PremultipliedImage)>;
+    using PointForFn = std::function<ScreenCoordinate (const LatLng&)>;
+    using Callback = std::function<void (std::exception_ptr, PremultipliedImage, PointForFn)>;
     void snapshot(ActorRef<Callback>);
 
 private:
-- 
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