From 5e1b1a5ba6a5e13ad6275852d3ff9b47fb8db85c Mon Sep 17 00:00:00 2001
From: Dan Paulat <dpaulat@gmail.com>
Date: Wed, 16 Aug 2023 00:15:08 -0500
Subject: [PATCH] Map distance helper function

---
 scwx-qt/source/scwx/qt/util/maplibre.cpp | 8 ++++++++
 scwx-qt/source/scwx/qt/util/maplibre.hpp | 4 ++++
 2 files changed, 12 insertions(+)

diff --git a/scwx-qt/source/scwx/qt/util/maplibre.cpp b/scwx-qt/source/scwx/qt/util/maplibre.cpp
index c2170425..5b3f331e 100644
--- a/scwx-qt/source/scwx/qt/util/maplibre.cpp
+++ b/scwx-qt/source/scwx/qt/util/maplibre.cpp
@@ -1,5 +1,6 @@
 #include <scwx/qt/util/maplibre.hpp>
 
+#include <QMapLibreGL/utils.hpp>
 #include <mbgl/util/constants.hpp>
 
 namespace scwx
@@ -11,6 +12,13 @@ namespace util
 namespace maplibre
 {
 
+boost::units::quantity<boost::units::si::length>
+GetMapDistance(const QMapLibreGL::CustomLayerRenderParameters& params)
+{
+   return QMapLibreGL::metersPerPixelAtLatitude(params.latitude, params.zoom) *
+          (params.width + params.height) / 2.0 * boost::units::si::meters;
+}
+
 glm::vec2 LatLongToScreenCoordinate(const QMapLibreGL::Coordinate& coordinate)
 {
    static constexpr double RAD2DEG_D = 180.0 / M_PI;
diff --git a/scwx-qt/source/scwx/qt/util/maplibre.hpp b/scwx-qt/source/scwx/qt/util/maplibre.hpp
index 03d548de..65aa4409 100644
--- a/scwx-qt/source/scwx/qt/util/maplibre.hpp
+++ b/scwx-qt/source/scwx/qt/util/maplibre.hpp
@@ -1,6 +1,8 @@
 #pragma once
 
 #include <QMapLibreGL/types.hpp>
+#include <boost/units/quantity.hpp>
+#include <boost/units/systems/si/length.hpp>
 #include <glm/gtc/type_ptr.hpp>
 
 namespace scwx
@@ -12,6 +14,8 @@ namespace util
 namespace maplibre
 {
 
+boost::units::quantity<boost::units::si::length>
+GetMapDistance(const QMapLibreGL::CustomLayerRenderParameters& params);
 glm::vec2 LatLongToScreenCoordinate(const QMapLibreGL::Coordinate& coordinate);
 
 } // namespace maplibre