Support proj versions >= 8 (#167)

Co-authored-by: Jim Minter <[email protected]>

src/goesproc/map_drawer.cc

@@ -36,8 +36,8 @@ void MapDrawer::generatePoints(
   double lat, lon;
   double x, y;
   for (const auto& coord : coords) {
-    lon = coord.at(0).get<double>() * DEG_TO_RAD;
-    lat = coord.at(1).get<double>() * DEG_TO_RAD;
+    lon = proj_torad(coord.at(0).get<double>());
+    lat = proj_torad(coord.at(1).get<double>());
     std::tie(x, y) = proj_.fwd(lon, lat);
 
     // If out of range, ignore

src/goesproc/proj.cc

@@ -5,8 +5,7 @@
 
 namespace {
 
-std::vector<std::string> toVector(
-  const std::map<std::string, std::string>& args) {
+std::vector<std::string> toVector(const std::map<std::string, std::string>& args) {
   std::vector<std::string> vargs;
   vargs.reserve(args.size());
   for (const auto& arg : args) {
@@ -17,6 +16,12 @@ std::vector<std::string> toVector(
   return vargs;
 }
 
+}
+
+#if PROJ_VERSION_MAJOR == 4
+
+namespace {
+
 std::string pj_error(std::string prefix = "proj: ") {
   std::stringstream ss;
   ss << prefix << pj_strerrno(pj_errno);
@@ -25,6 +30,11 @@ std::string pj_error(std::string prefix = "proj: ") {
 
 } // namespace
 
+// Forward compatibility.
+double proj_torad (double angle_in_degrees) {
+  return angle_in_degrees * DEG_TO_RAD;
+}
+
 Proj::Proj(const std::vector<std::string>& args) {
   std::vector<char*> argv;
   for (const auto& arg : args) {
@@ -58,3 +68,58 @@ std::tuple<double, double> Proj::inv(double x, double y) {
   projUV out = pj_inv(in, proj_);
   return std::make_tuple<double, double>(std::move(out.u), std::move(out.v));
 }
+
+#elif PROJ_VERSION_MAJOR >= 5
+
+namespace {
+
+std::string toString(const std::vector<std::string>& vargs) {
+  std::stringstream ss;
+  for (auto it = vargs.begin(); it != vargs.end(); it++) {
+    ss << "+" << *it;
+    if (std::next(it) != std::end(vargs)) {
+      ss << " ";
+    }
+  }
+  return ss.str();
+}
+
+std::string pj_error(std::string prefix = "proj: ") {
+  std::stringstream ss;
+  ss << prefix << proj_errno_string(proj_errno(NULL));
+  return ss.str();
+}
+
+} // namespace
+
+Proj::Proj(const std::vector<std::string>& vargs) {
+  const auto args = toString(vargs);
+  proj_ = proj_create(NULL, args.c_str());
+  if (!proj_) {
+    throw std::runtime_error(pj_error("proj initialization error: "));
+  }
+}
+
+Proj::Proj(const std::map<std::string, std::string>& args)
+  : Proj(toVector(args)) {
+}
+
+Proj::~Proj() {
+  proj_destroy(proj_);
+}
+
+std::tuple<double, double> Proj::fwd(double lon, double lat) {
+  PJ_COORD in;
+  in.uv = { lon, lat };
+  PJ_COORD out = proj_trans(proj_, PJ_FWD, in);
+  return std::make_tuple<double, double>(std::move(out.xy.x), std::move(out.xy.y));
+}
+
+std::tuple<double, double> Proj::inv(double x, double y) {
+  PJ_COORD in;
+  in.xy = { x, y };
+  PJ_COORD out = proj_trans(proj_, PJ_INV, in);
+  return std::make_tuple<double, double>(std::move(out.uv.u), std::move(out.uv.v));
+}
+
+#endif

src/goesproc/proj.h

@@ -1,20 +1,23 @@
 #pragma once
 
-#if PROJ_VERSION_MAJOR < 4
-#error "proj version >= 4 required"
+#if PROJ_VERSION_MAJOR == 4
+#include <proj_api.h>
+#elif PROJ_VERSION_MAJOR >= 5
+#include <proj.h>
 #else
-// Assume proj continues to ship with a backwards compatibility layer.
-// See for a migration guide https://proj.org/development/migration.html.
-#define ACCEPT_USE_OF_DEPRECATED_PROJ_API_H 1
+#error "proj version >= 4 required"
+#endif
+
+#if PROJ_VERSION_MAJOR == 4
+// Forward compatibility.
+double proj_torad (double angle_in_degrees);
 #endif
 
 #include <map>
 #include <string>
 #include <tuple>
 #include <vector>
 
-#include <proj_api.h>
-
 class Proj {
 public:
   explicit Proj(const std::vector<std::string>& args);
@@ -28,5 +31,9 @@ class Proj {
   std::tuple<double, double> inv(double x, double y);
 
 protected:
+#if PROJ_VERSION_MAJOR == 4
   projPJ proj_;
+#elif PROJ_VERSION_MAJOR >= 5
+  PJ *proj_;
+#endif
 };