g.region: Add JSON support (OSGeo#3941)

* g.region: add JSON support * add test and documentation * add gmt, wms to output * fix CI build issues * separate projection code and name fields
Mahesh1998 · Sep 19, 2024 · 7d6a3b4 · 7d6a3b4
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Showing 7 changed files with 357 additions and 46 deletions.
diff --git a/general/g.region/Makefile b/general/g.region/Makefile
@@ -2,7 +2,7 @@ MODULE_TOPDIR = ../..
 
 PGM = g.region
 
-LIBES = $(GPROJLIB) $(VECTORLIB) $(DIG2LIB) $(RASTER3DLIB) $(RASTERLIB) $(GISLIB) $(MATHLIB) $(PROJLIB)
+LIBES = $(GPROJLIB) $(VECTORLIB) $(DIG2LIB) $(RASTER3DLIB) $(RASTERLIB) $(GISLIB) $(MATHLIB) $(PROJLIB) $(PARSONLIB)
 DEPENDENCIES = $(GPROJDEP) $(VECTORDEP) $(DIG2DEP) $(RASTER3DDEP) $(RASTERDEP) $(GISDEP)
 EXTRA_INC = $(VECT_INC) $(PROJINC)
 EXTRA_CFLAGS = $(VECT_CFLAGS)

diff --git a/general/g.region/g.region.html b/general/g.region/g.region.html
@@ -457,6 +457,59 @@ <h3>Using g.region in a shell in combination with GDAL</h3>
 Here the input raster map does not have to match the project's
 coordinate reference system since it is reprojected on the fly.
 
+<h3>JSON Output</h3>
+<div class="code"><pre>
+g.region -p format=json
+</pre></div>
+<div class="code"><pre>
+{
+    "projection": "99 (Lambert Conformal Conic)",
+    "zone": 0,
+    "datum": "nad83",
+    "ellipsoid": "a=6378137 es=0.006694380022900787",
+    "region": {
+        "north": 320000,
+        "south": 10000,
+        "west": 120000,
+        "east": 935000,
+        "ns-res": 500,
+        "ns-res3": 1000,
+        "ew-res": 500,
+        "ew-res3": 1000
+    },
+    "top": 500,
+    "bottom": -500,
+    "tbres": 100,
+    "rows": 620,
+    "rows3": 310,
+    "cols": 1630,
+    "cols3": 815,
+    "depths": 10,
+    "cells": 1010600,
+    "cells3": 2526500
+}
+</pre></div>
+
+<div class="code"><pre>
+g.region -l format=json
+</pre></div>
+<div class="code"><pre>
+{
+    "nw_long": -78.688888505507336,
+    "nw_lat": 35.743893244701788,
+    "ne_long": -78.669097826118957,
+    "ne_lat": 35.743841072010554,
+    "se_long": -78.669158624787542,
+    "se_lat": 35.728968779193615,
+    "sw_long": -78.688945667963168,
+    "sw_lat": 35.729020942542441,
+    "center_long": -78.679022655614958,
+    "center_lat": 35.736431420327719,
+    "rows": 165,
+    "cols": 179
+}
+</pre></div>
+
 <h2>SEE ALSO</h2>
 
 <em>

diff --git a/general/g.region/local_proto.h b/general/g.region/local_proto.h
@@ -13,10 +13,15 @@
 #define PRINT_GMT    0x200
 #define PRINT_WMS    0x400
 
+#include <grass/parson.h>
+
+enum OutputFormat { PLAIN, SHELL, JSON };
+
 /* zoom.c */
 int zoom(struct Cell_head *, const char *, const char *);
 
 /* printwindow.c */
-void print_window(struct Cell_head *, int, int);
+void print_window(struct Cell_head *, int, int, enum OutputFormat,
+                  JSON_Object *);
 
 #endif
diff --git a/general/g.region/main.c b/general/g.region/main.c
@@ -20,6 +20,7 @@
 #include <grass/raster.h>
 #include <grass/raster3d.h>
 #include <grass/vector.h>
+#include <grass/parson.h>
 #include <grass/glocale.h>
 #include "local_proto.h"
 
@@ -41,6 +42,9 @@ int main(int argc, char *argv[])
     char **rast_ptr, **vect_ptr;
     int pix;
     bool update_file = false;
+    enum OutputFormat format;
+    JSON_Value *root_value;
+    JSON_Object *root_object;
 
     struct GModule *module;
     struct {
@@ -51,7 +55,7 @@ int main(int argc, char *argv[])
     struct {
         struct Option *north, *south, *east, *west, *top, *bottom, *res, *nsres,
             *ewres, *res3, *tbres, *rows, *cols, *save, *region, *raster,
-            *raster3d, *align, *zoom, *vect, *grow;
+            *raster3d, *align, *zoom, *vect, *grow, *format;
     } parm;
 
     G_gisinit(argv[0]);
@@ -358,6 +362,13 @@ int main(int argc, char *argv[])
     parm.save->gisprompt = "new,windows,region";
     parm.save->guisection = _("Effects");
 
+    parm.format = G_define_standard_option(G_OPT_F_FORMAT);
+    parm.format->options = "plain,shell,json";
+    parm.format->descriptions = _("plain;Plain text output;"
+                                  "shell;shell script style output;"
+                                  "json;JSON (JavaScript Object Notation);");
+    parm.format->guisection = _("Print");
+
     G_option_required(
         flag.dflt, flag.savedefault, flag.print, flag.lprint, flag.eprint,
         flag.center, flag.gmt_style, flag.wms_style, flag.dist_res, flag.nangle,
@@ -421,6 +432,24 @@ int main(int argc, char *argv[])
         print_flag |= PRINT_REG;
     }
 
+    if (strcmp(parm.format->answer, "json") == 0) {
+        format = JSON;
+        root_value = json_value_init_object();
+        if (root_value == NULL) {
+            G_fatal_error(
+                _("Failed to initialize JSON object. Out of memory?"));
+        }
+        root_object = json_object(root_value);
+    }
+    else if (strcmp(parm.format->answer, "shell") == 0 ||
+             (print_flag & PRINT_SH)) {
+        format = SHELL;
+        print_flag |= PRINT_SH;
+    }
+    else {
+        format = PLAIN;
+    }
+
     if (flag.dflt->answer)
         update_file = true;
     else
@@ -903,7 +932,18 @@ int main(int argc, char *argv[])
     } /* / flag.savedefault->answer */
 
     if (print_flag)
-        print_window(&window, print_flag, flat_flag);
+        print_window(&window, print_flag, flat_flag, format, root_object);
+
+    if (format == JSON) {
+        char *serialized_string = NULL;
+        serialized_string = json_serialize_to_string_pretty(root_value);
+        if (serialized_string == NULL) {
+            G_fatal_error(_("Failed to initialize pretty JSON string."));
+        }
+        puts(serialized_string);
+        json_free_serialized_string(serialized_string);
+        json_value_free(root_value);
+    }
 
     exit(EXIT_SUCCESS);
 }