start point for saving meta data in PNGs (issue #8)

- we could save georeferencing information
- or even a complete JSON output of all used parameters!

src/imagewriter.cpp

@@ -40,6 +40,8 @@
 #include <iostream>
 #include <string>
 
+using namespace std;
+
 
 #define DEFAULT_JPEG_QUALITY 90
 
@@ -65,9 +67,21 @@ ImageWriter::ImageWriter(const std::string &filename, ImageType imagetype,
     default:
 #ifdef HAVE_LIBPNG
     case IMAGETYPE_PNG:
-        m_png_ptr =
-            png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+        m_png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
         m_info_ptr = png_create_info_struct(m_png_ptr);
+        // write metadata
+        m_text_ptr[0].key = strdup("Title");
+        m_text_ptr[0].text = strdup("SPLAT!");
+        m_text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE;
+        m_text_ptr[1].key = strdup("projection");
+        m_text_ptr[1].text = strdup("EPSG:4326");
+        m_text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE;
+        m_text_ptr[2].key = strdup("bounds");
+        bounds_str = ("[["+to_string(m_south)+","+to_string(m_west)+"],["+to_string(m_north)+","+to_string(m_east)+"]]").c_str();
+		sprintf(bounds, "%s", bounds_str.c_str());
+        m_text_ptr[2].text = bounds;
+        m_text_ptr[2].compression = PNG_TEXT_COMPRESSION_NONE;
+        png_set_text(m_png_ptr, m_info_ptr, m_text_ptr, PNG_NTEXT);
         png_init_io(m_png_ptr, m_fp);
         png_set_IHDR(m_png_ptr, m_info_ptr, m_width, m_height,
                      8, /* 8 bits per color or 24 bits per pixel for RGB */

src/imagewriter.h

@@ -115,8 +115,12 @@ class ImageWriter {
     unsigned char *m_imgline_alpha = NULL;
 
 #ifdef HAVE_LIBPNG
+	#define PNG_NTEXT 4
     png_structp m_png_ptr = NULL;
     png_infop m_info_ptr = NULL;
+    png_text m_text_ptr[PNG_NTEXT] = {0};
+    std::string bounds_str;
+    char bounds[80];
 #endif
 #ifdef HAVE_LIBGDAL
 	GDALDriver *poDriver;

src/json.cpp

@@ -18,6 +18,8 @@
 #include <fstream>
 #include <bits/stdc++.h>
 
+using namespace std;
+
 Json::Json(const ElevationMap &em, const SplatRun &sr)
     : path(sr.arraysize, sr.ppd), em(em), sr(sr) {}
 
@@ -28,18 +30,18 @@ Json::Json(const ElevationMap &em, const SplatRun &sr)
     /* read in argv[] as an associative array.
 	 * You can now access the list e.g. by args["o"] which will not fail if the argument is not set
 	 * 
-	 *	std::map<std::string, std::string>::iterator i;
+	 *	map<string, string>::iterator i;
 	 *		for (i=args.begin(); i != args.end(); i++) {
-	 *		std::cout << i->first << ": " << i->second << std::endl;
+	 *		cout << i->first << ": " << i->second << endl;
 	 *	}
 	 */
-	//typedef std::map<std::string,std::string> arg_t;
+	//typedef map<string,string> arg_t;
 /*	arg_t args;
 	
-	std::string curr_arg = "";
+	string curr_arg = "";
 	int curr_arg_i = 0;
 	for(int i=0; i<argc; i++) {		// step through argv[] array
-		std::string arg = argv[i];
+		string arg = argv[i];
 		if(arg.find("-") == 0) {	// check if current argument has leading "-"
 			curr_arg = arg.erase(0,1);	// remove leading "-" and save as new array entry
 			curr_arg_i = i;		// save position for multiple parameters
@@ -61,7 +63,7 @@ Json::Json(const ElevationMap &em, const SplatRun &sr)
 // === unsorted end ===
 
 
-void Json::WriteJSON(arg_t args, Site tx_site, Lrp lrp, std::string mapfile) {
+void Json::WriteJSON(arg_t args, Site tx_site, Lrp lrp, string mapfile) {
 	int x;
 	char report_name[80];
 
@@ -73,7 +75,7 @@ void Json::WriteJSON(arg_t args, Site tx_site, Lrp lrp, std::string mapfile) {
             report_name[x] == 47)
             report_name[x] = '_';
 
-    std::ofstream reportfile(report_name);
+    ofstream reportfile(report_name);
 
     reportfile << "{\n";
     reportfile << "\t\"splat\": \"" << sr.splat_version.c_str() << "\",\n";
@@ -104,7 +106,7 @@ void Json::WriteJSON(arg_t args, Site tx_site, Lrp lrp, std::string mapfile) {
     reportfile << "\t},\n";
     reportfile << "\t\"arguments\": {\n";
 
-    std::map<std::string, std::string>::iterator i;
+    map<string, string>::iterator i;
     int pos = 0;
     int len = args.size();
     for (i=args.begin(); i != args.end(); i++, pos++) {
@@ -121,7 +123,7 @@ void Json::WriteJSON(arg_t args, Site tx_site, Lrp lrp, std::string mapfile) {
 
 	reportfile.close();
 
-	std::cout << "\nJSON file written to: " << report_name;
+	cout << "\nJSON file written to: " << report_name;
 
     fflush(stdout);
 }