Added initial JSON configuration support

README.md

@@ -13,3 +13,6 @@ A utility which can be used to create custom images for TRMNL devices via code
 
 ### Convert image with dithering
 `magick input.png -dither FloydSteinberg -remap pattern:gray50 -depth 1 -strip png:output.png`
+
+# Notes
+json.hpp from nlohmann/json v3.11.2

Widgets/Widget.h

@@ -14,7 +14,7 @@ private:
 
 public:
 	Widget(int width, int height);
-	~Widget();
+	virtual ~Widget();
 
 	// Method which updates the internal surface with the latest image
 	virtual void draw() = 0;

main.cpp

@@ -2,30 +2,59 @@
 #include <SDL2/SDL_ttf.h>
 #include <SDL2/SDL_image.h>
 
+#include <string>
 #include <vector>
 
 #include <stdio.h>
 
+#include "json.hpp"
+
 #include "sdl_helpers.h"
 #include "Widgets/Widget.h"
 
+using std::string;
 using std::vector;
+using nlohmann::json;
 
-int main(int argd, char **argv)
+int main(int argc, char **argv)
 {
 	int result = 0;
+	bool ok;
+
 	int screen_width = 800;
 	int screen_height = 600;
+	string output_filename = "trmnl.png";
+	string cfg_filename = "config.json";
+	json cfg;
 
+	SDL_Surface* main_surface = nullptr;
 	vector<Widget*> widgets;
 
-	if (!init_sdl())
+	ok = init_sdl();
+	if (!ok)
 	{
 		return -1;
 	}
 
+	if (argc > 1)
+	{
+		cfg_filename = argv[1];
+	}
+
+	// Read JSON CFG
+	ok = read_config_json(cfg, cfg_filename);
+	if (!ok)
+	{
+		result = -1;
+		goto cleanup;
+	}
+
+	// Change screen size from JSON
+	json_extract(cfg, "width", screen_width);
+	json_extract(cfg, "height", screen_height);
+
 	// Create surface
-	SDL_Surface* main_surface = SDL_CreateRGBSurfaceWithFormat(0, screen_width, screen_height, 32, SDL_PIXELFORMAT_RGBA8888);
+	main_surface = SDL_CreateRGBSurfaceWithFormat(0, screen_width, screen_height, 32, SDL_PIXELFORMAT_RGBA8888);
 	if (nullptr == main_surface)
 	{
 		printf("Could not allocate main surface\n");
@@ -33,20 +62,31 @@ int main(int argd, char **argv)
 		goto cleanup;
 	}
 
+	// TODO: Add Widgets From JSON
+
 	// Clear screen with white
-	SDL_FillRect(main_surface, nullptr, SDL_MapRGBA(main_surface->format, 255, 0, 255, 255));
+	SDL_FillRect(main_surface, nullptr, SDL_MapRGBA(main_surface->format, 255, 255, 255, 255));
 
 	// Apply all widgets
 	for (Widget* widget : widgets)
 	{
+		widget->draw();
 		SDL_Rect rect = widget->get_rect();
 		SDL_BlitSurface(widget->get_internal_surface(), nullptr, main_surface, &rect);
 	}
 
 	// Save image
-	IMG_SavePNG(main_surface, "asdf.png");
+	json_extract(cfg, "output", output_filename);
+	IMG_SavePNG(main_surface, output_filename.c_str());
 
 cleanup:
+	// Destroy All Widgets
+	for (Widget* widget : widgets)
+	{
+		delete widget;
+	}
+	widgets.clear();
+
 	clean_sdl();
 	return result;
 }

sdl_helpers.cpp

@@ -3,12 +3,14 @@
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_image.h>
 
+#include <fstream>
 #include <map>
 #include <utility>
 
 #include <stdio.h>
 
 using namespace std;
+using nlohmann::json;
 
 map<pair<string, int>, TTF_Font*> font_map;
 
@@ -74,3 +76,49 @@ TTF_Font* get_font(const string& filename, int size)
 		return font;
 	}
 }
+
+bool read_config_json(json& cfg, const string& filename, ostream* log)
+{
+	ifstream cfg_file(filename);
+
+	if (!cfg_file.is_open())
+	{
+		if (nullptr != log)
+		{
+			*log << "Could not open config.json" << endl;
+		}
+		return false;
+	}
+
+	// Parse with comments
+	try
+	{
+		cfg = json::parse(cfg_file, nullptr, true, true);
+	}
+	catch (const std::exception &e)
+	{
+		if (nullptr != log)
+		{
+			*log << e.what() << endl;
+		}
+		return false;
+	}
+
+	return true;
+}
+
+void json_extract(const json& j, const string& key, string& out)
+{
+	if (j.contains(key) && j[key].is_string())
+	{
+		out = j[key];
+	}
+}
+
+void json_extract(const nlohmann::json& j, const string& key, int& out)
+{
+	if (j.contains(key) && j[key].is_number_integer())
+	{
+		out = j[key];
+	}
+}

sdl_helpers.h

@@ -1,9 +1,13 @@
 #ifndef SDL_HELPERS_H_
 #define SDL_HELPERS_H_
 
-#include <string>
 #include <SDL2/SDL_ttf.h>
 
+#include <iostream>
+#include <string>
+
+#include "json.hpp"
+
 // Call this before everything
 // Prints its messages
 bool init_sdl();
@@ -15,4 +19,15 @@ void clean_sdl();
 // Can return NULL
 TTF_Font* get_font(const std::string& filename, int size);
 
+// Reads the file and tries to parse a JSON file with comments
+// cfg - output json struct
+// filename - filepath to open and read
+// log - output errors to this ostream, silent if NULL
+bool read_config_json(nlohmann::json& cfg, const std::string& filename, std::ostream* log = &std::cout);
+
+// JSON Extractors - They do not override already set values if key is not present
+
+void json_extract(const nlohmann::json& j, const std::string& key, std::string& out);
+void json_extract(const nlohmann::json& j, const std::string& key, int& out);
+
 #endif // SDL_HELPERS_H_