tried to make the engine retain the user selected resolution (#416)

I changed 3 files and created preference_data.hpp. You should be weary
of my lack of knowledge about how Frogatto treats it's virtual
gamescreen sizes. Basically I added an if statement that separates
presence and absence of a preferences.cfg. If the file exists, the
autoSelectResolution function is not called, because why should the
resolution be set automatically when user defined settings exist? Please
notify me if my changes require further explanation.
Also here's a video showing off the changes.
https://youtu.be/Wueo7ppIjr0

src/main.cpp

@@ -94,6 +94,8 @@
 #include "SceneNode.hpp"
 #include "WindowManager.hpp"
 
+#include "preference_data.hpp"
+
 #include "xhtml_render_ctx.hpp"
 
 #if defined(__APPLE__)
@@ -531,7 +533,11 @@ int main(int argcount, char* argvec[])
 		module::set_core_module_name(DEFAULT_MODULE);
 	}
 
-	preferences::load_preferences();
+	PreferenceData preference_data = preferences::load_preferences();
+
+	if(preference_data.error){
+		LOG_ERROR("Preference data error: " << preference_data.error_message);
+	}
 
 	// load difficulty settings after module, before rest of args.
 	try {
@@ -944,12 +950,22 @@ int main(int argcount, char* argvec[])
 		int width = 0;
 		int height = 0;
 
-		bool isFullscreen = preferences::get_screen_mode() != preferences::ScreenMode::WINDOWED;
-		graphics::GameScreen::autoSelectResolution(main_wnd, width, height, true, isFullscreen);
+		if(!preference_data.error){
+			bool isFullscreen = preferences::get_screen_mode() != preferences::ScreenMode::WINDOWED;
+			//graphics::GameScreen::autoSelectResolution(main_wnd, preference_data.resolution_width, preference_data.resolution_height, true, isFullscreen);
 
-		preferences::adjust_virtual_width_to_match_physical(width, height);
+			preferences::adjust_virtual_width_to_match_physical(preference_data.resolution_width, preference_data.resolution_height);
+
+			main_wnd->setWindowSize(preference_data.resolution_width, preference_data.resolution_height);
+		}
+		else{
+			bool isFullscreen = preferences::get_screen_mode() != preferences::ScreenMode::WINDOWED;
+			graphics::GameScreen::autoSelectResolution(main_wnd, width, height, true, isFullscreen);
 
-		main_wnd->setWindowSize(width, height);
+			preferences::adjust_virtual_width_to_match_physical(width, height);
+
+			main_wnd->setWindowSize(width, height);
+		}
 	}
 
 	int vw = preferences::requested_virtual_window_width() > 0
@@ -968,6 +984,13 @@ int main(int argcount, char* argvec[])
 
 	graphics::GameScreen::get().setDimensions(main_wnd->width(), main_wnd->height());
 	graphics::GameScreen::get().setVirtualDimensions(vw, vh);
+
+	std::cout << "Virtual dimensions: " << vw << ", " << vh << std::endl;
+	std::cout << "Screen virtual dimensions: " << graphics::GameScreen::get().getVirtualWidth() << ", " << graphics::GameScreen::get().getVirtualHeight() << std::endl;
+	std::cout << "main_wnd->width(): " << main_wnd->width() << ", " << main_wnd->height() << std::endl;
+
+	//graphics::GameScreen::get().setDimensions(preference_data.resolution_width, preference_data.resolution_height);
+	//graphics::GameScreen::get().setVirtualDimensions(preference_data.resolution_width, preference_data.resolution_height);
 	//main_wnd->setWindowIcon(module::map_file("images/window-icon.png"));
 
 	//we prefer late swap tearing so as to minimize frame loss when possible

src/preference_data.hpp

@@ -0,0 +1,13 @@
+#ifndef PREFERENCE_DATA
+#define PREFERENCE_DATA
+
+#include <string>
+
+struct PreferenceData{
+    int resolution_width;
+    int resolution_height;
+    bool error = false;
+    std::string error_message = "";
+};
+
+#endif

src/preferences.cpp

@@ -54,6 +54,8 @@
 #include "sys.hpp"
 #include "string_utils.hpp"
 #include "variant_utils.hpp"
+#include "screen_handling.hpp"
+#include "preference_data.hpp"
 
 #include <time.h>
 
@@ -869,7 +871,7 @@ namespace preferences
 		return &GameRegistry::getInstance();
 	}
 
-	void load_preferences()
+	PreferenceData load_preferences()
 	{
 		std::string path;
 		if(preferences_path_.empty()) {
@@ -894,15 +896,15 @@ namespace preferences
 				sys::write_file(path + "preferences.cfg", module::get_default_preferences().write_json());
 				node = module::get_default_preferences();
 			} else {
-				return;
+				return PreferenceData{1600,800,true,"Default preferences.cfg does not exist"};
 			}
 		}
 
 		if(node.is_null()) {
 			try {
 				node = json::parse_from_file(path + "preferences.cfg");
 			} catch(const json::ParseError&) {
-				return;
+				return PreferenceData{1600,800,true,"Could not parse preferences.cfg"};
 			}
 		}
 
@@ -963,6 +965,8 @@ namespace preferences
 		}
 
         preferences::set_32bpp_textures_if_kb_memory_at_least(512000);
+
+		return PreferenceData{node["resolution_width"].as_int(), node["resolution_height"].as_int()};
 	}
 
 	void save_preferences()
@@ -1010,6 +1014,11 @@ namespace preferences
 			}
 		}
 
+		node.add("resolution_width", variant(graphics::GameScreen::get().getWidth()));
+		node.add("resolution_height", variant(graphics::GameScreen::get().getHeight()));
+
+		std::cout << "save_preferences() :" << graphics::GameScreen::get().getWidth() << ", " << graphics::GameScreen::get().getHeight() << std::endl;
+
 		LOG_INFO("WRITE PREFS: " << (preferences_path_ + "preferences.cfg"));
 		sys::write_file(preferences_path_ + "preferences.cfg", node.build().write_json());
 	}

src/preferences.hpp

@@ -28,6 +28,7 @@
 
 #include "uri.hpp"
 #include "variant.hpp"
+#include "preference_data.hpp"
 
 namespace game_logic
 {
@@ -204,7 +205,7 @@ namespace preferences
 
 	game_logic::FormulaCallable* registry();
 
-	void load_preferences();
+	PreferenceData load_preferences();
 	void save_preferences();
 
 	uri::uri get_tbs_uri();