Minor cleanups to some resolution/window size code

* Cleaned up preferences::resolution() implementation.
* Don't call the above twice on SDL window init.
* Made a variable name clearer.

src/preferences/general.cpp

@@ -374,17 +374,18 @@ void set_scroll_to_action(bool ison)
 
 point resolution()
 {
-	const std::string& x = prefs["xresolution"], y = prefs["yresolution"];
-
-	if (!x.empty() && !y.empty()) {
-		try {
-			return point(
-				std::max(std::stoi(x), min_window_width),
-				std::max(std::stoi(y), min_window_height));
-		} catch(std::invalid_argument&) {}
+	const unsigned x_res = prefs["xresolution"].to_unsigned();
+	const unsigned y_res = prefs["yresolution"].to_unsigned();
+
+	// Either resolution was unspecified, return default.
+	if(x_res == 0 || y_res == 0) {
+		return point(def_window_width, def_window_height);
 	}
 
-	return point(def_window_width, def_window_height);
+	return point(
+		std::max<unsigned>(x_res, min_window_width),
+		std::max<unsigned>(y_res, min_window_height)
+	);
 }
 
 bool maximized()

src/video.cpp

@@ -223,23 +223,23 @@ void CVideo::init_window()
 	const int y = preferences::fullscreen() ? SDL_WINDOWPOS_UNDEFINED : SDL_WINDOWPOS_CENTERED;
 
 	// Dimensions
-	const int w = preferences::resolution().x;
-	const int h = preferences::resolution().y;
+	const point res = preferences::resolution();
+	const int w = res.x;
+	const int h = res.y;
 
-	// Video flags
-	int video_flags = 0;
+	uint32_t window_flags = 0;
 
 	// Add any more default flags here
-	video_flags |= SDL_WINDOW_RESIZABLE;
+	window_flags |= SDL_WINDOW_RESIZABLE;
 
 	if(preferences::fullscreen()) {
-		video_flags |= SDL_WINDOW_FULLSCREEN_DESKTOP;
+		window_flags |= SDL_WINDOW_FULLSCREEN_DESKTOP;
 	} else if(preferences::maximized()) {
-		video_flags |= SDL_WINDOW_MAXIMIZED;
+		window_flags |= SDL_WINDOW_MAXIMIZED;
 	}
 
 	// Initialize window
-	window.reset(new sdl::window("", x, y, w, h, video_flags, SDL_RENDERER_SOFTWARE));
+	window.reset(new sdl::window("", x, y, w, h, window_flags, SDL_RENDERER_SOFTWARE));
 
 	std::cerr << "Setting mode to " << w << "x" << h << std::endl;