feat: Implemented Integer scaling (fixes #1352)

Added Integer scaling as an option in the Display panel.
This saves to the config file, and can be set in amiberry.conf as well.
The value 2 can be used in the scaling_method option, to set this as the default.

src/osdep/amiberry.cpp

@@ -2244,8 +2244,8 @@ void target_default_options(struct uae_prefs* p, int type)
 	p->scaling_method = -1; //Default is Auto
 	if (amiberry_options.default_scaling_method != -1)
 	{
-		// only valid values are -1 (Auto), 0 (Nearest) and 1 (Linear)
-		if (amiberry_options.default_scaling_method == 0 || amiberry_options.default_scaling_method == 1)
+		// only valid values are -1 (Auto), 0 (Nearest), 1 (Linear) 2 (Integer)
+		if (amiberry_options.default_scaling_method >= 0 && amiberry_options.default_scaling_method <= 2)
 			p->scaling_method = amiberry_options.default_scaling_method;
 	}
 

src/osdep/amiberry_gfx.cpp

@@ -184,6 +184,8 @@ void set_scaling_option(uae_prefs* p, int width, int height)
 #else
 		SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "linear");
 #endif
+	else if (p->scaling_method == 2)
+		SDL_RenderSetIntegerScale(AMonitors[0].amiga_renderer, SDL_TRUE);
 }
 
 static float SDL2_getrefreshrate(int monid)

src/osdep/gui/PanelDisplay.cpp

@@ -31,7 +31,7 @@ static gcn::StringListModel fullscreen_modes_list(fullscreen_modes);
 static const std::vector<std::string> resolution = { "LowRes", "HighRes (normal)", "SuperHighRes" };
 static gcn::StringListModel resolution_list(resolution);
 
-static const std::vector<std::string> scaling_method = { "Auto", "Pixelated", "Smooth" };
+static const std::vector<std::string> scaling_method = { "Auto", "Pixelated", "Smooth", "Integer" };
 static gcn::StringListModel scaling_method_list(scaling_method);
 
 static gcn::Window* grpAmigaScreen;