basic tablet/phone/watch autodetection

Until we're able to detect touchscreen itself, let's have a detection
based on a form factor of the device.

Tablets and handhelds are usually equiped with touchscreens, so as a
default enable touchscreen GUI there.

 - Windows and Linux supports autodetection.
 - Android is hardcoded as touch-based.
 - MacOS staying same as before without detection.

Heavily "inspired" by systemd way of handling detection.

Signed-off-by: David Heidelberg <[email protected]>

src/defaultsettings.cpp

@@ -26,6 +26,68 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "mapgen/mapgen.h" // Mapgen::setDefaultSettings
 #include "util/string.h"
 
+
+
+bool detect_touch()
+{
+#if ENABLE_TOUCH  // Android & special builds
+	return true;
+#else
+	std::string chassis_type;
+#if defined(__linux__) || defined(__ANDROID__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__DragonFly__)
+	// device-tree platforms (non-X86)
+	std::ifstream dtb_file("/proc/device-tree/chassis-type");
+	if (dtb_file.is_open()) {
+		std::getline(dtb_file, chassis_type);
+		chassis_type.pop_back();
+
+		if (chassis_type == "convertible" || // user has to set it by hand anyway
+		    chassis_type == "desktop" ||
+		    chassis_type == "laptop" ||
+		    chassis_type == "server" ||
+		    chassis_type == "embedded")
+			return false;
+
+		if (chassis_type == "tablet" ||
+		    chassis_type == "handset" ||
+		    chassis_type == "watch")
+			return true;
+
+		return false;
+	}
+	// SMBIOS (x86)
+	std::ifstream dmi_file("/sys/class/dmi/id/chassis_type");
+	if (dmi_file.is_open()) {
+		std::getline(dmi_file, chassis_type);
+
+		if (chassis_type == "11" /* Handheld */ ||
+		    chassis_type == "30" /* Tablet */)
+			return true;
+
+		return false;
+	}
+
+	// ACPI-based platforms
+	std::ifstream acpi_file("/sys/firmware/acpi/pm_profile");
+	if (acpi_file.is_open()) {
+		std::getline(acpi_file, chassis_type);
+
+		if (chassis_type == "8" /* Tablet */)
+			return true;
+
+		return false;
+	}
+#elif defined(_WIN32)
+	if (GetSystemMetrics(SM_TABLETPC))
+		return true;
+
+	return false;
+#endif
+	// we don't know, return default
+	return false;
+#endif
+}
+
 void set_default_settings()
 {
 	Settings *settings = Settings::createLayer(SL_DEFAULTS);
@@ -39,11 +101,7 @@ void set_default_settings()
 	// Client
 	settings->setDefault("address", "");
 	settings->setDefault("enable_sound", "true");
-#if ENABLE_TOUCH
-	settings->setDefault("enable_touch", "true");
-#else
-	settings->setDefault("enable_touch", "false");
-#endif
+	settings->setDefault("enable_touch", bool_to_cstr(detect_touch()));
 	settings->setDefault("sound_volume", "0.8");
 	settings->setDefault("sound_volume_unfocused", "0.3");
 	settings->setDefault("mute_sound", "false");
@@ -95,12 +153,10 @@ void set_default_settings()
 	settings->setDefault("keymap_cmd_local", ".");
 	settings->setDefault("keymap_minimap", "KEY_KEY_V");
 	settings->setDefault("keymap_console", "KEY_F10");
-#if ENABLE_TOUCH
+
 	// See https://github.com/minetest/minetest/issues/12792
-	settings->setDefault("keymap_rangeselect", "KEY_KEY_R");
-#else
-	settings->setDefault("keymap_rangeselect", "");
-#endif
+	settings->setDefault("keymap_rangeselect", detect_touch() ? "KEY_KEY_R" : "");
+
 	settings->setDefault("keymap_freemove", "KEY_KEY_K");
 	settings->setDefault("keymap_pitchmove", "");
 	settings->setDefault("keymap_fastmove", "KEY_KEY_J");
@@ -197,11 +253,7 @@ void set_default_settings()
 	settings->setDefault("screen_h", "600");
 	settings->setDefault("window_maximized", "false");
 	settings->setDefault("autosave_screensize", "true");
-#ifdef ENABLE_TOUCH
-	settings->setDefault("fullscreen", "true");
-#else
-	settings->setDefault("fullscreen", "false");
-#endif
+	settings->setDefault("fullscreen", bool_to_cstr(detect_touch()));
 	settings->setDefault("vsync", "false");
 	settings->setDefault("fov", "72");
 	settings->setDefault("leaves_style", "fancy");
@@ -307,11 +359,7 @@ void set_default_settings()
 	settings->setDefault("aux1_descends", "false");
 	settings->setDefault("doubletap_jump", "false");
 	settings->setDefault("always_fly_fast", "true");
-#ifdef ENABLE_TOUCH
-	settings->setDefault("autojump", "true");
-#else
-	settings->setDefault("autojump", "false");
-#endif
+	settings->setDefault("autojump", bool_to_cstr(detect_touch()));
 	settings->setDefault("continuous_forward", "false");
 	settings->setDefault("enable_joysticks", "false");
 	settings->setDefault("joystick_id", "0");
@@ -491,11 +539,7 @@ void set_default_settings()
 	settings->setDefault("touch_use_crosshair", "false");
 	settings->setDefault("fixed_virtual_joystick", "false");
 	settings->setDefault("virtual_joystick_triggers_aux1", "false");
-#ifdef ENABLE_TOUCH
-	settings->setDefault("clickable_chat_weblinks", "false");
-#else
-	settings->setDefault("clickable_chat_weblinks", "true");
-#endif
+	settings->setDefault("clickable_chat_weblinks", bool_to_cstr(!detect_touch()));
 	// Altered settings for Android
 #ifdef __ANDROID__
 	settings->setDefault("screen_w", "0");