EmuWindow: refactor touch input into a TouchDevice

src/citra/config.cpp

@@ -78,6 +78,8 @@ void Config::ReadValues() {
 
     Settings::values.motion_device = sdl2_config->Get(
         "Controls", "motion_device", "engine:motion_emu,update_period:100,sensitivity:0.01");
+    Settings::values.touch_device =
+        sdl2_config->Get("Controls", "touch_device", "engine:emu_window");
 
     // Core
     Settings::values.use_cpu_jit = sdl2_config->GetBoolean("Core", "use_cpu_jit", true);

src/citra/default_ini.h

@@ -62,6 +62,10 @@ c_stick=
 #      - "sensitivity": the coefficient converting mouse movement to tilting angle (default to 0.01)
 motion_device=
 
+# for touch input, the following devices are available:
+#  - "emu_window" (default) for emulating touch input from mouse input to the emulation window. No parameters required
+touch_device=
+
 [Core]
 # Whether to use the Just-In-Time (JIT) compiler for CPU emulation
 # 0: Interpreter (slow), 1 (default): JIT (fast)