Define touchscreen support when in use. (#3296)

esphome/components/touchscreen/__init__.py

@@ -4,6 +4,7 @@ import esphome.codegen as cg
 from esphome.components import display
 from esphome import automation
 from esphome.const import CONF_ON_TOUCH
+from esphome.core import coroutine_with_priority
 
 CODEOWNERS = ["@jesserockz"]
 DEPENDENCIES = ["display"]
@@ -39,3 +40,9 @@ async def register_touchscreen(var, config):
             [(TouchPoint, "touch")],
             config[CONF_ON_TOUCH],
         )
+
+
+@coroutine_with_priority(100.0)
+async def to_code(config):
+    cg.add_global(touchscreen_ns.using)
+    cg.add_define("USE_TOUCHSCREEN")

esphome/core/defines.h

@@ -40,6 +40,7 @@
 #define USE_SWITCH
 #define USE_TEXT_SENSOR
 #define USE_TIME
+#define USE_TOUCHSCREEN
 #define USE_UART_DEBUGGER
 #define USE_WIFI