[CSM] add screenshot api lua (#5674)

* [CSM] add screenshot api lua

doc/client_lua_api.md

@@ -703,6 +703,8 @@ Call these functions only at load time!
 * `minetest.get_protocol_version()`
     * Returns the protocol version of the server.
     * Might not be accurate at start up as the client might not be connected to the server yet, in that case it will return 0.
+* `minetest.take_screenshot()`
+    * Take a screenshot.
 
 ### Misc.
 * `minetest.parse_json(string[, nullvalue])`: returns something

src/client.h

@@ -509,6 +509,8 @@ public:
 	void showGameFog(const bool show = true);
 	void showGameDebug(const bool show = true);
 
+	IrrlichtDevice *getDevice() const { return m_device; }
+
 private:
 
 	// Virtual methods from con::PeerHandler

src/script/lua_api/l_client.cpp

@@ -241,6 +241,13 @@ int ModApiClient::l_get_protocol_version(lua_State *L)
 	return 1;
 }
 
+int ModApiClient::l_take_screenshot(lua_State *L)
+{
+	Client *client = getClient(L);
+	client->makeScreenshot(client->getDevice());
+	return 0;
+}
+
 void ModApiClient::Initialize(lua_State *L, int top)
 {
 	API_FCT(get_current_modname);
@@ -259,4 +266,5 @@ void ModApiClient::Initialize(lua_State *L, int top)
 	API_FCT(sound_play);
 	API_FCT(sound_stop);
 	API_FCT(get_protocol_version);
+	API_FCT(take_screenshot);
 }

src/script/lua_api/l_client.h

@@ -72,6 +72,8 @@ private:
 	// get_protocol_version()
 	static int l_get_protocol_version(lua_State *L);
 
+	static int l_take_screenshot(lua_State *L);
+
 public:
 	static void Initialize(lua_State *L, int top);
 };