Merge #4132

4132: document CComponent r=Jupeyy a=edg-l

I think this will make it easier for future people looking into this class.

## Checklist

- [ ] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test if it works standalone, system.c especially
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)


Co-authored-by: Edgar Luque <git@edgarluque.com>

src/game/client/component.h

@@ -18,6 +18,11 @@
 
 class CGameClient;
 
+/**
+* This class is inherited by all the client components.
+*
+* These components can implement the virtual methods such as OnInit(), OnMessage(int Msg, void *pRawMsg) to provide their functionality.
+*/
 class CComponent
 {
 protected:
@@ -25,54 +30,178 @@ protected:
 
 	CGameClient *m_pClient;
 
-	// perhaps propagte pointers for these as well
+	// perhaps propagate pointers for these as well
+
+	/**
+	 * Get the kernel interface.
+	 */
 	class IKernel *Kernel() const;
+	/**
+	 * Get the graphics interface.
+	 */
 	class IGraphics *Graphics() const;
+	/**
+	 * Get the text rendering interface.
+	 */
 	class ITextRender *TextRender() const;
+	/**
+	 * Get the input interface.
+	 */
 	class IInput *Input() const;
+	/**
+	 * Get the storage interface.
+	 */
 	class IStorage *Storage() const;
+	/**
+	 * Get the ui interface.
+	 */
 	class CUI *UI() const;
+	/**
+	 * Get the sound interface.
+	 */
 	class ISound *Sound() const;
+	/**
+	 * Get the render tools interface.
+	 */
 	class CRenderTools *RenderTools() const;
+	/**
+	 * Get the config interface.
+	 */
 	class CConfig *Config() const;
+	/**
+	 * Get the console interface.
+	 */
 	class IConsole *Console() const;
+	/**
+	 * Get the demo player interface.
+	 */
 	class IDemoPlayer *DemoPlayer() const;
+	/**
+	 * Get the demo recorder interface.
+	 *
+	 * @param Recorder A member of the RECORDER_x enum
+	 * @see RECORDER_MANUAL
+	 * @see RECORDER_AUTO
+	 * @see RECORDER_RACE
+	 * @see RECORDER_REPLAYS
+	 */
 	class IDemoRecorder *DemoRecorder(int Recorder) const;
+	/**
+	 * Get the server browser interface.
+	 */
 	class IServerBrowser *ServerBrowser() const;
+	/**
+	 * Get the layers interface.
+	 */
 	class CLayers *Layers() const;
+	/**
+	 * Get the collision interface.
+	 */
 	class CCollision *Collision() const;
 #if defined(CONF_AUTOUPDATE)
+	/**
+	 * Get the updater interface.
+	 */
 	class IUpdater *Updater() const;
 #endif
 
 #if defined(CONF_VIDEORECORDER)
+	/**
+	 * Gets the current time.
+	 * @see time_get()
+	 */
 	int64_t time() const
 	{
 		return IVideo::Current() ? IVideo::Time() : time_get();
 	}
 #else
+	/**
+	 * Gets the current time.
+	 * @see time_get()
+	 */
 	int64_t time() const
 	{
 		return time_get();
 	}
 #endif
+	/**
+	 * Gets the local time.
+	 */
 	float LocalTime() const;
 
 public:
+	/**
+	 * The component virtual destructor.
+	 */
 	virtual ~CComponent() {}
+	/**
+	 * Get a pointer to the game client.
+	 */
 	class CGameClient *GameClient() const { return m_pClient; }
+	/**
+	 * Get the client interface.
+	 */
 	class IClient *Client() const;
 
+	/**
+	 * This method is called when the client changes state, e.g from offline to online.
+	 * @see IClient::STATE_CONNECTING
+	 * @see IClient::STATE_LOADING
+	 * @see IClient::STATE_ONLINE
+	 */
 	virtual void OnStateChange(int NewState, int OldState){};
+	/**
+	 * Called to let the components register their console commands.
+	 */
 	virtual void OnConsoleInit(){};
+	/**
+	 * Called to let the components run initialization code.
+	 */
 	virtual void OnInit(){};
+	/**
+	 * Called to reset the component.
+	 * This method is usually called on your component constructor to avoid code duplication.
+	 * @see CHud::CHud()
+	 * @see CHud::OnReset()
+	 */
 	virtual void OnReset(){};
+	/**
+	 * Called when the window has been resized.
+	 */
 	virtual void OnWindowResize() {}
+	/**
+	 * Called when the component should get rendered.
+	 *
+	 * The render order depends on the component insertion order.
+	 */
 	virtual void OnRender(){};
+	/**
+	 * Called when the input gets released, for example when a text box loses focus.
+	 */
 	virtual void OnRelease(){};
+	/**
+	 * Called on map load.
+	 */
 	virtual void OnMapLoad(){};
+	/**
+	 * Called when receiving a network message.
+	 * @param Msg The message type.
+	 * @param pRawMsg The message data.
+	 * @see NETMSGTYPE_SV_DDRACETIME
+	 * @see CNetMsg_Sv_DDRaceTime
+	 */
 	virtual void OnMessage(int Msg, void *pRawMsg) {}
+	/**
+	 * Called on mouse movement, where the x and y values are deltas.
+	 *
+	 * @param x The amount of change in the x coordinate since the last call.
+	 * @param y The amount of change in the y coordinate since the last call.
+	 */
 	virtual bool OnMouseMove(float x, float y) { return false; }
+	/**
+	 * Called on a input event.
+	 * @param e The input event.
+	 */
 	virtual bool OnInput(IInput::CEvent e) { return false; }
 };