Main classes: CL_InputContext, CL_InputDevice, CL_InputEvent, CL_InputBuffer.

There are two ways to deal with input from the user; via events generated by the operating system, or by polling the input devices. Access to both polling and event handlers hookups is provided by the CL_InputContext class, available from CL_DisplayWindow::get_ic(), as shown earlier.

The CL_InputContext class is a container for all the different types of input devices available from a window, categorized as either keyboards, mice or joysticks (game controllers). Here's an example of getting the input device for common devices:

	CL_DisplayWindow window("My ClanLib Window", 640, 480);
	CL_InputContext *ic = window.get_ic();
	CL_InputDevice keyboard = ic->get_keyboard();
	CL_InputDevice mouse = ic->get_mouse();
	CL_InputDevice joystick = ic->get_joystick();

CL_InputDevice is an abstraction for any input device type. It has a set of polling functions for both keyboards, mice and joysticks:

	bool space_down = keyboard.get_keycode(CL_KEY_SPACE);
	std::string name_of_space = keyboard.get_key_name(CL_KEY_SPACE);
	int mouse_x = mouse.get_x();
	int mouse_y = mouse.get_y();
	float axis_x = joystick.get_axis(0);
	float axis_y = joystick.get_axis(1);

In addition to the polling functions, CL_InputDevice also has a list of signals that are emitted when ClanLib receives input events for the specific device. When any of those events occur, a CL_InputEvent is passed along to any slot listening for that event. Here's an example of a handler routine listening for key down events from the keyboard:

	CL_Slot slot_key_down;
	
	void setup_slot(CL_InputContext *ic)
	{
		CL_InputDevice keyboard = ic->get_keyboard();
		slot_key_down = keyboard.sig_key_down().connect(&on_key_down);
	}
	
	void on_key_down(const CL_InputEvent &event)
	{
		std::cout << "User pressed: " << event.str.c_str() << std::endl;
	}

Note: ClanLib only polls the operating system for new events when you call CL_System::keep_alive(), so make sure you call that at least once a frame.

CL_InputBuffer is a class that helps you capture keyboard press events and convert them into a poll-able buffer. This is useful if you want to avoid setting up an event handler when you want the user to enter a string of text:

	CL_InputBuffer buffer(keyboard);
	bool quit = false;
	std::string text;
	while (!quit)
	{
		while (buffer.keys_left() > 0)
		{
			CL_InputEvent key = buffer.pop_key();
			if (key.type != CL_InputEvent::pressed) continue;
			if (key.id == CL_KEY_ENTER)
			{
				quit = true;
				break;
			}
			else
			{
				text += key.str;
			}
		}
	
		draw_gfx(text);
		window.flip();
		CL_System::keep_alive();
	}
	std::cout << "User wrote: " << text.c_str() << std::endl;

The following table shows the keycodes available for ClanLib. Codes that start with CL_KEY are for use with the CL_Keyboard class, and codes that start with CL_MOUSE are for use with the CL_Mouse class: