Detailed Description

Represents a key on the keyboard.

The easiest way to detect a key is to create the Key value you want to detect and then compare for equality. For example, you can create the up arrow Key with Key::up(), or the uppercase M key with ‘Key::code('M’)`.

Here's an example of key handling:

void on_key(Key key) override
{
    if (key == Key::code('q'))
        quit();
    else if (key == Key::up())
        move_up();
    else if (key == Key::down())
        move_down();
}

Another way to recognize a key is to look at its two properties:

type() const — will be the value Key::Type::code if the key represents a Unicode character (code point), or some other value of the Key::Type enumeration for non-Unicode keys.
code() const — will be the Unicode code point value of the key if type() const is Key::Type::code, and will be 0 otherwise.

Here is an example distinguishing several keys by switching on their properties:

void on_key(Key key) override
{
    switch (key.type()) {
    case Key::Type::up:
        move_up();
        break;
    case Key::Type::down:
        move_down();
        break;
    case Key::Type::code: {
        char c = key.code();
        switch (c) {
        case '\b':
            backspace();
            break;
        case '\r':
            enter();
            break;
        default:
            add_to_buffer(c);
        }
        break;
   }
}

Currently this type supports keys that deliver Unicode values using whatever input method is supported by your operating system, as well as the arrow keys and modifier keys shift, control, option/alt, and command/meta. If you need to handle other keys, contact me and I will add them.

Definition at line 127 of file ge211_event.hxx.

Public Types
enum	Type { code, up, down, left, right, shift, control, alt, command, other }
	The possible types of keys. More...

Public Member Functions
Type	type () const
	The type of the key.

char32_t	code () const
	The Unicode code point of the key, if it has one.

bool	is_textual () const
	Does the key represent printable text? This is true for some but not all Type::code keys. More...

std::string	as_text () const
	Returns a representation of the key's code as a std::string. More...

Constructor and factories
	Key ()
	Constructs the empty key, with type Key::Type::other.

static Key	code (char32_t c)
	Constructs a key with the given Unicode code point code. More...

static Key	up ()
	Constructs the up arrow key.

static Key	down ()
	Constructs the down arrow key.

static Key	left ()
	Constructs the left arrow key.

static Key	right ()
	Constructs the right arrow key.

static Key	shift ()
	Constructs the shift key.

static Key	control ()
	Constructs the control key.

static Key	alt ()
	Constructs the alt (or option) key.

static Key	command ()
	Constructs the command (or meta) key.

static Key	other ()
	Constructs an invalid or unknown key. More...

Member Enumeration Documentation

◆ Type

enum Type

strong

The possible types of keys.

Enumerator
code	Indicates a key with an Unicode value, which can be gotten with Key::code() const.
up	The up arrow key.
down	The down arrow key.
left	The left arrow key.
right	The right arrow key.
shift	The shift key.
control	The control key.
alt	The alt or option key.
command	The command or meta key.
other	Any other, unknown or invalid key.

Definition at line 180 of file ge211_event.hxx.

Member Function Documentation

◆ as_text()

std::string as_text ( ) const

Returns a representation of the key's code as a std::string.

This could be useful if you want to capture typing text, rather than game control, because concatenating a string to a string is easier than concatenating the char32_t code() const to a string, when that could be an arbitrary Unicode code point.

The result of this function is only meaningful when is_textual() const returns true.

Definition at line 141 of file ge211_event.cxx.

◆ code()

static Key code ( char32_t c )

inlinestatic

Constructs a key with the given Unicode code point code.

Throws exceptions::Client_logic_error if c is not a valid Unicode code point. Valid code points are from 0 to 0x10FFFF, except for 0xD800 to 0xDFFF.

Definition at line 141 of file ge211_event.hxx.

◆ is_textual()

bool is_textual ( ) const

Does the key represent printable text? This is true for some but not all Type::code keys.

It's never true for other types of keys.

Definition at line 136 of file ge211_event.cxx.

◆ other()

static Key other ( )

inlinestatic

Constructs an invalid or unknown key.

This returns the same value as the default constructor Key().

Definition at line 175 of file ge211_event.hxx.

The documentation for this class was generated from the following files:

/Users/tov/school/cs211/dev/ge211/include/ge211_event.hxx
/Users/tov/school/cs211/dev/ge211/src/ge211_event.cxx