Simple graphics library

The library contains wrappers around basic primitives from the SDL_gfx library. It is intended to provide basic graphics capabilities to the beginners learning C. It is expected, that after getting enough proficiency in C, the programmer will use SDL library directly. The library is contained in the file primlib.c. Every file using it should include primlib.h. The library requires SDL 1.2 and SDL_gfx and can be downloaded here

The coordinate system

The coordinate system origin is located at upper-left corner of a graphics window. Width and height of the graphics window can be queried using the screenWidth() and screenHeight() functions, respectively. Before using any of the graphics functions initgraph() must be called. After the drawing operations, to make the updates to the screen visible, call updateScreen(). Before calling updateScreen() once again, you must clear the screen and redraw the entire scene.

Compilation

The following command line can be used to compile programs using the library:

gcc -D_REENTRANT progname.c primlib.c -o progname -lm -lSDL -lpthread -lSDL_gfx

where progname.c is the name of the main program module.

Function reference

int initGraph();

Must be called before any graphic operation. Returns 0 on success, non-zero on failure.

enum color {BLACK, RED, GREEN, BLUE, CYAN, MAGENTA, YELLOW, WHITE, COLOR_MAX};

Enumeration type, representing available colors.

void pixel(int x, int y, enum color c);

Put pixel with color c at coordinates (x,y).

void line(int x1, int y1, int x2, int y2, enum color c);

Draw line from (x1,y1) to (x2,y2), using color c.

void rect(int x1, int y1, int x2, int y2, enum color c);

Draw rectangle with upper left corner at (x1,y1) and lower right corner at (x2,y2), using color c.

void filledRect(int x1, int y1, int x2, int y2, enum color c);

Draw filled rectangle with upper left corner at (x1,y1) and lower right corner at (x2,y2), using color c.

void circle(int x, int y, int r, enum color c);

Draw circle with a center at (x,y) and radius r, using color c.

void filledCircle(int x, int y, int r, enum color c);

Draw filled circle with a center at (x,y) and radius r, using color c.

void textout(int x, int y, char *s, enum color c);

Print text s starting at the coordinates (x,y), using color c.

int screenWidth();

Get the width of the screen.

int screenHeight();

Get the height of the screen.

void updateScreen();

Makes the result of drawing functions since the last update visible on the screen.

int pollkey();

Return the code of pressed key, do not wait for the keypress. Return-1 if no key has been pressed.

int getkey();

Wait for the keypress and return the key code.

int isKeyDown(int key);

Return 1, if the key key is pressed, 0 otherwise.

List of keycodes used by keyboard functions


Keycode

ASCII value

Common name

SDLK_BACKSPACE

'\b'

backspace

SDLK_TAB

'\t'

tab

SDLK_CLEAR

 

clear

SDLK_RETURN

'\r'

return

SDLK_PAUSE

 

pause

SDLK_ESCAPE

'^['

escape

SDLK_SPACE

' '

space

SDLK_EXCLAIM

'!'

exclaim

SDLK_QUOTEDBL

'"'

quotedbl

SDLK_HASH

'#'

hash

SDLK_DOLLAR

'$'

dollar

SDLK_AMPERSAND

'&'

ampersand

SDLK_QUOTE

'''

quote

SDLK_LEFTPAREN

'('

left parenthesis

SDLK_RIGHTPAREN

')'

right parenthesis

SDLK_ASTERISK

'*'

asterisk

SDLK_PLUS

'+'

plus sign

SDLK_COMMA

','

comma

SDLK_MINUS

'-'

minus sign

SDLK_PERIOD

'.'

period

SDLK_SLASH

'/'

forward slash

SDLK_0

'0'

0

SDLK_1

'1'

1

SDLK_2

'2'

2

SDLK_3

'3'

3

SDLK_4

'4'

4

SDLK_5

'5'

5

SDLK_6

'6'

6

SDLK_7

'7'

7

SDLK_8

'8'

8

SDLK_9

'9'

9

SDLK_COLON

':'

colon

SDLK_SEMICOLON

';'

semicolon

SDLK_LESS

'<'

less-than sign

SDLK_EQUALS

'='

equals sign

SDLK_GREATER

'>'

greater-than sign

SDLK_QUESTION

'?'

question mark

SDLK_AT

'@'

at

SDLK_LEFTBRACKET

'['

left bracket

SDLK_BACKSLASH

'\'

backslash

SDLK_RIGHTBRACKET

']'

right bracket

SDLK_CARET

'^'

caret

SDLK_UNDERSCORE

'_'

underscore

SDLK_BACKQUOTE

'`'

grave

SDLK_a

'a'

a

SDLK_b

'b'

b

SDLK_c

'c'

c

SDLK_d

'd'

d

SDLK_e

'e'

e

SDLK_f

'f'

f

SDLK_g

'g'

g

SDLK_h

'h'

h

SDLK_i

'i'

i

SDLK_j

'j'

j

SDLK_k

'k'

k

SDLK_l

'l'

l

SDLK_m

'm'

m

SDLK_n

'n'

n

SDLK_o

'o'

o

SDLK_p

'p'

p

SDLK_q

'q'

q

SDLK_r

'r'

r

SDLK_s

's'

s

SDLK_t

't'

t

SDLK_u

'u'

u

SDLK_v

'v'

v

SDLK_w

'w'

w

SDLK_x

'x'

x

SDLK_y

'y'

y

SDLK_z

'z'

z

SDLK_DELETE

 

delete

SDLK_KP0

 

keypad 0

SDLK_KP1

 

keypad 1

SDLK_KP2

 

keypad 2

SDLK_KP3

 

keypad 3

SDLK_KP4

 

keypad 4

SDLK_KP5

 

keypad 5

SDLK_KP6

 

keypad 6

SDLK_KP7

 

keypad 7

SDLK_KP8

 

keypad 8

SDLK_KP9

 

keypad 9

SDLK_KP_PERIOD

'.'

keypad period

SDLK_KP_DIVIDE

'/'

keypad divide

SDLK_KP_MULTIPLY

'*'

keypad multiply

SDLK_KP_MINUS

'-'

keypad minus

SDLK_KP_PLUS

'+'

keypad plus

SDLK_KP_ENTER

'\r'

keypad enter

SDLK_KP_EQUALS

'='

keypad equals

SDLK_UP

 

up arrow

SDLK_DOWN

 

down arrow

SDLK_RIGHT

 

right arrow

SDLK_LEFT

 

left arrow

SDLK_INSERT

 

insert

SDLK_HOME

 

home

SDLK_END

 

end

SDLK_PAGEUP

 

page up

SDLK_PAGEDOWN

 

page down

SDLK_F1

 

F1

SDLK_F2

 

F2

SDLK_F3

 

F3

SDLK_F4

 

F4

SDLK_F5

 

F5

SDLK_F6

 

F6

SDLK_F7

 

F7

SDLK_F8

 

F8

SDLK_F9

 

F9

SDLK_F10

 

F10

SDLK_F11

 

F11

SDLK_F12

 

F12

SDLK_F13

 

F13

SDLK_F14

 

F14

SDLK_F15

 

F15

SDLK_NUMLOCK

 

numlock

SDLK_CAPSLOCK

 

capslock

SDLK_SCROLLOCK

 

scrollock

SDLK_RSHIFT

 

right shift

SDLK_LSHIFT

 

left shift

SDLK_RCTRL

 

right ctrl

SDLK_LCTRL

 

left ctrl

SDLK_RALT

 

right alt

SDLK_LALT

 

left alt

SDLK_RMETA

 

right meta

SDLK_LMETA

 

left meta

SDLK_LSUPER

 

left windows key

SDLK_RSUPER

 

right windows key

SDLK_MODE

 

mode shift

SDLK_HELP

 

help

SDLK_PRINT

 

print-screen

SDLK_SYSREQ

 

SysRq

SDLK_BREAK

 

break

SDLK_MENU

 

menu

SDLK_POWER

 

power

SDLK_EURO

 

euro