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