libfb

A simple framebuffer library

Types

• The actual framebuffer object.

  typedef struct {
      int fd;
      uint8_t *fbmem;       /* mapped framebuffer */
      size_t screensize;
      unsigned width;
      unsigned height;
      unsigned bpp;
      unsigned line_length;
  
      /* optional software back buffer */
      uint8_t *backbuf;
  } fb_t;
  

• A colour object. Effectively a tuple

  typedef struct {
      uint8_t r, g, b;
  } color_t;
  

Functions

• Initialises a framebuffer object.

  fb_t fb_init(void);
  

• Opens a framebuffer device into the object

  int fb_open(fb_t *fb, const char *dev);
  

• Closes the framebuffer device and unmaps memory

  void fb_close(fb_t *fb);
  

Drawing Primitives

• Clears the screen

  void fb_clear(const fb_t *fb, color_t c);
  

• Draws a pixel at the specified coordinate

  void fb_putpixel(const fb_t *fb, unsigned x, unsigned y, color_t c);
  

• Draws a horizontal line

  void fb_hline(const fb_t *fb, unsigned x, unsigned y, unsigned w, color_t c);
  

• Draws a vertical line

  void fb_vline(const fb_t *fb, unsigned x, unsigned y, unsigned h, color_t c);
  

• Draws a filled rectangle

  void fb_fillrect(const fb_t *fb, unsigned x, unsigned y, unsigned w, unsigned h, color_t c);
  

• Draws a rectangle outline

  void fb_fillrect(const fb_t *fb, unsigned x, unsigned y, unsigned w, unsigned h, color_t c);
  

• Draws a line between 2 points

  void fb_line(const fb_t *fb, int x0, int y0, int x1, int y1, color_t c);
  

• Draws a single character

  void fb_draw_char(const fb_t *fb, unsigned x, unsigned y,
                char ch, color_t fg, color_t bg);
  

• Draws a string

  void fb_draw_string(const fb_t *fb, unsigned x, unsigned y,
                  const char *str, color_t fg, color_t bg);
  

• Flips the back and the front buffer

  void fb_flip(const fb_t* fb);
  

Macros

• Creates a colour object

  #define COLOR(r,g,b) ((color_t){(r),(g),(b)})
  

• Creates a colour object using a preset

  #define COLOR_BLACK  COLOR(0,0,0)
  #define COLOR_WHITE  COLOR(255,255,255)
  #define COLOR_RED    COLOR(255,0,0)
  #define COLOR_GREEN  COLOR(0,255,0)
  #define COLOR_BLUE   COLOR(0,0,255)