path: root/fbgl.h

#ifndef __FBGL_H__
#define __FBGL_H__

#define VERSION "0.1.0"
#define NAME "FBGL"
#define DEFAULT_FB "/dev/fb0"

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <linux/fb.h>
#include <stddef.h>
#include <stdio.h>
#include <termios.h>
#include <signal.h>

static struct termios orig_termios;

/**
* Structs
*/
typedef struct fbgl {
	int width;
	int height;
	int fd;
	size_t screen_size;
	uint32_t *pixels;
	struct fb_var_screeninfo vinfo; // Variable screen information
	struct fb_fix_screeninfo finfo; // Fixed screen information
} fbgl_t;

typedef struct fbgl_window {
	int x; // Top-left x-coordinate of the window
	int y; // Top-left y-coordinate of the window
	int width; // Width of the window
	int height; // Height of the window
	fbgl_t *fb; // Pointer to the framebuffer context
} fbgl_window_t;

typedef struct fbgl_psf2_header {
	uint8_t magic[2]; // Magic number, should be {0x72, 0xB5}
	uint8_t version; // Version of PSF2 (usually 0)
	uint8_t header_size; // Size of the header (usually 32 bytes)
	uint16_t flags; // Flags (usually 0)
	uint16_t numglyphs; // Number of glyphs (characters)
	uint16_t bytes_per_glyph; // Number of bytes per glyph (depends on font size)
	uint16_t height; // Height of each character in pixels
	uint16_t width; // Width of each character in pixels
	uint8_t *glyphs; // Pointer to the glyph data
} fbgl_psf2_header_t;

#ifdef FBGL_HIDE_CURSOR
#include <linux/kd.h>
int fbgl_hide_cursor(int fd)
{
	int tty_fd = open("/dev/tty0", O_RDWR);
	if (tty_fd == -1) {
		perror("Error opening /dev/tty0");
		return -1;
	}

	if (ioctl(tty_fd, KDSETMODE, KD_GRAPHICS) == -1) {
		perror("Error setting graphics mode");
		close(tty_fd);
		return -1;
	}

	close(tty_fd);
	return 0;
}
#endif //FBGL_HIDE_CURSOR

#ifdef __cplusplus
extern "C" {
#endif

/**
 * General purpose methods
 */
char const *fbgl_name_info(void);
char const *fbgl_version_info(void);
void fbgl_enable_raw_mode();
void fbgl_disable_raw_mode();
void fbgl_cleanup(int sig);
int fbgl_check_esc_key();
void fbgl_set_signal_handlers();

/*Create and destroy methods*/
int fbgl_init(const char *device, fbgl_t *fb);
void fbgl_destroy(fbgl_t *fb);

/**
* Drawing functions
*/
void fbgl_clear(uint32_t color);
void fbgl_put_pixel(int x, int y, uint32_t color, fbgl_t *fb);
void fbgl_draw_line(int x0, int y0, int x1, int y1, uint32_t color);
void fbgl_set_bg();

/**
* Display methods
*/
void fbgl_display();

/**
* Access framebuffer data methods
*/
uint32_t *fb_get_data(void);
int fb_get_width(void);
int fb_get_height(void);

/**
* PSF2 Font Methods
*/
fbgl_psf2_header_t *fbgl_load_psf2_font(const char *font_file);
void fbgl_render_char(fbgl_t *framebuffer, int fb_width, int fb_height, int x,
		      int y, char ch, fbgl_psf2_header_t *font);
void fbgl_render_text(fbgl_t *framebuffer, int fb_width, int fb_height, int x,
		      int y, const char *text, fbgl_psf2_header_t *font);
void fbgl_free_psf2_font(fbgl_psf2_header_t *font);

#ifdef FBGL_IMPLEMENTATION

char const *fbgl_name_info(void)
{
	return NAME;
}

char const *fbgl_version_info(void)
{
	return VERSION;
}

int fbgl_init(const char *device, fbgl_t *fb)
{
	if (!fb) {
		fprintf(stderr, "Error: fbgl_t pointer is NULL.");
		return -1;
	}

	fb->fd = device == NULL ? open(DEFAULT_FB, O_RDWR) :
				  open(device, O_RDWR);
	if (fb->fd == -1) {
		perror("Error openning framebuffer device");
		return -1;
	}

	if (ioctl(fb->fd, FBIOGET_FSCREENINFO, &fb->finfo) == -1) {
		perror("Error: Reading fixed information.");
		close(fb->fd);
		return -1;
	}
	if (ioctl(fb->fd, FBIOGET_VSCREENINFO, &fb->vinfo) == -1) {
		perror("Error reading variable information");
		close(fb->fd);
		return -1;
	}

#ifdef FBGL_HIDE_CURSOR
	fbgl_hide_cursor(fb->fd);
	fbgl_set_signal_handlers();
	fbgl_enable_raw_mode();
#endif //FBGL_HIDE_CURSOR

	fb->width = fb->vinfo.xres;
	fb->height = fb->vinfo.yres;
	fb->screen_size = fb->finfo.smem_len;

	// Map framebuffer to memory
	fb->pixels = (uint32_t *)mmap(NULL, fb->screen_size,
				      PROT_READ | PROT_WRITE, MAP_SHARED,
				      fb->fd, 0);
	if (fb->pixels == MAP_FAILED) {
		perror("Error mapping framebuffer device to memory");
		close(fb->fd);
		return -1;
	}

	return 0;
}

void fbgl_destroy(fbgl_t *fb)
{
	if (!fb || fb->fd == -1) {
		fprintf(stderr,
			"Error: framebuffer not initialized or already destroyed.\n");
		return;
	}

	if (fb->pixels && fb->pixels != MAP_FAILED) {
		munmap(fb->pixels, fb->screen_size);
	}

	close(fb->fd);
	fb->fd = -1;

#ifdef FBGL_HIDE_CURSOR
	fbgl_disable_raw_mode();
#endif // FBGL_HIDE_CURSOR
}

void fbgl_set_bg(fbgl_t *fb, uint32_t color)
{
	if (!fb || fb->fd == -1) {
		fprintf(stderr, "Error: framebuffer not initialized.\n");
		return;
	}

	// Fill the entire framebuffer with the specified color
	for (size_t i = 0; i < (fb->width * fb->height); ++i) {
		fb->pixels[i] = color;
	}
}

void fbgl_put_pixel(int x, int y, uint32_t color, fbgl_t *fb)
{
	if (!fb || !fb->pixels) {
		fprintf(stderr, "Error: framebuffer not initialized.\n");
		return;
	}

	if (x < 0 || x >= fb->width || y < 0 || y >= fb->height) {
		return; // Ignore out-of-bound coordinates
	}

	size_t index = y * fb->width + x;
	fb->pixels[index] = color;
}

void fbgl_enable_raw_mode()
{
	struct termios raw;

	if (tcgetattr(STDIN_FILENO, &orig_termios) == -1) {
		perror("tcgetattr");
		exit(EXIT_FAILURE);
	}
	raw = orig_termios;
	raw.c_lflag &= ~(ECHO | ICANON);
	if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1) {
		perror("tcsetattr");
		exit(EXIT_FAILURE);
	}
}

void fbgl_disable_raw_mode()
{
	if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &orig_termios) == -1) {
		perror("tcsetattr");
	}
}

void fbgl_cleanup(int sig)
{
	fbgl_disable_raw_mode();
	printf("\033[2J\033[H"); // Clear the terminal screen and move the cursor to top-left
	exit(sig);
}

int fbgl_check_esc_key()
{
	char c;
	struct timeval tv = { 0, 0 };
	fd_set fds;
	FD_ZERO(&fds);
	FD_SET(STDIN_FILENO, &fds);

	// Check if there's input available
	if (select(STDIN_FILENO + 1, &fds, NULL, NULL, &tv) == -1) {
		perror("select");
		return 0;
	}

	if (FD_ISSET(STDIN_FILENO, &fds)) {
		if (read(STDIN_FILENO, &c, 1) == -1) {
			perror("read");
			return 0;
		}
		return c == 27; // ASCII value of the `Esc` key
	}

	return 0;
}

void fbgl_set_signal_handlers()
{
	struct sigaction sa;
	sa.sa_handler = fbgl_cleanup;
	sa.sa_flags = 0;
	sigemptyset(&sa.sa_mask);

	if (sigaction(SIGINT, &sa, NULL) == -1 ||
	    sigaction(SIGTERM, &sa, NULL) == -1) {
		perror("sigaction");
		exit(EXIT_FAILURE);
	}
}

fbgl_psf2_header_t *fbgl_load_psf2_font(const char *font_file)
{
	fbgl_psf2_header_t *font = NULL;
	int fd = open(font_file, O_RDONLY);
	if (fd == -1) {
		perror("Error opening font file");
		return NULL;
	}

	// Read the font header
	font = (fbgl_psf2_header_t *)malloc(sizeof(fbgl_psf2_header_t));
	if (read(fd, font, sizeof(fbgl_psf2_header_t)) !=
	    sizeof(fbgl_psf2_header_t)) {
		perror("Error reading font header");
		free(font);
		close(fd);
		return NULL;
	}

	// Check magic number
	if (font->magic[0] != 0x72 || font->magic[1] != 0xB5) {
		fprintf(stderr, "Invalid PSF2 font magic number.\n");
		free(font);
		close(fd);
		return NULL;
	}

	// Read the font glyph data
	font->glyphs =
		(uint8_t *)malloc(font->numglyphs * font->bytes_per_glyph);
	if (read(fd, font->glyphs, font->numglyphs * font->bytes_per_glyph) !=
	    font->numglyphs * font->bytes_per_glyph) {
		perror("Error reading glyph data");
		free(font->glyphs);
		free(font);
		close(fd);
		return NULL;
	}

	close(fd);
	return font;
    }

    void fbgl_render_char(fbgl_t *framebuffer, int fb_width, int fb_height, int x, int y, char ch, fbgl_psf2_header_t *font)
{
    if (!framebuffer || !font) return;

    int glyph_idx = (uint8_t)ch; // Get the glyph index for the character
    if (glyph_idx >= font->numglyphs) return;

    uint8_t *glyph_data = font->glyphs + (glyph_idx * font->bytes_per_glyph);
    for (int j = 0; j < font->height; ++j) {
        for (int i = 0; i < font->width; ++i) {
            if (glyph_data[j] & (1 << (7 - i))) {
                fbgl_put_pixel(x + i, y + j, 0xFFFFFF, framebuffer);
            }
        }
    }
}

void fbgl_render_text(fbgl_t *framebuffer, int fb_width, int fb_height, int x, int y, const char *text, fbgl_psf2_header_t *font)
{
    while (*text) {
        fbgl_render_char(framebuffer, fb_width, fb_height, x, y, *text, font);
        x += font->width;
        ++text;
    }
}

void fbgl_free_psf2_font(fbgl_psf2_header_t *font)
{
    if (font) {
        free(font->glyphs);
        free(font);
    }
}

#endif

#ifdef __cplusplus
} // extern "C"
#endif
#endif // __FBGL_H__