gfx.c

#include "gfx.h"
#include "framebuffer.h"
#include <math.h>
#include <stddef.h>
#include <stdlib.h>

const struct gfx_color_rgb gfx_colors_rgb[COLORS] = {
	{ 255, 255, 255 }, /* WHITE */
	{ 0, 0, 0 },       /* BLACK */
	{ 255, 0, 0 },     /* RED */
	{ 0, 255, 0 },     /* GREEN */
	{ 0, 0, 255 },     /* BLUE */
	{ 255, 255, 0 }    /* YELLOW */
};

void gfx_setpixel(struct gfx_region *r, int x, int y, Color c)
{
	if (x < 0 || y < 0)
		return;
	if (x >= r->width || y >= r->height)
		return;

	fb_setpixel(r->fb, r->x + x, r->y + y, c);
}

struct gfx_region gfx_screen(struct framebuffer *fb)
{
	struct gfx_region r = { .fb     = fb,
				.x      = 0,
				.y      = 0,
				.width  = fb->width,
				.height = fb->height };
	return r;
}

static inline int letter_bit(sFONT *font, char c, int x, int y)
{
	if (x < 0 || y < 0)
		return 0;
	if (x >= font->Width || y >= font->Height)
		return 0;
	if (c < ' ' || c > '~')
		return 0;

	size_t bytes_per_row      = font->Width / 8 + 1;
	size_t bytes_per_letter   = bytes_per_row * font->Height;
	int letter                = c - ' ';
	const uint8_t *letter_ptr = font->table + bytes_per_letter * letter;
	int horz_byte             = x / 8;
	int horz_bit              = 7 - x % 8;

	return (*(letter_ptr + y * bytes_per_row + horz_byte) >> horz_bit) & 1;
}

void gfx_putchar(
	sFONT *font,
	struct gfx_region *r,
	int x,
	int y,
	char ch,
	Color fg,
	Color bg
) {
	for (int yo = 0; yo < font->Height; yo++) {
		for (int xo = 0; xo < font->Width; xo++) {
			int lb = letter_bit(font, ch, xo, yo);

			if (fg != bg) {
				Color c = lb ? fg : bg;
				gfx_setpixel(r, x + xo, y + yo, c);