/* draw a line like Brensenham did... (roughly) */
void fb_rgb332_lineto(uint16_t x2,uint16_t y2){
uint8_t *p,pixel; /* framebuffer pointer */
int delta_regular; /* framebuffer offset per step */
int delta_step; /* " */
uint16_t x1 = framebuffer->cursor_x; /* start */
uint16_t y1 = framebuffer->cursor_y;
int t,tmax; /* counter for steps */
int err_inc,err_accu=0; /* error delta and accumulator for */
/* Brensenham's algorhithm */
fb_limit_fb_range(&x1,&y1);
fb_limit_fb_range(&x2,&y2);
fb_rgb332_update_damage(x1,y1,x2,y2);
framebuffer->cursor_x = x2; /* end pixel */
framebuffer->cursor_y = y2;
/* pointer to first pixel, pixel value in FB memory */
p = fb_rgb332->mem + framebuffer->width * y1 + x1;
pixel = rgb_to_pixel(framebuffer->fg_color);
if(abs(x2-x1) >= abs(y2-y1)){ /* shallow line */
/* set pointer deltas for directions */
delta_regular = 1; /* X */
if(x2 < x1)
delta_regular = -delta_regular;
delta_step = framebuffer->width; /* Y */
if(y2 < y1)
delta_step = -delta_step;
tmax = abs(x2-x1);
err_inc = abs(y2-y1);
} else { /* steep line */
delta_regular = framebuffer->width; /* Y */
if(y2 < y1)
delta_regular = -delta_regular;
delta_step = 1; /* X */
if(x2 < x1)
delta_step = -1;
tmax = abs(y2-y1);
err_inc = abs(x2-y1);
}
#if 0
printf("%s: (%d,%d) -> (%d,%d) step=%d regular=%d err_inc=%d tmax=%d\n",
__FUNCTION__,x1,y1,x2,y2,delta_step,delta_regular,err_inc,tmax);
#endif
for(t=0;t<=tmax;t++){
*p = pixel;
err_accu += err_inc;
if(err_accu >= tmax){
p += delta_step;
err_accu -= tmax;
}
p += delta_regular;
}
}
lcd_inline void write_data(uint16_t datain)
{
uint16_t dataout = 0x0100 | fix_rrr(rgb_to_pixel(datain));
uwire_xfer(SSD1783_DEV_ID,SSD1783_UWIRE_BITLEN,&dataout, NULL);
}
static void set_pix(uint8_t *pixel,uint32_t color){
if(color == FB_COLOR_TRANSP)
return;
*pixel = rgb_to_pixel(color);
}
