small bug in ssd1306_draw_line #22
Description
in the sample
for(int y=0, i=1; y>=0; y+=i) {
ssd1306_draw_line(&disp, 0, 31-y, 127, 31+y);
ssd1306_draw_line(&disp, 0, 31+y, 127, 31-y);
ssd1306_show(&disp);
sleep_ms(SLEEPTIME);
ssd1306_clear(&disp);
if(y==32) i=-1;
}
only one line (and a dot) is drawn!
The function should read:
void ssd1306_draw_line(ssd1306_t *p, uint32_t x1, uint32_t y1, uint32_t x2, uint32_t y2)
{
if (x1 > x2)
{
swap(&x1, &x2);
swap(&y1, &y2);
}
if (x1 == x2)
{
if (y1 > y2)
swap(&y1, &y2);
for (int32_t i = y1; i <= y2; ++i)
ssd1306_draw_pixel(p, x1, i);
return;
}
// NOTE The cast to int32_t before subtracting y2 - y1
float m = (float)((int32_t)y2 - (int32_t)y1) / (float)(x2 - x1);
for (int32_t i = x1; i <= x2; ++i)
{
float y = m * (float)(i - x1) + (float)y1;
ssd1306_draw_pixel(p, i, (uint32_t)y);
}
}