hexagram/src/anim.c

#include <stdlib.h>
#include <string.h>

#include <hexagram/anim.h>

void hexagram_anim_init(hexagram_anim *anim) {
    anim->current = 0;

    gettimeofday(&anim->start, NULL);
}

static inline double tv_seconds(struct timeval *tv) {
    return (double)tv->tv_sec + (double)tv->tv_usec / 1000000.0;
}

static inline double stop_offset(hexagram_anim *anim, size_t index) {
    double offset = 0.0;
    size_t i;

    for (i=0; i<index; i++) {
        offset += anim->stops[i].duration;
    }

    return offset;
}

static inline size_t stop_index(hexagram_anim *anim, double offset) {
    return 0;
}

int hexagram_anim_step(hexagram_anim *anim, cairo_t *bg, cairo_t *fg) {
    struct timeval tv;
    double offset, interval;
    size_t i;

    if (anim->current >= anim->count) {
        goto done;
    }

    gettimeofday(&anim->now, NULL);

    timersub(&anim->now, &anim->start, &tv);

    interval = tv_seconds(&tv);

done:
    return 0;

next:
    return 1;
}