static int png_write_row(PNGContext *s, const uint8_t *data, int size) { int ret; s->zstream.avail_in = size; s->zstream.next_in = (uint8_t *)data; while (s->zstream.avail_in > 0) { ret = deflate(&s->zstream, Z_NO_FLUSH); if (ret != Z_OK) return -1; if (s->zstream.avail_out == 0) { png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE); s->zstream.avail_out = IOBUF_SIZE; s->zstream.next_out = s->buf; } } return 0; }