+ *
+ * @param[in] frameIndex required frame index to be returned.
+ * @return TextureSet of the frame index.
+ */
+ virtual TextureSet Frame(uint32_t frameIndex) = 0;
+
+ /**
+ * @brief Get the interval(ms) of Nth frame.
+ *
+ * @param[in] frameIndex frame index to get frame interval.
+ * @return Time interval in millisecond between frames of frameIndex and frameIndex + 1.
+ */
+ virtual uint32_t GetFrameInterval(uint32_t frameIndex) const = 0;
+
+ /**
+ * @brief Get the current rendered frame index.
+ * If there isn't any loaded frame, returns -1.
+ *
+ * @return Frame index of currently showing frame.