-LOT_EXPORT void lottie_animation_get_size(const Lottie_Animation *animation, size_t *w, size_t *h);
+
+/**
+ * @brief Returns default viewport size of the Lottie resource.
+ *
+ * @param[in] animation Animation object.
+ * @param[out] w default width of the viewport.
+ * @param[out] h default height of the viewport.
+ *
+ * @ingroup Lottie_Animation
+ * @internal
+ */
+LOT_EXPORT void lottie_animation_get_size(const Lottie_Animation *animation, size_t *width, size_t *height);
+
+/**
+ * @brief Returns total animation duration of Lottie resource in second.
+ * it uses totalFrame() and frameRate() to calculate the duration.
+ * duration = totalFrame() / frameRate().
+ *
+ * @param[in] animation Animation object.
+ *
+ * @return total animation duration in second.
+ * @c 0 if the Lottie resource has no animation.
+ *
+ * @see lottie_animation_get_totalframe()
+ * @see lottie_animation_get_framerate()
+ *
+ * @ingroup Lottie_Animation
+ * @internal
+ */