Merge pull request #25608 from sturkmen72:animated_webp_support

Animated WebP Support #25608

related issues #24855 #22569 

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/imgcodecs/include/opencv2/imgcodecs.hpp

@@ -236,6 +236,36 @@ enum ImwriteGIFCompressionFlags {
 
 //! @} imgcodecs_flags
 
+/** @brief Represents an animation with multiple frames.
+The `Animation` struct is designed to store and manage data for animated sequences such as those from animated formats (e.g., GIF, AVIF, APNG, WebP).
+It provides support for looping, background color settings, frame timing, and frame storage.
+*/
+struct CV_EXPORTS_W_SIMPLE Animation
+{
+    //! Number of times the animation should loop. 0 means infinite looping.
+    CV_PROP_RW int loop_count;
+    //! Background color of the animation in BGRA format.
+    CV_PROP_RW Scalar bgcolor;
+    //! Duration for each frame in milliseconds.
+    CV_PROP_RW std::vector<int> durations;
+    //! Vector of frames, where each Mat represents a single frame.
+    CV_PROP_RW std::vector<Mat> frames;
+
+    /** @brief Constructs an Animation object with optional loop count and background color.
+
+    @param loopCount An integer representing the number of times the animation should loop:
+    - `0` (default) indicates infinite looping, meaning the animation will replay continuously.
+    - Positive values denote finite repeat counts, allowing the animation to play a limited number of times.
+    - If a negative value or a value beyond the maximum of `0xffff` (65535) is provided, it is reset to `0`
+    (infinite looping) to maintain valid bounds.
+
+    @param bgColor A `Scalar` object representing the background color in BGRA format:
+    - Defaults to `Scalar()`, indicating an empty color (usually transparent if supported).
+    - This background color provides a solid fill behind frames that have transparency, ensuring a consistent display appearance.
+    */
+    Animation(int loopCount = 0, Scalar bgColor = Scalar());
+};
+
 /** @brief Loads an image from a file.
 
 @anchor imread
@@ -323,6 +353,38 @@ The function imreadmulti loads a specified range from a multi-page image from th
 */
 CV_EXPORTS_W bool imreadmulti(const String& filename, CV_OUT std::vector<Mat>& mats, int start, int count, int flags = IMREAD_ANYCOLOR);
 
+/** @example samples/cpp/tutorial_code/imgcodecs/animations.cpp
+An example to show usage of cv::imreadanimation and cv::imwriteanimation functions.
+Check @ref tutorial_animations "the corresponding tutorial" for more details
+*/
+
+/** @brief Loads frames from an animated image file into an Animation structure.
+
+The function imreadanimation loads frames from an animated image file (e.g., GIF, AVIF, APNG, WEBP) into the provided Animation struct.
+
+@param filename A string containing the path to the file.
+@param animation A reference to an Animation structure where the loaded frames will be stored. It should be initialized before the function is called.
+@param start The index of the first frame to load. This is optional and defaults to 0.
+@param count The number of frames to load. This is optional and defaults to 32767.
+
+@return Returns true if the file was successfully loaded and frames were extracted; returns false otherwise.
+*/
+CV_EXPORTS_W bool imreadanimation(const String& filename, CV_OUT Animation& animation, int start = 0, int count = INT16_MAX);
+
+/** @brief Saves an Animation to a specified file.
+
+The function imwriteanimation saves the provided Animation data to the specified file in an animated format.
+Supported formats depend on the implementation and may include formats like GIF, AVIF, APNG, or WEBP.
+
+@param filename The name of the file where the animation will be saved. The file extension determines the format.
+@param animation A constant reference to an Animation struct containing the frames and metadata to be saved.
+@param params Optional format-specific parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, ...).
+These parameters are used to specify additional options for the encoding process. Refer to `cv::ImwriteFlags` for details on possible parameters.
+
+@return Returns true if the animation was successfully saved; returns false otherwise.
+*/
+CV_EXPORTS_W bool imwriteanimation(const String& filename, const Animation& animation, const std::vector<int>& params = std::vector<int>());
+
 /** @brief Returns the number of images inside the given file
 
 The function imcount returns the number of pages in a multi-page image (e.g. TIFF), the number of frames in an animation (e.g. AVIF), and 1 otherwise.