rlottie is a platform independent standalone c++ library for rendering vector based animations and art in realtime.
Lottie loads and renders animations and vectors exported in the bodymovin JSON format. Bodymovin JSON can be created and exported from After Effects with [bodymovin](https://github.com/bodymovin/bodymovin), Sketch with [Lottie Sketch Export](https://github.com/buba447/Lottie-Sketch-Export), and from [Haiku](https://www.haiku.ai).
For the first time, designers can create and ship beautiful animations without an engineer painstakingly recreating it by hand. Since the animation is backed by JSON they are extremely small in size but can be large in complexity!
rlottie supports [meson](https://mesonbuild.com/) and [cmake](https://cmake.org/) build system. rlottie is written in `C++14`. and has a public header dependency of `C++11`
[rlottie online viewer](http://rlottie.com) uses rlottie wasm library to render the resource locally in your browser. To test your JSON resource drag and drop it to the browser window.
#
## Quick Start
Lottie loads and renders animations and vectors exported in the bodymovin JSON format. Bodymovin JSON can be created and exported from After Effects with [bodymovin](https://github.com/bodymovin/bodymovin), Sketch with [Lottie Sketch Export](https://github.com/buba447/Lottie-Sketch-Export), and from [Haiku](https://www.haiku.ai).
You can quickly load a Lottie animation with:
```cpp
auto animation = rlottie::Animation::loadFromFile("absolute_path/test.json");
```
You can load a lottie animation from raw data with:
```cpp
auto animation = rlottie::Animation::loadFromData(std::string(rawData), std::string(cacheKey));
```
Properties like `frameRate` , `totalFrame` , `duration` can be queried with:
```cpp
# get the frame rate of the resource.
double frameRate = animation->frameRate();
#get total frame that exists in the resource
size_t totalFrame = animation->totalFrame();
#get total animation duration in sec for the resource
double duration = animation->duration();
```
Render a particular frame in a surface buffer `immediately` with:
To understand how to change animation properties in Lottie, you should first understand how animation properties are stored in Lottie. Animation properties are stored in a data tree that mimics the information hierarchy of After Effects. In After Effects a Composition is a collection of Layers that each have their own timelines. Layer objects have string names, and their contents can be an image, shape layers, fills, strokes, or just about anything that is drawable. Each object in After Effects has a name. Lottie can find these objects and properties by their name using a KeyPath.
To update a property at runtime, you need 3 things:
1. KeyPath
2. rLottie::Property
3. setValue()
### KeyPath
A KeyPath is used to target a specific content or a set of contents that will be updated. A KeyPath is specified by a list of strings that correspond to the hierarchy of After Effects contents in the original animation.
KeyPaths can include the specific name of the contents or wildcards:
- Wildcard *
- Wildcards match any single content name in its position in the keypath.
- Globstar **
- Globstars match zero or more layers.
### Properties
`rLottie::Property` is an enumeration of properties that can be set. They correspond to the animatable value in After Effects and the available properties are listed below.
`setValue()` requires a keypath of string and value. The value can be `Color`, `Size` and `Point` structure or a function that returns them. `Color`, `Size`, and `Point` vary depending on the type of `rLottie::Property`. This value or function(callback) is called and applied to every frame. This value can be set differently for each frame by using the `FrameInfo` argument passed to the function.
File github issues for anything that is broken. Be sure to check the [list of supported features](#supported-after-effects-features) before submitting. If an animation is not working, please attach the After Effects file to your issue. Debugging without the original can be very difficult. For immidiate assistant or support please reach us in [Gitter](https://gitter.im/rLottie-dev/community#)
