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107 lines
3.6 KiB
Markdown
107 lines
3.6 KiB
Markdown
2 years ago
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# Lottie player
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Allows to use Lottie animations in LVGL. Taken from this [base repository](https://github.com/ValentiWorkLearning/lv_rlottie)
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LVGL provides the interface to [Samsung/rlottie](https://github.com/Samsung/rlottie) library's C API. That is the actual Lottie player is not part of LVGL, it needs to be built separately.
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## Build Rlottie
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To build Samsung's Rlottie C++14-compatible compiler and optionally CMake 3.14 or higher is required.
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To build on desktop you can follow the instructions from Rlottie's [README](https://github.com/Samsung/rlottie/blob/master/README.md). In the most basic case it looks like this:
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```
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mkdir rlottie_workdir
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cd rlottie_workdir
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git clone https://github.com/Samsung/rlottie.git
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mkdir build
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cd build
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cmake ../rlottie
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make -j
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sudo make install
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```
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And finally add the `-lrlottie` flag to your linker.
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On embedded systems you need to take care of integrating Rlottie to the given build system.
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## Usage
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You can use animation from files or raw data (text). In either case first you need to enable `LV_USE_RLOTTIE` in `lv_conf.h`.
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The `width` and `height` of the object be set in the *create* function and the animation will be scaled accordingly.
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### Use Rlottie from file
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To create a Lottie animation from file use:
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```c
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lv_obj_t * lottie = lv_rlottie_create_from_file(parent, width, height, "path/to/lottie.json");
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```
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Note that, Rlottie uses the standard STDIO C file API, so you can use the path "normally" and no LVGL specific driver letter is required.
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### Use Rlottie from raw string data
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`lv_example_rlottie_approve.c` contains an example animation in raw format. Instead storing the JSON string a hex array is stored for the following reasons:
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- avoid escaping `"` in the JSON file
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- some compilers don't support very long strings
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`lvgl/scripts/filetohex.py` can be used to convert a Lottie file a hex array. E.g.:
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```
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./filetohex.py path/to/lottie.json > out.txt
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```
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To create an animation from raw data:
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```c
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extern const uint8_t lottie_data[];
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lv_obj_t* lottie = lv_rlottie_create_from_raw(parent, width, height, (const char *)lottie_data);
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```
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## Getting animations
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Lottie is standard and popular format so you can find many animation files on the web.
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For example: https://lottiefiles.com/
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You can also create your own animations with Adobe After Effects or similar software.
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## Controlling animations
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LVGL provides two functions to control the animation mode: `lv_rlottie_set_play_mode` and `lv_rlottie_set_current_frame`.
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You'll combine your intentions when calling the first method, like in these examples:
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```c
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lv_obj_t * lottie = lv_rlottie_create_from_file(scr, 128, 128, "test.json");
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lv_obj_center(lottie);
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// Pause to a specific frame
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lv_rlottie_set_current_frame(lottie, 50);
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lv_rlottie_set_play_mode(lottie, LV_RLOTTIE_CTRL_PAUSE); // The specified frame will be displayed and then the animation will pause
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// Play backward and loop
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lv_rlottie_set_play_mode(lottie, LV_RLOTTIE_CTRL_PLAY | LV_RLOTTIE_CTRL_BACKWARD | LV_RLOTTIE_CTRL_LOOP);
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// Play forward once (no looping)
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lv_rlottie_set_play_mode(lottie, LV_RLOTTIE_CTRL_PLAY | LV_RLOTTIE_CTRL_FORWARD);
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```
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The default animation mode is **play forward with loop**.
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If you don't enable looping, a `LV_EVENT_READY` is sent when the animation can not make more progress without looping.
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To get the number of frames in an animation or the current frame index, you can cast the `lv_obj_t` instance to a `lv_rlottie_t` instance and inspect the `current_frame` and `total_frames` members.
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## Example
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```eval_rst
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.. include:: ../../examples/libs/rlottie/index.rst
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```
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## API
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```eval_rst
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.. doxygenfile:: lv_rlottie.h
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:project: lvgl
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