init lvgl code

LVGL.Simulator/lvgl/docs/libs/gif.md

@@ -0,0 +1,43 @@
+```eval_rst
+.. include:: /header.rst
+:github_url: |github_link_base|/libs/gif.md
+```
+
+# GIF decoder
+Allow using GIF images in LVGL. Based on https://github.com/lecram/gifdec
+
+When enabled in `lv_conf.h` with `LV_USE_GIF` `lv_gif_create(parent)` can be used to create a gif widget.
+
+`lv_gif_set_src(obj, src)` works very similarly to `lv_img_set_src`. As source, it also accepts images as variables (`lv_img_dsc_t`) or files.
+
+
+## Convert GIF files to C array
+To convert a GIF file to byte values array use [LVGL's online converter](https://lvgl.io/tools/imageconverter). Select "Raw" color format and "C array" Output format.
+
+
+## Use GIF images from file
+For example:
+```c
+lv_gif_set_src(obj, "S:path/to/example.gif");
+```
+
+Note that, a file system driver needs to be registered to open images from files. Read more about it [here](https://docs.lvgl.io/master/overview/file-system.html) or just enable one in `lv_conf.h` with `LV_USE_FS_...`
+
+
+## Memory requirements
+To decode and display a GIF animation the following amount of RAM is required:
+- `LV_COLOR_DEPTH 8`: 3 x image width x image height
+- `LV_COLOR_DEPTH 16`: 4 x image width x image height
+- `LV_COLOR_DEPTH 32`: 5 x image width x image height
+
+## Example
+```eval_rst
+.. include:: ../../examples/libs/gif/index.rst
+```
+
+## API
+
+```eval_rst
+.. doxygenfile:: lv_gif.h
+  :project: lvgl
+```