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chore(docs): fix heading levels in micropython.md

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Gabor Kiss-Vamosi
2022-11-05 18:29:00 +01:00
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docs/get-started/bindings/micropython.md
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@@ -99,12 +99,12 @@ lv_micropython already contains these drivers:
- At Micropython: [docs](http://docs.micropython.org/en/latest/) and [forum](https://forum.micropython.org/) - At Micropython: [docs](http://docs.micropython.org/en/latest/) and [forum](https://forum.micropython.org/)
- [Blog Post](https://blog.lvgl.io/2019-02-20/micropython-bindings), a little outdated. - [Blog Post](https://blog.lvgl.io/2019-02-20/micropython-bindings), a little outdated.
# The Micropython Binding is auto generated! ## The Micropython Binding is auto generated!
LVGL is a git submodule inside [lv_micropython](https://github.com/lvgl/lv_micropython) (LVGL is a git submodule of [lv_binding_micropython](https://github.com/lvgl/lv_binding_micropython) which is itself a submodule of [lv_micropython](https://github.com/lvgl/lv_micropython)). LVGL is a git submodule inside [lv_micropython](https://github.com/lvgl/lv_micropython) (LVGL is a git submodule of [lv_binding_micropython](https://github.com/lvgl/lv_binding_micropython) which is itself a submodule of [lv_micropython](https://github.com/lvgl/lv_micropython)).
When building lv_micropython, the public LVGL C API is scanned and Micropython API is auto-generated. That means that lv_micropython provides LVGL API for **any** LVGL version, and generally does not require code changes as LVGL evolves. When building lv_micropython, the public LVGL C API is scanned and Micropython API is auto-generated. That means that lv_micropython provides LVGL API for **any** LVGL version, and generally does not require code changes as LVGL evolves.
## LVGL C API Coding Conventions ### LVGL C API Coding Conventions
To support the auto-generation of the Python API, the LVGL C API must follow some coding conventions: To support the auto-generation of the Python API, the LVGL C API must follow some coding conventions:
@@ -124,7 +124,7 @@ To support the auto-generation of the Python API, the LVGL C API must follow som
Most of these rules are simple and straightforward but there are two related concepts that worth a deeper look: **Memory Management** and **Callbacks**. Most of these rules are simple and straightforward but there are two related concepts that worth a deeper look: **Memory Management** and **Callbacks**.
## Memory Management ### Memory Management
When LVGL runs in Micropython, all dynamic memory allocations (`lv_malloc`) are handled by Micropython's memory manager which is [garbage-collected](https://en.wikipedia.org/wiki/Garbage_collection_(computer_science)) (GC). When LVGL runs in Micropython, all dynamic memory allocations (`lv_malloc`) are handled by Micropython's memory manager which is [garbage-collected](https://en.wikipedia.org/wiki/Garbage_collection_(computer_science)) (GC).
To prevent GC from collecting memory prematurely, all dynamic allocated RAM must be reachable by GC. To prevent GC from collecting memory prematurely, all dynamic allocated RAM must be reachable by GC.
@@ -135,26 +135,26 @@ GC is aware of most allocations, except from pointers on the [Data Segment](http
Such pointers need to be defined in a special way to make them reachable by GC Such pointers need to be defined in a special way to make them reachable by GC
### Identify The Problem #### Identify The Problem
Problem happens when an allocated memory's pointer (return value of `lv_malloc`) is stored only in either **global**, **static global** or **static local** pointer variable and not as part of a previously allocated `struct` or other variable. Problem happens when an allocated memory's pointer (return value of `lv_malloc`) is stored only in either **global**, **static global** or **static local** pointer variable and not as part of a previously allocated `struct` or other variable.
### Solve The Problem #### Solve The Problem
- Replace the global/static local var with `LV_GC_ROOT(_var)` - Replace the global/static local var with `LV_GC_ROOT(_var)`
- Include `lv_gc.h` on files that use `LV_GC_ROOT` - Include `lv_gc.h` on files that use `LV_GC_ROOT`
- Add `_var` to `LV_ITERATE_ROOTS` on `lv_gc.h` - Add `_var` to `LV_ITERATE_ROOTS` on `lv_gc.h`
### Example #### Example
https://github.com/lvgl/lvgl/commit/adced46eccfa0437f84aa51aedca4895cc3c679c https://github.com/lvgl/lvgl/commit/adced46eccfa0437f84aa51aedca4895cc3c679c
### More Information #### More Information
- [In the README](https://github.com/lvgl/lv_binding_micropython#memory-management) - [In the README](https://github.com/lvgl/lv_binding_micropython#memory-management)
- [In the Blog](https://blog.lvgl.io/2019-02-20/micropython-bindings#i-need-to-allocate-a-littlevgl-struct-such-as-style-color-etc-how-can-i-do-that-how-do-i-allocatedeallocate-memory-for-it) - [In the Blog](https://blog.lvgl.io/2019-02-20/micropython-bindings#i-need-to-allocate-a-littlevgl-struct-such-as-style-color-etc-how-can-i-do-that-how-do-i-allocatedeallocate-memory-for-it)
## Callbacks ### Callbacks
In C a callback is just a function pointer. In C a callback is just a function pointer.
But in Micropython we need to register a *Micropython callable object* for each callback. But in Micropython we need to register a *Micropython callable object* for each callback.
@@ -179,14 +179,14 @@ There are a few options for defining a callback in LVGL C API:
In practice it's also possible to mix these options, for example provide a struct pointer when registering a callback (option 1) and provide `user_data` argument when calling the callback (options 2), **as long as the same `user_data` that was registered is passed to the callback when it's called**. In practice it's also possible to mix these options, for example provide a struct pointer when registering a callback (option 1) and provide `user_data` argument when calling the callback (options 2), **as long as the same `user_data` that was registered is passed to the callback when it's called**.
### Examples #### Examples
- [lv_anim_t](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L73-L100) contains `user_data` field. - [lv_anim_t](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L73-L100) contains `user_data` field.
[lv_anim_set_path_cb](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L197) registers `path_cb` callback. Both `lv_anim_set_path_cb` and [`lv_anim_path_cb_t`](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L46) recieve `lv_anim_t` as their first argument [lv_anim_set_path_cb](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L197) registers `path_cb` callback. Both `lv_anim_set_path_cb` and [`lv_anim_path_cb_t`](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L46) recieve `lv_anim_t` as their first argument
- [`path_cb` field](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L83) can also be assigned directly in the Python code because it's a member of `lv_anim_t` which contains `user_data` field, and [`lv_anim_path_cb_t`](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L46) recieve `lv_anim_t` as its first argument. - [`path_cb` field](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L83) can also be assigned directly in the Python code because it's a member of `lv_anim_t` which contains `user_data` field, and [`lv_anim_path_cb_t`](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/misc/lv_anim.h#L46) recieve `lv_anim_t` as its first argument.
- [`lv_imgfont_create`](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/others/imgfont/lv_imgfont.h#L43) registers `path_cb` and recieves `user_data` as the last argument. The callback [`lv_imgfont_get_path_cb_t`](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/others/imgfont/lv_imgfont.h#L29-L31) also receieves the `user_data` as the last argument. - [`lv_imgfont_create`](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/others/imgfont/lv_imgfont.h#L43) registers `path_cb` and recieves `user_data` as the last argument. The callback [`lv_imgfont_get_path_cb_t`](https://github.com/lvgl/lvgl/blob/5d50fbc066938d1a4eb43a8366cf83fbd4ce29f2/src/others/imgfont/lv_imgfont.h#L29-L31) also receieves the `user_data` as the last argument.
### More Information #### More Information
- In the [Blog](https://blog.lvgl.io/2019-08-05/micropython-pure-display-driver#using-callbacks) and in the [README](https://github.com/lvgl/lv_binding_micropython#callbacks) - In the [Blog](https://blog.lvgl.io/2019-08-05/micropython-pure-display-driver#using-callbacks) and in the [README](https://github.com/lvgl/lv_binding_micropython#callbacks)
- [[v6.0] Callback conventions #1036](https://github.com/lvgl/lvgl/issues/1036) - [[v6.0] Callback conventions #1036](https://github.com/lvgl/lvgl/issues/1036)