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124 lines
4.3 KiB
Markdown
124 lines
4.3 KiB
Markdown
# Coding style
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## File format
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Use [misc/lv_templ.c](https://github.com/lvgl/lvgl/blob/master/src/misc/lv_templ.c) and [misc/lv_templ.h](https://github.com/lvgl/lvgl/blob/master/src/misc/lv_templ.h)
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## Naming conventions
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* Words are separated by '_'
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* In variable and function names use only lower case letters (e.g. *height_tmp*)
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* In enums and defines use only upper case letters (e.g. *e.g. MAX_LINE_NUM*)
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* Global names (API):
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* start with *lv*
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* followed by module name: *btn*, *label*, *style* etc.
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* followed by the action (for functions): *set*, *get*, *refr* etc.
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* closed with the subject: *name*, *size*, *state* etc.
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* Typedefs
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* prefer `typedef struct` and `typedef enum` instead of `struct name` and `enum name`
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* always end `typedef struct` and `typedef enum` type names with `_t`
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* Abbreviations:
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* Only words longer or equal than 6 characters can be abbreviated.
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* Abbreviate only if it makes the word at least half as long
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* Use only very straightforward and well-known abbreviations (e.g. pos: position, def: default, btn: button)
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## Coding guide
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* Functions:
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* Try to write function shorter than is 50 lines
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* Always shorter than 200 lines (except very straightforwards)
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* Variables:
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* One line, one declaration (BAD: char x, y;)
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* Use `<stdint.h>` (*uint8_t*, *int32_t* etc)
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* Declare variables where needed (not all at function start)
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* Use the smallest required scope
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* Variables in a file (outside functions) are always *static*
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* Do not use global variables (use functions to set/get static variables)
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## Comments
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Before every function have a comment like this:
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```c
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/**
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* Return with the screen of an object
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* @param obj pointer to an object
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* @return pointer to a screen
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*/
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lv_obj_t * lv_obj_get_scr(lv_obj_t * obj);
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```
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Always use `/*Something*/` format and NOT `//Something`
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Write readable code to avoid descriptive comments like:
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`x++; /*Add 1 to x*/`.
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The code should show clearly what you are doing.
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You should write **why** have you done this:
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`x++; /*Because of closing '\0' of the string*/`
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Short "code summaries" of a few lines are accepted. E.g. `/*Calculate the new coordinates*/`
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In comments use \` \` when referring to a variable. E.g. ``/*Update the value of `x_act`*/``
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### Formatting
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Here is example to show bracket placing and using of white spaces:
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```c
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/**
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* Set a new text for a label. Memory will be allocated to store the text by the label.
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* @param label pointer to a label object
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* @param text '\0' terminated character string. NULL to refresh with the current text.
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*/
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void lv_label_set_text(lv_obj_t * label, const char * text)
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{ /*Main brackets of functions in new line*/
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if(label == NULL) return; /*No bracket only if the command is inline with the if statement*/
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lv_obj_inv(label);
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lv_label_ext_t * ext = lv_obj_get_ext(label);
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/*Comment before a section*/
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if(text == ext->txt || text == NULL) { /*Bracket of statements start inline*/
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lv_label_refr_text(label);
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return;
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}
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...
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}
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```
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Use 4 spaces indentation instead of tab.
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You can use **astyle** to format the code. Run `code-formatter.sh` from the `scrips` folder.
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#### pre-commit
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[pre-commit](https://pre-commit.com/) is a multi-language package manager for pre-commit hooks.
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See the [instalation guide](https://pre-commit.com/#installation) to get pre-commit python package
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installed into your development machine.
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Once you have `pre-commit` installed you will need to [set up the git hook scripts](https://pre-commit.com/#3-install-the-git-hook-scripts) with:
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```console
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pre-commit install
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```
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now `pre-commit` will run automatically on `git commit`!
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##### Hooks
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The `format-source` local hook (see `.pre-commit-config.yaml`) runs **astyle** on all the staged source and header
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files (that are not excluded, see `exclude` key of the hook configuration) before entering the commit message,
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if any file gets formatted by **astyle** you will need to add the change to the staging area and run `git commit` again.
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The `trailing-whitespace` hook fixes trailing whitespaces on all of the files.
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##### Skipping hooks
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If you want to skip any particular hook you can do so with:
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```console
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SKIP=name-of-the-hook git commit
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```
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##### Testing hooks
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It's no necessary to do a commit to test the hooks, you can test hooks by adding the files into the staging area and run:
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```console
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pre-commit run name-of-the-hook
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``` |