lib/gui/lvgl: Add user config file

[krip-tip]

Add custom preferences file, for example
to enable custom fonts and change preferences.

Signed-off-by: Krivorot Oleg [email protected]

[stephanosio]

Please amend commits instead of adding new ones for the changes.

[stephanosio]

https://docs.zephyrproject.org/latest/contribute/index.html#contribution-workflow

Please see #15.

[krip-tip]

https://docs.zephyrproject.org/latest/contribute/index.html#contribution-workflow

Please see #15.

I'm sorry, I think I figured out how to change and not produce commits. This is my first pull request for a large project

[gmarull]

The same behavior can be achieved by setting Kconfig options in prj.conf.

[krip-tip]

The same behavior can be achieved by setting Kconfig options in prj.conf.

This is if you define the standard options in Kconfig. But there are options that need to be written in lv_config.h so that the lvgl library itself can use them. For example, I have not found any other way to completely replace the standard fonts and use several of my fonts in my theme. All of this is simply solved by including an additional header file at the end.
And in the example from lvgl itself, the user's fonts are included in the configuration file.
it will be more difficult to implement the mechanism for connecting fonts via commands in Kconfig.
And in my program self-written lvgl objects are defined. which are also written to the settings file and collected together with the library.

[gmarull]

The same behavior can be achieved by setting Kconfig options in prj.conf.

This is if you define the standard options in Kconfig. But there are options that need to be written in lv_config.h so that the lvgl library itself can use them. For example, I have not found any other way to completely replace the standard fonts and use several of my fonts in my theme. All of this is simply solved by including an additional header file at the end.
And in the example from lvgl itself, the user's fonts are included in the configuration file.
it will be more difficult to implement the mechanism for connecting fonts via commands in Kconfig.
And in my program self-written lvgl objects are defined. which are also written to the settings file and collected together with the library.

There is no need to add an extra header for custom fonts. The auto-generated C font files can be added to the application (target_sources(app PRIVATE my_font.c)) and then you can just use them using LV_FONT_DECLARE(my_font). You can create application level Kconfig options for custom fonts if needed.

[krip-tip]

The same behavior can be achieved by setting Kconfig options in prj.conf.

This is if you define the standard options in Kconfig. But there are options that need to be written in lv_config.h so that the lvgl library itself can use them. For example, I have not found any other way to completely replace the standard fonts and use several of my fonts in my theme. All of this is simply solved by including an additional header file at the end.
And in the example from lvgl itself, the user's fonts are included in the configuration file.
it will be more difficult to implement the mechanism for connecting fonts via commands in Kconfig.
And in my program self-written lvgl objects are defined. which are also written to the settings file and collected together with the library.

There is no need to add an extra header for custom fonts. The auto-generated C font files can be added to the application (target_sources(app PRIVATE my_font.c)) and then you can just use them using LV_FONT_DECLARE(my_font). You can create application level Kconfig options for custom fonts if needed.

I agree with the help of the specified definitions and the indication void * lv_theme_default_font_small_custom_ptr and others, I managed to connect my fonts.
But what cannot be done: connect CONFIG_LVGL_USE_THEME_CUSTOM.
Do you have an example?
defined:

CONFIG_LVGL_USE_THEME_CUSTOM = y
CONFIG_LVGL_THEME_CUSTOM_INIT_FUNCTION = "lv_theme_my_init"

but it fails to compile:

lv_conf.h: 280: 1: error: unknown type name 'lv_theme_t'
   280 | lv_theme_t * LVGL_THEME_CUSTOM_INIT_FUNCTION (

but if in lv_conf.h

#define LV_THEME_DEFAULT_FLAG 0
#define LV_THEME_DEFAULT_INCLUDE <lv_theme_my.h>
#define LV_THEME_DEFAULT_INIT lv_theme_my_init

everything compiles fine.

There is a proposal to modify the connection of a custom theme
I was unable to pass the name of the initialization function from Kconfig, since all text constants are always quoted there when they are passed to autoconf.h

[krip-tip]

and the custom theme through my proposal is connected as a hack, I do not type a custom theme and then redefined the variables :-(
this is not pretty, but it allows you to work until this case is thought out and implemented.

[gmarull]

@oleg-krv you're right, the Kconfig custom options do not work (Kconfig options expand as a string). An issue should be opened to fix/remove that.

What I've done for custom themes in the past is:

1. create a theme using something like https://github.com/lvgl/lvgl/blob/master/src/extra/themes/basic/lv_theme_basic.c
2. Set the theme when app is started, ie

lv_theme_set_act(my_theme_init())

[krip-tip]

@oleg-krv you're right, the Kconfig custom options do not work (Kconfig options expand as a string). An issue should be opened to fix/remove that.

What I've done for custom themes in the past is:

1. create a theme using something like https://github.com/lvgl/lvgl/blob/master/src/extra/themes/basic/lv_theme_basic.c
2. Set the theme when app is started, ie

lv_theme_set_act(my_theme_init())

This can be done, but how to remove the initialization of the standard theme so that it does not take up memory?

Alternative. Replace block:

#if CONFIG_LVGL_USE_THEME_CUSTOM

lv_theme_t *LVGL_THEME_CUSTOM_INIT_FUNCTION(
	lv_color_t color_primary, lv_color_t color_secondary, uint32_t flags,
	const lv_font_t *font_small, const lv_font_t *font_normal,
	const lv_font_t *font_subtitle, const lv_font_t *font_title);

#define LV_THEME_DEFAULT_INIT LVGL_THEME_CUSTOM_INIT_FUNCTION

#endif

to this code:

#if CONFIG_LVGL_USE_THEME_CUSTOM

#define LV_THEME_DEFAULT_FLAG 0
#define LV_THEME_DEFAULT_INCLUDE  CONFIG_LVGL_CUSTOM_THEME_INCLUDE

#ifndef LV_THEME_DEFAULT_INIT
#error "Define LV_THEME_DEFAULT_INIT in CMake or custom theme header file. In the variable, specify the name of the custom theme initialization function."
#endif

#endif

also a hack, but more elegant :-)

[github-actions]

This pull request has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 14 days. Note, that you can always re-open a closed pull request at any time.