lv_obj_set_property() with selector

[hyansuper]

Introduce the problem

can I set property for different state/part with code described in https://docs.lvgl.io/master/others/obj_property.html#a-step-further.
for example, I want to specify PART_INDECATOR color property in the array, how to do it?

Proposal

No response

[hyansuper]

Oh, I think I figure it out:

lv_property_t props[] = {
    { .id = LV_STYLE_BG_COLOR | LV_PART_INDICATOR, .color = (lv_color_t){.red = 0x11, .green = 0x22, .blue = 0x33}, },
}

LV_OBJ_SET_PROPERTY_ARRAY(obj, props);

This is really neat!

[hyansuper]

There's a small error:
LV_PROPERTY_ID_BUILTIN_LAST should be larger than LV_PROPERTY_IMAGE_END

[kisvegabor]

Hi @hyansuper,

Thanks you for opening this issue.

LV_STYLE_BG_COLOR | LV_PART_INDICATOR

I can't see in the code where/why it should work. See here.

@XuNeo Is the set_property feature still interesting for you? If so we can plan to finish it and make it more compete.

[hyansuper]

LV_STYLE_BG_COLOR | LV_PART_INDICATOR

my mistake, that won't work😂

[XuNeo]

I have looked into the issue, and found out no easy solution. Let's discuss.
There are two main solutions.

1. add selector to all property APIs. There could be requirement to specify selector in a const property array. Thus it may also required to add selector field in lv_property_t.
   Note that selector is only used when id is style ID.

typedef struct {
    lv_prop_id_t id;                /**< property ID, includes style ID(lv_style_prop_t) and widgets property ID.*/
    lv_style_selector_t selector;   /**< style selector, only used for when id is style ID*/
    union {
        int32_t num;                /**< Number integer number (opacity, enums, booleans or "normal" numbers)*/
        const void * ptr;           /**< Constant pointers  (font, cone text, etc)*/
        lv_color_t color;           /**< Colors*/
        lv_value_precise_t precise; /**< float or int for precise value*/
        lv_style_value_t _style;    /**< A place holder for style value which is same as property value.*/
    };
} lv_property_t;

lv_result_t lv_obj_set_property(lv_obj_t * obj, const lv_property_t * value, lv_style_selector_t selector);
lv_property_t lv_obj_get_property(lv_obj_t * obj, lv_prop_id_t id, lv_style_selector_t selector);

2. Remove style ID support from property API, lv_obj_set_local_style_prop can be used directly. Widget general properties and styles are two categories and they deserve two sets of API.

lv_result_t lv_obj_set_property(lv_obj_t * obj, const lv_property_t * value);
void lv_obj_set_local_style_prop(lv_obj_t * obj, lv_style_prop_t prop, lv_style_value_t value,
                                 lv_style_selector_t selector);

I vote for 2, since mixing them looks really neat.

Oh, I think I figure it out:

lv_property_t props[] = {
    { .id = LV_STYLE_BG_COLOR | LV_PART_INDICATOR, .color = (lv_color_t){.red = 0x11, .green = 0x22, .blue = 0x33}, },
}

LV_OBJ_SET_PROPERTY_ARRAY(obj, props);

This is really neat!

[hyansuper]

lv_property_t props[] = {
{ .id = LV_STYLE_BG_COLOR | LV_PART_INDICATOR, .color = (lv_color_t){.red = 0x11, .green = 0x22, .blue = 0x33}, },
}

Do you mean to make this usable?
I like this solution too, you already mixed data type into id by bitwise operation, we can also mix in selectors

Widget general properties and styles are two categories and they deserve two sets of API.

I am not sure, is label_long_mode considered a property or a style? to me it controls how label looks, just like label size.

[XuNeo]

you already mixed data type into id by bitwise operation, we can also mix in selectors

The issue is that selector is 32bit long(state + part). So id alone is not enough.

I am not sure, is label_long_mode considered a property or a style? to me it controls how label looks, just like label size.

It feels like style is a special property one widget can have. Widget can also have normal properties like label long mode etc.

Do you mean to make this usable?

I mean that we should drop style prop ID support from API lv_obj_set_property and call lv_obj_set_local_style_prop (with some helpers) if you want to set a style value.

[hyansuper]

Hi @XuNeo , I hope you keep the property API that unifies style and properties.

It's ok if selectors can't be used. I can add 'LV_PROPERTY_BAR_INDICATOR_COLOR' if I need it. just like you did in lv_image.c.

With lv_obj_set_property(), I can make my device swap UI easily by parsing a portable bin file that contains a list of property id-value pairs.

[lvgl-bot]

We need some feedback on this issue.

Now we mark this as "stale" because there was no activity here for 14 days.

Remove the "stale" label or comment else this will be closed in 7 days.

[XuNeo]

Not stale.

Hi @kisvegabor ,

What do you think of adding selector filed to property struct and APIs?

[XuNeo]

Hi @XuNeo , I hope you keep the property API that unifies style and properties.

Since style is a special property, how about change the value of property for style, to include state and part selectors?

typedef struct {
    lv_prop_id_t id;
    union {
        int32_t num;                /**< Number integer number (opacity, enums, booleans or "normal" numbers)*/
        const void * ptr;           /**< Constant pointers  (font, cone text, etc)*/
        lv_color_t color;           /**< Colors*/
        lv_value_precise_t precise; /**< float or int for precise value*/
        struct {
            uint32_t selector;
            lv_style_value_t _style;
        } style;
    };
} lv_property_t;

The struct size will 4bytes longer of cause.

[hyansuper]

Sounds good to me😃