LVGL 主题

修改样式的一点个人心得

lvgl的样式众多，本人是记不住的，用的时候可以快速查找即可

1. 查看官方例子
   查看官方例子可以快速了解组件的基础样式
   

2. 使用官方的 SquareLineStudio 软件，配置出想要的效果，再生成参考代码

SquareLineStudio 配置界面很是方便，但是奈何UI和其他任务总是分离的不彻底，因此个人习惯只是参考生成的代码，然后利用之前的界面管理工具，为每个界面都创建一个.c文件。

3. 参考 lv_theme_default.c 中 theme_apply 函数的相关部分
   
   

在 lv_port_disp_init 函数中会应用默认的主题，这也是为什么创建出控件时会自带样式。

对对应控件的默认样式进行屏蔽或修改，测试出要修改样式的部分，然后再恢复默认样式，在创建控件后 使用 lv_obj_set_style_xxxx 单独对控件样式进行修改。

通过修改主题，使字体图片选中时反色

有时候需要全局修改某个控件样式，最简单的就是通过主题修改，当然创建控件后进行单独修改也是可以的。

extern const lv_img_dsc_t CS_ImgSignalWifi;
extern const lv_img_dsc_t CS_ImgSignal4g;

static lv_style_t s_style_bg_color;
static lv_style_t s_style_list_color;
static lv_style_t s_style_focus_bg_color;
static lv_style_t s_style_focus_img_color;
static lv_style_t s_style_text_selected_color;


/**
 * @brief 聚焦后改变图片状态 从而改变图片颜色
 * @param e
*/
static void img_focus_event_cb(lv_event_t* e)
{
    lv_obj_t* btn = lv_event_get_target(e);
    lv_event_code_t code = lv_event_get_code(e);

    if (code == LV_EVENT_FOCUSED)
    {
        for (int i = 0; i < lv_obj_get_child_cnt(btn); i++)
        {
            lv_obj_t* obj = lv_obj_get_child(btn, i);
            if (lv_obj_check_type(obj, &lv_img_class))
            {
                lv_obj_add_state(obj, LV_STATE_USER_1);
            }
        }
    }
    else if (code == LV_EVENT_DEFOCUSED)
    {
        for (int i = 0; i < lv_obj_get_child_cnt(btn); i++)
        {
            lv_obj_t* obj = lv_obj_get_child(btn, i);
            if (lv_obj_check_type(obj, &lv_img_class))
            {
                lv_obj_clear_state(obj, LV_STATE_USER_1);
            }
        }
    }
}


/*Will be called when the styles of the base theme are already added
  to add new styles*/
static void new_theme_apply_cb(lv_theme_t* th, lv_obj_t* obj)
{
    LV_UNUSED(th);

    /* 配置下拉列表 主题样式 */
    if (lv_obj_check_type(obj, &lv_dropdown_class)) {
        lv_obj_add_style(obj, &s_style_bg_color, LV_PART_MAIN | LV_STATE_DEFAULT);
        lv_obj_add_style(obj, &s_style_focus_bg_color, LV_PART_MAIN | LV_STATE_FOCUS_KEY);
        lv_obj_add_style(obj, &s_style_focus_bg_color, LV_PART_MAIN | LV_STATE_FOCUSED);
    }

    if (lv_obj_check_type(obj, &lv_dropdownlist_class)) {
        lv_obj_add_style(obj, &s_style_text_selected_color, LV_PART_SELECTED | LV_STATE_CHECKED);
        lv_obj_add_style(obj, &s_style_list_color, LV_PART_MAIN | LV_STATE_DEFAULT);
    }

    /* 配置按键 主题样式 */
    if (lv_obj_check_type(obj, &lv_btn_class))
    {
        /* 选中时样式 */
        lv_obj_add_style(obj, &s_style_focus_bg_color, LV_PART_MAIN | LV_STATE_FOCUS_KEY);
        lv_obj_add_style(obj, &s_style_focus_bg_color, LV_PART_MAIN | LV_STATE_FOCUSED);

        lv_obj_add_style(obj, &s_style_bg_color, LV_PART_MAIN | LV_STATE_DEFAULT);
    }

    /* 配置图片 主题样式 */
    if (lv_obj_check_type(obj, &lv_img_class))
    {
        /* LV_STATE_USER_1 时样式  */
        lv_obj_add_style(obj, &s_style_focus_img_color, LV_PART_MAIN | LV_STATE_USER_1);
    }
}


static lv_obj_t* theme_test(const uint32_t id, void* param)
{
    lv_obj_t* screen = lv_obj_create(NULL);

    lv_disp_t* dispp = lv_disp_get_default();
    lv_theme_t* theme = lv_theme_default_init(dispp, lv_color_hex(0xffff), lv_color_hex(0xffffff), true, &lv_font_montserrat_14);
    lv_disp_set_theme(dispp, theme);

#if 1
    lv_style_init(&s_style_bg_color);
    lv_style_set_bg_color(&s_style_bg_color, lv_color_hex(0x505050));
    lv_style_set_bg_opa(&s_style_bg_color, 255);

    lv_style_init(&s_style_list_color);
    lv_style_set_bg_color(&s_style_list_color, lv_color_hex(0x929495));
    lv_style_set_bg_opa(&s_style_list_color, 255);

    lv_style_init(&s_style_focus_bg_color);
    lv_style_set_bg_color(&s_style_focus_bg_color, lv_color_hex(0xffff));
    lv_style_set_text_color(&s_style_focus_bg_color, lv_color_hex(0));
    lv_style_set_text_opa(&s_style_focus_bg_color, LV_OPA_100);
    lv_style_set_border_width(&s_style_focus_bg_color, 0);
    lv_style_set_outline_pad(&s_style_focus_bg_color, 0);
    lv_style_set_outline_width(&s_style_focus_bg_color, 0);

    lv_style_init(&s_style_focus_img_color);
    lv_style_set_img_recolor(&s_style_focus_img_color, lv_color_hex(0x0));
    lv_style_set_img_recolor_opa(&s_style_focus_img_color, LV_OPA_100);

    lv_style_init(&s_style_text_selected_color);
    lv_style_set_text_color(&s_style_text_selected_color, lv_color_hex(0));

    lv_theme_t* th_act = lv_disp_get_theme(NULL);
    static lv_theme_t th_new;
    th_new = *th_act;

    /*Set the parent theme and the style apply callback for the new theme*/
    lv_theme_set_parent(&th_new, th_act);
    lv_theme_set_apply_cb(&th_new, new_theme_apply_cb);

    /*Assign the new theme the the current display*/
    lv_disp_set_theme(NULL, &th_new);

#endif

    lv_obj_t* dropdown = lv_dropdown_create(screen);
    
    lv_dropdown_set_options(dropdown, "Apple\n"
        "Banana\n"
        "Orange\n"
        "Cherry\n"
        "Grape\n"
        "Raspberry\n"
        "Melon\n"
        "Orange\n"
        "Lemon\n"
        "Nuts");

    lv_obj_align(dropdown, LV_ALIGN_TOP_MID, 0, 100);

    {
        lv_obj_t* btn = lv_btn_create(screen);
        lv_obj_align(btn, LV_ALIGN_TOP_MID, -100, 20);
        lv_obj_set_size(btn, 100, 40);
        lv_obj_add_event_cb(btn, img_focus_event_cb, LV_EVENT_ALL, NULL);

        lv_obj_t* lab = lv_label_create(btn);
        lv_label_set_text(lab, "btn1");
        lv_obj_align(lab, LV_ALIGN_RIGHT_MID, 0, 0);

        lv_obj_t* img = lv_img_create(btn);
        lv_img_set_src(img, &CS_ImgSignalWifi);
        lv_obj_align(img, LV_ALIGN_LEFT_MID, 0, 0);
    }

    {
        lv_obj_t* btn = lv_btn_create(screen);
        lv_obj_align(btn, LV_ALIGN_TOP_MID, 100, 20);
        lv_obj_set_size(btn, 100, 40);
        lv_obj_add_event_cb(btn, img_focus_event_cb, LV_EVENT_ALL, NULL);

        lv_obj_t* lab = lv_label_create(btn);
        lv_label_set_text(lab, "btn2");
        lv_obj_align(lab, LV_ALIGN_RIGHT_MID, 0, 0);

        lv_obj_t* img = lv_img_create(btn);
        lv_img_set_src(img, &CS_ImgSignal4g);
        lv_obj_align(img, LV_ALIGN_LEFT_MID, 0, 0);
    }
    return screen;
}

想要图片选中反色，需要使用.png图片，在官网 转换时转换为带透明通道格式的