static lv_style_t style_btn;
static lv_style_t style_btn_pressed;
static lv_style_t style_btn_red;static lv_color_t darken(const lv_color_filter_dsc_t * dsc, lv_color_t color, lv_opa_t opa)
{LV_UNUSED(dsc);return lv_color_darken(color, opa);  //使能变暗 
}static void style_init(void)
{/*Create a simple button style*/lv_style_init(&style_btn);lv_style_set_radius(&style_btn, 10);    //圆角 lv_style_set_bg_opa(&style_btn, LV_OPA_COVER);  // 设置透明度lv_style_set_bg_color(&style_btn, lv_palette_lighten(LV_PALETTE_GREY, 3));  //背景色lv_style_set_bg_grad_color(&style_btn, lv_palette_main(LV_PALETTE_GREY)); //渐变lv_style_set_bg_grad_dir(&style_btn, LV_GRAD_DIR_VER); //渐变 方向 垂直lv_style_set_border_color(&style_btn, lv_color_black());  //相框色lv_style_set_border_opa(&style_btn, LV_OPA_20);  lv_style_set_border_width(&style_btn, 2);lv_style_set_text_color(&style_btn, lv_color_black());/*Create a style for the pressed state.*Use a color filter to simply modify all colors in this state*/static lv_color_filter_dsc_t color_filter;  //颜色过滤器lv_color_filter_dsc_init(&color_filter, darken); //初始化 过滤器lv_style_init(&style_btn_pressed);  //初始化 按下 格式lv_style_set_color_filter_dsc(&style_btn_pressed, &color_filter);// 设置 按下过滤器格式lv_style_set_color_filter_opa(&style_btn_pressed, LV_OPA_20);/*Create a red style. Change only some colors.*/lv_style_init(&style_btn_red);lv_style_set_bg_color(&style_btn_red, lv_palette_main(LV_PALETTE_RED));lv_style_set_bg_grad_color(&style_btn_red, lv_palette_lighten(LV_PALETTE_RED, 3));
}/*** Create styles from scratch for buttons.*/
void btn_filter_demo(void)
{/*Initialize the style*/style_init();/*Create a button and use the new styles*/lv_obj_t * btn = lv_btn_create(lv_scr_act());/* Remove the styles coming from the theme* Note that size and position are also stored as style properties* so lv_obj_remove_style_all will remove the set size and position too */lv_obj_remove_style_all(btn);lv_obj_set_pos(btn, 100, 100);lv_obj_set_size(btn, 60, 40);lv_obj_add_style(btn, &style_btn, 0);lv_obj_add_style(btn, &style_btn_pressed, LV_STATE_PRESSED);/*Add a label to the button*/lv_obj_t * label = lv_label_create(btn);lv_label_set_text(label, "b1");lv_obj_center(label);/*Create another button and use the red style too*/lv_obj_t * btn2 = lv_btn_create(lv_scr_act());lv_obj_remove_style_all(btn2);                      /*Remove the styles coming from the theme*/lv_obj_set_pos(btn2, 60, 100);lv_obj_set_size(btn2, 60, 40);lv_obj_add_style(btn2, &style_btn, 0);lv_obj_add_style(btn2, &style_btn_red, 0);lv_obj_add_style(btn2, &style_btn_pressed, LV_STATE_PRESSED);lv_obj_set_style_radius(btn2, LV_RADIUS_CIRCLE, 0); /*Add a local style too*/label = lv_label_create(btn2);lv_label_set_text(label, "b2");lv_obj_center(label);
}