LVGL，解决画面切换慢的问题（lvgl画面好卡）

在Linux嵌入式设备上，界面滚动和tabview页签切换时，画面就像慢动作，定位是和LVGL的心跳设置有关：

改动前在main函数里是这样的，使用lv_tick_inc(5);作为心跳，这样的话，会影响心跳效果，数值不准确：

/*Handle LitlevGL tasks (tickless mode)*/

while(1) {

lv_tick_inc(5);

lv_task_handler();

usleep(5000);

}

需要自定义自己的心跳函数：

/*Set in lv_conf.h as `LV_TICK_CUSTOM_SYS_TIME_EXPR`*/

uint32_t custom_tick_get(void)

{

static uint64_t start_ms = 0;

if(start_ms == 0) {

struct timeval tv_start;

gettimeofday(&tv_start, NULL);

start_ms = (tv_start.tv_sec * 1000000 + tv_start.tv_usec) / 1000;

}
struct timeval tv_now;

gettimeofday(&tv_now, NULL);

uint64_t now_ms;

now_ms = (tv_now.tv_sec * 1000000 + tv_now.tv_usec) / 1000;
uint32_t time_ms = now_ms - start_ms;

return time_ms;

}

然后在lv.conf.h里要使能：

uint32_t custom_tick_get(void);

#define LV_TICK_CUSTOM 1

#if LV_TICK_CUSTOM

#define LV_TICK_CUSTOM_INCLUDE <stdint.h> /*Header for the system time function*/

#define LV_TICK_CUSTOM_SYS_TIME_EXPR (custom_tick_get()) /*Expression evaluating to current system time in ms*/

#endif /*LV_TICK_CUSTOM*/

这样修改完后，显示效果就很快，很流畅了。