一般来讲下载了 https://github.com/lvgl/lvgl.git 就能够使用文件系统了,不需要额外下载lv_fs_if那个代码。
参考lvgl/examples/porting目录下的lv_port_fs_template.c文件实现各种方法即可。
static lv_fs_res_t open_cb(struct _lv_fs_drv_t * drv, void * file_p, const char * path, lv_fs_mode_t mode)
{
(void) drv;
//ESP_LOGI(TAG, "lvgl open file: path=%s mode=%d", path, mode);
FILE *fp = NULL;
if (mode == LV_FS_MODE_RD) {
fp = fopen(path, "rb"); // only reading is supported
} else if (mode == LV_FS_MODE_WR) {
fp = fopen(path, "wb");
} else {
ESP_LOGE(TAG, "lvfs open mode error!");
return LV_FS_RES_UNKNOWN;
}
*((FILE **)file_p) = fp;
return NULL == fp ? LV_FS_RES_UNKNOWN : LV_FS_RES_OK;
}
static lv_fs_res_t close_cb(struct _lv_fs_drv_t * drv, void * file_p)
{
(void) drv;
FILE * fp = *((FILE **) file_p);
fclose(fp);
return LV_FS_RES_OK;
}
static lv_fs_res_t read_cb(struct _lv_fs_drv_t * drv, void * file_p, void * buf, uint32_t btr, uint32_t * br)
{
(void) drv;
FILE * fp = *((FILE **) file_p);
*br = fread(buf, 1, btr, fp);
return (*br <= 0) ? LV_FS_RES_UNKNOWN : LV_FS_RES_OK;
}
static lv_fs_res_t write_cb(struct _lv_fs_drv_t * drv, void * file_p, const void * buf, uint32_t btw, uint32_t * bw)
{
(void)drv;
FILE * fp = *((FILE **) file_p);
*bw = fwrite(buf, 1, btw, fp);
return (*bw != btw) ? LV_FS_RES_UNKNOWN : LV_FS_RES_OK;
}
static lv_fs_res_t seek_cb(struct _lv_fs_drv_t * drv, void * file_p, uint32_t pos)
{
(void) drv;
//printf("--->fs seek\r\n");
FILE * fp = *((FILE **) file_p);
fseek (fp, pos, SEEK_SET);
return LV_FS_RES_OK;
}
static lv_fs_res_t tell_cb(struct _lv_fs_drv_t * drv, void * file_p, uint32_t * pos_p)
{
(void) drv;
FILE * fp = *((FILE **) file_p);
*pos_p = ftell(fp);
return LV_FS_RES_OK;
}
static bool ready_cb(struct _lv_fs_drv_t * drv)
{
(void) drv;
return true;
}
static lv_fs_res_t size_cb(struct _lv_fs_drv_t * drv, void * file_p, uint32_t * size_p)
{
(void)drv;
FILE * fp = *((FILE **) file_p);
uint32_t curpos, length;
curpos = ftell(fp);
fseek(fp, 0L, SEEK_END);
length = ftell(fp);
fseek(fp, curpos, SEEK_SET);
*size_p = length;
return LV_FS_RES_OK;
}
在lvgl_init初始化之后需要调用注册函数将以上定义的接口注册到lvgl系统中
lv_fs_drv_t drv;
lv_fs_drv_init(&drv); /*Basic initialization*/
drv.letter = 'S'; /*An uppercase letter to identify the drive */
drv.file_size = sizeof(FILE *); /*Size required to store a file object*/
drv.ready_cb = ready_cb; /*Callback to tell if the drive is ready to use */
drv.open_cb = open_cb; /*Callback to open a file */
drv.close_cb = close_cb; /*Callback to close a file */
drv.read_cb = read_cb; /*Callback to read a file */
drv.write_cb = write_cb;
drv.seek_cb = seek_cb; /*Callback to seek in a file (Move cursor) */
drv.tell_cb = tell_cb; /*Callback to tell the cursor position */
drv.size_cb = size_cb;
lv_fs_drv_register(&drv); /*Finally register the drive*/
在调用lv_fs_open的时候需要注意一下文件的开始是"S:"
比如我们在spiffs中保存的文件路径为"/spiffs/image.bin",那么使用lvgl_fs_open的时候输入的文件路径就需要是"S:/spiffs/image.bin",这样才能正确的寻找到文件。
以上就是在lvgl中使用文件系统的简单记录。