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50 lines
1.5 KiB
Markdown
50 lines
1.5 KiB
Markdown
2 years ago
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# Logging
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LVGL has a built-in *Log* module to inform the user about what is happening in the library.
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## Log level
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To enable logging, set `LV_USE_LOG 1` in `lv_conf.h` and set `LV_LOG_LEVEL` to one of the following values:
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- `LV_LOG_LEVEL_TRACE` A lot of logs to give detailed information
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- `LV_LOG_LEVEL_INFO` Log important events
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- `LV_LOG_LEVEL_WARN` Log if something unwanted happened but didn't cause a problem
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- `LV_LOG_LEVEL_ERROR` Only critical issues, where the system may fail
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- `LV_LOG_LEVEL_USER` Only user messages
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- `LV_LOG_LEVEL_NONE` Do not log anything
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The events which have a higher level than the set log level will be logged too. E.g. if you `LV_LOG_LEVEL_WARN`, errors will be also logged.
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## Printing logs
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### Logging with printf
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If your system supports `printf`, you just need to enable `LV_LOG_PRINTF` in `lv_conf.h` to send the logs with `printf`.
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### Custom log function
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If you can't use `printf` or want to use a custom function to log, you can register a "logger" callback with `lv_log_register_print_cb()`.
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For example:
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```c
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void my_log_cb(const char * buf)
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{
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serial_send(buf, strlen(buf));
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}
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...
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lv_log_register_print_cb(my_log_cb);
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```
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## Add logs
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You can also use the log module via the `LV_LOG_TRACE/INFO/WARN/ERROR/USER(text)` or `LV_LOG(text)` functions. Here:
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- `LV_LOG_TRACE/INFO/WARN/ERROR/USER(text)` append following information to your `text`
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- Log Level
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- \_\_FILE\_\_
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- \_\_LINE\_\_
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- \_\_func\_\_
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- `LV_LOG(text)` is similar to `LV_LOG_USER` but has no extra information attached.
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