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74 lines
1.8 KiB
ReStructuredText
74 lines
1.8 KiB
ReStructuredText
.. _logging:
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=======
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Logging
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=======
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LVGL has a built-in *Log* module to inform the user about what is
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happening in the library.
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Log Level
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*********
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To enable logging, set :c:macro:`LV_USE_LOG` in ``lv_conf.h`` and set
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:c:macro:`LV_LOG_LEVEL` to one of the following values:
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- :c:macro:`LV_LOG_LEVEL_TRACE`: A lot of logs to give detailed information
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- :c:macro:`LV_LOG_LEVEL_INFO`: Log important events
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- :c:macro:`LV_LOG_LEVEL_WARN`: Log if something unwanted happened but didn't cause a problem
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- :c:macro:`LV_LOG_LEVEL_ERROR`: Only critical issues, where the system may fail
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- :c:macro:`LV_LOG_LEVEL_USER`: Only user messages
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- :c:macro:`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
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as well. E.g. if you :c:macro:`LV_LOG_LEVEL_WARN`, errors will be also logged.
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Printing Logs
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*************
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Logging with printf
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-------------------
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If your system supports ``printf``, you just need to enable
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:c:macro:`LV_LOG_PRINTF` in ``lv_conf.h`` to send the logs with ``printf``.
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Custom log function
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-------------------
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If you can't use ``printf`` or want to use a custom function to log, you
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can register a "logger" callback with :cpp:func:`lv_log_register_print_cb`.
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For example:
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.. code-block:: c
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void my_log_cb(lv_log_level_t level, 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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Add Logs
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********
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You can also use the log module via the
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``LV_LOG_TRACE/INFO/WARN/ERROR/USER(text)`` or ``LV_LOG(text)``
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functions. Here:
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- ``LV_LOG_TRACE/INFO/WARN/ERROR/USER(text)`` append the 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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API
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***
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