52 CONTENTS
• Please note that each setting location step in the figure from above internally contains two search steps. First
the framework will try to locate a setting with user scope and if this can't be located, the same setting will be
searched with global (system-wide) scope. Under Windows® this e.g. will access either the HKEY_CURR←-
ENT_USER or (in the second step) the HKEY_LOCAL_MACHINE branch in the Registry.
• Whenever storing a product specific setting, the device specific setting of the device used for storing will be
deleted (if existing). So when the user is currently working with a device 'VD000001' belonging to the product
group 'VirtualDevice' and there is a setting exclusively for this device storing a product specific setting now will
automatically delete the setting for 'VD000001'. Otherwise a product specific setting would never be loaded
as a device specific setting will always be found first.
• The very same thing will also happen when opening a device from any other application! wxPropView (p. 74)
does not behave in a special way but only acts as an arbitrary user application.
• Whenever storing a device family specific setting, the device specific or product specific setting of the device
used for storing will be deleted (if existing). See above to find out why.
• Under Windows® the driver will not look for a matching XML file during start-up automatically as the native
storage location for settings is the Windows® Registry. This must be loaded explicitly by the user by using
the appropriate API function offered by the SDK. However, under Linux XML files are the only setting formats
understood by the driver framework thus here the driver will also look for them at start-up. The device specific
setting will be an XML file with the serial number of the device as the file name, the product specific setting
will be an XML file with the product string as the filename, the device family specific setting will be an XML
file with the device family name as the file name. All other XML files containing settings will be ignored!
• Only the data contained in the lists displayed as
– "Image Setting",
– "Digital I/O", and
– "Device Specific Data" under wxPropView (p. 74) will be stored in these settings!
• Restoring of settings previously stored works in a similar way. After a device has been opened the settings
will be loaded automatically as described above.
• A detailed description of the individual properties offered by a device will not be provided here but can be
found in the C++ API reference, where descriptions for all properties relevant for the user (grouped together in
classes sorted by topic) can be found. As wxPropView (p. 74) doesn't introduce new functionality but simply
evaluates the list of features offered by the device driver and lists them any modification made using the GUI
controls just calls the underlying function needed to write to the selected component. wxPropView (p. 74)
also doesn't know about the type of component or e.g. the list of allowed values for a property. This again is
information delivered by the driver and therefore can be queried by the user as well without the need to have
special inside information. One version of the tool will always be delivered in source so it can be used as a
reference to find out how to get the desired information from the device driver.
MATRIX VISION GmbH
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