can only be set in the constructor
just there for back-compat, hide
is an input argument (one we depend on)
the input argument will be modified
no flags
is an output argument (depends on us)
must be set in the constructor
don't do use-before-set checks
can only be set once
Flags we associate with each object argument.
Have separate input & output flags. Both set is an error; neither set is OK.
Input gobjects are automatically reffed, output gobjects automatically ref us. We also automatically watch for "destroy" and unlink.
VIPS_ARGUMENT_SET_ALWAYSis handy for arguments which are set from C. For example, VipsImage::width is a property that gives access to the Xsize member of struct _VipsImage. We default its 'assigned' to TRUE since the field is always set directly by C.VIPS_ARGUMENT_DEPRECATEDarguments are not shown in help text, are not looked for if required, are not checked for "have-been-set". You can deprecate a required argument, but you must obviously add a new required argument if you do.Input args with
VIPS_ARGUMENT_MODIFYwill be modified by the operation. This is used for things like the in-place drawing operations.