Apple Newton Programmer’s Newton 2.0 (for Newton 2.0) - Manual (Page 385)

C H A P T E R 1 0
Recognition: Advanced Topics
Using Advanced Topics in Recognition 10-9
Creating a recConfig Frame 10
For any view that is to use a recConfig frame, you must supply a recConfig
slot, usually by defining it in your view’s template. The frame in your view’s
recConfig slot must be modifiable; that is, it must be RAM-based. When your
view template supplies a recConfig frame, the view system builds a RAM-based
recConfig frame along with the view—you need not do anything more to cause
the view to use the recConfig frame.
To create your own recConfig frame at run time, you need to call the
PrepRecConfig function to create a RAM-based recConfig frame that the
system can use. Although you could obtain similar results by cloning a
recConfig frame that your view template defines, using the PrepRecConfig
function is more efficient:
■ The PrepRecConfig function creates a smaller frame than that obtained by
cloning your view template’s recConfig frame.
■ The frame that the PrepRecConfig function returns can be used as it is by the
recognition system. Any other frame that you place in the view’s recConfig
slot is used by the system to create the recConfig frame actually used by the
view, with the result being the creation of two frames in RAM rather than just one.
■ Consistent use of this function to create recConfig frames saves RAM by
permitting similar recConfig frames to share the same frame map.
A function similar to the PrepRecConfig function, the BuildRecConfig
function, is provided for debugging use. Do not use the BuildRecConfig
function to create your RAM-based recConfig frame. The argument to the
BuildRecConfig function is the view itself, rather than its recConfig frame.
This function builds an appropriate recConfig frame for the specified view,
regardless of whether the view defines one. The system does not use the
recConfig frame that this function returns, however—as stated previously, this
frame is for debugging use only.
IMPORTANT
The contents of the inputMask slot in the view’s recConfig
frame must match the input mask (the recognition-related bits)
provided by the view’s
viewFlags slot. For more information on
this slot and others that the recConfig frame may contain, see
“protoRecConfig” (page 8-36) in Newton Programmer’s
Reference.
▲
You can base your recConfig frame on one of the system-supplied recConfig
frames by simply placing the appropriate constant in your view template’s
recConfig slot. Alternatively, you can place in this slot a frame that uses its
_proto slot to reference one of the system-supplied recConfig frames. A third
way to define a recConfig frame is to supply all necessary values yourself. The