DTWAIN_GetCapDataType

Top Previous Next

The DTWAIN_GetCapDataType returns the TWAIN data type to use when retrieving or setting a capability's values.

LONG DTWAIN_GetCapDataType (

DTWAIN_SOURCE	Source,
LONG	Capability );

Parameters

Source

A valid DTWAIN_SOURCE if Capability is a custom capability. NULL otherwise.

Capability

The capability that is to be queried for the data type.

Return Values

The actual TWAIN data type that the capability uses to retrieve or set values.

Comments

The DTWAIN_GetCapDataType function returns the TWAIN data type for a particular capability The return values are the same as defined by the Twain specification version 1.8. The following are the possible return values:

Twain constant	Value
TWTY_INT8	0
TWTY_INT16	1
TWTY_INT32	2
TWTY_UINT8	3
TWTY_UINT16	4
TWTY_UINT32	5
TWTY_BOOL	6
TWTY_FIX32	7
TWTY_FRAME	8
TWTY_STR32	9
TWTY_STR64	10
TWTY_STR128	11
TWTY_STR255	12
TWTY_STR1024	13

Please note:

DTWAIN_GetCapDataType is provided only for informational purposes. Do not use the value returned by DTWAIN_GetCapDataType for any DTWAIN functions that involve setting or getting capability values. For example, if you are calling DTWAIN_ArrayCreate or DTWAIN_RangeCreate for the purposes of setting values within these structures, the return value for DTWAIN_GetCapDataType can not be used as the datatype argument for these functions.

Instead, call DTWAIN_GetCapArrayType to determine the proper DTWAIN data type to use when creating a DTWAIN_ARRAY or DTWAIN_RANGE, or more directly, call DTWAIN_ArrayCreateFromCap or DTWAIN_RangeCreateFromCap to create a DTWAIN_ARRAY or DTWAIN_RANGE that is compatible with DTWAIN capability functions..

The TWTY_xxx constants are found in the TWAIN.H header file that is included in the INCLUDE directory of the DTWAIN installation, can be obtained at the TWAIN Working Group at http://www.twain.org.

Note that capability handling using the DTWAIN functions do not require your application to know the specific TWAIN types since DTWAIN_ARRAYs are used to retrieve or set capability information

For most cases, the Source argument should be NULL to DTWAIN_GetCapDataType. The only exception is if the capability is a custom capability, the Source argument to DTWAIN_GetCapDataType must be an open DTWAIN_SOURCE. This is the only way that DTWAIN can determine the data type used for custom capabilities.

TWAIN State Transitions

The Source must be in State 4 or higher (depending on the capability).

Prerequisite Function Call(s)

DTWAIN_SysInitialize

DTWAIN Source Selection Function