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C-API Documentation

C-API Version

SignWare C-API [Core]

The API documentation is structured in object modules. Each module describes the accessible types, variables, and functions for the corresponding object. Major headers are If you are new to SignWare, begin reading at SPSignWare.h.

Error handling and debugging

All SignWare functions return an error code as described in the function description. The lists of error codes need not be comprehensive.

FAQs: Frequently Asked Questions

What databases are supported by SignWare?
SignWare does not access any database directly. SignWare converts (serializes) some objects such as signatures, references, and templates to a binary flat file format that may be inserted into any database as a blob.

How can I check if a tablet is installed and connected?
Create an SPTablet object, then check the device. A Tablet is connected if the driver is not SP_UNKNOWN_DRV and the resolution is non-zero. Please note that there is a limitation on Wacom tablets: the driver returns a valid tablet ID and resolution even if no tablet is connected to the system.

Are there any restrictions on the size and resolution of static images?
The static compare engine rejects images with a width smaller than 20 pixels or a height smaller than 10 pixels. Moreover, the width must not exceed 2560 pixels and the height must not exceed 1920 pixels. The minimum resolution of static images is 150 DPI, resolutions 200 DPI through 300 DPI are recommended.

How can I determine if a static image is empty?
Query the signature region (SPImageGetSignatureRegion) and check if the resulting rectangle is smaller than 5mm by 5mm.
You may want to clean the image first to remove any dirt by calling SPImageCleanSignature.

How can I determine if a dynamic signature is empty?
Check if the number of vectors in the signature (see SPSignatureGetNrVectors) is greater than 5.
This check might include vectors having a pressure level of 0. Alternatively, you may check the size of the signature image (see SPSignatureGetImageSize), but this is more expensive in terms of CPU time.
The above checking is implemented in a single call to SPSignatureCheck or SPReferenceCheck with SP_SIGNATURE_MIN_VECTORS or SP_SIGNATURE_MIN_WIDTH and SP_SIGNATURE_MIN_HEIGHT set accordingly.

How can I read the background image of a tablet for audit purposes?
Query the background image (SPGuiAcquGetBackgroundImage).
The returned Image equals the image as it was sent to the tablet (or PC screen) without signature strokes.


SignWare version history

Please see ReleaseNotes.html for details on the version history.