Wimp_Extend (get validation string) (changes)

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WindowManager

» SWI Calls

» Wimp_Extend

» Wimp_Extend (get validation string)

Wimp_Extend (get validation string)

(SWI &400FB)

Use

This call allows programs to easily read the validation string of arbitrary icons (e.g. icons owned by other tasks).

Notes

To determine the required buffer size, first call with R4 = 0. If the call returns with R4 = 0 then the icon has no validation string. Else, -R4 provides the required buffer size to use when reading the string.

Care must be taken to ensure the buffer is not allocated from application space, as the Wimp will temporarily page out the current task when reading the string.

For convenience, the Wimp will null-terminate the string (the string pointed to by the icon block may be control-terminated)

This call was introduced by Wimp 5.64. On older Wimp versions, it’s possible to use Wimp_TransferBlock to read the validation string. However using that SWI will be less efficient because there is no direct way to determine the string length.

See also

• Icon Block
• Validation Strings
• Wimp_TransferBlock