WIAS_ERROR macro (wiautil.h)

Article
07/27/2021

The WIAS_ERROR macro writes a diagnostic message to the Wiatrace.log file.

Syntax

void WIAS_ERROR(
   x
);

Parameters

x

HInst - Handle to the DLL (driver).
format_string, ... - Specifies a variable argument list, which starts with an ANSI format string that describes the message and any format identifiers. The ellipsis (...) specifies a variable number of arguments that need to be output. The error text should be prefixed with the full name of the method or function and generate the message in the format of "class::method, error-text".

Return value

None

Remarks

This macro is the recommended way to implement error logging on Windows Vista, because unlike WIAS_LERROR, WIA_ERROR allows error messages to be written to the log file (Wiatrace.log). The Wiatrace.log file is only available in Windows Vista and later versions of the operating system. The utility used to view the contents of this log file is WiaTrcVw.exe.

To enable tracing in free builds, drivers must define the WIA_DEBUG macro by adding #define WIA_DEBUG before including any of the WIA headers. Tracing is enabled by default in checked and debug builds of the operating system.

The following is an example of how the macro can be used:

WIAS_ERROR((g_hInst, "Failed to read (%ws) entry under %ws section of device registry",REG_ENTRY_STORAGEPATH,REG_ENTRY_DEVICEDATA));

This code snippet was taken from Wiadriver.cpp, which is included with the Windows Image Acquisition (WIA) driver samples on GitHub.

Requirements

Requirement	Value
Minimum supported client	Available in Windows Vista and later versions of the operating system.
Target Platform	Desktop
Header	wiautil.h (include Wiautil.h)