Setting Accessibility Time-out Periods

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Windows Embedded CE 6.0 R3

4/8/2010

You should use the accessibility time-out option for computers that several users with different accessibility preferences share. Each user can use hot keys or the AccessibilityControl Panel to enable preferred functionality. The accessibility time-out period is the length of time that must pass without keyboard or mouse input before the operating system (OS) automatically turns off accessibility functionality. The time-out affects the following accessibility functionality: mouse keys, sticky keys, toggle keys, and high contrast.

The user can control the settings for the accessibility time-out option by using the Generaltab of the AccessibilityControl Panel application or another application for customizing the environment.

Applications use the SPI_GETACCESSTIMEOUT and SPI_SETACCESSTIMEOUT flags with the SystemParametersInfofunction to get and set the accessibility time-out option. The ACCESSTIMEOUTstructure defines the parameters for the accessibility time-out option. To set the accessibility time-out option, call SystemParametersInfowith the uiActionparameter set to SPI_SETACCESSTIMEMOUT, the uiParamparameter set to the size of the ACCESSTIMEOUTstructure, and the pvParamparameter set to a pointer to an ACCESSTIMEOUTstructure that contains the new time-out parameters that you want to use. You should set the ATF_TIMEOUTON flag in the dwFlagsmember of the ACCESSTIMEOUTstructure that you pass to SystemParametersInfoand set the iTimeOutMSecmember to the length of the time-out period in milliseconds.

The following code example shows how to set the accessibility time-out period to 10 minutes and how to specify that the OS should play a descending siren sound when the time-out period elapses and the OS turns off the accessibility options.

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ACCESSTIMEOUT atf; BOOL bSuccess; // Fill in the members of the ACCESSTIMEOUT structure. atf.cbSize = sizeof(ACCESSTIMEOUT); atf.dwFlags = (ATF_ONOFFFEEDBACK \| ATF_TIMEOUTON); atf.iTimeOutMSec = 600000; // Call SystemParametersInfo with the SPI_SETACCESSTIMEOUT flag. bSuccess = SystemParametersInfo(SPI_SETACCESSTIMEOUT, sizeof(ACCESSTIMEOUT), (LPVOID) &atf, 0);

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ACCESSTIMEOUT atf;
BOOL bSuccess;

// Fill in the members of the ACCESSTIMEOUT structure.

atf.cbSize = sizeof(ACCESSTIMEOUT);
atf.dwFlags = (ATF_ONOFFFEEDBACK | ATF_TIMEOUTON);
atf.iTimeOutMSec = 600000;

// Call SystemParametersInfo with the SPI_SETACCESSTIMEOUT flag. 

bSuccess = SystemParametersInfo(SPI_SETACCESSTIMEOUT, 
								sizeof(ACCESSTIMEOUT), (LPVOID)
&atf, 0);

To retrieve information about the time-out period, including whether a time-out period is set and the length of the time-out period, call SystemParametersInfowith uiActionset to SPI_GETACCESSTIMEOUT, uiParamset to the size of the ACCESSTIMEOUTstructure, and pvParamset to a pointer to an ACCESSTIMEOUTstructure. Examine the values of the members of the ACCESSTIMEOUTstructure after SystemParametersInforeturns to obtain the information that you want about the accessibility time-out option.

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