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HIGHCONTRASTW structure (winuser.h)

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Contains information about the high contrast accessibility feature.This feature sets the appearance scheme of the user interface for maximum visibility for a visually-impaired user, and advises applications to comply with this appearance scheme.

Syntax

typedef struct tagHIGHCONTRASTW {
  UINT   cbSize;
  DWORD  dwFlags;
  LPWSTR lpszDefaultScheme;
} HIGHCONTRASTW, *LPHIGHCONTRASTW;

Members

cbSize

Type: UINT

Specifies the size, in bytes, of this structure.

dwFlags

Type: DWORD

Specifies a combination of the following values:

Value Meaning
HCF_HIGHCONTRASTON
0x00000001
 The high contrast feature is on.
HCF_AVAILABLE
0x00000002
 The high contrast feature is available.
HCF_HOTKEYACTIVE
0x00000004
 The user can turn the high contrast feature on and off by simultaneously pressing the left ALT, left SHIFT, and PRINT SCREEN keys.
HCF_CONFIRMHOTKEY
0x00000008
 A confirmation dialog appears when the high contrast feature is activated by using the hot key.
HCF_HOTKEYSOUND
0x00000010
 A siren is played when the user turns the high contrast feature on or off by using the hot key.
HCF_INDICATOR
0x00000020
 A visual indicator is displayed when the high contrast feature is on. This value is not currently used and is ignored.
HCF_HOTKEYAVAILABLE
0x00000040
 The hot key associated with the high contrast feature can be enabled. An application can retrieve this value, but cannot set it.
HCF_OPTION_NOTHEMECHANGE
0x00001000

Passing HIGHCONTRASTSTRUCTURE in calls to SystemParametersInfoW can cause theme change effects even if the theme isn't being changed. For example, the WM_THEMECHANGED message is sent to Windows even if the only change is to HCF_HOTKEYSOUND.

To prevent this, include the HCF_OPTION_NOTHEMECHANGE flag in the call to SystemParametersInfo.

Note

The HCF_OPTION_NOTHEMECHANGE flag should not be used when toggling the high contrast mode (HCF_HIGHCONTRASTON).
HCF_OPTION_NOTHEMECHANGE
0x00001000

Passing HIGHCONTRASTSTRUCTURE in calls to SystemParametersInfoW can cause theme change effects even if the theme isn't being changed. For example, the WM_THEMECHANGED message is sent to Windows even if the only change is to HCF_HOTKEYSOUND.

To prevent this, include the HCF_OPTION_NOTHEMECHANGE flag in the call to SystemParametersInfo.

Note

The HCF_OPTION_NOTHEMECHANGE flag should not be used when toggling the high contrast mode (HCF_HIGHCONTRASTON).

lpszDefaultScheme

Type: LPTSTR

Points to a string that contains the name of the color scheme that will be set to the default scheme. The system allocates this buffer, free it with LocalFree.

Remarks

An application uses this structure when calling the SystemParametersInfoW function with the SPI_GETHIGHCONTRAST or SPI_SETHIGHCONTRAST value. When using SPI_GETHIGHCONTRAST, an application must specify the cbSize member of the HIGHCONTRAST structure; the SystemParametersInfo function fills the remaining members. An application must specify all structure members when using the SPI_SETHIGHCONTRAST value.

Note

The winuser.h header defines HIGHCONTRAST as an alias that automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that is not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Header winuser.h (include Windows.h)

See also

SystemParametersInfoW function, HIGHCONTRASTA structure, Accessibility Structures, SystemParametersInfo