IPropertySystem::FormatForDisplayAlloc method (propsys.h)

  • Article

Gets a string representation of a property value to an allocated memory buffer.

Syntax

HRESULT FormatForDisplayAlloc(
  [in]  REFPROPERTYKEY        key,
  [in]  REFPROPVARIANT        propvar,
  [in]  PROPDESC_FORMAT_FLAGS pdff,
  [out] LPWSTR                *ppszDisplay
);

Parameters

[in] key

Type: REFPROPERTYKEY

A reference to the desired PROPERTYKEY.

[in] propvar

Type: REFPROPVARIANT

A reference to a PROPVARIANT structure that contains the type and value of the property.

[in] pdff

Type: PROPDESC_FORMAT_FLAGS

The format of the property string. See PROPDESC_FORMAT_FLAGS.

[out] ppszDisplay

Type: LPWSTR*

When this method returns, contains a pointer to the formatted value as a null-terminated, Unicode string.

Return value

Type: HRESULT

Returns one of the following values.

Return code Description
S_OK
 Formatted string is created. This string may be returned empty due to an empty input string or from a non-empty value that was formatted as an empty string.
S_FALSE
 Formatted string is not created. Indicates that the empty string resulted from a VT_EMPTY.
E_OUTOFMEMORY
 Indicates allocation failed.

Remarks

You must initialize Component Object Model (COM) with CoInitialize or OleInitialize before calling IPropertySystem::FormatForDisplayAlloc.

On success, this method gets a formatted Unicode string representation of a property value for a specified PROPERTYKEY, and one or more PROPDESC_FORMAT_FLAGS. If the PROPERTYKEY is not recognized by the schema subsystem, IPropertySystem::FormatForDisplayAlloc attempts to format the value according to its VARTYPE.

This method allocates memory for the buffer and returns a pointer to it at ppszDisplay. The calling application must use CoTaskMemFree to release the string specified by ppszDisplay when it is no longer needed.

The purpose of this method is to convert data into a string suitable for display to the user. The value is formatted according to the current locale, the language of the user, the PROPDESC_FORMAT_FLAGS, and the property description specified by the property key. For information about how the property description schema influences the formatting of the value, see displayInfo, stringFormat, booleanFormat, numberFormat, NMDATETIMEFORMAT, and enumeratedList. Typically, the PROPDESC_FORMAT_FLAGS are used to modify the format prescribed by the property description.

The output string may contain Unicode directional characters. These nonspacing characters influence the Unicode bidirectional algorithm so that the values appear correctly when a left to right (LTR) language is drawn on a right to left (RTL) window, and vice versa. These characters include the following: "\x200e", "\x200f", "\x202a", "\x202b", "\x202c", "\x202d", "\x202e".

The following properties use special formats and are unaffected by the PROPDESC_FORMAT_FLAGS (examples cited are for strings with a current locale set to English; typically, output is localized except where noted).

Property Format
System.FileAttributes The following file attributes are converted to letters and appended to create a string (for example, a value of 0x1801 (FILE_ATTRIBUTE_READONLY | FILE_ATTRIBUTE_COMPRESSED | FILE_ATTRIBUTE_OFFLINE) is converted to "RCO"):
  • FILE_ATTRIBUTE_READONLY (0x00000001) - 'R'
  • FILE_ATTRIBUTE_SYSTEM (0x00000004) - 'S'
  • FILE_ATTRIBUTE_ARCHIVE (0x00000020) -'A'
  • FILE_ATTRIBUTE_COMPRESSED (0x00000800) - 'C'
  • FILE_ATTRIBUTE_ENCRYPTED (0x00004000) - 'E'
  • FILE_ATTRIBUTE_OFFLINE (0x00001000) - 'O'
  • FILE_ATTRIBUTE_NOT_CONTENT_INDEXED (0x00002000) - 'I'
System.Photo.ISOSpeed For example, "ISO-400".
System.Photo.ShutterSpeed The APEX value is converted to an exposure time using this formula:

Exposure_time = 2^(-APEX_value)

For example, "2 sec."or "1/125 sec.".
System.Photo.ExposureTime For example, "2 sec."or "1/125 sec."
System.Photo.Aperture The APEX value is converted to an F number using this formula:

F_Number = 2^(APEX_Value / 2)

For example, "f/5.6".
System.Photo.FNumber For example, "f/5.6".
System.Photo.SubjectDistance For example, "15 m"or "250 mm".
System.Photo.FocalLength For example, "50 mm".
System.Photo.FlashEnergy For example, "500 bpcs".
System.Photo.ExposureBias For example, "-2 step", " 0 step", or "+3 step".
System.Computer.DecoratedFreeSpace For example, "105 MB free of 13.2 GB".
System.ItemType For example, "Application" or "JPEG Image".
System.ControlPanel.Category For example, "Appearance and Personalization".
System.ComputerName For example, "LITWARE05 (this computer)" or "testbox07".
 

If the property key does not correspond to a property description in any of the registered property schemas, then this method chooses a format based on the type of the value.

Type of the value Format
VT_BOOLEAN Not supported.
VT_FILETIME Date/time string as specified by PROPDESC_FORMAT_FLAGS and the current locale. PDFF_SHORTTIME and PDFF_SHORTDATE are the default. For example, "11/13/2006 3:22 PM".
Numeric VARTYPE Decimal string in the current locale. For example, "42".
VT_LPWSTR or other Converted to a string. Sequences of "\r", "\t", or "\n" are replaced with a single space.
VT_VECTOR | anything Semicolon separated values—a semicolon is used regardless of locale.

Requirements

Requirement Value
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2008 [desktop apps only]
Target Platform Windows
Header propsys.h
Redistributable Windows Desktop Search (WDS) 3.0

See also

IPropertySystem

Property Description Schema