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Chapter 5 - Text Utilities / Text Utilities Reference

Routines / Truncating Strings

TruncString

The TruncString function ensures that a Pascal string fits into the specified pixel width, by truncating the string as necessary. This function makes use of the current script and font.

FUNCTION TruncString (width: Integer; VAR theString: Str255; 
                      truncWhere: TruncCode): Integer;

width

The number of pixels in which the string must be displayed in the current script and font.

theString

The Pascal string to be displayed. On output, contains a version of the string that has been truncated (if necessary) to fit in the number of pixels specified by width.

truncWhere

A constant that indicates where the string should be truncated. You must set this parameter to one of the constants truncEnd or truncMiddle.

DESCRIPTION

The TruncString function ensures that a Pascal string fits into the pixel width specified by the width parameter by modifying the string, if necessary, through truncation. TruncString uses the font script to determine how to perform truncation. If truncation occurs, TruncString inserts a truncation indicator, which is the ellipsis (...) in the Roman script system. You can specify which token to use for indicating truncation as the tokenEllipsis token type in the untoken table of a tokens ('itl4') resource.

The truncWhere parameter specifies where truncation is performed. If you supply the truncEnd value, characters are truncated off the end of the string. If you supply the truncMiddle value, characters are truncated from the middle of the string; this is useful when displaying pathnames.

The TruncString function returns a result code that indicates whether the string
was truncated.

SPECIAL CONSIDERATIONS

TruncString may move memory; your application should not call this function at interrupt time.

ASSEMBLY-LANGUAGE INFORMATION

The trap macro and routine selector for the TruncString function are

Trap macro	Selector
_ScriptUtil	$8208 FFE0

RESULT CODES

Truncated	1	Truncation performed
NotTruncated	0	No truncation necessary
TruncErr	-1	Truncation necessary, but cannot be performed within the specified width
resNotFound	-192	Cannot get the correct 'itl4' resource or resource is not in current format

SEE ALSO

To determine the width of a string in the current font and script, use the QuickDraw StringWidth function, which is described in the chapter "QuickDraw Text" in this book.