Manual Pages for UNIX Darwin command on man MeasureChar

TkMeasureChars(3) Tk Library Procedures TkMeasureChars(3)

NAME

TkMeasureChars, TkTextWidth, TkDrawChars, TkUnderlineChars - rou-

tines to measure and display simple single-line strings.

SYNOPSIS

##iinncclluuddee <>

int TTkkMMeeaassuurreeCChhaarrss((tkfont, string, numBytes, maxPixels, flags, lengthPtr)) int TTkkTTeexxttWWiiddtthh((tkfont, string, numBytes)) void TTkkDDrraawwCChhaarrss((display, drawable, gc, tkfont, string, numBytes, x, y)) void TTkkUUnnddeerrlliinneeCChhaarrss((display, drawable, gc, tkfont, string, x, y, firstByte, lastByte)) AARRGGUUMMEENNTTSS TkFont tkfont (in) Token for font in which text is to be drawn or measured. Must have been returned by a previous call to TTkkGGeettFFoonntt. const char *string (in) Text to be measured or displayed. Need not be null terminated. Any

non-printing meta-characters in the

string (such as tabs, newlines, and other control characters) will be

measured or displayed in a platform-

dependent manner. |

int num- |

Bytes (in) | |

The maximum number of bytes to con- |

sider when measuring or drawing | string. Must be greater than or | equal to 0. int maxPixels (in) If maxPixels is >= 0, it specifies the longest permissible line length in pixels. Characters from string are processed only until this many

pixels have been covered. If max-

Pixels is < 0, then the line length is unbounded and the flags argument is ignored.

int flags (in) Various flag bits OR-ed together:

TKPARTIALOK means include a char-

acter as long as any part of it fits in the length given by maxPixels;

otherwise, a character must fit com-

pletely to be considered. TKWHOLEWORDS means stop on a word boundary, if possible. If TKATLEASTONE is set, it means return at least one character even if no characters could fit in the length given by maxPixels. If TKATLEASTONE is set and TKWHOLEWORDS is also set, it means that if not even one word fits on

the line, return the first few let-

ters of the word that did fit; if not even one letter of the word fit, then the first letter will still be returned. int *lengthPtr (out) Filled with the number of pixels occupied by the number of characters

returned as the result of TTkkMMeeaa-

ssuurreeCChhaarrss. Display *display (in) Display on which to draw. Drawable drawable (in) Window or pixmap in which to draw.

GC gc (in) Graphics context for drawing charac-

ters. The font selected into this GC must be the same as the tkfont. int x, y (in) Coordinates at which to place the

left edge of the baseline when dis-

playing string. |

int first- |

int last- |

Byte (in) | | The index of the first byte of the | last character up to which the |

underline will be drawn. The char- |

acter specified by lastByte will not | itself be underlined.

DESCRIPTION

These routines are for measuring and displaying simple single-font,

single-line, strings. To measure and display single-font, multi-line,

justified text, refer to the documentation for TTkkCCoommppuutteeTTeexxttLLaayyoouutt. There is no programming interface in the core of Tk that supports

multi-font, multi-line text; support for that behavior must be built on

top of simpler layers. Note that the interfaces described here are |

byte-oriented not character-oriented, so index values coming from Tcl |

scripts need to be converted to byte offsets using the TTccllUUttffAAttIInnddeexx | and related routines. A glyph is the displayable picture of a letter, number, or some other

symbol. Not all character codes in a given font have a glyph. Charac-

ters such as tabs, newlines/returns, and control characters that have

no glyph are measured and displayed by these procedures in a platform-

dependent manner; under X, they are replaced with backslashed escape sequences, while under Windows and Macintosh hollow or solid boxes may be substituted. Refer to the documentation for TTkkCCoommppuutteeTTeexxttLLaayyoouutt

for a programming interface that supports the platform-independent

expansion of tab characters into columns and newlines/returns into

multi-line text.

TTkkMMeeaassuurreeCChhaarrss is used both to compute the length of a given string and to compute how many characters from a string fit in a given amount of space. The return value is the number of bytes from string that fit in the space specified by maxPixels subject to the conditions described by flags. If all characters fit, the return value will be numBytes. *lengthPtr is filled with the computed width, in pixels, of the portion of the string that was measured. For example, if the return value is 5, then *lengthPtr is filled with the distance between the left edge of string[0] and the right edge of string[4]. TTkkTTeexxttWWiiddtthh is a wrapper function that provides a simpler interface to the TTkkMMeeaassuurreeCChhaarrss function. The return value is how much space in pixels the given string needs.

TTkkDDrraawwCChhaarrss draws the string at the given location in the given draw-

able. TTkkUUnnddeerrlliinneeCChhaarrss underlines the given range of characters in the given string. It doesn't draw the characters (which are assumed to have been displayed previously by TTkkDDrraawwCChhaarrss); it just draws the underline. This procedure is used to underline a few characters without having to construct an underlined font. To produce natively underlined text, the appropriate underlined font should be constructed and used. KKEEYYWWOORRDDSS font