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author | rjohnson <rjohnson> | 1998-04-01 09:37:39 (GMT) |
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committer | rjohnson <rjohnson> | 1998-04-01 09:37:39 (GMT) |
commit | 13242623d2ff3ea02ab6a62bfb48a7dbb5c27e22 (patch) | |
tree | 3100714738a7941b590efee466a774862f9671c3 /doc/MeasureChar.3 | |
parent | e4ab1102029f9ac557ff190bfb9d34408340f345 (diff) | |
download | tk-13242623d2ff3ea02ab6a62bfb48a7dbb5c27e22.zip tk-13242623d2ff3ea02ab6a62bfb48a7dbb5c27e22.tar.gz tk-13242623d2ff3ea02ab6a62bfb48a7dbb5c27e22.tar.bz2 |
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diff --git a/doc/MeasureChar.3 b/doc/MeasureChar.3 new file mode 100644 index 0000000..3d54578 --- /dev/null +++ b/doc/MeasureChar.3 @@ -0,0 +1,130 @@ +'\" +'\" Copyright (c) 1996 Sun Microsystems, Inc. +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +'\" SCCS: @(#) MeasureChar.3 1.5 97/06/10 17:33:36 +'\" +.so man.macros +.TH Tk_MeasureChars 3 "" Tk "Tk Library Procedures" +.BS +.SH NAME +Tk_MeasureChars, Tk_TextWidth, Tk_DrawChars, Tk_UnderlineChars \- routines to measure and display simple single-line strings. +.SH SYNOPSIS +.nf +\fB#include <tk.h>\fR +.sp +int +\fBTk_MeasureChars(\fItkfont, string, maxChars, maxPixels, flags, lengthPtr\fB)\fR +.sp +int +\fBTk_TextWidth(\fItkfont, string, numChars\fB)\fR +.sp +void +\fBTk_DrawChars(\fIdisplay, drawable, gc, tkfont, string, numChars, x, y\fB)\fR +.sp +void +\fBTk_UnderlineChars(\fIdisplay, drawable, gc, tkfont, string, x, y, firstChar, lastChar\fB)\fR +.sp +.SH ARGUMENTS +.AS "const char" firstChar +.AP Tk_Font tkfont in +Token for font in which text is to be drawn or measured. Must have been +returned by a previous call to \fBTk_GetFont\fR. +.AP "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. +.AP int maxChars in +The maximum number of characters to consider when measuring \fIstring\fR. +Must be greater than or equal to 0. +.AP int maxPixels in +If \fImaxPixels\fR is greater than 0, it specifies the longest permissible +line length in pixels. Characters from \fIstring\fR are processed only +until this many pixels have been covered. If \fImaxPixels\fR is <= 0, then +the line length is unbounded and the \fIflags\fR argument is ignored. +.AP int flags in +Various flag bits OR-ed together: TK_PARTIAL_OK means include a character +as long as any part of it fits in the length given by \fImaxPixels\fR; +otherwise, a character must fit completely to be considered. +TK_WHOLE_WORDS means stop on a word boundary, if possible. If +TK_AT_LEAST_ONE is set, it means return at least one character even if no +characters could fit in the length given by \fImaxPixels\fR. If +TK_AT_LEAST_ONE is set and TK_WHOLE_WORDS is also set, it means that if +not even one word fits on the line, return the first few letters of the +word that did fit; if not even one letter of the word fit, then the first +letter will still be returned. +.AP int *lengthPtr out +Filled with the number of pixels occupied by the number of characters +returned as the result of \fBTk_MeasureChars\fR. +.AP int numChars in +The total number of characters to measure or draw from \fIstring\fR. Must +be greater than or equal to 0. +.AP Display *display in +Display on which to draw. +.AP Drawable drawable in +Window or pixmap in which to draw. +.AP GC gc in +Graphics context for drawing characters. The font selected into this GC +must be the same as the \fItkfont\fR. +.AP int "x, y" in +Coordinates at which to place the left edge of the baseline when displaying +\fIstring\fR. +.AP int firstChar in +The index of the first character to underline in the \fIstring\fR. +Underlining begins at the left edge of this character. +.AP int lastChar in +The index of the last character up to which the underline will +be drawn. The character specified by \fIlastChar\fR will not itself be +underlined. +.BE + +.SH DESCRIPTION +.PP +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 \fBTk_ComputeTextLayout\fR. +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. +.PP +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. +Characters 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 +\fBTk_ComputeTextLayout\fR for a programming interface that supports the +platform-independent expansion of tab characters into columns and +newlines/returns into multi-line text. +.PP +\fBTk_MeasureChars\fR 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 characters from +\fIstring\fR that fit in the space specified by \fImaxPixels\fR subject to +the conditions described by \fIflags\fR. If all characters fit, the return +value will be \fImaxChars\fR. \fI*lengthPtr\fR 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 \fI*lengthPtr\fR is filled with the +distance between the left edge of \fIstring\fR[0] and the right edge of +\fIstring\fR[4]. +.PP +\fBTk_TextWidth\fR is a wrapper function that provides a simpler interface +to the \fBTk_MeasureChars\fR function. The return value is how much +space in pixels the given \fIstring\fR needs. +.PP +\fBTk_DrawChars\fR draws the \fIstring\fR at the given location in the +given \fIdrawable\fR. +.PP +\fBTk_UnderlineChars\fR underlines the given range of characters in the +given \fIstring\fR. It doesn't draw the characters (which are assumed to +have been displayed previously by \fBTk_DrawChars\fR); 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. + +.SH KEYWORDS +font |