96 lines
3.3 KiB
Groff
96 lines
3.3 KiB
Groff
'\"
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'\" Copyright (c) 1990 The Regents of the University of California.
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'\" Copyright (c) 1994-1998 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH Tk_GetPixelsFromObj 3 8.1 Tk "Tk Library Procedures"
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.so man.macros
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.BS
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.SH NAME
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Tk_GetPixelsFromObj, Tk_GetPixels, Tk_GetMMFromObj, Tk_GetScreenMM \- translate between strings and screen units
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.SH SYNOPSIS
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.nf
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\fB#include <tk.h>\fR
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.sp
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int
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\fBTk_GetPixelsFromObj(\fIinterp, tkwin, objPtr, intPtr\fB)\fR
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.sp
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int
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\fBTk_GetPixels(\fIinterp, tkwin, string, intPtr\fB)\fR
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.sp
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int
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\fBTk_GetMMFromObj(\fIinterp, tkwin, objPtr, doublePtr\fB)\fR
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.sp
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int
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\fBTk_GetScreenMM(\fIinterp, tkwin, string, doublePtr\fB)\fR
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.SH ARGUMENTS
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.AS "Tcl_Interp" *joinPtr
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.AP Tcl_Interp *interp in
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Interpreter to use for error reporting.
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.AP Tk_Window tkwin in
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Window whose screen geometry determines the conversion between absolute
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units and pixels.
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.AP Tcl_Obj *objPtr in/out
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String value specifies a distance on the screen;
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internal rep will be modified to cache converted distance.
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.AP "const char" *string in
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Same as \fIobjPtr\fR except specification of distance is passed as
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a string.
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.AP int *intPtr out
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Pointer to location in which to store converted distance in pixels.
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.AP double *doublePtr out
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Pointer to location in which to store converted distance in millimeters.
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.BE
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.SH DESCRIPTION
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.PP
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These procedures take as argument a specification of distance on
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the screen (\fIobjPtr\fR or \fIstring\fR) and compute the
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corresponding distance either in integer pixels or floating-point millimeters.
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In either case,
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\fIobjPtr\fR or \fIstring\fR
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specifies a screen distance as a
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floating-point number followed by one of the following characters
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that indicates units:
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.TP
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<none>
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The number specifies a distance in pixels.
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.TP
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\fBc\fR
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The number specifies a distance in centimeters on the screen.
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.TP
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\fBi\fR
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The number specifies a distance in inches on the screen.
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.TP
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\fBm\fR
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The number specifies a distance in millimeters on the screen.
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.TP
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\fBp\fR
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The number specifies a distance in printer's points (1/72 inch)
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on the screen.
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.PP
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\fBTk_GetPixelsFromObj\fR converts the value of \fIobjPtr\fR to the
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nearest even number of pixels and stores that value at \fI*intPtr\fR.
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It returns \fBTCL_OK\fR under normal circumstances.
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If an error occurs (e.g. \fIobjPtr\fR contains a number followed
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by a character that is not one of the ones above) then
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\fBTCL_ERROR\fR is returned and an error message is left
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in \fIinterp\fR's result if \fIinterp\fR is not NULL.
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\fBTk_GetPixelsFromObj\fR caches information about the return
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value in \fIobjPtr\fR, which speeds up future calls to
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\fBTk_GetPixelsFromObj\fR with the same \fIobjPtr\fR.
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.PP
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\fBTk_GetPixels\fR is identical to \fBTk_GetPixelsFromObj\fR except
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that the screen distance is specified with a string instead
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of an object. This prevents \fBTk_GetPixels\fR from caching the
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return value, so \fBTk_GetPixels\fR is less efficient than
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\fBTk_GetPixelsFromObj\fR.
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.PP
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\fBTk_GetMMFromObj\fR and \fBTk_GetScreenMM\fR are similar to
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\fBTk_GetPixelsFromObj\fR and \fBTk_GetPixels\fR (respectively) except
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that they convert the screen distance to millimeters and
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store a double-precision floating-point result at \fI*doublePtr\fR.
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.SH KEYWORDS
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centimeters, convert, inches, millimeters, pixels, points, screen units
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