tk_getpixelsfromobj(3)

NAME

Tk_GetPixelsFromObj, Tk_GetPixels, Tk_GetMMFromObj,
Tk_GetScreenMM - translate between strings and screen
units

SYNOPSIS

#include <tk.h>
int
Tk_GetPixelsFromObj(interp, tkwin, objPtr, intPtr)
int
Tk_GetPixels(interp, tkwin, string, intPtr)
int
Tk_GetMMFromObj(interp, tkwin, objPtr, doublePtr)
int
Tk_GetScreenMM(interp, tkwin, string, doublePtr)

ARGUMENTS

Tcl_Interp *interp (in) Interpreter to use for

error reporting.

Tk_Window tkwin (in) Window whose screen

geometry determines the
conversion between abso
lute units and pixels.

Tcl_Obj *objPtr (in/out)

String value specifies a
distance on the screen;
internal rep will be
modified to cache con
verted distance.

CONST
char *string (in)

Same as objPtr except specification of dis
tance is passed as a
string.

int *intPtr (out) Pointer to location in

which to store converted
distance in pixels.

double *doublePtr (out) Pointer to location in

which to store converted
distance in millimeters.

DESCRIPTION

These procedures take as argument a specification of dis
tance on the screen (objPtr or string) and compute the corresponding distance either in integer pixels or float
ing-point millimeters. In either case, objPtr or string specifies a screen distance as a floating-point number
followed by one of the following characters that indicates
units:

<none> The number specifies a distance in pixels.

c The number specifies a distance in centimeters on

the screen.

i The number specifies a distance in inches on the

screen.

m The number specifies a distance in millimeters on

the screen.

p The number specifies a distance in printer's points

(1/72 inch) on the screen.

Tk_GetPixelsFromObj converts the value of objPtr to the nearest even number of pixels and stores that value at
*intPtr. It returns TCL_OK under normal circumstances. If an error occurs (e.g. objPtr contains a number followed by a character that isn't one of the ones above) then
TCL_ERROR is returned and an error message is left in interp's result if interp isn't NULL. Tk_GetPixelsFromObj caches information about the return value in objPtr, which speeds up future calls to Tk_GetPixelsFromObj with the same objPtr.

Tk_GetPixels is identical to Tk_GetPixelsFromObj except that the screen distance is specified with a string
instead of an object. This prevents Tk_GetPixels from caching the return value, so Tk_GetAnchor is less effi cient than Tk_GetPixelsFromObj.

Tk_GetMMFromObj and Tk_GetScreenMM are similar to Tk_Get PixelsFromObj and Tk_GetPixels (respectively) except that they convert the screen distance to millimeters and store
a double-precision floating-point result at *doublePtr.

KEYWORDS

centimeters, convert, inches, millimeters, pixels, points,
screen units

Tk 8.1 Tk_GetPixelsFromObj(3)