Tk_GetPixels — C Library Procedures

NAME

Tk_GetPixels, Tk_GetScreenMM − translate between strings and screen units

SYNOPSIS

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

ARGUMENTS

Tcl_Interp∗interp(in) Interpreter to use for error reporting.

Tk_Windowtkwin(in) Window whose screen geometry determines the conversion between absolute units and pixels.

char∗string(in) String that specifies a distance on the screen.

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 two procedures take as argument a specification of distance on the screen (string) and compute the corresponding distance either in integer pixels or floating-point millimeters. In either case, 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_GetPixels converts string to the nearest even number of pixels and stores that value at ∗intPtr. Tk_GetScreenMM converts string to millimeters and stores the double-precision floating-point result at ∗doublePtr.

Both procedures return TCL_OK under normal circumstances. If an error occurs (e.g. string 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->result.

KEYWORDS

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