getpixels(3) - Linux man page

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 absolute units and pixels.

│ Tcl_Obj *objPtr (in/out) ││ │

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

CONST │ char *string (in) │ │

Same as objPtr except specification │ of distance 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 distance on the │ screen (objPtr or string) and compute the corresponding distance either in integer pixels or floating-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 efficient than Tk_GetPixelsFromObj. │

Tk_GetMMFromObj and Tk_GetScreenMM are similar to Tk_GetPixelsFromObj │ 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