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. |
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.
_________________________________________________________________
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
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