tcldoc Tcl/Tk 9.0.4
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Tk_GetScrollInfo C API

Parse arguments for scrolling commands

Also documents Tk_GetScrollInfoObj

literal type exactly as shown argument replace with your value ?optional? may be omitted

Synopsis#

#include <tk.h>

int Tk_GetScrollInfoObj(interp, objc, objv, fractionPtr, stepsPtr)#

int Tk_GetScrollInfo(interp, argc, argv, fractionPtr, stepsPtr)#

Arguments#

Tcl_Interp *interp (in)

Interpreter to use for error reporting.

Tcl_Size objc (in)

Number of Tcl_Obj's in objv array.

Tcl_Obj *const * objv (in)

Argument objects. These represent the entire widget command, of which the first word is typically the widget name and the second word is typically xview or yview.

int argc (in)

Number of strings in argv array.

const char ** argv (in)

Argument strings. These represent the entire widget command, of which the first word is typically the widget name and the second word is typically xview or yview.

double *fractionPtr (out)

Filled in with fraction from moveto option, if any.

int *stepsPtr (out)

Filled in with line or page count from scroll option, if any. The value may be negative.

Description#

Tk_GetScrollInfoObj parses the arguments expected by widget scrolling commands such as xview and yview. It receives the entire list of words that make up a widget command and parses the words starting with objv[2]. The words starting with objv[2] must have one of the following forms:

moveto fraction
scroll number pages
scroll number units

Any of the moveto, scroll, pages, and units keywords may be abbreviated. If objv has the moveto form, TK_SCROLL_MOVETO is returned as result and *fractionPtr is filled in with the fraction argument to the command, which must be a proper real value. If objv has the scroll form, TK_SCROLL_PAGES or TK_SCROLL_UNITS is returned and *stepsPtr is filled in with the number value, which must be a integer or a float, but if it is a float then it is converted to an integer, rounded away from 0. If an error occurs in parsing the arguments, TK_SCROLL_ERROR is returned and an error message is left in interpreter interp's result.

Tk_GetScrollInfo is identical in function to Tk_GetScrollInfoObj. However, Tk_GetScrollInfo accepts string arguments, making it more appropriate for use with legacy widgets.

Keywords#

parse · scrollbar · scrolling command · xview · yview

Copyright#