Tk_GetAnchorFromObj manual page - Tk Library Procedures

## Tcl8.6.16/Tk8.6.16 Documentation > Tk C API, version 8.6.16 > GetAnchor

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  NAME
    Tk_GetAnchorFromObj, Tk_GetAnchor, Tk_NameOfAnchor — translate between strings and anchor positions
  SYNOPSIS
    #include <tk.h>
    int
    Tk_GetAnchorFromObj(interp, objPtr, anchorPtr)
    int
    Tk_GetAnchor(interp, string, anchorPtr)
    const char *
    Tk_NameOfAnchor(anchor)
  ARGUMENTS
  DESCRIPTION
  KEYWORDS

### NAME

Tk_GetAnchorFromObj, Tk_GetAnchor, Tk_NameOfAnchor — translate between strings and anchor positions

### SYNOPSIS

#include <tk.h>
int
Tk_GetAnchorFromObj(interp, objPtr, anchorPtr)
int
Tk_GetAnchor(interp, string, anchorPtr)
const char *
Tk_NameOfAnchor(anchor)

### ARGUMENTS

Tcl_Interp *interp (in)
  Interpreter to use for error reporting, or NULL.

Tcl_Obj *objPtr (in/out)
  String value contains name of anchor point: “n”, “ne”, “e”, “se”, “s”, “sw”, “w”, “nw”, or “center”; internal rep will be modified to cache corresponding Tk_Anchor. In the case of “center” on input, a non-empty abbreviation of it may also be used on input.

const char *string (in)
  Same as objPtr except description of anchor point is passed as a string.

int *anchorPtr (out)
  Pointer to location in which to store anchor position corresponding to objPtr or string.

Tk_Anchor anchor (in)
  Anchor position, e.g. TCL_ANCHOR_CENTER.

### DESCRIPTION

Tk_GetAnchorFromObj places in *anchorPtr an anchor position (enumerated type Tk_Anchor) corresponding to objPtr's value. The result will be one of TK_ANCHOR_N, TK_ANCHOR_NE, TK_ANCHOR_E, TK_ANCHOR_SE, TK_ANCHOR_S, TK_ANCHOR_SW, TK_ANCHOR_W, TK_ANCHOR_NW, or TK_ANCHOR_CENTER. Anchor positions are typically used for indicating a point on an object that will be used to position the object, e.g. TK_ANCHOR_N means position the top center point of the object at a particular place.

Under normal circumstances the return value is TCL_OK and interp is unused. If string does not contain a valid anchor position or an abbreviation of one of these names, TCL_ERROR is returned, *anchorPtr is unmodified, and an error message is stored in interp's result if interp is not NULL. Tk_GetAnchorFromObj caches information about the return value in objPtr, which speeds up future calls to Tk_GetAnchorFromObj with the same objPtr.

Tk_GetAnchor is identical to Tk_GetAnchorFromObj except that the description of the anchor is specified with a string instead of an object. This prevents Tk_GetAnchor from caching the return value, so Tk_GetAnchor is less efficient than Tk_GetAnchorFromObj.

Tk_NameOfAnchor is the logical inverse of Tk_GetAnchor. Given an anchor position such as TK_ANCHOR_N it returns a statically-allocated string corresponding to anchor. If anchor is not a legal anchor value, then “unknown anchor position” is returned.

### KEYWORDS

anchor position
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