Name

PSTXAL − Controls the position of the text extent parallelogram in relation to the text position. 

Operating States: PHOP, ∗, STOP, ∗
PHIGS standard function
Creates a structure element

Syntax

PSTXAL (TXALH, TXALV)

Argument       Data Type      Access    Description
---------------------------------------------------------------------------
TXALH          Integer        Read      Horizontal text alignment
TXALV          Integer        Read      Vertical text alignment
---------------------------------------------------------------------------

Constants

Defined Argument     Constant      Description
---------------------------------------------------------------------------
TXALH                PAHNOR        Normal horizontal alignment.  This is
                                   the default value.
                     PALEFT        Left horizontal alignment.
                     PACENT        Center horizontal alignment.
                     PARITE        Right horizontal alignment.
 
TXALV                PAVNOR        Normal vertical alignment.  This is the
                                   default value.
                     PATOP         Top vertical alignment.
                     PACAP         Cap vertical alignment.
                     PAHALF        Half vertical alignment.
                     PABASE        Base vertical alignment.
                     PABOTT        Bottom vertical alignment.
---------------------------------------------------------------------------

Description

PSTXAL uses the text alignment horizontal and text alignment vertical values to control the position of the text extent parallelogram in relation to the text position.  Depending on the current edit mode, this function either inserts the new structure element directly after the element indicated by the pointer or replaces the element indicated by the pointer.  The pointer then points to the new set text alignment element. 

The set text alignment element sets the specified values for the current text alignment entry in the PHIGS traversal state list.  Digital PHIGS uses the value when traversing subsequent text and text 3 primitives. 

Digital PHIGS defines a text string within a text extent rectangle.  This rectangle is an imaginary parallelogram that completely contains the text string to be displayed.  It is established when you create a text primitive with the PTX output function. 

The text alignment attribute controls the positioning of this text extent parallelogram in relation to the text position.  The text alignment is described in terms of the default character up vector and character base vector.  The horizontal component of text alignment has four possible values:

•LEFT---The left side of the text extent parallelogram passes through the text position. 

•RIGHT---The right side of the text extent parallelogram passes through the text position. 

•CENTRE---The text position lies midway between the left and right sides of the text extent parallelogram.  If the text path is UP or DOWN, the straight line passing through the centerlines of the characters also passes through the text position. 

•NORMAL---At traversal, the meaning of NORMAL will be the same as one of the other values, according to the current value of the text path attribute. 

Each of the possible values for the vertical component of the text alignment corresponds to one of the font-specific lines in the definition of a character (see the DEC PHIGS Developer’s Guide for more information on characters).   The vertical component of the text alignment has six possible values:

•NORMAL---The default positioning, which depends on the text path used. 

•TOP---The top of the text extent parallelogram passes through the text position. 

•CAP---If the text path is either LEFT or RIGHT, the text position lies on the capline of the whole string.  If the text path is either UP or DOWN, the text position lies on the capline of the topmost character in the string. 

•HALF---If the text path is either LEFT or RIGHT, the text position lies on the half line of the whole string.  If the text path is either UP or DOWN, the text position lies on a line halfway between the half lines of the top and bottom characters. 

•BASE---If the text path is either LEFT or RIGHT, the text position lies on the baseline of the whole string.  If the text path is UP or DOWN, the text position lies on the baseline of the bottom character in the string. 

•BOTTOM---The bottom of the text extent parallelogram passes through the text position. 

During structure traversal, Digital PHIGS sets the current text alignment entry in the PHIGS traversal state list to the value defined by the specified values. 

If Digital PHIGS is in immediate mode, it performs this function immediately, but the function does not create a structure element. 

See Also

PQTXX
PQTXF
PSATAL
PSTXP
PTX
PTX3