Manual pages › X Window and screen libraries (3X)

XSeLAttr(3X)

GC convenience routines

From the original Amiga UNIX 2.1 manual. Some things it mentions may not be in this release.

NAME

XSetLineAttribute, XSetDashes - GC convenience routines

SYNTAX

XSetLineAttributes(display, gc, line_width, line_style,
cap_style, join_style)
      Display *display;
      GC gc;
      unsigned int line_width;
      int line_style;
      int cap_style;
      int join_style;

XSetDashes(display, gc, dash_offset, dash_list, n)
        Display *display;
        GC gc;
        int dash_offset;
        char dash_list[];
        int n;

ARGUMENTS

cap_style Specifies the line-style and cap-style you want to
          set for the specified GC.  You can pass CapNot-
          Last, CapButt, CapRound, or CapProjecting.

dash_list Specifies the dash-list for the dashed line-style
          you want to set for the specified GC.

dash_offset

Specifies the phase of the pattern for the dashed line-style you want to set for the specified GC.

     display   Specifies the connection to the XWIN server.

     gc        Specifies the GC.

     join_style
               Specifies the line join-style you want to set for
               the specified GC.  You can pass JoinMiter, Join-
               Round, or JoinBevel.

     line_style
               Specifies the line-style you want to set for the
               specified GC.  You can pass LineSolid, LineOnOff-
               Dash, or
               LineDoubleDash.

     line_width
               Specifies the line-width you want to set for the
               specified GC.

     n         Specifies the number of elements in dash_list.

XWIN 3.0               Last change: 9/1/88                 .ie t

DESCRIPTION

The XSetLineAttributes function sets the line drawing com-
ponents in the specified GC.

XSetLineAttributes can generate BadAlloc, BadGC, and Bad-
Value errors.

The XSetDashes function sets the dash-offset and dash-list
attributes for dashed line styles in the specified GC.
There must be at least one element in the specified
dash_list, or a BadValue error results. The initial and
alternating elements (second, fourth, and so on) of the
dash_list are the even dashes, and the others are the odd
dashes.  Each element specifies a dash length in pixels.
All of the elements must be nonzero, or a BadValue error
results.  Specifying an odd-length list is equivalent to
specifying the same list concatenated with itself to produce
an even-length list.

The dash-offset defines the phase of the pattern, specifying how many pixels into the dash-list the pattern should actually begin in any single graphics request. Dashing is continuous through path elements combined with a join-style but is reset to the dash-offset each time a cap-style is applied at a line endpoint.

The unit of measure for dashes is the same for the ordinary
coordinate system.  Ideally, a dash length is measured along
the slope of the line, but implementations are only required
to match this ideal for horizontal and vertical lines.
Failing the ideal semantics, it is suggested that the length
be measured along the major axis of the line.  The major
axis is defined as the x axis for lines drawn at an angle of
between -45 and +45 degrees or between 315 and 225 degrees
from the x axis.  For all other lines, the major axis is the
y axis.

XSetDashes can generate BadAlloc, BadGC, and BadValue
errors.

DIAGNOSTICS

BadAlloc  The server failed to allocate the requested

resource or server memory.

BadGC     A value for a GContext argument does not name a
          defined GContext.

BadValue  Some numeric value falls outside the range of
          values accepted by the request.  Unless a specific
          range is specified for an argument, the full range
          defined by the argument's type is accepted.  Any
          argument defined as a set of alternatives can