XDrawLine(XS)     X Version 11 (Release 5) 6 January 1993      XDrawLine(XS)


 Name

    XDrawLine - draw lines, polygons, and line structure

 Syntax


    XDrawLine(display, d, gc, x1, y1, x2, y2)
          Display *display;
          Drawable d;
          GC gc;
          int x1, y1, x2, y2;

    XDrawLines(display, d, gc, points, npoints, mode)
          Display *display;
          Drawable d;
          GC gc;
          XPoint *points;
          int npoints;
          int mode;

    XDrawSegments(display, d, gc, segments, nsegments)
          Display *display;
          Drawable d;
          GC gc;
          XSegment *segments;
          int nsegments;


 Arguments


    d           Specifies the drawable.

    display     Specifies the connection to the X server.

    gc          Specifies the GC.

    mode        Specifies the coordinate mode.  You can pass CoordModeOrigin
                or CoordModePrevious.

    npoints     Specifies the number of points in the array.

    nsegments   Specifies the number of segments in the array.

    points      Specifies an array of points.

    segments    Specifies an array of segments.

    x1
    y1
    x2
    y2          Specify the points (x1, y1) and (x2, y2) to be connected.

 Description

    The XDrawLine function uses the components of the specified GC to draw a
    line between the specified set of points (x1, y1) and (x2, y2).  It does
    not perform joining at coincident endpoints.  For any given line, XDraw-
    Line does not draw a pixel more than once.  If lines intersect, the
    intersecting pixels are drawn multiple times.

    The XDrawLines function uses the components of the specified GC to draw
    npoints-1 lines between each pair of points (point[i], point[i+1]) in the
    array of XPoint structures.  It draws the lines in the order listed in
    the array.  The lines join correctly at all intermediate points, and if
    the first and last points coincide, the first and last lines also join
    correctly.  For any given line, XDrawLines does not draw a pixel more
    than once.  If thin (zero line-width) lines intersect, the intersecting
    pixels are drawn multiple times.  If wide lines intersect, the intersect-
    ing pixels are drawn only once, as though the entire PolyLine protocol
    request were a single, filled shape.  CoordModeOrigin treats all coordi-
    nates as relative to the origin, and CoordModePrevious treats all coordi-
    nates after the first as relative to the previous point.

    The XDrawSegments function draws multiple, unconnected lines.  For each
    segment, XDrawSegments draws a line between (x1, y1) and (x2, y2).  It
    draws the lines in the order listed in the array of XSegment structures
    and does not perform joining at coincident endpoints.  For any given
    line, XDrawSegments does not draw a pixel more than once.  If lines
    intersect, the intersecting pixels are drawn multiple times.

    All three functions use these GC components:  function, plane-mask,
    line-width, line-style, cap-style, fill-style, subwindow-mode, clip-x-
    origin, clip-y-origin, and clip-mask.  The XDrawLines function also uses
    the join-style GC component.  All three functions also use these GC
    mode-dependent components:  foreground, background, tile, stipple, tile-
    stipple-x-origin, tile-stipple-y-origin, dash-offset, and dash-list.

    XDrawLine, XDrawLines, and XDrawSegments can generate ``BadDrawable'',
    ``BadGC'', and ``BadMatch'' errors.  XDrawLines can also generate a
    ``BadValue'' error.

 Structures

    The XSegment structure contains:

       typedef struct {
             short x1, y1, x2, y2;
       } XSegment;


    All x and y members are signed integers.  The width and height members
    are 16-bit unsigned integers.  You should be careful not to generate
    coordinates and sizes out of the 16-bit ranges, because the protocol only
    has 16-bit fields for these values.

 Diagnostics


    ``BadDrawable''
                   A value for a Drawable argument does not name a defined
                   Window or Pixmap.

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

    ``BadMatch''   An InputOnly window is used as a Drawable.

    ``BadMatch''   Some argument or pair of arguments has the correct type
                   and range but fails to match in some other way required by
                   the request.

    ``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 generate this error.

 See also

    XDrawArc(XS), XDrawPoint(XS), XDrawRectangle(XS)
    Xlib - C Language X Interface