XDrawLine(3) XLIB FUNCTIONS XDrawLine(3)
NAME
XDrawLine, XDrawLines, XDrawSegments, XSegment - draw lines, polygons,
and line structure
SYNTAX
int XDrawLine(Display *display, Drawable d, GC gc, int x1, int y1, int
x2, int y2);
int XDrawLines(Display *display, Drawable d, GC gc, XPoint *points, int
npoints, int mode);
int XDrawSegments(Display *display, Drawable d, GC gc, XSegment *seg-
ments, 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 in-
tersecting 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 inter-
secting pixels are drawn multiple times. If wide lines intersect, the
intersecting pixels are drawn only once, as though the entire PolyLine
protocol request were a single, filled shape. CoordModeOrigin treats
all coordinates as relative to the origin, and CoordModePrevious treats
all coordinates 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 in-
tersect, 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-de-
pendent 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 er-
ror.
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 co-
ordinates 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 GCon-
text.
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 re-
quest.
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 ac-
cepted. Any argument defined as a set of alternatives can
generate this error.
SEE ALSO
XDrawArc(3), XDrawPoint(3), XDrawRectangle(3)
Xlib - C Language X Interface
X Version 11 libX11 1.8.12 XDrawLine(3)
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