XDrawLine(3X11) XLIB FUNCTIONS XDrawLine(3X11)
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, XSeg-
ment *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 Coord-
ModeOrigin 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, XDrawLine 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
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XDrawLine(3X11) XLIB FUNCTIONS XDrawLine(3X11)
correctly. For any given line, XDrawLines does not draw a
pixel more than once. If thin (zero line-width) lines inter-
sect, the intersecting 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 per-
form 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 com-
ponent. 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 Bad-
Drawable, 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.
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XDrawLine(3X11) XLIB FUNCTIONS XDrawLine(3X11)
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 gen-
erate this error.
SEE ALSO
XDrawArc(3X11), XDrawPoint(3X11), XDrawRectangle(3X11)
Xlib - C Language X Interface
XFree86 Version 4.5.0 3