XLIB FUNCTIONS XDrawArc(3x11)
NAME
XDrawArc, XDrawArcs, XArc - draw arcs and arc structure
SYNTAXcc [ flag... ] file... -lX11 [ library... ]
int XDrawArc(Display *display, Drawable d, GC gc, int x, int y, unsigned int width, unsigned int height, int angle1, int angle2);int XDrawArcs(Display *display, Drawable d, GC gc, XArc
*arcs, int narcs); ARGUMENTS angle1 Specifies the start of the arc relative to thethree-o'clock position from the center, in units
of degrees * 64. angle2 Specifies the path and extent of the arc relative to the start of the arc, in units of degrees * 64. arcs Specifies an array of arcs. d Specifies the drawable. display Specifies the connection to the X server. gc Specifies the GC. narcs Specifies the number of arcs in the array. width height Specify the width and height, which are the major and minor axes of the arc. xy Specify the x and y coordinates, which are rela-
tive to the origin of the drawable and specify theupper-left corner of the bounding rectangle.
DESCRIPTION
XDrawArc draws a single circular or elliptical arc, andXDrawArcs draws multiple circular or elliptical arcs. Each
arc is specified by a rectangle and two angles. The center of the circle or ellipse is the center of the rectangle, and the major and minor axes are specified by the width and height. Positive angles indicate counterclockwise motion,and negative angles indicate clockwise motion. If the magni-
tude of angle2 is greater than 360 degrees, XDrawArc orXDrawArcs truncates it to 360 degrees.
X Version 11 Last change: libX11 1.3.5 1 XLIB FUNCTIONS XDrawArc(3x11)For an arc specifiedw_aisdt_h_, y+height]. hT_eh_ie_gs_he_t_]c,ooarnddintahtees can
[binexf,fwinriyadi,cttethwi,lioydnyta]thlhh,aeinanihndgedhpi[tagsx]tho+hta,ander2daesnicgnnrlotieteb1ri,tsnwreg_aucinnttdgcshtlaehett,2ehe]deny,t+itvtoehrhree2edticiigoschircatrirl]cgelitaaenexnoidocsrfoeoatrtlhdleiip-se
mn[[iaaxxnjt++toewersirs.2datenhcdT,tshmeyi+tnphoaert2hhaoxsrehisozouilnsdtaabltea[dxxei+fsian2etd[xb,y yt+he 2ideal mathematicalpath. For a wide line with line-width lw, the bounding out-
lines for filling are given by the two infinitely thin paths consisting of all points whose perpendicular distance from the path of the circle/ellipse is equal to lw/2 (which maybe a fractional value). The cap-style and join-style are
applied the same as for a line corresponding to the tangent of the circle/ellipse at the endpoint. For an arc specified as [ x, y, width, height, angle1, angle2], the angles must be specified in the effectively skewed coordinate system of the ellipse (for a circle, the angles and coordinate systems are identical). The relationship between these angles and angles expressed in the normal coordinate system of the screen (as measured with a protractor) is as follows:skewed-angle = atan( _w_i_d_t_h_)
(tan(normal-angle)*height)+adjust
The skewed-angle and normal-angle are expressed inn-]raadnidans
(ardajtuhsetritsh:an in degrees scaled by 64) in the ran-n,ge2 [0, 2-n] 3_-n,3_-2n]n-]
a2nn-d where atan returns a value in theforranngoerm[a-l2-angle in the range [-2n, -2n]
0Fn-or any given arc, XDrawArc and XDrafwfoAorrrcnsnoordrmomaalnl-o-atanngdglrleaewiinan tthhee rraannggee [[02, 2
pixel more than once. If two arcs join correctly and if theline-width is greater than zero and the arcs intersect,
XDrawArc and XDrawArcs do not draw a pixel more than once.
Otherwise, the intersecting pixels of intersecting arcs are drawn multiple times. Specifying an arc with one endpoint and a clockwise extent draws the same pixels as specifying the other endpoint and an equivalent counterclockwise extent, except as it affects joins. If the last point in one arc coincides with the first point in the following arc, the two arcs will join correctly. If the first point in the first arc coincides with the last point in the last arc, the two arcs will join correctly. By specifying one axis to be zero, a horizontal or vertical line can be drawn. Angles are computed based solely on the X Version 11 Last change: libX11 1.3.5 2 XLIB FUNCTIONS XDrawArc(3x11) coordinate system and ignore the aspect ratio.Both functions use these GC components: function, plane-
mask, line-width, line-style, cap-style, join-style, fill-
style, subwindow-mode, clip-x-origin, clip-y-origin, and
clip-mask. They also use these GC mode-dependent com-
ponents: foreground, background, tile, stipple, tile-
stipple-x-origin, tile-stipple-y-origin, dash-offset, and
dash-list.
XDrawArc and XDrawArcs can generate BadDrawable, BadGC, and
BadMatch errors. STRUCTURES The XArc structure contains: typedef struct { short x, y; unsigned short width, height; short angle1, angle2; /* Degrees * 64 */ } XArc; All x and y members are signed integers. The width andheight members are 16-bit unsigned integers. You should be
careful not to generate coordinates and sizes out of the16-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.SEE ALSO
XDrawLine(3x11), XDrawPoint(3x11), XDrawRectangle(3x11)Xlib - C Language X Interface
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes: X Version 11 Last change: libX11 1.3.5 3 XLIB FUNCTIONS XDrawArc(3x11)____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | x11/library/libx11 ||_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | See XInitThreads(3X11) |
|_____________________________|_____________________________|
X Version 11 Last change: libX11 1.3.5 4