FrameArc

Draw an arc

#include <Quickdraw.h> Quickdraw

void FrameArc( theRect, startAngle, arcAngle );

Rect *theRect ; rectangle defining position and size

short startAngle ; position where arc begins

short arcAngle ; extent of the arc

FrameArc draws an arc (a portion of an oval) just inside a specified

rectangle. The figure is drawn in the current pen size, pattern and transfer

mode.

theRect is the address of an 8-byte Rect structure, defined in local

coordinates. It defines the size and position of an oval, of which the

arc to be framed is a subset.

startAngle is a short value treated as an angle, MOD 360. It indicates the

starting position for the arc, in Quickdraw "rectangular degrees".

Positive values are clockwise from 0° (at 12 o'clock). Negative

values are counterclockwise.

arcAngle specifies the amount of the arc to draw, in "rectangular degrees".

90° specifies 1/4 of the oval, 180° specifies 1/2, 360° specifies

the entire oval, and so forth. See the figures, below.

Notes: This call is similar to framing an oval, but lets you select a subset of the

oval to draw. As with oval-drawing functions, FrameArc uses

"rectangular degrees" which are based on the positions of the corners of the

underlying rectangle:

The startAngle can be anywhere around the outside of the oval (0-359).

The arcAngle specifies the " length" of the arc, relative to a full oval:

Positive values for arcAngle cause the arc to be drawn in a clockwise

direction; negative values specify counterclockwise.

Notice in the rightmost figure, that if theRect is elongated there is a

significant change to the actual angle, but 45° still aligns with the corner of

the rectangle.

The pen position is not changed by this function.

As with all Quickdraw drawing, the output is clipped to the intersection of

the current GrafPort's bitMap boundary rectangle, the port rectangle,

clipping region, and visible region.

Unlike other FrameXxx functions, the area of a FrameArc figure is not

added to a region that is being recorded (see OpenRgn).

Referenced by (15):