FrameArc

FrameArc
Header:	Quickdraw.h		Carbon status:	Supported

Draws an arc of the oval that fits inside a rectangle.

void FrameArc (
    const Rect *r, 
    SInt16 startAngle, 
    SInt16 arcAngle
);

Parameter descriptions

r: The rectangle that defines an oval’s boundaries.
startAngle: The angle indicating the start of the arc.
arcAngle: The angle indicating the arc’s extent.

DISCUSSION

Using the pattern, pattern mode, and size of the graphics pen for the current graphics port, the FrameArc function draws an arc of the oval bounded by the rectangle that you specify in the r parameter. Use the startAngle parameter to specify where the arc begins as modulo 360. Use the arcAngle parameter to specify how many degrees the arc covers. Specify whether the angles are in positive or negative degrees; a positive angle goes clockwise, while a negative angle goes counterclockwise. Zero degrees is at 12 o’clock high, 90∞ (or –270∞) is at 3 o’clock, 180∞ (or –180∞) is at 6 o’clock, and 270∞ (or –90∞) is at 9 o’clock. Measure other angles relative to the bounding rectangle.

A line from the center of the rectangle through its upper-right corner is at 45∞, even if the rectangle is not square; a line through the lower-right corner is at 135∞, and so on.

The arc is as wide as the pen width and as tall as the pen height. The pen location does not change.

SPECIAL CONSIDERATIONS

The FrameArc function differs from other QuickDraw functions that frame shapes in that the arc is not mathematically added to the boundary of a region that’s open and being formed.

The FrameArc function may move or purge memory blocks in the application heap; do not call this function at interrupt time.

AVAILABILITY

Supported in Carbon. Available in Carbon 1.0.2 and later when running Mac OS 8.1 or later.