**Important:**
The information in this document is obsolete and should not be used for new development.

**Inside Macintosh:****Imaging With QuickDraw**/**Chapter 3 - QuickDraw Drawing**/**QuickDraw Drawing Reference****Routines**/**Creating and Managing Rectangles**

## PtToAngle

To calculate an angle between a vertical line pointing straight up from the center of a rectangle and a line from the center to a given point, use the`PtToAngle`

procedure.

PROCEDURE PtToAngle (r:\xDDRect; pt: Point; VAR angle: Integer);

`r`

- The rectangle to examine.
`pt`

- The point to which an angle is to be calculated.
`angle`

- The resulting angle.
## DESCRIPTION

The`PtToAngle`

procedure returns in the`angle`

parameter the angle between a vertical line (pointing straight up from the center of the rectangle that you specify in the`r`

parameter) and a line from the center of that rectangle to a point (which you specify in the`pt`

parameter).The result returned in the

`angle`

parameter is specified in degrees from 0 to 359, measured clockwise from 12 o'clock, with 90 at 3 o'clock, 180 at 6 o'clock, and 270 at 9 o'clock. Other angles are measured relative to the rectangle. If the line to the given point goes through the upper-right corner of the rectangle, the angle returned is 45, even if the rectangle isn't square; if it goes through the lower-right corner, the angle is 135, and so on, as shown in Figure 3-18.

Figure 3-18 Forty-five-degree angles as returned by the`PtToAngle`

procedure

The angle returned might be used as input to one of the procedures that manipulate arcs and wedges, as described in "Drawing Arcs and Wedges" beginning on page 3-67.

7 JUL 1996