Important: The information in this document is obsolete and should not be used for new development.
Drawing Arcs and WedgesAn arc is defined as a portion of an oval's circumference bounded by a pair of radii. A wedge is a pie-shaped segment bounded by a pair of radii, and it extends from the center of the oval to the circumference. You use the
FrameArcprocedure to draw an arc, and you use the
FillArcprocedure to draw a wedge. Using the
EraseArcprocedure, you can erase a wedge, and, using
InvertArc, you can reverse the colors of all pixels within a wedge. (Although this procedure operates on color pixels in color graphics ports, the results of
InvertArcare predictable only with 1-bit and direct color pixels.)
These procedures take three parameters: a rectangle that defines an oval's boundaries, an angle indicating the start of the arc (the variable
startAngle), and an angle indicating the arc's extent (the variable
arcAngle). For the angle parameters, 0 indicates a
vertical line straight up from the center of the oval. Positive values indicate angles in the clockwise direction from this vertical line, and negative values indicate angles in the counterclockwise direction, as shown in Figure 3-20.
Figure 3-20 Using angles to define the radii for arcs and wedges