Tasks

Instance Methods

closePath

Close the current sub path. You must call either pen.closePath() or pen.endPath() after each sub path.

- (void)closePath

curveTo:off1:off2:

Draw a cubic bezier with an arbitrary number of control points.

- (void)curveTo:(NSPoint)pt off1:(NSPoint)off1 off2:(NSPoint)off2

Discussion

The last point specified is on-curve, all others are off-curve (control) points. If the number of control points is > 2, the segment is split into multiple bezier segments. This works like this:

Let n be the number of control points (which is the number of arguments to this call minus 1). If n==2, a plain vanilla cubic bezier is drawn. If n==1, we fall back to a quadratic segment and if n==0 we draw a straight line. It gets interesting when n>2: n-1 PostScript-style cubic segments will be drawn as if it were one curve. See decomposeSuperBezierSegment().

The conversion algorithm used for n>2 is inspired by NURB splines, and is conceptually equivalent to the TrueType “implied points” principle. See also decomposeQuadraticSegment().

endPath

End the current sub path, but don’t close it. You must call either pen.closePath() or pen.endPath() after each sub path.

- (void)endPath

lineTo:

Draw a straight line from the current point to ‘pt’.

- (void)lineTo:(NSPoint)pt

moveTo:

Begin a new sub path, set the current point to ‘pt’. You must end each sub path with a call to pen.closePath() or pen.endPath().

- (void)moveTo:(NSPoint)pt

qCurveTo:

Draw a whole string of quadratic curve segments.

- (void)qCurveTo:(NSArray *)Points

Discussion

The last point specified is on-curve, all others are off-curve points.

This method implements TrueType-style curves, breaking up curves using ‘implied points’: between each two consequtive off-curve points, there is one implied point exactly in the middle between them. See also decomposeQuadraticSegment().

The last argument (normally the on-curve point) may be None. This is to support contours that have NO on-curve points (a rarely seen feature of TrueType outlines).

startGlyph:

To initialize stuff

- (void)startGlyph:(GSLayer *)Layer