UXPathElement

UXPathElement is one step of a UXShapePath: what to do, and where.

#use <UXKit>            // or #import "UXShapePath.xc"

Overview

class UXPathElement : Object {
    i32 type;                    // UXPE_MOVE / UXPE_LINE / UXPE_CLOSE / UXPE_CURVE
    i16 x;   i16 y;              // the on-curve point
    i16 c1x; i16 c1y;            // UXPE_CURVE only
    i16 c2x; i16 c2y;
}

A path is an array of these, in order. You build them with moveTo and related methods instead of constructing them yourself. The class is public because reading a path back (to serialise it, edit it, or draw handles for it) means walking the elements.

The four types

constant	meaning	fields used
`UXPE_MOVE`	start a new subpath at `x,y`	`x`, `y`
`UXPE_LINE`	straight line to `x,y`	`x`, `y`
`UXPE_CLOSE`	close the current subpath	none
`UXPE_CURVE`	cubic Bézier to `x,y`	all six

There is no quadratic type. quadTo elevates its control point to a cubic pair on the way in, so flattening, bounds and containment handle one curve form. A path you read back shows UXPE_CURVE where you wrote a quad.

UXPE_CLOSE carries no coordinates: the subpath’s start is already known from the UXPE_MOVE that opened it.

The control points are the previous point’s partners

A cubic needs four points, and the element stores three. The fourth, the start, is the current point: wherever the previous element left off.

p.moveTo(20, 50);                          // current point is 20,50
p.curveTo(20, 10, 80, 10, 80, 50);         // P0 = 20,50 implicitly

This is the usual path convention. Elements cannot be reordered or removed independently, because each one’s meaning depends on the one before it.

Coordinates are `i16`

Whole pixels, with a range of ±32767. That is an authoring range, well past any window and any printed page at device resolution.

The precision rendering needs lives elsewhere: the flattener can emit 1/16-pixel units, which the stroker works in and rounds once at the end. See sub-pixel output. The element type stays small and exact, and the fractional work happens where it is needed.

Fields

type

i32 type

One of the four constants above.

x / y

i16 x; i16 y

The on-curve point this element ends at. Unused by UXPE_CLOSE.

c1x / c1y / c2x / c2y

i16 c1x; i16 c1y;    // first control point
i16 c2x; i16 c2y;    // second

Meaningful only for UXPE_CURVE. For other types they are zero: init clears them, so a move or line element reads as 0,0, not as leftover memory.

Conforms to

Inherits Object