Struct XPathSeg 

pub struct XPathSeg {
    pub x0: f64,
    pub y0: f64,
    pub x1: f64,
    pub y1: f64,
    pub dxdy: f64,
    pub dxdy_fp: i32,
    pub flags: XPathFlags,
}

A single line segment in the edge table, in device space.

Matches SplashXPathSeg from splash/SplashXPath.h.

Invariant

After construction by XPath::add_segment (internal), every non-horizontal segment satisfies y0 ≤ y1. Horizontal segments (HORIZ flag set) are exempt.

Fields

x0: f64

X coordinate of the segment start point, in device space.

y0: f64

Y coordinate of the segment start point, in device space.

Invariant: y0 ≤ y1 for all non-horizontal segments after construction. XPathFlags::FLIPPED is set when the original input had y0 > y1 and the endpoints were swapped to enforce this invariant.

x1: f64

X coordinate of the segment end point, in device space.

y1: f64

Y coordinate of the segment end point, in device space.

Always y0 ≤ y1 for non-horizontal segments after construction.

dxdy: f64

Slope (x1-x0)/(y1-y0), stored as both f64 (for initialising the fixed-point accumulator) and as a 16.16 fixed-point i32 (dxdy_fp) for the per-scanline stepping hot loop.

Set to 0.0 / 0 for horizontal and vertical segments.

dxdy_fp: i32

Slope in 16.16 fixed-point: (dxdy * 65536.0).round() as i32.

Used by the scanner’s incremental x-accumulator: xx_fp += dxdy_fp per scanline. Integer addition instead of f64 addition eliminates floating- point dependency chains in the inner loop and is trivially vectorizable.

Precision: 1/65536 ≈ 1.5 × 10⁻⁵ device pixels per scanline — sufficient for any realistic document (the error accumulates as at most one pixel per ~65536 scanlines, far beyond any real page height).

flags: XPathFlags

Orientation and flip flags; see XPathFlags for the set of valid bits.

Trait Implementations

impl Clone for XPathSeg

fn clone(&self) -> XPathSeg

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for XPathSeg

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.