84 lines
2.9 KiB
Rust
84 lines
2.9 KiB
Rust
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// pathfinder/geometry/src/dilation.rs
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//
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// Copyright © 2019 The Pathfinder Project Developers.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use crate::basic::point::Point2DF32;
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use crate::outline::Contour;
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pub struct ContourDilator<'a> {
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contour: &'a mut Contour,
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amount: Point2DF32,
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}
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impl<'a> ContourDilator<'a> {
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pub fn new(contour: &'a mut Contour, amount: Point2DF32) -> ContourDilator<'a> {
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ContourDilator { contour, amount }
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}
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pub fn dilate(&mut self) {
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let mut position = self.contour.position_of(0);
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let mut prev_point_index = 0;
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let mut prev_position;
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loop {
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prev_point_index = self.contour.prev_point_index_of(prev_point_index);
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prev_position = self.contour.position_of(prev_point_index);
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if prev_point_index == 0 || prev_position != position {
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break;
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}
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}
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let mut point_index = 0;
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loop {
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// Find the next non-degenerate position.
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let mut next_point_index = point_index;
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let mut next_position;
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loop {
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next_point_index = self.contour.next_point_index_of(next_point_index);
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next_position = self.contour.position_of(next_point_index);
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if next_point_index == point_index || next_position != position {
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break;
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}
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}
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// Calculate new position by moving the point by the bisector.
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let (prev_vector, next_vector) = (position - prev_position, next_position - position);
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let bisector = prev_vector.scale(next_vector.length()) +
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next_vector.scale(prev_vector.length());
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let bisector_length = bisector.length();
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let new_position = if bisector_length == 0.0 {
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position
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} else {
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position - bisector.scale_xy(self.amount).scale(1.0 / bisector_length)
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};
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/*println!("dilate({:?}): {:?} -> {:?} (bisector {:?}, length {:?})",
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self.amount,
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position,
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new_position,
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bisector,
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bisector_length);*/
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// Update all points.
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for point_index in point_index..next_point_index {
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self.contour.points[point_index as usize] = new_position;
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}
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// We're done if we start to loop around.
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if next_point_index < point_index {
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break;
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}
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// Continue.
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prev_position = position;
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position = next_position;
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point_index = next_point_index;
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}
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}
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}
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