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|
use scene::SplitMaskParams;
use tiny_skia::{
Color, GradientStop, LinearGradient, Paint, Path, PathBuilder, Pixmap, Point, SpreadMode,
Transform,
};
use crate::geometry::{
INTERSECTION_EPSILON, MIN_POLYGON_AREA_PX, SplitLine, half_plane_sign, line_edge_intersection,
polygon_area, split_line_geometry,
};
fn canvas_edges(width: f64, height: f64) -> [(f64, f64, f64, f64); 4] {
[
(0.0, 0.0, width, 0.0),
(width, 0.0, width, height),
(width, height, 0.0, height),
(0.0, height, 0.0, 0.0),
]
}
fn points_equal(a: (f64, f64), b: (f64, f64)) -> bool {
(a.0 - b.0).abs() <= INTERSECTION_EPSILON && (a.1 - b.1).abs() <= INTERSECTION_EPSILON
}
fn split_line(params: &SplitMaskParams, width: f64, height: f64) -> SplitLine {
split_line_geometry(
params.center_x,
params.center_y,
params.rotation,
width,
height,
)
}
pub fn split_stroke_segment(
params: &SplitMaskParams,
width: f64,
height: f64,
) -> Option<[(f64, f64); 2]> {
let line = split_line(params, width, height);
let mut intersections: Vec<(f64, f64)> = Vec::new();
for &(x1, y1, x2, y2) in &canvas_edges(width, height) {
let Some(hit) = line_edge_intersection(line, x1, y1, x2, y2) else {
continue;
};
if intersections.iter().any(|&point| points_equal(point, hit)) {
continue;
}
intersections.push(hit);
}
if intersections.len() != 2 {
return None;
}
Some([intersections[0], intersections[1]])
}
pub fn split_stroke_path(params: &SplitMaskParams, width: f64, height: f64) -> Option<Path> {
let segment = split_stroke_segment(params, width, height)?;
let mut builder = PathBuilder::new();
builder.move_to(segment[0].0 as f32, segment[0].1 as f32);
builder.line_to(segment[1].0 as f32, segment[1].1 as f32);
builder.finish()
}
pub fn split_opaque_body_path(params: &SplitMaskParams, width: f64, height: f64) -> Option<Path> {
let line = split_line(params, width, height);
let is_inside = |x: f64, y: f64| half_plane_sign(line, x, y) >= 0.0;
let mut vertices: Vec<(f64, f64)> = Vec::new();
for &(x1, y1, x2, y2) in &canvas_edges(width, height) {
let vertex1_inside = is_inside(x1, y1);
let vertex2_inside = is_inside(x2, y2);
if vertex1_inside && vertex2_inside {
vertices.push((x2, y2));
} else if vertex1_inside {
if let Some(hit) = line_edge_intersection(line, x1, y1, x2, y2) {
vertices.push(hit);
}
} else if vertex2_inside {
if let Some(hit) = line_edge_intersection(line, x1, y1, x2, y2) {
vertices.push(hit);
vertices.push((x2, y2));
}
}
}
if vertices.len() < 3 || polygon_area(&vertices) < MIN_POLYGON_AREA_PX {
return None;
}
let mut builder = PathBuilder::new();
builder.move_to(vertices[0].0 as f32, vertices[0].1 as f32);
for &(x, y) in &vertices[1..] {
builder.line_to(x as f32, y as f32);
}
builder.close();
builder.finish()
}
pub fn fill_split_feather_body(
params: &SplitMaskParams,
width: f64,
height: f64,
pixmap: &mut Pixmap,
) {
let line = split_line(params, width, height);
let feather_half = params.feather / 2.0;
let Some(shader) = LinearGradient::new(
Point::from_xy(
(line.line_x - line.normal_x * feather_half) as f32,
(line.line_y - line.normal_y * feather_half) as f32,
),
Point::from_xy(
(line.line_x + line.normal_x * feather_half) as f32,
(line.line_y + line.normal_y * feather_half) as f32,
),
vec![
GradientStop::new(0.0, Color::from_rgba8(255, 255, 255, 0)),
GradientStop::new(1.0, Color::from_rgba8(255, 255, 255, 255)),
],
SpreadMode::Pad,
Transform::default(),
) else {
return;
};
let paint = Paint {
shader,
anti_alias: true,
..Paint::default()
};
let Some(rect) = tiny_skia::Rect::from_xywh(0.0, 0.0, width as f32, height as f32) else {
return;
};
pixmap.fill_rect(rect, &paint, Transform::default(), None);
}
|
