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use std::rc::Rc;
use serde::{Deserialize, Serialize};
use super::{Constrained, Constraints};
use crate::color::Color;
use crate::font::FaceId;
use crate::geom::{Length, Path, Point, Size};
use crate::image::ImageId;
/// A finished layout with elements at fixed positions.
#[derive(Debug, Default, Clone, Eq, PartialEq, Serialize, Deserialize)]
pub struct Frame {
/// The size of the frame.
pub size: Size,
/// The baseline of the frame measured from the top.
pub baseline: Length,
/// The elements composing this layout.
children: Vec<(Point, Child)>,
}
/// An iterator over all elements in a frame, alongside with their positions.
#[derive(Debug, Clone)]
pub struct ElementIter<'a> {
stack: Vec<(usize, Point, &'a Frame)>,
}
impl<'a> Iterator for ElementIter<'a> {
type Item = (Point, &'a Element);
/// Get the next element, if any.
fn next(&mut self) -> Option<Self::Item> {
let (cursor, offset, frame) = self.stack.last_mut()?;
match frame.children.get(*cursor) {
Some((pos, Child::Frame(f))) => {
let new_offset = *offset + *pos;
self.stack.push((0, new_offset, f.as_ref()));
self.next()
}
Some((pos, Child::Element(e))) => {
*cursor += 1;
Some((*offset + *pos, e))
}
None => {
self.stack.pop();
if let Some((cursor, _, _)) = self.stack.last_mut() {
*cursor += 1;
}
self.next()
}
}
}
}
impl Frame {
/// Create a new, empty frame.
pub fn new(size: Size, baseline: Length) -> Self {
assert!(size.is_finite());
Self { size, baseline, children: vec![] }
}
/// Add an element at a position in the foreground.
pub fn push(&mut self, pos: Point, element: Element) {
self.children.push((pos, Child::Element(element)));
}
/// Add an element at a position in the background.
pub fn prepend(&mut self, pos: Point, element: Element) {
self.children.insert(0, (pos, Child::Element(element)))
}
/// Add a frame element.
pub fn push_frame(&mut self, pos: Point, subframe: Rc<Self>) {
self.children.push((pos, Child::Frame(subframe)))
}
/// Add all elements of another frame, placing them relative to the given
/// position.
pub fn merge_frame(&mut self, pos: Point, subframe: Self) {
if pos == Point::zero() && self.children.is_empty() {
self.children = subframe.children;
} else {
for (subpos, child) in subframe.children {
self.children.push((pos + subpos, child));
}
}
}
/// Wraps the frame with constraints.
pub fn constrain(self, constraints: Constraints) -> Constrained<Rc<Self>> {
Constrained { item: Rc::new(self), constraints }
}
/// Returns an iterator over all elements in the frame and its children.
pub fn elements(&self) -> ElementIter {
ElementIter { stack: vec![(0, Point::zero(), self)] }
}
}
/// A frame can contain multiple children: elements or other frames, complete
/// with their children.
#[derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize)]
enum Child {
Element(Element),
Frame(Rc<Frame>),
}
/// The building block frames are composed of.
#[derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize)]
pub enum Element {
/// Shaped text.
Text(Text),
/// A geometric shape and the paint which with it should be filled or
/// stroked.
Geometry(Geometry, Paint),
/// A raster image.
Image(ImageId, Size),
}
/// A run of shaped text.
#[derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize)]
pub struct Text {
/// The font face the glyphs are contained in.
pub face_id: FaceId,
/// The font size.
pub size: Length,
/// Glyph color.
pub fill: Paint,
/// The glyphs.
pub glyphs: Vec<Glyph>,
}
/// A glyph in a run of shaped text.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Serialize, Deserialize)]
pub struct Glyph {
/// The glyph's index in the face.
pub id: u16,
/// The advance width of the glyph.
pub x_advance: Length,
/// The horizontal offset of the glyph.
pub x_offset: Length,
}
impl Text {
/// Encode the glyph ids into a big-endian byte buffer.
pub fn encode_glyphs_be(&self) -> Vec<u8> {
let mut bytes = Vec::with_capacity(2 * self.glyphs.len());
for glyph in &self.glyphs {
bytes.push((glyph.id >> 8) as u8);
bytes.push((glyph.id & 0xff) as u8);
}
bytes
}
}
/// A geometric shape.
#[derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize)]
pub enum Geometry {
/// A filled rectangle with its origin in the topleft corner.
Rect(Size),
/// A filled ellipse with its origin in the center.
Ellipse(Size),
/// A stroked line to a point (relative to its position) with a thickness.
Line(Point, Length),
/// A filled bezier path.
Path(Path),
}
/// How a fill or stroke should be painted.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
pub enum Paint {
/// A solid color.
Color(Color),
}
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