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//! Layouting infrastructure.
mod constraints;
#[cfg(feature = "layout-cache")]
mod incremental;
mod regions;
pub use constraints::*;
#[cfg(feature = "layout-cache")]
pub use incremental::*;
pub use regions::*;
use std::fmt::{self, Debug, Formatter};
use std::hash::{Hash, Hasher};
use std::rc::Rc;
use crate::font::FontStore;
use crate::frame::Frame;
use crate::image::ImageStore;
use crate::library::DocumentNode;
use crate::Context;
/// Layout a document node into a collection of frames.
pub fn layout(ctx: &mut Context, node: &DocumentNode) -> Vec<Rc<Frame>> {
let mut ctx = LayoutContext::new(ctx);
node.layout(&mut ctx)
}
/// The context for layouting.
pub struct LayoutContext<'a> {
/// Stores parsed font faces.
pub fonts: &'a mut FontStore,
/// Stores decoded images.
pub images: &'a mut ImageStore,
/// Caches layouting artifacts.
#[cfg(feature = "layout-cache")]
pub layouts: &'a mut LayoutCache,
/// How deeply nested the current layout tree position is.
#[cfg(feature = "layout-cache")]
pub level: usize,
}
impl<'a> LayoutContext<'a> {
/// Create a new layout context.
pub fn new(ctx: &'a mut Context) -> Self {
Self {
fonts: &mut ctx.fonts,
images: &mut ctx.images,
#[cfg(feature = "layout-cache")]
layouts: &mut ctx.layouts,
#[cfg(feature = "layout-cache")]
level: 0,
}
}
}
/// A node that can be layouted into a sequence of regions.
///
/// Layout return one frame per used region alongside constraints that define
/// whether the result is reusable in other regions.
pub trait Layout: Debug {
/// Layout the node into the given regions, producing constrained frames.
fn layout(
&self,
ctx: &mut LayoutContext,
regions: &Regions,
) -> Vec<Constrained<Rc<Frame>>>;
/// Convert to a packed node.
fn pack(self) -> PackedNode
where
Self: Sized + Hash + 'static,
{
PackedNode {
#[cfg(feature = "layout-cache")]
hash: {
use std::any::Any;
let mut state = fxhash::FxHasher64::default();
self.type_id().hash(&mut state);
self.hash(&mut state);
state.finish()
},
node: Rc::new(self),
}
}
}
/// A packed layouting node with precomputed hash.
#[derive(Clone)]
pub struct PackedNode {
node: Rc<dyn Layout>,
#[cfg(feature = "layout-cache")]
hash: u64,
}
impl Layout for PackedNode {
fn layout(
&self,
ctx: &mut LayoutContext,
regions: &Regions,
) -> Vec<Constrained<Rc<Frame>>> {
#[cfg(not(feature = "layout-cache"))]
return self.node.layout(ctx, regions);
#[cfg(feature = "layout-cache")]
ctx.layouts.get(self.hash, regions).unwrap_or_else(|| {
ctx.level += 1;
let frames = self.node.layout(ctx, regions);
ctx.level -= 1;
let entry = FramesEntry::new(frames.clone(), ctx.level);
#[cfg(debug_assertions)]
if !entry.check(regions) {
eprintln!("node: {:#?}", self.node);
eprintln!("regions: {:#?}", regions);
eprintln!(
"constraints: {:#?}",
frames.iter().map(|c| c.cts).collect::<Vec<_>>()
);
panic!("constraints did not match regions they were created for");
}
ctx.layouts.insert(self.hash, entry);
frames
})
}
fn pack(self) -> PackedNode
where
Self: Sized + Hash + 'static,
{
self
}
}
impl Hash for PackedNode {
fn hash<H: Hasher>(&self, _state: &mut H) {
#[cfg(feature = "layout-cache")]
_state.write_u64(self.hash);
#[cfg(not(feature = "layout-cache"))]
unimplemented!()
}
}
impl Debug for PackedNode {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
self.node.fmt(f)
}
}
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