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|
use super::*;
use smallvec::smallvec;
/// Layouts syntax trees into boxes.
pub fn layout_tree(tree: &SyntaxTree, ctx: LayoutContext) -> LayoutResult<MultiLayout> {
let mut layouter = TreeLayouter::new(ctx);
layouter.layout(tree)?;
layouter.finish()
}
#[derive(Debug, Clone)]
struct TreeLayouter<'a, 'p> {
ctx: LayoutContext<'a, 'p>,
flex: FlexLayouter,
style: TextStyle,
}
impl<'a, 'p> TreeLayouter<'a, 'p> {
/// Create a new layouter.
fn new(ctx: LayoutContext<'a, 'p>) -> TreeLayouter<'a, 'p> {
TreeLayouter {
flex: FlexLayouter::new(FlexContext {
flex_spacing: flex_spacing(&ctx.text_style),
spaces: ctx.spaces.clone(),
axes: ctx.axes,
shrink_to_fit: ctx.shrink_to_fit,
}),
style: ctx.text_style.clone(),
ctx,
}
}
/// Layout a syntax tree.
fn layout(&mut self, tree: &SyntaxTree) -> LayoutResult<()> {
for node in &tree.nodes {
match &node.val {
Node::Text(text) => {
self.flex.add(layout_text(text, TextContext {
loader: &self.ctx.loader,
style: &self.style,
})?);
}
Node::Space => {
if !self.flex.run_is_empty() && !self.flex.run_last_is_space() {
let space = self.style.word_spacing * self.style.font_size;
self.flex.add_primary_space(space, true);
}
}
Node::Newline => {
if !self.flex.run_is_empty() {
self.break_paragraph()?;
}
}
Node::ToggleItalics => self.style.toggle_class(FontClass::Italic),
Node::ToggleBold => self.style.toggle_class(FontClass::Bold),
Node::ToggleMonospace => self.style.toggle_class(FontClass::Monospace),
Node::Func(func) => self.layout_func(func)?,
}
}
Ok(())
}
/// Layout a function.
fn layout_func(&mut self, func: &FuncCall) -> LayoutResult<()> {
let (flex_spaces, stack_spaces) = self.flex.remaining()?;
let ctx = |spaces| LayoutContext {
top_level: false,
text_style: &self.style,
spaces,
shrink_to_fit: true,
.. self.ctx
};
// Try putting it in the flex space first, but if that is not enough
// space, use the other space.
let commands = match func.body.val.layout(ctx(flex_spaces)) {
Ok(c) => c,
Err(LayoutError::NotEnoughSpace(_)) => {
func.body.val.layout(ctx(stack_spaces))?
},
e => e?,
};
for command in commands {
self.execute(command)?;
}
Ok(())
}
fn execute(&mut self, command: Command) -> LayoutResult<()> {
match command {
Command::LayoutTree(tree) => self.layout(tree)?,
Command::Add(layout) => self.flex.add(layout),
Command::AddMultiple(layouts) => self.flex.add_multiple(layouts),
Command::AddPrimarySpace(space) => self.flex.add_primary_space(space, false),
Command::AddSecondarySpace(space) => self.flex.add_secondary_space(space)?,
Command::FinishLine => self.flex.add_break(),
Command::FinishRun => self.flex.finish_run()?,
Command::FinishSpace => self.flex.finish_space(true)?,
Command::BreakParagraph => self.break_paragraph()?,
Command::SetTextStyle(style) => self.style = style,
Command::SetPageStyle(style) => {
if !self.ctx.top_level {
Err(LayoutError::Unallowed("can only set page style from top level"))?;
}
self.ctx.page_style = style;
self.flex.set_spaces(smallvec![
LayoutSpace {
dimensions: style.dimensions,
padding: style.margins,
}
], true);
},
Command::SetAxes(axes) => {
self.flex.set_axes(axes);
self.ctx.axes = axes;
}
}
Ok(())
}
/// Finish the layout.
fn finish(self) -> LayoutResult<MultiLayout> {
self.flex.finish()
}
/// Finish the current flex layout and add space after it.
fn break_paragraph(&mut self) -> LayoutResult<()> {
self.flex.add_secondary_space(paragraph_spacing(&self.style))
}
}
fn flex_spacing(style: &TextStyle) -> Size {
(style.line_spacing - 1.0) * style.font_size
}
fn paragraph_spacing(style: &TextStyle) -> Size {
(style.paragraph_spacing - 1.0) * style.font_size
}
|
