3 releases (breaking)
0.3.0 | Jan 28, 2024 |
---|---|
0.2.0 | Jan 5, 2024 |
0.1.0 | Jan 4, 2024 |
#940 in Text processing
35KB
705 lines
text-layout
text-layout
provides algorithms for laying out text prior to rendering.
Features
no_std
support for constrained environments
Usage
Laying out a paragraph for display in a terminal:
fn layout_paragraph<'a, P: ParagraphLayout>(
paragraph: &'a str,
layout: &P,
max_width: usize,
) -> Vec<&'a str> {
// Process the paragraph into its items.
let mut items = Vec::new();
for c in paragraph.chars() {
items.push(if c.is_whitespace() && items.len() != 0 {
Item::Glue {
width: 1.0,
stretch: 1.0,
shrink: 0.0,
data: (),
}
} else {
Item::Box {
width: 1.0,
data: (),
}
});
}
items.push(Item::Glue {
width: 0.0,
stretch: 100000.0,
shrink: 0.0,
data: (),
});
items.push(Item::Penalty {
width: 0.0,
cost: f32::NEG_INFINITY,
flagged: true,
data: (),
});
// Calculate the paragraph's breaks.
let breaks = layout.layout_paragraph(&items, max_width as f32);
// Render the laid-out paragraph using the break positions.
let mut cursor = 0;
let mut lines = Vec::new();
let mut start = 0;
for (i, _) in paragraph.chars().enumerate() {
if i == breaks[cursor].break_at {
lines.push(¶graph[start..i]);
start = i + 1;
cursor += 1;
}
}
lines.push(¶graph[start..]);
lines
}
fn layout_text() -> Result<String, fmt::Error> {
let text = " Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-two million miles is an utterly insignificant little blue-green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea.";
let knuth_plass = KnuthPlass::new().with_threshold(f32::INFINITY);
let lines = layout_paragraph(&text, &knuth_plass, 80);
let mut result = String::new();
writeln!(&mut result, "┏{}┓", "━".repeat(80))?;
for l in lines {
let pad = 80 - l.chars().count();
writeln!(&mut result, "┃{}{}┃", l, " ".repeat(pad))?;
}
writeln!(&mut result, "┗{}┛", "━".repeat(80))?;
Ok(result)
}
fn main() -> Result<(), fmt::Error> {
print!("{}", layout_text()?);
Ok(())
}
This prints:
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ Far out in the uncharted backwaters of the unfashionable end of the western ┃
┃spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a ┃
┃distance of roughly ninety-two million miles is an utterly insignificant little ┃
┃blue-green planet whose ape-descended life forms are so amazingly primitive that┃
┃they still think digital watches are a pretty neat idea. ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
Dependencies
~2.5MB
~49K SLoC