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//! Turns placed marks into PDF drawing operators
//!
//! Typesetting puts the origin at the top left and counts y downward, but PDF puts the origin
//! at the bottom left and counts y upward. The conversion between them is done only here.
use crate::draw::{Letter, Mark, Page};
use crate::font::{self, Library};
use crate::text::{hex_number, number};
/// For a circle drawn with 4 curves, the distance to the control points as a ratio to the radius
const CIRCLE_ARM: f64 = 0.5523;
/// The drawing operators for one page
pub fn render(page: &Page, library: &Library) -> Vec<u8> {
let mut out = String::from("0 g 0 G\n");
for one in join(&page.mark, library) {
write_mark(&mut out, &one, page.height);
}
out.into_bytes()
}
/// Writes one placed mark
fn write_mark(out: &mut String, mark: &Mark, height: f64) {
match mark {
Mark::Text {face, size, stretch, x, y, letter} => {
out.push_str("BT\n");
out.push_str(&format!("/F{face} {} Tf\n", number(*size)));
out.push_str(&format!(
"1 0 0 {} {} {} Tm\n",
number(*stretch),
number(*x),
number(height - y)
));
out.push('<');
for one in letter {
out.push_str(&hex_number(one.glyph));
}
out.push_str("> Tj\nET\n");
}
Mark::Rule {x, y, width, height: thickness} => {
out.push_str(&format!(
"{} {} {} {} re f\n",
number(*x),
number(height - y - thickness),
number(*width),
number(*thickness)
));
}
Mark::Stroke {point, width} => {
if point.len() < 2 {
return;
}
out.push_str(&format!("{} w\n", number(*width)));
for (index, place) in point.iter().enumerate() {
let mark = if index == 0 {"m"} else {"l"};
out.push_str(&format!(
"{} {} {mark}\n",
number(place.0),
number(height - place.1)
));
}
out.push_str("S\n");
}
Mark::Fill {point} => {
if point.len() < 3 {
return;
}
for (index, place) in point.iter().enumerate() {
let mark = if index == 0 {"m"} else {"l"};
out.push_str(&format!(
"{} {} {mark}\n",
number(place.0),
number(height - place.1)
));
}
out.push_str("h f\n");
}
Mark::Circle {x, y, radius, width} => {
write_circle(out, *x, height - y, *radius, *width);
}
Mark::Image {index, x, y, width, height: tall} => {
out.push_str(&format!(
"q {} 0 0 {} {} {} cm /Im{index} Do Q\n",
number(*width),
number(*tall),
number(*x),
number(height - y - tall)
));
}
}
}
/// Draws a circle with 4 cubic curves
fn write_circle(out: &mut String, x: f64, y: f64, radius: f64, width: f64) {
let arm = radius * CIRCLE_ARM;
out.push_str(&format!("{} w\n", number(width)));
out.push_str(&format!("{} {} m\n", number(x + radius), number(y)));
let corner = [
(x + radius, y + arm, x + arm, y + radius, x, y + radius),
(x - arm, y + radius, x - radius, y + arm, x - radius, y),
(x - radius, y - arm, x - arm, y - radius, x, y - radius),
(x + arm, y - radius, x + radius, y - arm, x + radius, y),
];
for (x1, y1, x2, y2, x3, y3) in corner {
out.push_str(&format!(
"{} {} {} {} {} {} c\n",
number(x1),
number(y1),
number(x2),
number(y2),
number(x3),
number(y3)
));
}
out.push_str("S\n");
}
/// Joins letters placed one after another into one run. This makes the PDF operators shorter
fn join(mark: &[Mark], library: &Library) -> Vec<Mark> {
let mut out: Vec<Mark> = Vec::new();
for one in mark {
if let Mark::Text {face, size, stretch, x, y, letter} = one {
if let Some(Mark::Text {
face: last_face,
size: last_size,
stretch: last_stretch,
x: last_x,
y: last_y,
letter: last_letter,
}) = out.last_mut()
{
let same = last_face == face
&& (*last_size - size).abs() < 1e-9
&& (*last_stretch - stretch).abs() < 1e-9
&& (*last_y - y).abs() < 1e-9;
let end = *last_x + run_width(library, *last_face, *last_size, last_letter);
if same && (end - x).abs() < 0.02 {
last_letter.extend(letter.iter().cloned());
continue;
}
}
}
out.push(one.clone());
}
out
}
/// The total advance of a run of letters
fn run_width(library: &Library, face: usize, size: f64, letter: &[Letter]) -> f64 {
let found = match library.face.get(face) {
Some(found) => found,
None => return 0.0,
};
letter
.iter()
.map(|one| font::advance(found, one.glyph) * size)
.sum()
}
