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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
// external
use unicode_segmentation::UnicodeSegmentation;
use usvg;
// self
use geom::*;
pub struct TextBlock<Font> {
pub text: String,
pub is_visible: bool,
pub bbox: Rect,
pub rotate: f64,
pub fill: Option<usvg::Fill>,
pub stroke: Option<usvg::Stroke>,
pub font: Font,
pub font_ascent: f64,
pub decoration: usvg::TextDecoration,
}
pub trait FontMetrics<Font> {
fn set_font(&mut self, font: &usvg::Font);
fn font(&self) -> Font;
fn width(&self, text: &str) -> f64;
fn ascent(&self) -> f64;
fn height(&self) -> f64;
}
pub fn draw_blocks<Font, Draw>(
blocks: Vec<TextBlock<Font>>,
mut draw: Draw,
) -> Rect
where Draw: FnMut(&TextBlock<Font>)
{
let mut bbox = Rect::new_bbox();
for block in blocks {
bbox.expand(block.bbox);
if block.is_visible {
draw(&block);
}
}
bbox
}
pub fn prepare_blocks<Font>(
text_kind: &usvg::Text,
font_metrics: &mut FontMetrics<Font>,
) -> Vec<TextBlock<Font>> {
fn first_number_or(list: &Option<usvg::NumberList>, def: f64) -> f64 {
list.as_ref().map(|list| list[0]).unwrap_or(def)
}
let mut blocks: Vec<TextBlock<Font>> = Vec::new();
let mut last_x = 0.0;
let mut last_y = 0.0;
for chunk in &text_kind.chunks {
let mut chunk_x = first_number_or(&chunk.x, last_x);
let mut x = chunk_x;
let mut y = first_number_or(&chunk.y, last_y);
let start_idx = blocks.len();
let mut grapheme_idx = 0;
for tspan in &chunk.spans {
font_metrics.set_font(&tspan.font);
let iter = UnicodeSegmentation::graphemes(tspan.text.as_str(), true);
for (i, c) in iter.enumerate() {
let mut has_custom_offset = i == 0;
{
let mut number_at = |list: &Option<usvg::NumberList>| -> Option<f64> {
if let &Some(ref list) = list {
if let Some(n) = list.get(grapheme_idx) {
has_custom_offset = true;
return Some(*n);
}
}
None
};
if let Some(n) = number_at(&chunk.x) { x = n; }
if let Some(n) = number_at(&chunk.y) { y = n; }
if let Some(n) = number_at(&chunk.dx) { x += n; }
if let Some(n) = number_at(&chunk.dy) { y += n; }
if i == 0 {
if let Some(n) = number_at(&chunk.x) { chunk_x = n; }
if let Some(n) = number_at(&chunk.dx) { chunk_x += n; }
}
}
if text_kind.rotate.is_some() {
has_custom_offset = true;
}
let can_merge = !blocks.is_empty() && !has_custom_offset;
if can_merge {
let prev_idx = blocks.len() - 1;
blocks[prev_idx].text.push_str(c);
let w = font_metrics.width(&blocks[prev_idx].text);
blocks[prev_idx].bbox.width = w;
let mut new_w = chunk_x;
for i in start_idx..blocks.len() {
new_w += blocks[i].bbox.width;
}
x = new_w;
} else {
let baseline_shift = match tspan.baseline_shift {
usvg::BaselineShift::Baseline => 0.0,
usvg::BaselineShift::Subscript => font_metrics.height() / 2.0,
usvg::BaselineShift::Superscript => -font_metrics.height() / 2.0,
usvg::BaselineShift::Percent(n) => -font_metrics.height() * (n / 100.0),
usvg::BaselineShift::Number(n) => -n,
};
let font_ascent = font_metrics.ascent();
let width = font_metrics.width(c);
let yy = y - font_ascent + baseline_shift;
let height = font_metrics.height();
let bbox = Rect { x, y: yy, width, height };
x += width;
// TODO: rewrite, explain
let rotate = match text_kind.rotate {
Some(ref list) => list[blocks.len()],
None => 0.0,
};
blocks.push(TextBlock {
text: c.to_string(),
is_visible: tspan.visibility == usvg::Visibility::Visible,
bbox,
rotate,
fill: tspan.fill.clone(),
stroke: tspan.stroke.clone(),
font: font_metrics.font(),
font_ascent,
decoration: tspan.decoration.clone(),
});
}
grapheme_idx += 1;
}
}
let mut chunk_w = 0.0;
for i in start_idx..blocks.len() {
chunk_w += blocks[i].bbox.width;
}
let adx = process_text_anchor(chunk.anchor, chunk_w);
for i in start_idx..blocks.len() {
blocks[i].bbox.x -= adx;
}
last_x = chunk_x + chunk_w - adx;
last_y = y;
}
blocks
}
fn process_text_anchor(a: usvg::TextAnchor, text_width: f64) -> f64 {
match a {
usvg::TextAnchor::Start => 0.0, // Nothing.
usvg::TextAnchor::Middle => text_width / 2.0,
usvg::TextAnchor::End => text_width,
}
}
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