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use alloc::vec::Vec;
use euclid::num::{One, Zero};
use crate::items::{TextHorizontalAlignment, TextOverflow, TextVerticalAlignment, TextWrap};
#[cfg(feature = "unicode-linebreak")]
mod linebreak_unicode;
#[cfg(feature = "unicode-linebreak")]
use linebreak_unicode::{BreakOpportunity, LineBreakIterator};
#[cfg(not(feature = "unicode-linebreak"))]
mod linebreak_simple;
#[cfg(not(feature = "unicode-linebreak"))]
use linebreak_simple::{BreakOpportunity, LineBreakIterator};
mod fragments;
mod glyphclusters;
mod shaping;
use shaping::ShapeBuffer;
pub use shaping::{AbstractFont, FontMetrics, Glyph, TextShaper};
mod linebreaker;
pub use linebreaker::TextLine;
pub use linebreaker::TextLineBreaker;
pub struct TextLayout<'a, Font: AbstractFont> {
pub font: &'a Font,
pub letter_spacing: Option<<Font as TextShaper>::Length>,
}
impl<'a, Font: AbstractFont> TextLayout<'a, Font> {
pub fn text_size(
&self,
text: &str,
max_width: Option<Font::Length>,
) -> (Font::Length, Font::Length)
where
Font::Length: core::fmt::Debug,
{
let mut max_line_width = Font::Length::zero();
let mut line_count: i16 = 0;
let shape_buffer = ShapeBuffer::new(self, text);
for line in TextLineBreaker::<Font>::new(text, &shape_buffer, max_width) {
max_line_width = euclid::approxord::max(max_line_width, line.text_width);
line_count += 1;
}
(max_line_width, self.font.height() * line_count.into())
}
}
pub struct PositionedGlyph<'a, Length, PlatformGlyphData> {
pub x: Length,
pub y: Length,
pub platform_glyph: &'a PlatformGlyphData,
}
pub struct TextParagraphLayout<'a, Font: AbstractFont> {
pub string: &'a str,
pub layout: TextLayout<'a, Font>,
pub max_width: Font::Length,
pub max_height: Font::Length,
pub horizontal_alignment: TextHorizontalAlignment,
pub vertical_alignment: TextVerticalAlignment,
pub wrap: TextWrap,
pub overflow: TextOverflow,
pub single_line: bool,
}
impl<'a, Font: AbstractFont> TextParagraphLayout<'a, Font> {
pub fn layout_lines(
&self,
mut line_callback: impl FnMut(
&mut dyn Iterator<Item = PositionedGlyph<'_, Font::Length, Font::PlatformGlyphData>>,
Font::Length,
Font::Length,
),
) -> Font::Length {
let wrap = self.wrap == TextWrap::word_wrap;
let elide_glyph = if self.overflow == TextOverflow::elide {
self.layout.font.glyph_for_char('…')
} else {
None
};
let max_width_without_elision =
self.max_width - elide_glyph.as_ref().map_or(Font::Length::zero(), |g| g.advance);
let shape_buffer = ShapeBuffer::new(&self.layout, self.string);
let new_line_break_iter = || {
TextLineBreaker::<Font>::new(
self.string,
&shape_buffer,
if wrap { Some(self.max_width) } else { None },
)
};
let mut text_lines = None;
let mut text_height = || {
if self.single_line {
self.layout.font.height()
} else {
text_lines = Some(new_line_break_iter().collect::<Vec<_>>());
self.layout.font.height() * (text_lines.as_ref().unwrap().len() as i16).into()
}
};
let two = Font::LengthPrimitive::one() + Font::LengthPrimitive::one();
let baseline_y = match self.vertical_alignment {
TextVerticalAlignment::top => Font::Length::zero(),
TextVerticalAlignment::center => self.max_height / two - text_height() / two,
TextVerticalAlignment::bottom => self.max_height - text_height(),
};
let mut y = baseline_y;
let mut process_line =
|line: &TextLine<Font::Length>,
glyphs: &[Glyph<Font::Length, Font::PlatformGlyphData>]| {
let x = match self.horizontal_alignment {
TextHorizontalAlignment::left => Font::Length::zero(),
TextHorizontalAlignment::center => {
self.max_width / two
- euclid::approxord::min(self.max_width, line.text_width) / two
}
TextHorizontalAlignment::right => {
self.max_width - euclid::approxord::min(self.max_width, line.text_width)
}
};
let mut elide_glyph = elide_glyph.as_ref().clone();
let glyph_it = glyphs[line.glyph_range.clone()].iter();
let mut glyph_x = Font::Length::zero();
let mut positioned_glyph_it = glyph_it.map_while(|glyph| {
if glyph_x > max_width_without_elision {
if let Some(elide_glyph) = elide_glyph.take() {
return Some(PositionedGlyph {
x: glyph_x,
y: Font::Length::zero(),
platform_glyph: &elide_glyph.platform_glyph,
});
} else {
return None;
}
}
let positioned_glyph = PositionedGlyph {
x: glyph_x,
y: Font::Length::zero(),
platform_glyph: &glyph.platform_glyph,
};
glyph_x += glyph.advance;
Some(positioned_glyph)
});
line_callback(&mut positioned_glyph_it, x, y);
y += self.layout.font.height();
};
if let Some(lines_vec) = text_lines.take() {
for line in lines_vec {
process_line(&line, &shape_buffer.glyphs);
}
} else {
for line in new_line_break_iter() {
process_line(&line, &shape_buffer.glyphs);
}
}
baseline_y
}
}
#[test]
fn test_no_linebreak_opportunity_at_eot() {
let mut it = LineBreakIterator::new("Hello World");
assert_eq!(it.next(), Some((6, BreakOpportunity::Allowed)));
assert_eq!(it.next(), None);
}
#[cfg(test)]
pub struct FixedTestFont;
#[cfg(test)]
impl TextShaper for FixedTestFont {
type LengthPrimitive = f32;
type Length = f32;
type PlatformGlyphData = shaping::TestGlyphData;
fn shape_text<GlyphStorage: std::iter::Extend<Glyph<f32, Self::PlatformGlyphData>>>(
&self,
text: &str,
glyphs: &mut GlyphStorage,
) {
let glyph_iter = text.char_indices().map(|(byte_offset, char)| Glyph {
offset_x: 0.,
offset_y: 0.,
platform_glyph: Self::PlatformGlyphData {
bearing_x: 0.,
bearing_y: 0.,
width: 10.,
height: 10.,
glyph_id: None,
char: Some(char),
},
advance: 10.,
text_byte_offset: byte_offset,
});
glyphs.extend(glyph_iter);
}
fn glyph_for_char(&self, ch: char) -> Option<Glyph<f32, Self::PlatformGlyphData>> {
Glyph {
offset_x: 0.,
offset_y: 0.,
platform_glyph: Self::PlatformGlyphData {
bearing_x: 0.,
bearing_y: 0.,
width: 10.,
height: 10.,
glyph_id: None,
char: Some(ch),
},
advance: 10.,
text_byte_offset: 0,
}
.into()
}
}
#[cfg(test)]
impl FontMetrics<f32> for FixedTestFont {
fn ascent(&self) -> f32 {
5.
}
fn descent(&self) -> f32 {
-5.
}
}
#[test]
fn test_elision() {
let font = FixedTestFont;
let text = "This is a longer piece of text";
let mut lines = Vec::new();
let paragraph = TextParagraphLayout {
string: text,
layout: TextLayout { font: &font, letter_spacing: None },
max_width: 13. * 10.,
max_height: 10.,
horizontal_alignment: TextHorizontalAlignment::left,
vertical_alignment: TextVerticalAlignment::top,
wrap: TextWrap::no_wrap,
overflow: TextOverflow::elide,
single_line: true,
};
paragraph.layout_lines(|glyphs, _, _| {
lines.push(
glyphs
.map(|positioned_glyph| positioned_glyph.platform_glyph.clone())
.collect::<Vec<_>>(),
);
});
assert_eq!(lines.len(), 1);
let rendered_text =
lines[0].iter().map(|platform_glyph| platform_glyph.char.unwrap()).collect::<String>();
debug_assert_eq!(rendered_text, "This is a lon…")
}
#[test]
fn test_exact_fit() {
let font = FixedTestFont;
let text = "Fits";
let mut lines = Vec::new();
let paragraph = TextParagraphLayout {
string: text,
layout: TextLayout { font: &font, letter_spacing: None },
max_width: 4. * 10.,
max_height: 10.,
horizontal_alignment: TextHorizontalAlignment::left,
vertical_alignment: TextVerticalAlignment::top,
wrap: TextWrap::no_wrap,
overflow: TextOverflow::elide,
single_line: true,
};
paragraph.layout_lines(|glyphs, _, _| {
lines.push(
glyphs
.map(|positioned_glyph| positioned_glyph.platform_glyph.clone())
.collect::<Vec<_>>(),
);
});
assert_eq!(lines.len(), 1);
let rendered_text =
lines[0].iter().map(|platform_glyph| platform_glyph.char.unwrap()).collect::<String>();
debug_assert_eq!(rendered_text, "Fits")
}