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//! Fonts, font families and a font cache.
//!
//! Before you can use a font in a PDF document, you have to load the [`FontData`][] for it, either
//! from a file ([`FontData::load`][]) or from bytes ([`FontData::new`][]). See the [`rusttype`][]
//! crate for the supported data formats. Use the [`from_files`][] function to load a font family
//! from a set of files following the default naming conventions.
//!
//! The [`FontCache`][] caches all loaded fonts. A [`Font`][] is a reference to a cached font in
//! the [`FontCache`][]. A [`FontFamily`][] is a collection of a regular, a bold, an italic and a
//! bold italic font (raw data or cached).
//!
//! Add fonts to a document’s font cache by calling [`Document::add_font_family`][]. This method
//! returns a reference to the cached data that you then can use with the [`Style`][] struct to
//! change the font family of an element.
//!
//! There are two methods for using fonts in a PDF font: You can either embed the font data into
//! the PDF file. Or you can use one of the three built-in font families ([`Builtin`][]) that PDF
//! viewers are expected to support. You can choose between the two methods when loading the font
//! ([`from_files`][], [`FontData::load`][], [`FontData::new`][]).
//!
//! If you choose a built-in font family, you still have to provide the font data so that `rckive_genpdf`
//! has access to its glyph metrics. Note that it is sufficient to use a font that is metrically
//! identical to the built-in font. For example, you can use the Liberation fonts instad of the
//! proprietary Helvetica, Times and Courier fonts.
//!
//! Built-in fonts can only be used with characters that are supported by the [Windows-1252][]
//! encoding.
//!
//! **Note:** The [`Font`][] and [`FontFamily<Font>`][`FontFamily`] structs are only valid for the
//! [`FontCache`][] they have been created with. If you dont use the low-level [`render`][] module
//! directly, only use the [`Document::add_font_family`][] method to add fonts!
//!
//! # Internals
//!
//! There are two types of font data: A [`FontData`][] instance stores information about the glyph
//! metrics that is used to calculate the text size. It can be loaded at any time using the
//! [`FontData::load`][] and [`FontData::new`][] methods. Once the PDF document is rendered, a
//! [`printpdf::IndirectFontRef`][] is used to draw text in the PDF document. Before a font can be
//! used in a PDF document, it has to be embedded using the [`FontCache::load_pdf_fonts`][] method.
//!
//! If you use the high-level interface provided by [`Document`][] to generate a PDF document, these
//! steps are done automatically. You only have to manually populate the font cache if you use the
//! low-level interface in the [`render`][] module.
//!
//! [`render`]: ../render/
//! [`Document`]: ../struct.Document.html
//! [`Document::add_font_family`]: ../struct.Document.html#method.add_font_family
//! [`Style`]: ../style/struct.Style.html
//! [`from_files`]: fn.from_files.html
//! [`Builtin`]: enum.Builtin.html
//! [`FontCache`]: struct.FontCache.html
//! [`FontCache::load_pdf_fonts`]: struct.FontCache.html#method.load_pdf_fonts
//! [`FontData`]: struct.FontData.html
//! [`FontData::new`]: struct.FontData.html#method.new
//! [`FontData::load`]: struct.FontData.html#method.load
//! [`Font`]: struct.Font.html
//! [`FontFamily`]: struct.FontFamily.html
//! [`rusttype`]: https://docs.rs/rusttype
//! [`rusttype::Font`]: https://docs.rs/rusttype/0.8.3/rusttype/struct.Font.html
//! [`printpdf`]: https://docs.rs/printpdf
//! [`printpdf::IndirectFontRef`]: https://docs.rs/printpdf/0.3.2/printpdf/types/plugins/graphics/two_dimensional/font/struct.IndirectFontRef.html
//! [Windows-1252]: https://en.wikipedia.org/wiki/Windows-1252
use std::fmt;
use std::fs;
use std::path;
use crate::error::{Context as _, Error, ErrorKind};
use crate::render;
use crate::style::Style;
use crate::Mm;
/// Stores font data that can be referenced by a [`Font`][] or [`FontFamily`][].
///
/// If you use the high-level interface provided by [`Document`][], you don’t have to access this
/// type. See the [module documentation](index.html) for details on the internals.
///
/// [`Document`]: ../struct.Document.html
/// [`Font`]: struct.Font.html
/// [`FontFamily`]: struct.FontFamily.html
#[derive(Debug)]
pub struct FontCache {
fonts: Vec<FontData>,
pdf_fonts: Vec<printpdf::IndirectFontRef>,
// We have to use an option because we first have to construct the FontCache before we can load
// a font, but the default font is always loaded in new, so this options is always some
// (outside of new).
default_font_family: Option<FontFamily<Font>>,
}
impl FontCache {
/// Creates a new font cache with the given default font family.
pub fn new(default_font_family: FontFamily<FontData>) -> FontCache {
let mut font_cache = FontCache {
fonts: Vec::new(),
pdf_fonts: Vec::new(),
default_font_family: None,
};
font_cache.default_font_family = Some(font_cache.add_font_family(default_font_family));
font_cache
}
/// Adds the given font to the cache and returns a reference to it.
pub fn add_font(&mut self, font_data: FontData) -> Font {
let is_builtin = match &font_data.raw_data {
RawFontData::Builtin(_) => true,
RawFontData::Embedded(_) => false,
};
let font = Font::new(self.fonts.len(), is_builtin, &font_data.rt_font);
self.fonts.push(font_data);
font
}
/// Adds the given font family to the cache and returns a reference to it.
pub fn add_font_family(&mut self, family: FontFamily<FontData>) -> FontFamily<Font> {
FontFamily {
regular: self.add_font(family.regular),
bold: self.add_font(family.bold),
italic: self.add_font(family.italic),
bold_italic: self.add_font(family.bold_italic),
}
}
/// Embeds all loaded fonts into the document generated by the given renderer and caches a
/// reference to them.
pub fn load_pdf_fonts(&mut self, renderer: &render::Renderer) -> Result<(), Error> {
self.pdf_fonts.clear();
for font in &self.fonts {
let pdf_font = match &font.raw_data {
RawFontData::Builtin(builtin) => renderer.add_builtin_font(*builtin)?,
RawFontData::Embedded(data) => renderer.add_embedded_font(data)?,
};
self.pdf_fonts.push(pdf_font);
}
Ok(())
}
/// Returns the default font family for this font cache.
pub fn default_font_family(&self) -> FontFamily<Font> {
self.default_font_family
.expect("Invariant violated: no default font family for FontCache")
}
/// Returns a reference to the emebdded PDF font for the given font, if available.
///
/// This method may only be called with [`Font`][] instances that have been created by this
/// font cache. PDF fonts are only avaiable if [`load_pdf_fonts`][] has been called.
///
/// [`Font`]: struct.Font.html
/// [`load_pdf_fonts`]: #method.load_pdf_fonts
pub fn get_pdf_font(&self, font: Font) -> Option<&printpdf::IndirectFontRef> {
self.pdf_fonts.get(font.idx)
}
/// Returns a reference to the Rusttype font for the given font, if available.
///
/// This method may only be called with [`Font`][] instances that have been created by this
/// font cache.
///
/// [`Font`]: struct.Font.html
pub fn get_rt_font(&self, font: Font) -> &rusttype::Font<'static> {
&self.fonts[font.idx].rt_font
}
}
/// The data for a font that is cached by a [`FontCache`][].
///
/// [`FontCache`]: struct.FontCache.html
#[derive(Clone, Debug)]
pub struct FontData {
rt_font: rusttype::Font<'static>,
raw_data: RawFontData,
}
impl FontData {
/// Loads a font from the given data.
///
/// The provided data must by readable by [`rusttype`][]. If `builtin` is set, a built-in PDF
/// font is used instead of embedding the font in the PDF file (see the [module
/// documentation](index.html) for more information). In this case, the given font must be
/// metrically identical to the built-in font.
///
/// [`rusttype`]: https://docs.rs/rusttype
pub fn new(data: Vec<u8>, builtin: Option<printpdf::BuiltinFont>) -> Result<FontData, Error> {
let raw_data = if let Some(builtin) = builtin {
RawFontData::Builtin(builtin)
} else {
RawFontData::Embedded(data.clone())
};
let rt_font = rusttype::Font::try_from_vec(data)
.ok_or_else(|| Error::new("Failed to read rusttype font", ErrorKind::InvalidFont))?;
if rt_font.units_per_em() == 0 {
Err(Error::new(
"The font is not scalable",
ErrorKind::InvalidFont,
))
} else {
Ok(FontData { rt_font, raw_data })
}
}
/// Loads the font at the given path.
///
/// The path must point to a file that can be read by [`rusttype`][]. If `builtin` is set, a
/// built-in PDF font is used instead of embedding the font in the PDF file (see the [module
/// documentation](index.html) for more information). In this case, the given font must be
/// metrically identical to the built-in font.
///
/// [`rusttype`]: https://docs.rs/rusttype
pub fn load(
path: impl AsRef<path::Path>,
builtin: Option<printpdf::BuiltinFont>,
) -> Result<FontData, Error> {
let data = fs::read(path.as_ref())
.with_context(|| format!("Failed to open font file {}", path.as_ref().display()))?;
FontData::new(data, builtin)
}
}
#[derive(Clone, Debug)]
enum RawFontData {
Builtin(printpdf::BuiltinFont),
Embedded(Vec<u8>),
}
#[derive(Clone, Copy, Debug)]
enum FontStyle {
Regular,
Bold,
Italic,
BoldItalic,
}
impl FontStyle {
fn name(&self) -> &'static str {
match self {
FontStyle::Regular => "Regular",
FontStyle::Bold => "Bold",
FontStyle::Italic => "Italic",
FontStyle::BoldItalic => "BoldItalic",
}
}
}
impl fmt::Display for FontStyle {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str(self.name())
}
}
/// A built-in font family.
///
/// A PDF viewer typically supports three font families that don’t have to be embedded into the PDF
/// file: Times, Helvetica and Courier.
///
/// See the [module documentation](index.html) for more information.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum Builtin {
/// The Times font family.
Times,
/// The Helvetica font family.
Helvetica,
/// The Courier font family.
Courier,
}
impl Builtin {
fn style(&self, style: FontStyle) -> printpdf::BuiltinFont {
match self {
Builtin::Times => match style {
FontStyle::Regular => printpdf::BuiltinFont::TimesRoman,
FontStyle::Bold => printpdf::BuiltinFont::TimesBold,
FontStyle::Italic => printpdf::BuiltinFont::TimesItalic,
FontStyle::BoldItalic => printpdf::BuiltinFont::TimesBoldItalic,
},
Builtin::Helvetica => match style {
FontStyle::Regular => printpdf::BuiltinFont::Helvetica,
FontStyle::Bold => printpdf::BuiltinFont::HelveticaBold,
FontStyle::Italic => printpdf::BuiltinFont::HelveticaOblique,
FontStyle::BoldItalic => printpdf::BuiltinFont::HelveticaBoldOblique,
},
Builtin::Courier => match style {
FontStyle::Regular => printpdf::BuiltinFont::Courier,
FontStyle::Bold => printpdf::BuiltinFont::CourierBold,
FontStyle::Italic => printpdf::BuiltinFont::CourierOblique,
FontStyle::BoldItalic => printpdf::BuiltinFont::CourierBoldOblique,
},
}
}
}
/// A collection of fonts with different styles.
///
/// See the [module documentation](index.html) for details on the internals.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct FontFamily<T: Clone + fmt::Debug> {
/// The regular variant of this font family.
pub regular: T,
/// The bold variant of this font family.
pub bold: T,
/// The italic variant of this font family.
pub italic: T,
/// The bold italic variant of this font family.
pub bold_italic: T,
}
impl<T: Clone + Copy + fmt::Debug + PartialEq> FontFamily<T> {
/// Returns the font for the given style.
pub fn get(&self, style: Style) -> T {
if style.is_bold() && style.is_italic() {
self.bold_italic
} else if style.is_bold() {
self.bold
} else if style.is_italic() {
self.italic
} else {
self.regular
}
}
}
/// A reference to a font cached by a [`FontCache`][].
///
/// See the [module documentation](index.html) for details on the internals.
///
/// [`FontCache`]: struct.FontCache.html
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct Font {
idx: usize,
is_builtin: bool,
scale: rusttype::Scale,
line_height: Mm,
glyph_height: Mm,
ascent: Mm,
}
impl Font {
fn new(idx: usize, is_builtin: bool, rt_font: &rusttype::Font<'static>) -> Font {
let units_per_em = rt_font.units_per_em();
assert!(units_per_em != 0);
let units_per_em = f32::from(units_per_em);
let v_metrics = rt_font.v_metrics_unscaled();
let glyph_height = (v_metrics.ascent - v_metrics.descent) / units_per_em;
let scale = rusttype::Scale::uniform(glyph_height);
let ascent = v_metrics.ascent / units_per_em;
let line_height = glyph_height + v_metrics.line_gap / units_per_em;
Font {
idx,
is_builtin,
scale,
line_height: printpdf::Pt(f64::from(line_height)).into(),
glyph_height: printpdf::Pt(f64::from(glyph_height)).into(),
ascent: printpdf::Pt(f64::from(ascent)).into(),
}
}
/// Returns whether this font is a built-in PDF font.
pub fn is_builtin(&self) -> bool {
self.is_builtin
}
/// Returns the line height for text with this font and the given font size.
pub fn get_line_height(&self, font_size: u8) -> Mm {
self.line_height * f64::from(font_size)
}
/// Returns the glyph height for text with this font and the given font size.
pub fn glyph_height(&self, font_size: u8) -> Mm {
self.glyph_height * f64::from(font_size)
}
/// Returns the ascent for text with this font and the given font size.
pub fn ascent(&self, font_size: u8) -> Mm {
self.ascent * f64::from(font_size)
}
/// Returns the width of a character with this font and the given font size.
///
/// The given [`FontCache`][] must be the font cache that loaded this font.
///
/// [`FontCache`]: struct.FontCache.html
pub fn char_width(&self, font_cache: &FontCache, c: char, font_size: u8) -> Mm {
let advance_width = self.char_h_metrics(font_cache, c).advance_width;
Mm::from(printpdf::Pt(f64::from(
advance_width * f32::from(font_size),
)))
}
/// Returns the width of the empty space between the origin of the glyph bounding
/// box and the leftmost edge of the character, for a given font and font size.
///
/// The given [`FontCache`][] must be the font cache that loaded this font.
///
/// [`FontCache`]: struct.FontCache.html
pub fn char_left_side_bearing(&self, font_cache: &FontCache, c: char, font_size: u8) -> Mm {
let left_side_bearing = self.char_h_metrics(font_cache, c).left_side_bearing;
Mm::from(printpdf::Pt(f64::from(
left_side_bearing * f32::from(font_size),
)))
}
fn char_h_metrics(&self, font_cache: &FontCache, c: char) -> rusttype::HMetrics {
font_cache
.get_rt_font(*self)
.glyph(c)
.scaled(self.scale)
.h_metrics()
}
/// Returns the width of a string with this font and the given font size.
///
/// The given [`FontCache`][] must be the font cache that loaded this font.
///
/// [`FontCache`]: struct.FontCache.html
pub fn str_width(&self, font_cache: &FontCache, s: &str, font_size: u8) -> Mm {
let str_width: Mm = font_cache
.get_rt_font(*self)
.glyphs_for(s.chars())
.map(|g| g.scaled(self.scale).h_metrics().advance_width)
.map(|w| Mm::from(printpdf::Pt(f64::from(w * f32::from(font_size)))))
.sum();
let kerning_width: Mm = self
.kerning(font_cache, s.chars())
.into_iter()
.map(|val| val * f32::from(font_size))
.map(|val| Mm::from(printpdf::Pt(f64::from(val))))
.sum();
str_width + kerning_width
}
/// Returns the kerning data for the given sequence of characters.
///
/// The *i*-th value of the returned data is the amount of kerning to insert before the *i*-th
/// character of the sequence.
///
/// The given [`FontCache`][] must be the font cache that loaded this font.
///
/// [`FontCache`]: struct.FontCache.html
pub fn kerning<I>(&self, font_cache: &FontCache, iter: I) -> Vec<f32>
where
I: IntoIterator<Item = char>,
{
let font = font_cache.get_rt_font(*self);
font.glyphs_for(iter.into_iter())
.scan(None, |last, g| {
let pos = if let Some(last) = last {
Some(font.pair_kerning(self.scale, *last, g.id()))
} else {
Some(0.0)
};
*last = Some(g.id());
pos
})
.collect()
}
/// Returns the glyphs IDs for the given sequence of characters.
///
/// The given [`FontCache`][] must be the font cache that loaded this font.
///
/// [`FontCache`]: struct.FontCache.html
pub fn glyph_ids<I>(&self, font_cache: &FontCache, iter: I) -> Vec<u16>
where
I: IntoIterator<Item = char>,
{
let font = font_cache.get_rt_font(*self);
font.glyphs_for(iter.into_iter())
.map(|g| g.id().0 as u16)
.collect()
}
/// Calculate the metrics of a given font size for this font.
pub fn metrics(&self, font_size: u8) -> Metrics {
Metrics::new(
self.line_height * f64::from(font_size),
self.glyph_height * f64::from(font_size),
self.ascent * f64::from(font_size),
)
}
}
fn from_file(
dir: impl AsRef<path::Path>,
name: &str,
style: FontStyle,
builtin: Option<Builtin>,
) -> Result<FontData, Error> {
let builtin = builtin.map(|b| b.style(style));
FontData::load(
&dir.as_ref().join(format!("{}-{}.ttf", name, style)),
builtin,
)
}
/// Loads the font family at the given path with the given name.
///
/// This method assumes that at the given path, these files exist and are valid font files:
/// - `{name}-Regular.ttf`
/// - `{name}-Bold.ttf`
/// - `{name}-Italic.ttf`
/// - `{name}-BoldItalic.ttf`
///
/// If `builtin` is set, built-in PDF fonts are used instead of embedding the fonts in the PDF file
/// (see the [module documentation](index.html) for more information). In this case, the given
/// fonts must be metrically identical to the built-in fonts.
pub fn from_files(
dir: impl AsRef<path::Path>,
name: &str,
builtin: Option<Builtin>,
) -> Result<FontFamily<FontData>, Error> {
let dir = dir.as_ref();
Ok(FontFamily {
regular: from_file(dir, name, FontStyle::Regular, builtin)?,
bold: from_file(dir, name, FontStyle::Bold, builtin)?,
italic: from_file(dir, name, FontStyle::Italic, builtin)?,
bold_italic: from_file(dir, name, FontStyle::BoldItalic, builtin)?,
})
}
/// The metrics of a font at a given scale.
#[derive(Clone, Copy, Debug, Default, PartialEq)]
pub struct Metrics {
/// The line height of the font at a given scale.
pub line_height: Mm,
/// The glyph height of the font at a given scale.
pub glyph_height: Mm,
/// The ascent of the font at a given scale.
pub ascent: Mm,
}
impl Metrics {
/// Create a new metrics instance with the given heights.
pub fn new(line_height: Mm, glyph_height: Mm, ascent: Mm) -> Metrics {
Metrics {
line_height,
glyph_height,
ascent,
}
}
/// Returns the maximum metrics from two metrics instances.
pub fn max(&self, other: &Self) -> Self {
Self {
line_height: self.line_height.max(other.line_height),
glyph_height: self.glyph_height.max(other.glyph_height),
ascent: self.ascent.max(other.ascent),
}
}
}