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-rw-r--r--font/src/ft/mod.rs787
1 files changed, 0 insertions, 787 deletions
diff --git a/font/src/ft/mod.rs b/font/src/ft/mod.rs
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--- a/font/src/ft/mod.rs
+++ /dev/null
@@ -1,787 +0,0 @@
-//! Rasterization powered by FreeType and Fontconfig.
-
-use std::cmp::{min, Ordering};
-use std::collections::HashMap;
-use std::fmt::{self, Display, Formatter};
-use std::rc::Rc;
-
-use freetype::face::LoadFlag;
-use freetype::tt_os2::TrueTypeOS2Table;
-use freetype::{self, Library, Matrix};
-use freetype::{freetype_sys, Face as FTFace};
-use libc::{c_long, c_uint};
-use log::{debug, trace};
-
-pub mod fc;
-
-use fc::{CharSet, FTFaceLocation, Pattern, PatternHash, PatternRef};
-
-use super::{
- BitmapBuffer, FontDesc, FontKey, GlyphKey, Metrics, Rasterize, RasterizedGlyph, Size, Slant,
- Style, Weight,
-};
-
-struct FallbackFont {
- pattern: Pattern,
- key: FontKey,
-}
-
-impl FallbackFont {
- fn new(pattern: Pattern, key: FontKey) -> FallbackFont {
- Self { pattern, key }
- }
-}
-
-impl FontKey {
- fn from_pattern_hashes(lhs: PatternHash, rhs: PatternHash) -> Self {
- // XOR two hashes to get a font ID.
- Self { token: lhs.0.rotate_left(1) ^ rhs.0 }
- }
-}
-
-#[derive(Default)]
-struct FallbackList {
- list: Vec<FallbackFont>,
- coverage: CharSet,
-}
-
-struct FaceLoadingProperties {
- load_flags: LoadFlag,
- render_mode: freetype::RenderMode,
- lcd_filter: c_uint,
- non_scalable: Option<f32>,
- colored: bool,
- embolden: bool,
- matrix: Option<Matrix>,
- pixelsize_fixup_factor: Option<f64>,
- ft_face: Rc<FTFace>,
-}
-
-impl fmt::Debug for FaceLoadingProperties {
- fn fmt(&self, f: &mut Formatter) -> fmt::Result {
- f.debug_struct("Face")
- .field("ft_face", &self.ft_face)
- .field("load_flags", &self.load_flags)
- .field("render_mode", &match self.render_mode {
- freetype::RenderMode::Normal => "Normal",
- freetype::RenderMode::Light => "Light",
- freetype::RenderMode::Mono => "Mono",
- freetype::RenderMode::Lcd => "Lcd",
- freetype::RenderMode::LcdV => "LcdV",
- freetype::RenderMode::Max => "Max",
- })
- .field("lcd_filter", &self.lcd_filter)
- .finish()
- }
-}
-
-/// Rasterizes glyphs for a single font face.
-pub struct FreeTypeRasterizer {
- library: Library,
- faces: HashMap<FontKey, FaceLoadingProperties>,
- ft_faces: HashMap<FTFaceLocation, Rc<FTFace>>,
- fallback_lists: HashMap<FontKey, FallbackList>,
- device_pixel_ratio: f32,
-}
-
-#[inline]
-fn to_freetype_26_6(f: f32) -> isize {
- ((1i32 << 6) as f32 * f).round() as isize
-}
-
-#[inline]
-fn to_fixedpoint_16_6(f: f64) -> c_long {
- (f * 65536.0) as c_long
-}
-
-impl Rasterize for FreeTypeRasterizer {
- type Err = Error;
-
- fn new(device_pixel_ratio: f32, _: bool) -> Result<FreeTypeRasterizer, Error> {
- let library = Library::init()?;
-
- unsafe {
- // Initialize default properties, like user preferred interpreter.
- freetype_sys::FT_Set_Default_Properties(library.raw());
- };
-
- Ok(FreeTypeRasterizer {
- faces: HashMap::new(),
- ft_faces: HashMap::new(),
- fallback_lists: HashMap::new(),
- library,
- device_pixel_ratio,
- })
- }
-
- fn metrics(&self, key: FontKey, _size: Size) -> Result<Metrics, Error> {
- let face = &mut self.faces.get(&key).ok_or(Error::FontNotLoaded)?;
- let full = self.full_metrics(&face)?;
-
- let height = (full.size_metrics.height / 64) as f64;
- let descent = (full.size_metrics.descender / 64) as f32;
-
- // Get underline position and thickness in device pixels.
- let x_scale = full.size_metrics.x_scale as f32 / 65536.0;
- let mut underline_position = f32::from(face.ft_face.underline_position()) * x_scale / 64.;
- let mut underline_thickness = f32::from(face.ft_face.underline_thickness()) * x_scale / 64.;
-
- // Fallback for bitmap fonts which do not provide underline metrics.
- if underline_position == 0. {
- underline_thickness = (descent.abs() / 5.).round();
- underline_position = descent / 2.;
- }
-
- // Get strikeout position and thickness in device pixels.
- let (strikeout_position, strikeout_thickness) =
- match TrueTypeOS2Table::from_face(&mut (*face.ft_face).clone()) {
- Some(os2) => {
- let strikeout_position = f32::from(os2.y_strikeout_position()) * x_scale / 64.;
- let strikeout_thickness = f32::from(os2.y_strikeout_size()) * x_scale / 64.;
- (strikeout_position, strikeout_thickness)
- },
- _ => {
- // Fallback if font doesn't provide info about strikeout.
- trace!("Using fallback strikeout metrics");
- let strikeout_position = height as f32 / 2. + descent;
- (strikeout_position, underline_thickness)
- },
- };
-
- Ok(Metrics {
- average_advance: full.cell_width,
- line_height: height,
- descent,
- underline_position,
- underline_thickness,
- strikeout_position,
- strikeout_thickness,
- })
- }
-
- fn load_font(&mut self, desc: &FontDesc, size: Size) -> Result<FontKey, Error> {
- self.get_face(desc, size)
- }
-
- fn get_glyph(&mut self, glyph_key: GlyphKey) -> Result<RasterizedGlyph, Error> {
- self.get_rendered_glyph(glyph_key)
- }
-
- fn update_dpr(&mut self, device_pixel_ratio: f32) {
- self.device_pixel_ratio = device_pixel_ratio;
- }
-}
-
-pub trait IntoFontconfigType {
- type FcType;
- fn into_fontconfig_type(&self) -> Self::FcType;
-}
-
-impl IntoFontconfigType for Slant {
- type FcType = fc::Slant;
-
- fn into_fontconfig_type(&self) -> Self::FcType {
- match *self {
- Slant::Normal => fc::Slant::Roman,
- Slant::Italic => fc::Slant::Italic,
- Slant::Oblique => fc::Slant::Oblique,
- }
- }
-}
-
-impl IntoFontconfigType for Weight {
- type FcType = fc::Weight;
-
- fn into_fontconfig_type(&self) -> Self::FcType {
- match *self {
- Weight::Normal => fc::Weight::Regular,
- Weight::Bold => fc::Weight::Bold,
- }
- }
-}
-
-struct FullMetrics {
- size_metrics: freetype::ffi::FT_Size_Metrics,
- cell_width: f64,
-}
-
-impl FreeTypeRasterizer {
- /// Load a font face according to `FontDesc`.
- fn get_face(&mut self, desc: &FontDesc, size: Size) -> Result<FontKey, Error> {
- // Adjust for DPR.
- let size = f64::from(size.as_f32_pts() * self.device_pixel_ratio * 96. / 72.);
-
- let config = fc::Config::get_current();
- let mut pattern = Pattern::new();
- pattern.add_family(&desc.name);
- pattern.add_pixelsize(size);
-
- // Add style to a pattern.
- match desc.style {
- Style::Description { slant, weight } => {
- // Match nearest font.
- pattern.set_weight(weight.into_fontconfig_type());
- pattern.set_slant(slant.into_fontconfig_type());
- },
- Style::Specific(ref style) => {
- // If a name was specified, try and load specifically that font.
- pattern.add_style(style);
- },
- }
-
- // Hash requested pattern.
- let hash = pattern.hash();
-
- pattern.config_substitute(config, fc::MatchKind::Pattern);
- pattern.default_substitute();
-
- // Get font list using pattern. First font is the primary one while the rest are fallbacks.
- let matched_fonts =
- fc::font_sort(&config, &pattern).ok_or_else(|| Error::MissingFont(desc.to_owned()))?;
- let mut matched_fonts = matched_fonts.into_iter();
-
- let primary_font =
- matched_fonts.next().ok_or_else(|| Error::MissingFont(desc.to_owned()))?;
-
- // We should render patterns to get values like `pixelsizefixupfactor`.
- let primary_font = pattern.render_prepare(config, primary_font);
-
- // Hash pattern together with request pattern to include requested font size in the hash.
- let primary_font_key = FontKey::from_pattern_hashes(hash, primary_font.hash());
-
- // Return if we already have the same primary font.
- if self.fallback_lists.contains_key(&primary_font_key) {
- return Ok(primary_font_key);
- }
-
- // Load font if we haven't loaded it yet.
- if !self.faces.contains_key(&primary_font_key) {
- self.face_from_pattern(&primary_font, primary_font_key)
- .and_then(|pattern| pattern.ok_or_else(|| Error::MissingFont(desc.to_owned())))?;
- }
-
- // Coverage for fallback fonts.
- let coverage = CharSet::new();
- let empty_charset = CharSet::new();
-
- let list: Vec<FallbackFont> = matched_fonts
- .map(|fallback_font| {
- let charset = fallback_font.get_charset().unwrap_or(&empty_charset);
-
- // Use original pattern to preserve loading flags.
- let fallback_font = pattern.render_prepare(config, fallback_font);
- let fallback_font_key = FontKey::from_pattern_hashes(hash, fallback_font.hash());
-
- let _ = coverage.merge(&charset);
-
- FallbackFont::new(fallback_font, fallback_font_key)
- })
- .collect();
-
- self.fallback_lists.insert(primary_font_key, FallbackList { list, coverage });
-
- Ok(primary_font_key)
- }
-
- fn full_metrics(&self, face_load_props: &FaceLoadingProperties) -> Result<FullMetrics, Error> {
- let ft_face = &face_load_props.ft_face;
- let size_metrics = ft_face.size_metrics().ok_or(Error::MissingSizeMetrics)?;
-
- let width = match ft_face.load_char('0' as usize, face_load_props.load_flags) {
- Ok(_) => ft_face.glyph().metrics().horiAdvance / 64,
- Err(_) => size_metrics.max_advance / 64,
- } as f64;
-
- Ok(FullMetrics { size_metrics, cell_width: width })
- }
-
- fn load_ft_face(&mut self, ft_face_location: FTFaceLocation) -> Result<Rc<FTFace>, Error> {
- let mut ft_face = self.library.new_face(&ft_face_location.path, ft_face_location.index)?;
- if ft_face.has_color() {
- unsafe {
- // Select the colored bitmap size to use from the array of available sizes.
- freetype_sys::FT_Select_Size(ft_face.raw_mut(), 0);
- }
- }
-
- let ft_face = Rc::new(ft_face);
- self.ft_faces.insert(ft_face_location, Rc::clone(&ft_face));
-
- Ok(ft_face)
- }
-
- fn face_from_pattern(
- &mut self,
- pattern: &PatternRef,
- font_key: FontKey,
- ) -> Result<Option<FontKey>, Error> {
- if let Some(ft_face_location) = pattern.ft_face_location(0) {
- if self.faces.get(&font_key).is_some() {
- return Ok(Some(font_key));
- }
-
- trace!("Got font path={:?}, index={:?}", ft_face_location.path, ft_face_location.index);
-
- let ft_face = match self.ft_faces.get(&ft_face_location) {
- Some(ft_face) => Rc::clone(ft_face),
- None => self.load_ft_face(ft_face_location)?,
- };
-
- let non_scalable = if pattern.scalable().next().unwrap_or(true) {
- None
- } else {
- Some(pattern.pixelsize().next().expect("has 1+ pixelsize") as f32)
- };
-
- let embolden = pattern.embolden().next().unwrap_or(false);
-
- let matrix = pattern.get_matrix().map(|matrix| {
- // Convert Fontconfig matrix to FreeType matrix.
- let xx = to_fixedpoint_16_6(matrix.xx);
- let xy = to_fixedpoint_16_6(matrix.xy);
- let yx = to_fixedpoint_16_6(matrix.yx);
- let yy = to_fixedpoint_16_6(matrix.yy);
-
- Matrix { xx, xy, yx, yy }
- });
-
- let pixelsize_fixup_factor = pattern.pixelsizefixupfactor().next();
-
- let face = FaceLoadingProperties {
- load_flags: Self::ft_load_flags(pattern),
- render_mode: Self::ft_render_mode(pattern),
- lcd_filter: Self::ft_lcd_filter(pattern),
- non_scalable,
- colored: ft_face.has_color(),
- embolden,
- matrix,
- pixelsize_fixup_factor,
- ft_face,
- };
-
- debug!("Loaded Face {:?}", face);
-
- self.faces.insert(font_key, face);
-
- Ok(Some(font_key))
- } else {
- Ok(None)
- }
- }
-
- fn face_for_glyph(&mut self, glyph_key: GlyphKey) -> Result<FontKey, Error> {
- if let Some(face) = self.faces.get(&glyph_key.font_key) {
- let index = face.ft_face.get_char_index(glyph_key.c as usize);
-
- if index != 0 {
- return Ok(glyph_key.font_key);
- }
- }
-
- Ok(self.load_face_with_glyph(glyph_key).unwrap_or(glyph_key.font_key))
- }
-
- fn load_face_with_glyph(&mut self, glyph: GlyphKey) -> Result<FontKey, Error> {
- let fallback_list = self.fallback_lists.get(&glyph.font_key).unwrap();
-
- // Check whether glyph is presented in any fallback font.
- if !fallback_list.coverage.has_char(glyph.c) {
- return Ok(glyph.font_key);
- }
-
- for fallback_font in &fallback_list.list {
- let font_key = fallback_font.key;
- let font_pattern = &fallback_font.pattern;
- match self.faces.get(&font_key) {
- Some(face) => {
- let index = face.ft_face.get_char_index(glyph.c as usize);
-
- // We found something in a current face, so let's use it.
- if index != 0 {
- return Ok(font_key);
- }
- },
- None => {
- if font_pattern.get_charset().map(|cs| cs.has_char(glyph.c)) != Some(true) {
- continue;
- }
-
- let pattern = font_pattern.clone();
- let key = self.face_from_pattern(&pattern, font_key)?.unwrap();
-
- return Ok(key);
- },
- }
- }
-
- // You can hit this return, if you're failing to get charset from a pattern.
- Ok(glyph.font_key)
- }
-
- fn get_rendered_glyph(&mut self, glyph_key: GlyphKey) -> Result<RasterizedGlyph, Error> {
- // Render a normal character if it's not a cursor.
- let font_key = self.face_for_glyph(glyph_key)?;
- let face = &self.faces[&font_key];
- let index = face.ft_face.get_char_index(glyph_key.c as usize);
- let pixelsize = face
- .non_scalable
- .unwrap_or_else(|| glyph_key.size.as_f32_pts() * self.device_pixel_ratio * 96. / 72.);
-
- if !face.colored {
- face.ft_face.set_char_size(to_freetype_26_6(pixelsize), 0, 0, 0)?;
- }
-
- unsafe {
- let ft_lib = self.library.raw();
- freetype::ffi::FT_Library_SetLcdFilter(ft_lib, face.lcd_filter);
- }
-
- face.ft_face.load_glyph(index as u32, face.load_flags)?;
-
- let glyph = face.ft_face.glyph();
-
- // Generate synthetic bold.
- if face.embolden {
- unsafe {
- freetype_sys::FT_GlyphSlot_Embolden(glyph.raw()
- as *const freetype_sys::FT_GlyphSlotRec
- as *mut freetype_sys::FT_GlyphSlotRec);
- }
- }
-
- // Transform glyphs with the matrix from Fontconfig. Primarily used to generate italics.
- if let Some(matrix) = face.matrix.as_ref() {
- let glyph = face.ft_face.raw().glyph;
-
- unsafe {
- // Check that the glyph is a vectorial outline, not a bitmap.
- if (*glyph).format == freetype_sys::FT_GLYPH_FORMAT_OUTLINE {
- let outline = &(*glyph).outline;
-
- freetype_sys::FT_Outline_Transform(outline, matrix);
- }
- }
- }
-
- glyph.render_glyph(face.render_mode)?;
-
- let (pixel_height, pixel_width, buf) = Self::normalize_buffer(&glyph.bitmap())?;
-
- let rasterized_glyph = RasterizedGlyph {
- c: glyph_key.c,
- top: glyph.bitmap_top(),
- left: glyph.bitmap_left(),
- width: pixel_width,
- height: pixel_height,
- buf,
- };
-
- if face.colored {
- let fixup_factor = if let Some(pixelsize_fixup_factor) = face.pixelsize_fixup_factor {
- pixelsize_fixup_factor
- } else {
- // Fallback if user has bitmap scaling disabled.
- let metrics = face.ft_face.size_metrics().ok_or(Error::MissingSizeMetrics)?;
- f64::from(pixelsize) / f64::from(metrics.y_ppem)
- };
- Ok(downsample_bitmap(rasterized_glyph, fixup_factor))
- } else {
- Ok(rasterized_glyph)
- }
- }
-
- fn ft_load_flags(pattern: &PatternRef) -> LoadFlag {
- let antialias = pattern.antialias().next().unwrap_or(true);
- let autohint = pattern.autohint().next().unwrap_or(false);
- let hinting = pattern.hinting().next().unwrap_or(true);
- let rgba = pattern.rgba().next().unwrap_or(fc::Rgba::Unknown);
- let embedded_bitmaps = pattern.embeddedbitmap().next().unwrap_or(true);
- let scalable = pattern.scalable().next().unwrap_or(true);
- let color = pattern.color().next().unwrap_or(false);
-
- // Disable hinting if so was requested.
- let hintstyle = if hinting {
- pattern.hintstyle().next().unwrap_or(fc::HintStyle::Full)
- } else {
- fc::HintStyle::None
- };
-
- let mut flags = match (antialias, hintstyle, rgba) {
- (false, fc::HintStyle::None, _) => LoadFlag::NO_HINTING | LoadFlag::MONOCHROME,
- (false, ..) => LoadFlag::TARGET_MONO | LoadFlag::MONOCHROME,
- (true, fc::HintStyle::None, _) => LoadFlag::NO_HINTING,
- // `hintslight` does *not* use LCD hinting even when a subpixel mode
- // is selected.
- //
- // According to the FreeType docs,
- //
- // > You can use a hinting algorithm that doesn't correspond to the
- // > same rendering mode. As an example, it is possible to use the
- // > ‘light’ hinting algorithm and have the results rendered in
- // > horizontal LCD pixel mode.
- //
- // In practice, this means we can have `FT_LOAD_TARGET_LIGHT` with
- // subpixel render modes like `FT_RENDER_MODE_LCD`. Libraries like
- // cairo take the same approach and consider `hintslight` to always
- // prefer `FT_LOAD_TARGET_LIGHT`.
- (true, fc::HintStyle::Slight, _) => LoadFlag::TARGET_LIGHT,
- (true, fc::HintStyle::Medium, _) => LoadFlag::TARGET_NORMAL,
- // If LCD hinting is to be used, must select hintmedium or hintfull,
- // have AA enabled, and select a subpixel mode.
- (true, fc::HintStyle::Full, fc::Rgba::Rgb)
- | (true, fc::HintStyle::Full, fc::Rgba::Bgr) => LoadFlag::TARGET_LCD,
- (true, fc::HintStyle::Full, fc::Rgba::Vrgb)
- | (true, fc::HintStyle::Full, fc::Rgba::Vbgr) => LoadFlag::TARGET_LCD_V,
- // For non-rgba modes with Full hinting, just use the default hinting algorithm.
- (true, fc::HintStyle::Full, fc::Rgba::Unknown)
- | (true, fc::HintStyle::Full, fc::Rgba::None) => LoadFlag::TARGET_NORMAL,
- };
-
- // Non scalable fonts only have bitmaps, so disabling them entirely is likely not a
- // desirable thing. Colored fonts aren't scalable, but also only have bitmaps.
- if !embedded_bitmaps && scalable && !color {
- flags |= LoadFlag::NO_BITMAP;
- }
-
- // Use color for colored fonts.
- if color {
- flags |= LoadFlag::COLOR;
- }
-
- // Force autohint if it was requested.
- if autohint {
- flags |= LoadFlag::FORCE_AUTOHINT;
- }
-
- flags
- }
-
- fn ft_render_mode(pat: &PatternRef) -> freetype::RenderMode {
- let antialias = pat.antialias().next().unwrap_or(true);
- let rgba = pat.rgba().next().unwrap_or(fc::Rgba::Unknown);
-
- match (antialias, rgba) {
- (false, _) => freetype::RenderMode::Mono,
- (_, fc::Rgba::Rgb) | (_, fc::Rgba::Bgr) => freetype::RenderMode::Lcd,
- (_, fc::Rgba::Vrgb) | (_, fc::Rgba::Vbgr) => freetype::RenderMode::LcdV,
- (true, _) => freetype::RenderMode::Normal,
- }
- }
-
- fn ft_lcd_filter(pat: &PatternRef) -> c_uint {
- match pat.lcdfilter().next().unwrap_or(fc::LcdFilter::Default) {
- fc::LcdFilter::None => freetype::ffi::FT_LCD_FILTER_NONE,
- fc::LcdFilter::Default => freetype::ffi::FT_LCD_FILTER_DEFAULT,
- fc::LcdFilter::Light => freetype::ffi::FT_LCD_FILTER_LIGHT,
- fc::LcdFilter::Legacy => freetype::ffi::FT_LCD_FILTER_LEGACY,
- }
- }
-
- /// Given a FreeType `Bitmap`, returns packed buffer with 1 byte per LCD channel.
- ///
- /// The i32 value in the return type is the number of pixels per row.
- fn normalize_buffer(
- bitmap: &freetype::bitmap::Bitmap,
- ) -> freetype::FtResult<(i32, i32, BitmapBuffer)> {
- use freetype::bitmap::PixelMode;
-
- let buf = bitmap.buffer();
- let mut packed = Vec::with_capacity((bitmap.rows() * bitmap.width()) as usize);
- let pitch = bitmap.pitch().abs() as usize;
- match bitmap.pixel_mode()? {
- PixelMode::Lcd => {
- for i in 0..bitmap.rows() {
- let start = (i as usize) * pitch;
- let stop = start + bitmap.width() as usize;
- packed.extend_from_slice(&buf[start..stop]);
- }
- Ok((bitmap.rows(), bitmap.width() / 3, BitmapBuffer::RGB(packed)))
- },
- PixelMode::LcdV => {
- for i in 0..bitmap.rows() / 3 {
- for j in 0..bitmap.width() {
- for k in 0..3 {
- let offset = ((i as usize) * 3 + k) * pitch + (j as usize);
- packed.push(buf[offset]);
- }
- }
- }
- Ok((bitmap.rows() / 3, bitmap.width(), BitmapBuffer::RGB(packed)))
- },
- // Mono data is stored in a packed format using 1 bit per pixel.
- PixelMode::Mono => {
- fn unpack_byte(res: &mut Vec<u8>, byte: u8, mut count: u8) {
- // Mono stores MSBit at top of byte
- let mut bit = 7;
- while count != 0 {
- let value = ((byte >> bit) & 1) * 255;
- // Push value 3x since result buffer should be 1 byte
- // per channel.
- res.push(value);
- res.push(value);
- res.push(value);
- count -= 1;
- bit -= 1;
- }
- };
-
- for i in 0..(bitmap.rows() as usize) {
- let mut columns = bitmap.width();
- let mut byte = 0;
- let offset = i * bitmap.pitch().abs() as usize;
- while columns != 0 {
- let bits = min(8, columns);
- unpack_byte(&mut packed, buf[offset + byte], bits as u8);
-
- columns -= bits;
- byte += 1;
- }
- }
- Ok((bitmap.rows(), bitmap.width(), BitmapBuffer::RGB(packed)))
- },
- // Gray data is stored as a value between 0 and 255 using 1 byte per pixel.
- PixelMode::Gray => {
- for i in 0..bitmap.rows() {
- let start = (i as usize) * pitch;
- let stop = start + bitmap.width() as usize;
- for byte in &buf[start..stop] {
- packed.push(*byte);
- packed.push(*byte);
- packed.push(*byte);
- }
- }
- Ok((bitmap.rows(), bitmap.width(), BitmapBuffer::RGB(packed)))
- },
- PixelMode::Bgra => {
- let buf_size = (bitmap.rows() * bitmap.width() * 4) as usize;
- let mut i = 0;
- while i < buf_size {
- packed.push(buf[i + 2]);
- packed.push(buf[i + 1]);
- packed.push(buf[i]);
- packed.push(buf[i + 3]);
- i += 4;
- }
- Ok((bitmap.rows(), bitmap.width(), BitmapBuffer::RGBA(packed)))
- },
- mode => panic!("unhandled pixel mode: {:?}", mode),
- }
- }
-}
-
-/// Downscale a bitmap by a fixed factor.
-///
-/// This will take the `bitmap_glyph` as input and return the glyph's content downscaled by
-/// `fixup_factor`.
-fn downsample_bitmap(mut bitmap_glyph: RasterizedGlyph, fixup_factor: f64) -> RasterizedGlyph {
- // Only scale colored buffers which are bigger than required.
- let bitmap_buffer = match (&bitmap_glyph.buf, fixup_factor.partial_cmp(&1.0)) {
- (BitmapBuffer::RGBA(buffer), Some(Ordering::Less)) => buffer,
- _ => return bitmap_glyph,
- };
-
- let bitmap_width = bitmap_glyph.width as usize;
- let bitmap_height = bitmap_glyph.height as usize;
-
- let target_width = (bitmap_width as f64 * fixup_factor) as usize;
- let target_height = (bitmap_height as f64 * fixup_factor) as usize;
-
- // Number of pixels in the input buffer, per pixel in the output buffer.
- let downsampling_step = 1.0 / fixup_factor;
-
- let mut downsampled_buffer = Vec::<u8>::with_capacity(target_width * target_height * 4);
-
- for line_index in 0..target_height {
- // Get the first and last line which will be consolidated in the current output pixel.
- let line_index = line_index as f64;
- let source_line_start = (line_index * downsampling_step).round() as usize;
- let source_line_end = ((line_index + 1.) * downsampling_step).round() as usize;
-
- for column_index in 0..target_width {
- // Get the first and last column which will be consolidated in the current output
- // pixel.
- let column_index = column_index as f64;
- let source_column_start = (column_index * downsampling_step).round() as usize;
- let source_column_end = ((column_index + 1.) * downsampling_step).round() as usize;
-
- let (mut r, mut g, mut b, mut a) = (0u32, 0u32, 0u32, 0u32);
- let mut pixels_picked: u32 = 0;
-
- // Consolidate all pixels within the source rectangle into a single averaged pixel.
- for source_line in source_line_start..source_line_end {
- let source_pixel_index = source_line * bitmap_width;
-
- for source_column in source_column_start..source_column_end {
- let offset = (source_pixel_index + source_column) * 4;
- r += u32::from(bitmap_buffer[offset]);
- g += u32::from(bitmap_buffer[offset + 1]);
- b += u32::from(bitmap_buffer[offset + 2]);
- a += u32::from(bitmap_buffer[offset + 3]);
- pixels_picked += 1;
- }
- }
-
- // Add a single pixel to the output buffer for the downscaled source rectangle.
- downsampled_buffer.push((r / pixels_picked) as u8);
- downsampled_buffer.push((g / pixels_picked) as u8);
- downsampled_buffer.push((b / pixels_picked) as u8);
- downsampled_buffer.push((a / pixels_picked) as u8);
- }
- }
-
- bitmap_glyph.buf = BitmapBuffer::RGBA(downsampled_buffer);
-
- // Downscale the metrics.
- bitmap_glyph.top = (f64::from(bitmap_glyph.top) * fixup_factor) as i32;
- bitmap_glyph.left = (f64::from(bitmap_glyph.left) * fixup_factor) as i32;
- bitmap_glyph.width = target_width as i32;
- bitmap_glyph.height = target_height as i32;
-
- bitmap_glyph
-}
-
-/// Errors occurring when using the freetype rasterizer.
-#[derive(Debug)]
-pub enum Error {
- /// Error occurred within the FreeType library.
- FreeType(freetype::Error),
-
- /// Couldn't find font matching description.
- MissingFont(FontDesc),
-
- /// Tried to get size metrics from a Face that didn't have a size.
- MissingSizeMetrics,
-
- /// Requested an operation with a FontKey that isn't known to the rasterizer.
- FontNotLoaded,
-}
-
-impl std::error::Error for Error {
- fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
- match self {
- Error::FreeType(err) => err.source(),
- _ => None,
- }
- }
-}
-
-impl Display for Error {
- fn fmt(&self, f: &mut Formatter) -> fmt::Result {
- match self {
- Error::FreeType(err) => err.fmt(f),
- Error::MissingFont(err) => write!(f, "Unable to find the font {}", err),
- Error::FontNotLoaded => f.write_str("Tried to use a font that hasn't been loaded"),
- Error::MissingSizeMetrics => {
- f.write_str("Tried to get size metrics from a face without a size")
- },
- }
- }
-}
-
-impl From<freetype::Error> for Error {
- fn from(val: freetype::Error) -> Error {
- Error::FreeType(val)
- }
-}
-
-unsafe impl Send for FreeTypeRasterizer {}
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