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Quelle font.rs
Sprache: unbekannt
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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/. */
#![allow(non_camel_case_types)]
use api::{ColorU, GlyphDimensions, FontKey, FontRenderMode};
use api::{FontInstancePlatformOptions, FontLCDFilter, FontHinting};
use api::{FontInstanceFlags, FontTemplate, FontVariation, NativeFontHandle};
use freetype::freetype::{FT_BBox, FT_Outline_Translate, FT_Pixel_Mode, FT_Render_Mod e};
use freetype::freetype::{FT_Done_Face, FT_Error, FT_Get_Char_Index, FT_Int32};
use freetype::freetype::{FT_Done_FreeType, FT_Library_SetLcdFilter, FT_Pos};
use freetype::freetype::{FT_F26Dot6, FT_Face, FT_Glyph_Format, FT_Long, FT_UInt};
use freetype::freetype::{FT_GlyphSlot, FT_LcdFilter, FT_New_Face, FT_New_Memory_Face};
use freetype::freetype::{FT_Init_FreeType, FT_Load_Glyph, FT_Render_Glyph};
use freetype::freetype::{FT_Library, FT_Outline_Get_CBox, FT_Set_Char_Size, FT_Select_Size};
use freetype::freetype::{FT_Fixed, FT_Matrix, FT_Set_Transform, FT_String, FT_ULong, FT_Vector};
use freetype::freetype::{FT_Err_Unimplemented_Feature, FT_MulFix, FT_Outline_Embolden};
use freetype::freetype::{FT_LOAD_COLOR, FT_LOAD_DEFAULT, FT_LOAD_FORCE_AUTOHINT};
use freetype::freetype::{FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH, FT_LOAD_NO_AUTOHINT};
use freetype::freetype::{FT_LOAD_NO_BITMAP, FT_LOAD_NO_HINTING};
use freetype::freetype::{FT_FACE_FLAG_SCALABLE, FT_FACE_FLAG_FIXED_SIZES};
use freetype::freetype::FT_FACE_FLAG_MULTIPLE_MASTERS;
use freetype::succeeded;
use crate::rasterizer::{FontInstance, GlyphFormat, GlyphKey};
use crate::rasterizer::{GlyphRasterError, GlyphRasterResult, RasterizedGlyph};
use crate::types::FastHashMap;
#[cfg(any(not(target_os = "android"), feature = "dynamic_freetype"))]
use libc::{dlsym, RTLD_DEFAULT};
use libc::free;
use std::{cmp, mem, ptr, slice};
use std::cmp::max;
use std::ffi::CString;
use std::sync::{Arc, Condvar, Mutex, MutexGuard};
// These constants are not present in the freetype
// bindings due to bindgen not handling the way
// the macros are defined.
//const FT_LOAD_TARGET_NORMAL: FT_UInt = 0 << 16;
const FT_LOAD_TARGET_LIGHT: FT_UInt = 1 << 16;
const FT_LOAD_TARGET_MONO: FT_UInt = 2 << 16;
const FT_LOAD_TARGET_LCD: FT_UInt = 3 << 16;
const FT_LOAD_TARGET_LCD_V: FT_UInt = 4 << 16;
#[repr(C)]
struct FT_Var_Axis {
pub name: *mut FT_String,
pub minimum: FT_Fixed,
pub def: FT_Fixed,
pub maximum: FT_Fixed,
pub tag: FT_ULong,
pub strid: FT_UInt,
}
#[repr(C)]
struct FT_Var_Named_Style {
pub coords: *mut FT_Fixed,
pub strid: FT_UInt,
pub psid: FT_UInt,
}
#[repr(C)]
struct FT_MM_Var {
pub num_axis: FT_UInt,
pub num_designs: FT_UInt,
pub num_namedstyles: FT_UInt,
pub axis: *mut FT_Var_Axis,
pub namedstyle: *mut FT_Var_Named_Style,
}
#[inline]
pub fn unimplemented(error: FT_Error) -> bool {
error == FT_Err_Unimplemented_Feature as FT_Error
}
// Use dlsym to check for symbols. If not available. just return an unimplemented error.
#[cfg(any(not(target_os = "android"), feature = "dynamic_freetype"))]
macro_rules! ft_dyn_fn {
($func_name:ident($($arg_name:ident:$arg_type:ty),*) -> FT_Error) => {
#[allow(non_snake_case)]
unsafe fn $func_name($($arg_name:$arg_type),*) -> FT_Error {
extern "C" fn unimpl_func($(_:$arg_type),*) -> FT_Error {
FT_Err_Unimplemented_Feature as FT_Error
}
lazy_static! {
static ref FUNC: unsafe extern "C" fn($($arg_type),*) -> FT_Error = {
unsafe {
let cname = CString::new(stringify!($func_name)).unwrap();
let ptr = dlsym(RTLD_DEFAULT, cname.as_ptr());
if !ptr.is_null() { mem::transmute(ptr) } else { unimpl_func }
}
};
}
(*FUNC)($($arg_name),*)
}
}
}
// On Android, just statically link in the symbols...
#[cfg(all(target_os = "android", not(feature = "dynamic_freetype")))]
macro_rules! ft_dyn_fn {
($($proto:tt)+) => { extern "C" { fn $($proto)+; } }
}
ft_dyn_fn!(FT_Get_MM_Var(face: FT_Face, desc: *mut *mut FT_MM_Var) -> FT_Error);
ft_dyn_fn!(FT_Done_MM_Var(library: FT_Library, desc: *mut FT_MM_Var) -> FT_Error);
ft_dyn_fn!(FT_Set_Var_Design_Coordinates(face: FT_Face, num_vals: FT_UInt, vals: *mut FT_Fixed) -> FT_Error);
ft_dyn_fn!(FT_Get_Var_Design_Coordinates(face: FT_Face, num_vals: FT_UInt, vals: *mut FT_Fixed) -> FT_Error);
extern "C" {
fn FT_GlyphSlot_Embolden(slot: FT_GlyphSlot);
}
// Custom version of FT_GlyphSlot_Embolden to be less aggressive with outline
// fonts than the default implementation in FreeType.
#[no_mangle]
pub extern "C" fn mozilla_glyphslot_embolden_less(slot: FT_GlyphSlot) {
if slot.is_null() {
return;
}
let slot_ = unsafe { &mut *slot };
let format = slot_.format;
if format != FT_Glyph_Format::FT_GLYPH_FORMAT_OUTLINE {
// For non-outline glyphs, just fall back to FreeType's function.
unsafe { FT_GlyphSlot_Embolden(slot) };
return;
}
let face_ = unsafe { *slot_.face };
// FT_GlyphSlot_Embolden uses a divisor of 24 here; we'll be only half as
// bold.
let size_ = unsafe { *face_.size };
let strength =
unsafe { FT_MulFix(face_.units_per_EM as FT_Long,
size_.metrics.y_scale) / 48 };
unsafe { FT_Outline_Embolden(&mut slot_.outline, strength) };
// Adjust metrics to suit the fattened glyph.
if slot_.advance.x != 0 {
slot_.advance.x += strength;
}
if slot_.advance.y != 0 {
slot_.advance.y += strength;
}
slot_.metrics.width += strength;
slot_.metrics.height += strength;
slot_.metrics.horiAdvance += strength;
slot_.metrics.vertAdvance += strength;
slot_.metrics.horiBearingY += strength;
}
struct CachedFont {
template: FontTemplate,
face: FT_Face,
mm_var: *mut FT_MM_Var,
variations: Vec<FontVariation>,
}
impl Drop for CachedFont {
fn drop(&mut self) {
unsafe {
if !self.mm_var.is_null() &&
unimplemented(FT_Done_MM_Var((*(*self.face).glyph).library, self.mm_var)) {
free(self.mm_var as _);
}
FT_Done_Face(self.face);
}
}
}
struct FontCache {
lib: FT_Library,
// Maps a template to a cached font that may be used across all threads.
fonts: FastHashMap<FontTemplate, Arc<Mutex<CachedFont>>>,
// The current LCD filter installed in the library.
lcd_filter: FontLCDFilter,
// The number of threads currently relying on the LCD filter state.
lcd_filter_uses: usize,
}
// FreeType resources are safe to move between threads as long as they
// are not concurrently accessed. In our case, everything is behind a
// Mutex so it is safe to move them between threads.
unsafe impl Send for CachedFont {}
unsafe impl Send for FontCache {}
impl FontCache {
fn new() -> Self {
let mut lib: FT_Library = ptr::null_mut();
let result = unsafe { FT_Init_FreeType(&mut lib) };
if succeeded(result) {
// Ensure the library uses the default LCD filter initially.
unsafe { FT_Library_SetLcdFilter(lib, FT_LcdFilter::FT_LCD_FILTER_DEFAULT) };
} else {
panic!("Failed to initialize FreeType - {}", result)
}
FontCache {
lib,
fonts: FastHashMap::default(),
lcd_filter: FontLCDFilter::Default,
lcd_filter_uses: 0,
}
}
fn add_font(&mut self, template: FontTemplate) -> Result<Arc<Mutex<CachedFont>>, FT_Error> {
if let Some(cached) = self.fonts.get(&template) {
return Ok(cached.clone());
}
unsafe {
let mut face: FT_Face = ptr::null_mut();
let result = match template {
FontTemplate::Raw(ref bytes, index) => {
FT_New_Memory_Face(
self.lib,
bytes.as_ptr(),
bytes.len() as FT_Long,
index as FT_Long,
&mut face,
)
}
FontTemplate::Native(NativeFontHandle { ref path, index }) => {
let str = path.as_os_str().to_str().unwrap();
let cstr = CString::new(str).unwrap();
FT_New_Face(
self.lib,
cstr.as_ptr(),
index as FT_Long,
&mut face,
)
}
};
if !succeeded(result) || face.is_null() {
return Err(result);
}
let mut mm_var = ptr::null_mut();
if ((*face).face_flags & (FT_FACE_FLAG_MULTIPLE_MASTERS as FT_Long)) != 0 &&
succeeded(FT_Get_MM_Var(face, &mut mm_var)) {
// Calling this before FT_Set_Var_Design_Coordinates avoids a bug with font variations
// not initialized properly in the font face, even if we ignore the result.
// See bug 1647035.
let mut tmp = [0; 16];
let res = FT_Get_Var_Design_Coordinates(
face,
(*mm_var).num_axis.min(16),
tmp.as_mut_ptr()
);
debug_assert!(succeeded(res));
}
let cached = Arc::new(Mutex::new(CachedFont {
template: template.clone(),
face,
mm_var,
variations: Vec::new(),
}));
self.fonts.insert(template, cached.clone());
Ok(cached)
}
}
fn delete_font(&mut self, cached: Arc<Mutex<CachedFont>>) {
self.fonts.remove(&cached.lock().unwrap().template);
}
}
impl Drop for FontCache {
fn drop(&mut self) {
self.fonts.clear();
unsafe {
FT_Done_FreeType(self.lib);
}
}
}
lazy_static! {
static ref FONT_CACHE: Mutex<FontCache> = Mutex::new(FontCache::new());
static ref LCD_FILTER_UNUSED: Condvar = Condvar::new();
}
pub struct FontContext {
fonts: FastHashMap<FontKey, Arc<Mutex<CachedFont>>>,
}
fn get_skew_bounds(bottom: i32, top: i32, skew_factor: f32, _vertical: bool) -> (f32, f32) {
let skew_min = (bottom as f32 + 0.5) * skew_factor;
let skew_max = (top as f32 - 0.5) * skew_factor;
// Negative skew factor may switch the sense of skew_min and skew_max.
(skew_min.min(skew_max).floor(), skew_min.max(skew_max).ceil())
}
fn skew_bitmap(
bitmap: &[u8],
width: usize,
height: usize,
left: i32,
top: i32,
skew_factor: f32,
vertical: bool, // TODO: vertical skew not yet implemented!
) -> (Vec<u8>, usize, i32) {
let stride = width * 4;
// Calculate the skewed horizontal offsets of the bottom and top of the glyph.
let (skew_min, skew_max) = get_skew_bounds(top - height as i32, top, skew_factor, vertical);
// Allocate enough extra width for the min/max skew offsets.
let skew_width = width + (skew_max - skew_min) as usize;
let mut skew_buffer = vec![0u8; skew_width * height * 4];
for y in 0 .. height {
// Calculate a skew offset at the vertical center of the current row.
let offset = (top as f32 - y as f32 - 0.5) * skew_factor - skew_min;
// Get a blend factor in 0..256 constant across all pixels in the row.
let blend = (offset.fract() * 256.0) as u32;
let src_row = y * stride;
let dest_row = (y * skew_width + offset.floor() as usize) * 4;
let mut prev_px = [0u32; 4];
for (src, dest) in
bitmap[src_row .. src_row + stride].chunks(4).zip(
skew_buffer[dest_row .. dest_row + stride].chunks_mut(4)
) {
let px = [src[0] as u32, src[1] as u32, src[2] as u32, src[3] as u32];
// Blend current pixel with previous pixel based on blend factor.
let next_px = [px[0] * blend, px[1] * blend, px[2] * blend, px[3] * blend];
dest[0] = ((((px[0] << 8) - next_px[0]) + prev_px[0] + 128) >> 8) as u8;
dest[1] = ((((px[1] << 8) - next_px[1]) + prev_px[1] + 128) >> 8) as u8;
dest[2] = ((((px[2] << 8) - next_px[2]) + prev_px[2] + 128) >> 8) as u8;
dest[3] = ((((px[3] << 8) - next_px[3]) + prev_px[3] + 128) >> 8) as u8;
// Save the remainder for blending onto the next pixel.
prev_px = next_px;
}
// If the skew misaligns the final pixel, write out the remainder.
if blend > 0 {
let dest = &mut skew_buffer[dest_row + stride .. dest_row + stride + 4];
dest[0] = ((prev_px[0] + 128) >> 8) as u8;
dest[1] = ((prev_px[1] + 128) >> 8) as u8;
dest[2] = ((prev_px[2] + 128) >> 8) as u8;
dest[3] = ((prev_px[3] + 128) >> 8) as u8;
}
}
(skew_buffer, skew_width, left + skew_min as i32)
}
fn transpose_bitmap(bitmap: &[u8], width: usize, height: usize) -> Vec<u8> {
let mut transposed = vec![0u8; width * height * 4];
for (y, row) in bitmap.chunks(width * 4).enumerate() {
let mut offset = y * 4;
for src in row.chunks(4) {
transposed[offset .. offset + 4].copy_from_slice(src);
offset += height * 4;
}
}
transposed
}
fn flip_bitmap_x(bitmap: &mut [u8], width: usize, height: usize) {
assert!(bitmap.len() == width * height * 4);
let pixels = unsafe { slice::from_raw_parts_mut(bitmap.as_mut_ptr() as *mut u32, width * height) };
for row in pixels.chunks_mut(width) {
row.reverse();
}
}
fn flip_bitmap_y(bitmap: &mut [u8], width: usize, height: usize) {
assert!(bitmap.len() == width * height * 4);
let pixels = unsafe { slice::from_raw_parts_mut(bitmap.as_mut_ptr() as *mut u32, width * height) };
for y in 0 .. height / 2 {
let low_row = y * width;
let high_row = (height - 1 - y) * width;
for x in 0 .. width {
pixels.swap(low_row + x, high_row + x);
}
}
}
impl FontContext {
pub fn distribute_across_threads() -> bool {
false
}
pub fn new() -> FontContext {
FontContext {
fonts: FastHashMap::default(),
}
}
pub fn add_raw_font(&mut self, font_key: &FontKey, bytes: Arc<Vec<u8>>, index: u32) {
if !self.fonts.contains_key(font_key) {
let len = bytes.len();
match FONT_CACHE.lock().unwrap().add_font(FontTemplate::Raw(bytes, index)) {
Ok(font) => self.fonts.insert(*font_key, font),
Err(result) => panic!("adding raw font failed: {} bytes, err={:?}", len, result),
};
}
}
pub fn add_native_font(&mut self, font_key: &FontKey, native_font_handle: NativeFontHandle) {
if !self.fonts.contains_key(font_key) {
let path = native_font_handle.path.to_string_lossy().into_owned();
match FONT_CACHE.lock().unwrap().add_font(FontTemplate::Native(native_font_handle)) {
Ok(font) => self.fonts.insert(*font_key, font),
Err(result) => panic!("adding native font failed: file={} err={:?}", path, result),
};
}
}
pub fn delete_font(&mut self, font_key: &FontKey) {
if let Some(cached) = self.fonts.remove(font_key) {
// If the only references to this font are the FontCache and this FontContext,
// then delete the font as there are no other existing users.
if Arc::strong_count(&cached) <= 2 {
FONT_CACHE.lock().unwrap().delete_font(cached);
}
}
}
pub fn delete_font_instance(&mut self, _instance: &FontInstance) {
}
fn load_glyph(&mut self, font: &FontInstance, glyph: &GlyphKey)
-> Option<(MutexGuard<CachedFont>, FT_GlyphSlot, f32)> {
let mut cached = self.fonts.get(&font.font_key)?.lock().ok()?;
let face = cached.face;
let mm_var = cached.mm_var;
if !mm_var.is_null() && font.variations != cached.variations {
cached.variations.clear();
cached.variations.extend_from_slice(&font.variations);
unsafe {
let num_axis = (*mm_var).num_axis;
let mut coords: Vec<FT_Fixed> = Vec::with_capacity(num_axis as usize);
for i in 0 .. num_axis {
let axis = (*mm_var).axis.offset(i as isize);
let mut value = (*axis).def;
for var in &font.variations {
if var.tag as FT_ULong == (*axis).tag {
value = (var.value * 65536.0 + 0.5) as FT_Fixed;
value = cmp::min(value, (*axis).maximum);
value = cmp::max(value, (*axis).minimum);
break;
}
}
coords.push(value);
}
let res = FT_Set_Var_Design_Coordinates(face, num_axis, coords.as_mut_ptr());
debug_assert!(succeeded(res));
}
}
let mut load_flags = FT_LOAD_DEFAULT;
let FontInstancePlatformOptions { mut hinting, .. } = font.platform_options.unwrap_or_default();
// Disable hinting if there is a non-axis-aligned transform.
if font.synthetic_italics.is_enabled() ||
((font.transform.scale_x != 0.0 || font.transform.scale_y != 0.0) &&
(font.transform.skew_x != 0.0 || font.transform.skew_y != 0.0)) {
hinting = FontHinting::None;
}
match (hinting, font.render_mode) {
(FontHinting::None, _) => load_flags |= FT_LOAD_NO_HINTING,
(FontHinting::Mono, _) => load_flags = FT_LOAD_TARGET_MONO,
(FontHinting::Light, _) => load_flags = FT_LOAD_TARGET_LIGHT,
(FontHinting::LCD, FontRenderMode::Subpixel) => {
load_flags = if font.flags.contains(FontInstanceFlags::LCD_VERTICAL) {
FT_LOAD_TARGET_LCD_V
} else {
FT_LOAD_TARGET_LCD
};
if font.flags.contains(FontInstanceFlags::FORCE_AUTOHINT) {
load_flags |= FT_LOAD_FORCE_AUTOHINT;
}
}
_ => {
if font.flags.contains(FontInstanceFlags::FORCE_AUTOHINT) {
load_flags |= FT_LOAD_FORCE_AUTOHINT;
}
}
}
if font.flags.contains(FontInstanceFlags::NO_AUTOHINT) {
load_flags |= FT_LOAD_NO_AUTOHINT;
}
if !font.flags.contains(FontInstanceFlags::EMBEDDED_BITMAPS) {
load_flags |= FT_LOAD_NO_BITMAP;
}
let face_flags = unsafe { (*face).face_flags };
if (face_flags & (FT_FACE_FLAG_FIXED_SIZES as FT_Long)) != 0 {
// We only set FT_LOAD_COLOR if there are bitmap strikes;
// COLR (color-layer) fonts are handled internally by Gecko, and
// WebRender is just asked to paint individual layers.
load_flags |= FT_LOAD_COLOR;
}
load_flags |= FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH;
let (x_scale, y_scale) = font.transform.compute_scale().unwrap_or((1.0, 1.0));
let req_size = font.size.to_f64_px();
let mut result = if (face_flags & (FT_FACE_FLAG_FIXED_SIZES as FT_Long)) != 0 &&
(face_flags & (FT_FACE_FLAG_SCALABLE as FT_Long)) == 0 &&
(load_flags & FT_LOAD_NO_BITMAP) == 0 {
unsafe { FT_Set_Transform(face, ptr::null_mut(), ptr::null_mut()) };
self.choose_bitmap_size(face, req_size * y_scale)
} else {
let mut shape = font.transform.invert_scale(x_scale, y_scale);
if font.flags.contains(FontInstanceFlags::FLIP_X) {
shape = shape.flip_x();
}
if font.flags.contains(FontInstanceFlags::FLIP_Y) {
shape = shape.flip_y();
}
if font.flags.contains(FontInstanceFlags::TRANSPOSE) {
shape = shape.swap_xy();
}
let (mut tx, mut ty) = (0.0, 0.0);
if font.synthetic_italics.is_enabled() {
let (shape_, (tx_, ty_)) = font.synthesize_italics(shape, y_scale * req_size);
shape = shape_;
tx = tx_;
ty = ty_;
};
let mut ft_shape = FT_Matrix {
xx: (shape.scale_x * 65536.0) as FT_Fixed,
xy: (shape.skew_x * -65536.0) as FT_Fixed,
yx: (shape.skew_y * -65536.0) as FT_Fixed,
yy: (shape.scale_y * 65536.0) as FT_Fixed,
};
// The delta vector for FT_Set_Transform is in units of 1/64 pixel.
let mut ft_delta = FT_Vector {
x: (tx * 64.0) as FT_F26Dot6,
y: (ty * -64.0) as FT_F26Dot6,
};
unsafe {
FT_Set_Transform(face, &mut ft_shape, &mut ft_delta);
FT_Set_Char_Size(
face,
(req_size * x_scale * 64.0 + 0.5) as FT_F26Dot6,
(req_size * y_scale * 64.0 + 0.5) as FT_F26Dot6,
0,
0,
)
}
};
if !succeeded(result) {
error!("Unable to set glyph size and transform: {}", result);
//let raw_error = unsafe { FT_Error_String(result) };
//if !raw_error.is_ptr() {
// error!("\tcode {:?}", CStr::from_ptr(raw_error));
//}
debug!(
"\t[{}] for size {:?} and scale {:?} from font {:?}",
glyph.index(),
req_size,
(x_scale, y_scale),
font.font_key,
);
return None;
}
result = unsafe { FT_Load_Glyph(face, glyph.index() as FT_UInt, load_flags as FT_Int32) };
if !succeeded(result) {
error!("Unable to load glyph: {}", result);
//let raw_error = unsafe { FT_Error_String(result) };
//if !raw_error.is_ptr() {
// error!("\tcode {:?}", CStr::from_ptr(raw_error));
//}
debug!(
"\t[{}] with flags {:?} from font {:?}",
glyph.index(),
load_flags,
font.font_key,
);
return None;
}
let slot = unsafe { (*face).glyph };
assert!(slot != ptr::null_mut());
if font.flags.contains(FontInstanceFlags::SYNTHETIC_BOLD) {
mozilla_glyphslot_embolden_less(slot);
}
let format = unsafe { (*slot).format };
match format {
FT_Glyph_Format::FT_GLYPH_FORMAT_BITMAP => {
let bitmap_size = unsafe { (*(*(*slot).face).size).metrics.y_ppem };
Some((cached, slot, req_size as f32 / bitmap_size as f32))
}
FT_Glyph_Format::FT_GLYPH_FORMAT_OUTLINE => Some((cached, slot, 1.0)),
_ => {
error!("Unsupported format");
debug!("format={:?}", format);
None
}
}
}
fn pad_bounding_box(font: &FontInstance, cbox: &mut FT_BBox) {
// Apply extra pixel of padding for subpixel AA, due to the filter.
if font.render_mode == FontRenderMode::Subpixel {
// Using an LCD filter may add one full pixel to each side if support is built in.
// As of FreeType 2.8.1, an LCD filter is always used regardless of settings
// if support for the patent-encumbered LCD filter algorithms is not built in.
// Thus, the only reasonable way to guess padding is to unconditonally add it if
// subpixel AA is used.
let lcd_extra_pixels = 1;
let padding = (lcd_extra_pixels * 64) as FT_Pos;
if font.flags.contains(FontInstanceFlags::LCD_VERTICAL) {
cbox.yMin -= padding;
cbox.yMax += padding;
} else {
cbox.xMin -= padding;
cbox.xMax += padding;
}
}
}
// Get the bounding box for a glyph, accounting for sub-pixel positioning.
fn get_bounding_box(
slot: FT_GlyphSlot,
font: &FontInstance,
glyph: &GlyphKey,
scale: f32,
) -> FT_BBox {
// Get the estimated bounding box from FT (control points).
let mut cbox = FT_BBox { xMin: 0, yMin: 0, xMax: 0, yMax: 0 };
unsafe {
FT_Outline_Get_CBox(&(*slot).outline, &mut cbox);
}
// For spaces and other non-printable characters, early out.
if unsafe { (*slot).outline.n_contours } == 0 {
return cbox;
}
Self::pad_bounding_box(font, &mut cbox);
// Offset the bounding box by subpixel positioning.
// Convert to 26.6 fixed point format for FT.
let (dx, dy) = font.get_subpx_offset(glyph);
let (dx, dy) = (
(dx / scale as f64 * 64.0 + 0.5) as FT_Pos,
-(dy / scale as f64 * 64.0 + 0.5) as FT_Pos,
);
cbox.xMin += dx;
cbox.xMax += dx;
cbox.yMin += dy;
cbox.yMax += dy;
// Outset the box to device pixel boundaries
cbox.xMin &= !63;
cbox.yMin &= !63;
cbox.xMax = (cbox.xMax + 63) & !63;
cbox.yMax = (cbox.yMax + 63) & !63;
cbox
}
fn get_glyph_dimensions_impl(
slot: FT_GlyphSlot,
font: &FontInstance,
glyph: &GlyphKey,
scale: f32,
use_transform: bool,
) -> Option<GlyphDimensions> {
let format = unsafe { (*slot).format };
let (mut left, mut top, mut width, mut height) = match format {
FT_Glyph_Format::FT_GLYPH_FORMAT_BITMAP => {
unsafe { (
(*slot).bitmap_left as i32,
(*slot).bitmap_top as i32,
(*slot).bitmap.width as i32,
(*slot).bitmap.rows as i32,
) }
}
FT_Glyph_Format::FT_GLYPH_FORMAT_OUTLINE => {
let cbox = Self::get_bounding_box(slot, font, glyph, scale);
(
(cbox.xMin >> 6) as i32,
(cbox.yMax >> 6) as i32,
((cbox.xMax - cbox.xMin) >> 6) as i32,
((cbox.yMax - cbox.yMin) >> 6) as i32,
)
}
_ => return None,
};
let mut advance = unsafe { (*slot).metrics.horiAdvance as f32 / 64.0 };
if use_transform {
if scale != 1.0 {
let x0 = left as f32 * scale;
let x1 = width as f32 * scale + x0;
let y1 = top as f32 * scale;
let y0 = y1 - height as f32 * scale;
left = x0.round() as i32;
top = y1.round() as i32;
width = (x1.ceil() - x0.floor()) as i32;
height = (y1.ceil() - y0.floor()) as i32;
advance *= scale;
}
// An outline glyph's cbox would have already been transformed inside FT_Load_Glyph,
// so only handle bitmap glyphs which are not handled by FT_Load_Glyph.
if format == FT_Glyph_Format::FT_GLYPH_FORMAT_BITMAP {
if font.synthetic_italics.is_enabled() {
let (skew_min, skew_max) = get_skew_bounds(
top - height as i32,
top,
font.synthetic_italics.to_skew(),
font.flags.contains(FontInstanceFlags::VERTICAL),
);
left += skew_min as i32;
width += (skew_max - skew_min) as i32;
}
if font.flags.contains(FontInstanceFlags::TRANSPOSE) {
mem::swap(&mut width, &mut height);
mem::swap(&mut left, &mut top);
left -= width as i32;
top += height as i32;
}
if font.flags.contains(FontInstanceFlags::FLIP_X) {
left = -(left + width as i32);
}
if font.flags.contains(FontInstanceFlags::FLIP_Y) {
top = -(top - height as i32);
}
}
}
Some(GlyphDimensions {
left,
top,
width,
height,
advance,
})
}
pub fn get_glyph_index(&mut self, font_key: FontKey, ch: char) -> Option<u32> {
let cached = self.fonts.get(&font_key)?.lock().ok()?;
let face = cached.face;
unsafe {
let idx = FT_Get_Char_Index(face, ch as _);
if idx != 0 {
Some(idx)
} else {
None
}
}
}
pub fn get_glyph_dimensions(
&mut self,
font: &FontInstance,
key: &GlyphKey,
) -> Option<GlyphDimensions> {
let (_cached, slot, scale) = self.load_glyph(font, key)?;
Self::get_glyph_dimensions_impl(slot, &font, key, scale, true)
}
fn choose_bitmap_size(&self, face: FT_Face, requested_size: f64) -> FT_Error {
let mut best_dist = unsafe { *(*face).available_sizes.offset(0) }.y_ppem as f64 / 64.0 - requested_size;
let mut best_size = 0;
let num_fixed_sizes = unsafe { (*face).num_fixed_sizes };
for i in 1 .. num_fixed_sizes {
// Distance is positive if strike is larger than desired size,
// or negative if smaller. If previously a found smaller strike,
// then prefer a larger strike. Otherwise, minimize distance.
let dist = unsafe { *(*face).available_sizes.offset(i as isize) }.y_ppem as f64 / 64.0 - requested_size;
if (best_dist < 0.0 && dist >= best_dist) || dist.abs() <= best_dist {
best_dist = dist;
best_size = i;
}
}
unsafe { FT_Select_Size(face, best_size) }
}
pub fn prepare_font(font: &mut FontInstance) {
match font.render_mode {
FontRenderMode::Mono => {
// In mono mode the color of the font is irrelevant.
font.color = ColorU::new(0xFF, 0xFF, 0xFF, 0xFF);
// Subpixel positioning is disabled in mono mode.
font.disable_subpixel_position();
}
FontRenderMode::Alpha | FontRenderMode::Subpixel => {
// We don't do any preblending with FreeType currently, so the color is not used.
font.color = ColorU::new(0xFF, 0xFF, 0xFF, 0xFF);
}
}
}
fn rasterize_glyph_outline(
slot: FT_GlyphSlot,
font: &FontInstance,
key: &GlyphKey,
scale: f32,
) -> bool {
// Get the subpixel offsets in FT 26.6 format.
let (dx, dy) = font.get_subpx_offset(key);
let (dx, dy) = (
(dx / scale as f64 * 64.0 + 0.5) as FT_Pos,
-(dy / scale as f64 * 64.0 + 0.5) as FT_Pos,
);
// Move the outline curves to be at the origin, taking
// into account the subpixel positioning.
unsafe {
let outline = &(*slot).outline;
let mut cbox = FT_BBox { xMin: 0, yMin: 0, xMax: 0, yMax: 0 };
FT_Outline_Get_CBox(outline, &mut cbox);
Self::pad_bounding_box(font, &mut cbox);
FT_Outline_Translate(
outline,
dx - ((cbox.xMin + dx) & !63),
dy - ((cbox.yMin + dy) & !63),
);
}
let render_mode = match font.render_mode {
FontRenderMode::Mono => FT_Render_Mode::FT_RENDER_MODE_MONO,
FontRenderMode::Alpha => FT_Render_Mode::FT_RENDER_MODE_NORMAL,
FontRenderMode::Subpixel => if font.flags.contains(FontInstanceFlags::LCD_VERTICAL) {
FT_Render_Mode::FT_RENDER_MODE_LCD_V
} else {
FT_Render_Mode::FT_RENDER_MODE_LCD
},
};
let result = unsafe { FT_Render_Glyph(slot, render_mode) };
if !succeeded(result) {
error!("Unable to rasterize");
debug!(
"{:?} with {:?}, {:?}",
key,
render_mode,
result
);
false
} else {
true
}
}
pub fn begin_rasterize(font: &FontInstance) {
// The global LCD filter state is only used in subpixel rendering modes.
if font.render_mode == FontRenderMode::Subpixel {
let mut cache = FONT_CACHE.lock().unwrap();
let FontInstancePlatformOptions { lcd_filter, .. } = font.platform_options.unwrap_or_default();
// Check if the current LCD filter matches the requested one.
if cache.lcd_filter != lcd_filter {
// If the filter doesn't match, we have to wait for all other currently rasterizing threads
// that may use the LCD filter state to finish before we can override it.
while cache.lcd_filter_uses != 0 {
cache = LCD_FILTER_UNUSED.wait(cache).unwrap();
}
// Finally set the LCD filter to the requested one now that the library is unused.
cache.lcd_filter = lcd_filter;
let filter = match lcd_filter {
FontLCDFilter::None => FT_LcdFilter::FT_LCD_FILTER_NONE,
FontLCDFilter::Default => FT_LcdFilter::FT_LCD_FILTER_DEFAULT,
FontLCDFilter::Light => FT_LcdFilter::FT_LCD_FILTER_LIGHT,
FontLCDFilter::Legacy => FT_LcdFilter::FT_LCD_FILTER_LEGACY,
};
unsafe {
let result = FT_Library_SetLcdFilter(cache.lib, filter);
// Setting the legacy filter may fail, so just use the default filter instead.
if !succeeded(result) {
FT_Library_SetLcdFilter(cache.lib, FT_LcdFilter::FT_LCD_FILTER_DEFAULT);
}
}
}
cache.lcd_filter_uses += 1;
}
}
pub fn end_rasterize(font: &FontInstance) {
if font.render_mode == FontRenderMode::Subpixel {
let mut cache = FONT_CACHE.lock().unwrap();
// If this is the last use of the LCD filter, then signal that the LCD filter isn't used.
cache.lcd_filter_uses -= 1;
if cache.lcd_filter_uses == 0 {
LCD_FILTER_UNUSED.notify_all();
}
}
}
pub fn rasterize_glyph(&mut self, font: &FontInstance, key: &GlyphKey) -> GlyphRasterResult {
let (_cached, slot, scale) = self.load_glyph(font, key)
.ok_or(GlyphRasterError::LoadFailed)?;
// Get dimensions of the glyph, to see if we need to rasterize it.
// Don't apply scaling to the dimensions, as the glyph cache needs to know the actual
// footprint of the glyph.
let dimensions = Self::get_glyph_dimensions_impl(slot, font, key, scale, false)
.ok_or(GlyphRasterError::LoadFailed)?;
let GlyphDimensions { mut left, mut top, width, height, .. } = dimensions;
// For spaces and other non-printable characters, early out.
if width == 0 || height == 0 {
return Err(GlyphRasterError::LoadFailed);
}
let format = unsafe { (*slot).format };
match format {
FT_Glyph_Format::FT_GLYPH_FORMAT_BITMAP => {}
FT_Glyph_Format::FT_GLYPH_FORMAT_OUTLINE => {
if !Self::rasterize_glyph_outline(slot, font, key, scale) {
return Err(GlyphRasterError::LoadFailed);
}
}
_ => {
error!("Unsupported format");
debug!("format={:?}", format);
return Err(GlyphRasterError::LoadFailed);
}
};
debug!(
"Rasterizing {:?} as {:?} with dimensions {:?}",
key,
font.render_mode,
dimensions
);
let bitmap = unsafe { &(*slot).bitmap };
let pixel_mode = unsafe { mem::transmute(bitmap.pixel_mode as u32) };
let (mut actual_width, mut actual_height) = match pixel_mode {
FT_Pixel_Mode::FT_PIXEL_MODE_LCD => {
assert!(bitmap.width % 3 == 0);
((bitmap.width / 3) as usize, bitmap.rows as usize)
}
FT_Pixel_Mode::FT_PIXEL_MODE_LCD_V => {
assert!(bitmap.rows % 3 == 0);
(bitmap.width as usize, (bitmap.rows / 3) as usize)
}
FT_Pixel_Mode::FT_PIXEL_MODE_MONO |
FT_Pixel_Mode::FT_PIXEL_MODE_GRAY |
FT_Pixel_Mode::FT_PIXEL_MODE_BGRA => {
(bitmap.width as usize, bitmap.rows as usize)
}
_ => panic!("Unsupported mode"),
};
// If we need padding, we will need to expand the buffer size.
let (buffer_width, buffer_height, padding) = if font.use_texture_padding() {
(actual_width + 2, actual_height + 2, 1)
} else {
(actual_width, actual_height, 0)
};
let mut final_buffer = vec![0u8; buffer_width * buffer_height * 4];
// Extract the final glyph from FT format into BGRA8 format, which is
// what WR expects.
let subpixel_bgr = font.flags.contains(FontInstanceFlags::SUBPIXEL_BGR);
let mut src_row = bitmap.buffer;
let mut dest = 4 * padding * (padding + buffer_width);
let actual_end = final_buffer.len() - 4 * padding * (buffer_width + 1);
while dest < actual_end {
let mut src = src_row;
let row_end = dest + actual_width * 4;
match pixel_mode {
FT_Pixel_Mode::FT_PIXEL_MODE_MONO => {
while dest < row_end {
// Cast the byte to signed so that we can left shift each bit into
// the top bit, then right shift to fill out the bits with 0s or 1s.
let mut byte: i8 = unsafe { *src as i8 };
src = unsafe { src.offset(1) };
let byte_end = cmp::min(row_end, dest + 8 * 4);
while dest < byte_end {
let alpha = (byte >> 7) as u8;
final_buffer[dest + 0] = alpha;
final_buffer[dest + 1] = alpha;
final_buffer[dest + 2] = alpha;
final_buffer[dest + 3] = alpha;
dest += 4;
byte <<= 1;
}
}
}
FT_Pixel_Mode::FT_PIXEL_MODE_GRAY => {
while dest < row_end {
let alpha = unsafe { *src };
final_buffer[dest + 0] = alpha;
final_buffer[dest + 1] = alpha;
final_buffer[dest + 2] = alpha;
final_buffer[dest + 3] = alpha;
src = unsafe { src.offset(1) };
dest += 4;
}
}
FT_Pixel_Mode::FT_PIXEL_MODE_LCD => {
while dest < row_end {
let (mut r, g, mut b) = unsafe { (*src, *src.offset(1), *src.offset(2)) };
if subpixel_bgr {
mem::swap(&mut r, &mut b);
}
final_buffer[dest + 0] = b;
final_buffer[dest + 1] = g;
final_buffer[dest + 2] = r;
final_buffer[dest + 3] = max(max(b, g), r);
src = unsafe { src.offset(3) };
dest += 4;
}
}
FT_Pixel_Mode::FT_PIXEL_MODE_LCD_V => {
while dest < row_end {
let (mut r, g, mut b) =
unsafe { (*src, *src.offset(bitmap.pitch as isize),
*src.offset((2 * bitmap.pitch) as isize)) };
if subpixel_bgr {
mem::swap(&mut r, &mut b);
}
final_buffer[dest + 0] = b;
final_buffer[dest + 1] = g;
final_buffer[dest + 2] = r;
final_buffer[dest + 3] = max(max(b, g), r);
src = unsafe { src.offset(1) };
dest += 4;
}
src_row = unsafe { src_row.offset((2 * bitmap.pitch) as isize) };
}
FT_Pixel_Mode::FT_PIXEL_MODE_BGRA => {
// The source is premultiplied BGRA data.
let dest_slice = &mut final_buffer[dest .. row_end];
let src_slice = unsafe { slice::from_raw_parts(src, dest_slice.len()) };
dest_slice.copy_from_slice(src_slice);
}
_ => panic!("Unsupported mode"),
}
src_row = unsafe { src_row.offset(bitmap.pitch as isize) };
dest = row_end + 8 * padding;
}
if font.use_texture_padding() {
left -= padding as i32;
top += padding as i32;
actual_width = buffer_width;
actual_height = buffer_height;
}
match format {
FT_Glyph_Format::FT_GLYPH_FORMAT_BITMAP => {
if font.synthetic_italics.is_enabled() {
let (skew_buffer, skew_width, skew_left) = skew_bitmap(
&final_buffer,
actual_width,
actual_height,
left,
top,
font.synthetic_italics.to_skew(),
font.flags.contains(FontInstanceFlags::VERTICAL),
);
final_buffer = skew_buffer;
actual_width = skew_width;
left = skew_left;
}
if font.flags.contains(FontInstanceFlags::TRANSPOSE) {
final_buffer = transpose_bitmap(&final_buffer, actual_width, actual_height);
mem::swap(&mut actual_width, &mut actual_height);
mem::swap(&mut left, &mut top);
left -= actual_width as i32;
top += actual_height as i32;
}
if font.flags.contains(FontInstanceFlags::FLIP_X) {
flip_bitmap_x(&mut final_buffer, actual_width, actual_height);
left = -(left + actual_width as i32);
}
if font.flags.contains(FontInstanceFlags::FLIP_Y) {
flip_bitmap_y(&mut final_buffer, actual_width, actual_height);
top = -(top - actual_height as i32);
}
}
FT_Glyph_Format::FT_GLYPH_FORMAT_OUTLINE => {
unsafe {
left += (*slot).bitmap_left;
top += (*slot).bitmap_top - height as i32;
}
}
_ => {}
}
let glyph_format = match (pixel_mode, format) {
(FT_Pixel_Mode::FT_PIXEL_MODE_LCD, _) |
(FT_Pixel_Mode::FT_PIXEL_MODE_LCD_V, _) => font.get_subpixel_glyph_format(),
(FT_Pixel_Mode::FT_PIXEL_MODE_BGRA, _) => GlyphFormat::ColorBitmap,
(_, FT_Glyph_Format::FT_GLYPH_FORMAT_BITMAP) => GlyphFormat::Bitmap,
_ => font.get_alpha_glyph_format(),
};
Ok(RasterizedGlyph {
left: left as f32,
top: top as f32,
width: actual_width as i32,
height: actual_height as i32,
scale,
format: glyph_format,
bytes: final_buffer,
})
}
}
[ Dauer der Verarbeitung: 0.50 Sekunden
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]
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2026-04-06
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