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mod.rs
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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/. */
use api::{FontInstanceFlags, FontInstancePlatformOptions};
use api::{FontKey, FontInstanceKey, FontRenderMode, FontTemplate, FontVariation};
use api::{ColorU, GlyphIndex, GlyphDimensions, SyntheticItalics};
use api::units::*;
use api::{ImageDescriptor, ImageDescriptorFlags, ImageFormat, DirtyRect};
use crate::internal_types::ResourceCacheError;
use crate::platform::font::FontContext;
use crate::device::TextureFilter;
use crate::gpu_types::UvRectKind;
use crate::glyph_cache::{GlyphCache, CachedGlyphInfo, GlyphCacheEntry};
use crate::resource_cache::CachedImageData;
use crate::texture_cache::{TextureCache, TextureCacheHandle, Eviction};
use crate::gpu_cache::GpuCache;
use crate::render_task_graph::RenderTaskGraph;
use crate::render_task_cache::RenderTaskCache;
use crate::profiler::TextureCacheProfileCounters;
use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
use rayon::ThreadPool;
use rayon::prelude::*;
use euclid::approxeq::ApproxEq;
use euclid::size2;
use std::cmp;
use std::cell::Cell;
use std::hash::{Hash, Hasher};
use std::mem;
use std::ops::Deref;
use std::sync::{Arc, Condvar, Mutex, MutexGuard};
use std::sync::mpsc::{channel, Receiver, Sender};
use std::sync::atomic::{AtomicBool, Ordering};
pub static GLYPH_FLASHING: AtomicBool = AtomicBool::new(false);
impl FontContexts {
/// Get access to the font context associated to the current thread.
pub fn lock_current_context(&self) -> MutexGuard<FontContext> {
let id = self.current_worker_id();
self.lock_context(id)
}
pub(in super) fn current_worker_id(&self) -> Option<usize> {
self.workers.current_thread_index()
}
}
thread_local! {
pub static SEED: Cell<u32> = Cell::new(0);
}
// super simple random to avoid dependency on rand
fn random() -> u32 {
SEED.with(|seed| {
seed.set(seed.get().wrapping_mul(22695477).wrapping_add(1));
seed.get()
})
}
impl GlyphRasterizer {
pub fn request_glyphs(
&mut self,
glyph_cache: &mut GlyphCache,
font: FontInstance,
glyph_keys: &[GlyphKey],
texture_cache: &mut TextureCache,
gpu_cache: &mut GpuCache,
_: &mut RenderTaskCache,
_: &mut RenderTaskGraph,
) {
assert!(
self.font_contexts
.lock_shared_context()
.has_font(&font.font_key)
);
let mut new_glyphs = Vec::new();
let glyph_key_cache = glyph_cache.get_glyph_key_cache_for_font_mut(font.clone());
// select glyphs that have not been requested yet.
for key in glyph_keys {
if let Some(entry) = glyph_key_cache.try_get(key) {
match entry {
GlyphCacheEntry::Cached(ref glyph) => {
// Skip the glyph if it is already has a valid texture cache handle.
if !texture_cache.request(&glyph.texture_cache_handle, gpu_cache) {
continue;
}
// This case gets hit when we already rasterized the glyph, but the
// glyph has been evicted from the texture cache. Just force it to
// pending so it gets rematerialized.
}
// Otherwise, skip the entry if it is blank or pending.
GlyphCacheEntry::Blank | GlyphCacheEntry::Pending => continue,
}
}
new_glyphs.push(key.clone());
glyph_key_cache.add_glyph(key.clone(), GlyphCacheEntry::Pending);
}
if new_glyphs.is_empty() {
return;
}
self.pending_glyphs += 1;
self.request_glyphs_from_backend(font, new_glyphs);
}
pub fn enable_multithreading(&mut self, enable: bool) {
self.enable_multithreading = enable;
}
pub(in super) fn request_glyphs_from_backend(&mut self, font: FontInstance, glyphs: Vec<GlyphKey>) {
let font_contexts = Arc::clone(&self.font_contexts);
let glyph_tx = self.glyph_tx.clone();
fn process_glyph(key: &GlyphKey, font_contexts: &FontContexts, font: &FontInstance) -> GlyphRasterJob {
profile_scope!("glyph-raster");
let mut context = font_contexts.lock_current_context();
let mut job = GlyphRasterJob {
key: key.clone(),
result: context.rasterize_glyph(&font, key),
};
if let Ok(ref mut glyph) = job.result {
// Sanity check.
let bpp = 4; // We always render glyphs in 32 bits RGBA format.
assert_eq!(
glyph.bytes.len(),
bpp * (glyph.width * glyph.height) as usize
);
// a quick-and-dirty monochrome over
fn over(dst: u8, src: u8) -> u8 {
let a = src as u32;
let a = 256 - a;
let dst = ((dst as u32 * a) >> 8) as u8;
src + dst
}
if GLYPH_FLASHING.load(Ordering::Relaxed) {
let color = (random() & 0xff) as u8;
for i in &mut glyph.bytes {
*i = over(*i, color);
}
}
assert_eq!((glyph.left.fract(), glyph.top.fract()), (0.0, 0.0));
// Check if the glyph has a bitmap that needs to be downscaled.
glyph.downscale_bitmap_if_required(&font);
}
job
}
// if the number of glyphs is small, do it inline to avoid the threading overhead;
// send the result into glyph_tx so downstream code can't tell the difference.
if !self.enable_multithreading || glyphs.len() < 8 {
let jobs = glyphs.iter()
.map(|key: &GlyphKey| process_glyph(key, &font_contexts, &font))
.collect();
glyph_tx.send(GlyphRasterJobs { font, jobs }).unwrap();
} else {
// spawn an async task to get off of the render backend thread as early as
// possible and in that task use rayon's fork join dispatch to rasterize the
// glyphs in the thread pool.
self.workers.spawn(move || {
let jobs = glyphs
.par_iter()
.map(|key: &GlyphKey| process_glyph(key, &font_contexts, &font))
.collect();
glyph_tx.send(GlyphRasterJobs { font, jobs }).unwrap();
});
}
}
pub fn resolve_glyphs(
&mut self,
glyph_cache: &mut GlyphCache,
texture_cache: &mut TextureCache,
gpu_cache: &mut GpuCache,
_: &mut RenderTaskCache,
_: &mut RenderTaskGraph,
_: &mut TextureCacheProfileCounters,
) {
// Pull rasterized glyphs from the queue and update the caches.
while self.pending_glyphs > 0 {
self.pending_glyphs -= 1;
// TODO: rather than blocking until all pending glyphs are available
// we could try_recv and steal work from the thread pool to take advantage
// of the fact that this thread is alive and we avoid the added latency
// of blocking it.
let GlyphRasterJobs { font, mut jobs } = self.glyph_rx
.recv()
.expect("BUG: Should be glyphs pending!");
// Ensure that the glyphs are always processed in the same
// order for a given text run (since iterating a hash set doesn't
// guarantee order). This can show up as very small float inaccuracy
// differences in rasterizers due to the different coordinates
// that text runs get associated with by the texture cache allocator.
jobs.sort_by(|a, b| a.key.cmp(&b.key));
let glyph_key_cache = glyph_cache.get_glyph_key_cache_for_font_mut(font);
for GlyphRasterJob { key, result } in jobs {
let glyph_info = match result {
Err(_) => GlyphCacheEntry::Blank,
Ok(ref glyph) if glyph.width == 0 || glyph.height == 0 => {
GlyphCacheEntry::Blank
}
Ok(glyph) => {
let mut texture_cache_handle = TextureCacheHandle::invalid();
texture_cache.request(&texture_cache_handle, gpu_cache);
texture_cache.update(
&mut texture_cache_handle,
ImageDescriptor {
size: size2(glyph.width, glyph.height),
stride: None,
format: FORMAT,
flags: ImageDescriptorFlags::empty(),
offset: 0,
},
TextureFilter::Linear,
Some(CachedImageData::Raw(Arc::new(glyph.bytes))),
[glyph.left, -glyph.top, glyph.scale],
DirtyRect::All,
gpu_cache,
Some(glyph_key_cache.eviction_notice()),
UvRectKind::Rect,
Eviction::Auto,
);
GlyphCacheEntry::Cached(CachedGlyphInfo {
texture_cache_handle,
format: glyph.format,
})
}
};
glyph_key_cache.insert(key, glyph_info);
}
}
// Now that we are done with the critical path (rendering the glyphs),
// we can schedule removing the fonts if needed.
self.remove_dead_fonts();
}
}
#[allow(dead_code)]
pub const FORMAT: ImageFormat = ImageFormat::BGRA8;
#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, PartialOrd)]
#[cfg_attr(feature = "capture", derive(Serialize))]
#[cfg_attr(feature = "replay", derive(Deserialize))]
pub struct FontTransform {
pub scale_x: f32,
pub skew_x: f32,
pub skew_y: f32,
pub scale_y: f32,
}
// Floats don't impl Hash/Eq/Ord...
impl Eq for FontTransform {}
impl Ord for FontTransform {
fn cmp(&self, other: &Self) -> cmp::Ordering {
self.partial_cmp(other).unwrap_or(cmp::Ordering::Equal)
}
}
impl Hash for FontTransform {
fn hash<H: Hasher>(&self, state: &mut H) {
// Note: this is inconsistent with the Eq impl for -0.0 (don't care).
self.scale_x.to_bits().hash(state);
self.skew_x.to_bits().hash(state);
self.skew_y.to_bits().hash(state);
self.scale_y.to_bits().hash(state);
}
}
impl FontTransform {
const QUANTIZE_SCALE: f32 = 1024.0;
pub fn new(scale_x: f32, skew_x: f32, skew_y: f32, scale_y: f32) -> Self {
FontTransform { scale_x, skew_x, skew_y, scale_y }
}
pub fn identity() -> Self {
FontTransform::new(1.0, 0.0, 0.0, 1.0)
}
#[allow(dead_code)]
pub fn is_identity(&self) -> bool {
*self == FontTransform::identity()
}
pub fn quantize(&self) -> Self {
FontTransform::new(
(self.scale_x * Self::QUANTIZE_SCALE).round() / Self::QUANTIZE_SCALE,
(self.skew_x * Self::QUANTIZE_SCALE).round() / Self::QUANTIZE_SCALE,
(self.skew_y * Self::QUANTIZE_SCALE).round() / Self::QUANTIZE_SCALE,
(self.scale_y * Self::QUANTIZE_SCALE).round() / Self::QUANTIZE_SCALE,
)
}
#[allow(dead_code)]
pub fn determinant(&self) -> f64 {
self.scale_x as f64 * self.scale_y as f64 - self.skew_y as f64 * self.skew_x as f64
}
#[allow(dead_code)]
pub fn compute_scale(&self) -> Option<(f64, f64)> {
let det = self.determinant();
if det != 0.0 {
let x_scale = (self.scale_x as f64).hypot(self.skew_y as f64);
let y_scale = det.abs() / x_scale;
Some((x_scale, y_scale))
} else {
None
}
}
#[allow(dead_code)]
pub fn pre_scale(&self, scale_x: f32, scale_y: f32) -> Self {
FontTransform::new(
self.scale_x * scale_x,
self.skew_x * scale_y,
self.skew_y * scale_x,
self.scale_y * scale_y,
)
}
#[allow(dead_code)]
pub fn invert_scale(&self, x_scale: f64, y_scale: f64) -> Self {
self.pre_scale(x_scale.recip() as f32, y_scale.recip() as f32)
}
pub fn synthesize_italics(&self, angle: SyntheticItalics, size: f64, vertical: bool) -> (Self, (f64, f64)) {
let skew_factor = angle.to_skew();
if vertical {
// origin delta to be applied so that we effectively skew around
// the middle rather than edge of the glyph
let (tx, ty) = (0.0, -size * 0.5 * skew_factor as f64);
(FontTransform::new(
self.scale_x + self.skew_x * skew_factor,
self.skew_x,
self.skew_y + self.scale_y * skew_factor,
self.scale_y,
), (self.scale_x as f64 * tx + self.skew_x as f64 * ty,
self.skew_y as f64 * tx + self.scale_y as f64 * ty))
} else {
(FontTransform::new(
self.scale_x,
self.skew_x - self.scale_x * skew_factor,
self.skew_y,
self.scale_y - self.skew_y * skew_factor,
), (0.0, 0.0))
}
}
pub fn swap_xy(&self) -> Self {
FontTransform::new(self.skew_x, self.scale_x, self.scale_y, self.skew_y)
}
pub fn flip_x(&self) -> Self {
FontTransform::new(-self.scale_x, self.skew_x, -self.skew_y, self.scale_y)
}
pub fn flip_y(&self) -> Self {
FontTransform::new(self.scale_x, -self.skew_x, self.skew_y, -self.scale_y)
}
pub fn transform(&self, point: &LayoutPoint) -> DevicePoint {
DevicePoint::new(
self.scale_x * point.x + self.skew_x * point.y,
self.skew_y * point.x + self.scale_y * point.y,
)
}
pub fn get_subpx_dir(&self) -> SubpixelDirection {
if self.skew_y.approx_eq(&0.0) {
// The X axis is not projected onto the Y axis
SubpixelDirection::Horizontal
} else if self.scale_x.approx_eq(&0.0) {
// The X axis has been swapped with the Y axis
SubpixelDirection::Vertical
} else {
// Use subpixel precision on all axes
SubpixelDirection::Mixed
}
}
}
impl<'a> From<&'a LayoutToWorldTransform> for FontTransform {
fn from(xform: &'a LayoutToWorldTransform) -> Self {
FontTransform::new(xform.m11, xform.m21, xform.m12, xform.m22)
}
}
// Some platforms (i.e. Windows) may have trouble rasterizing glyphs above this size.
// Ensure glyph sizes are reasonably limited to avoid that scenario.
pub const FONT_SIZE_LIMIT: f32 = 320.0;
/// A mutable font instance description.
///
/// Performance is sensitive to the size of this structure, so it should only contain
/// the fields that we need to modify from the original base font instance.
#[derive(Clone, PartialEq, Eq, Debug, Ord, PartialOrd)]
#[cfg_attr(feature = "capture", derive(Serialize))]
#[cfg_attr(feature = "replay", derive(Deserialize))]
pub struct FontInstance {
pub base: Arc<BaseFontInstance>,
pub transform: FontTransform,
pub render_mode: FontRenderMode,
pub flags: FontInstanceFlags,
pub color: ColorU,
pub transform_glyphs: bool,
// The font size is in *device* pixels, not logical pixels.
// It is stored as an Au since we need sub-pixel sizes, but
// can't store as a f32 due to use of this type as a hash key.
// TODO(gw): Perhaps consider having LogicalAu and DeviceAu
// or something similar to that.
pub size: Au,
}
impl Hash for FontInstance {
fn hash<H: Hasher>(&self, state: &mut H) {
// Hash only the base instance's key to avoid the cost of hashing
// the rest.
self.base.instance_key.hash(state);
self.transform.hash(state);
self.render_mode.hash(state);
self.flags.hash(state);
self.color.hash(state);
self.size.hash(state);
}
}
/// Immutable description of a font instance requested by the user of the API.
///
/// `BaseFontInstance` can be identified by a `FontInstanceKey` so we should
/// never need to hash it.
#[derive(Clone, PartialEq, Eq, Debug, Ord, PartialOrd, MallocSizeOf)]
#[cfg_attr(feature = "capture", derive(Serialize))]
#[cfg_attr(feature = "replay", derive(Deserialize))]
pub struct BaseFontInstance {
pub instance_key: FontInstanceKey,
pub font_key: FontKey,
pub size: Au,
pub bg_color: ColorU,
pub render_mode: FontRenderMode,
pub flags: FontInstanceFlags,
pub synthetic_italics: SyntheticItalics,
#[cfg_attr(any(feature = "capture", feature = "replay"), serde(skip))]
pub platform_options: Option<FontInstancePlatformOptions>,
pub variations: Vec<FontVariation>,
}
impl Deref for FontInstance {
type Target = BaseFontInstance;
fn deref(&self) -> &BaseFontInstance {
self.base.as_ref()
}
}
impl MallocSizeOf for FontInstance {
fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize { 0 }
}
impl FontInstance {
pub fn new(
base: Arc<BaseFontInstance>,
color: ColorU,
render_mode: FontRenderMode,
flags: FontInstanceFlags,
) -> Self {
FontInstance {
transform: FontTransform::identity(),
transform_glyphs: false,
color,
size: base.size,
base,
render_mode,
flags,
}
}
pub fn from_base(
base: Arc<BaseFontInstance>,
) -> Self {
FontInstance {
transform: FontTransform::identity(),
transform_glyphs: false,
color: ColorU::new(0, 0, 0, 255),
size: base.size,
render_mode: base.render_mode,
flags: base.flags,
base,
}
}
pub fn get_alpha_glyph_format(&self) -> GlyphFormat {
if !self.transform_glyphs { GlyphFormat::Alpha } else { GlyphFormat::TransformedAlpha }
}
pub fn get_subpixel_glyph_format(&self) -> GlyphFormat {
if !self.transform_glyphs { GlyphFormat::Subpixel } else { GlyphFormat::TransformedSubpixel }
}
pub fn disable_subpixel_aa(&mut self) {
self.render_mode = self.render_mode.limit_by(FontRenderMode::Alpha);
}
pub fn disable_subpixel_position(&mut self) {
self.flags.remove(FontInstanceFlags::SUBPIXEL_POSITION);
}
pub fn use_subpixel_position(&self) -> bool {
self.flags.contains(FontInstanceFlags::SUBPIXEL_POSITION) &&
self.render_mode != FontRenderMode::Mono
}
pub fn get_subpx_dir(&self) -> SubpixelDirection {
if self.use_subpixel_position() {
let mut subpx_dir = self.transform.get_subpx_dir();
if self.flags.contains(FontInstanceFlags::TRANSPOSE) {
subpx_dir = subpx_dir.swap_xy();
}
subpx_dir
} else {
SubpixelDirection::None
}
}
#[allow(dead_code)]
pub fn get_subpx_offset(&self, glyph: &GlyphKey) -> (f64, f64) {
if self.use_subpixel_position() {
let (dx, dy) = glyph.subpixel_offset();
(dx.into(), dy.into())
} else {
(0.0, 0.0)
}
}
#[allow(dead_code)]
pub fn get_glyph_format(&self) -> GlyphFormat {
match self.render_mode {
FontRenderMode::Mono | FontRenderMode::Alpha => self.get_alpha_glyph_format(),
FontRenderMode::Subpixel => self.get_subpixel_glyph_format(),
}
}
#[allow(dead_code)]
pub fn get_extra_strikes(&self, x_scale: f64) -> usize {
if self.flags.contains(FontInstanceFlags::SYNTHETIC_BOLD) {
let mut bold_offset = self.size.to_f64_px() / 48.0;
if bold_offset < 1.0 {
bold_offset = 0.25 + 0.75 * bold_offset;
}
(bold_offset * x_scale).max(1.0).round() as usize
} else {
0
}
}
pub fn synthesize_italics(&self, transform: FontTransform, size: f64) -> (FontTransform, (f64, f64)) {
transform.synthesize_italics(self.synthetic_italics, size, self.flags.contains(FontInstanceFlags::VERTICAL))
}
}
#[repr(u32)]
#[derive(Copy, Clone, Hash, PartialEq, Eq, Debug, Ord, PartialOrd)]
pub enum SubpixelDirection {
None = 0,
Horizontal,
Vertical,
Mixed,
}
impl SubpixelDirection {
// Limit the subpixel direction to what is supported by the glyph format.
pub fn limit_by(self, glyph_format: GlyphFormat) -> Self {
match glyph_format {
GlyphFormat::Bitmap |
GlyphFormat::ColorBitmap => SubpixelDirection::None,
_ => self,
}
}
pub fn swap_xy(self) -> Self {
match self {
SubpixelDirection::None | SubpixelDirection::Mixed => self,
SubpixelDirection::Horizontal => SubpixelDirection::Vertical,
SubpixelDirection::Vertical => SubpixelDirection::Horizontal,
}
}
}
#[repr(u8)]
#[derive(Hash, Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
#[cfg_attr(feature = "capture", derive(Serialize))]
#[cfg_attr(feature = "replay", derive(Deserialize))]
pub enum SubpixelOffset {
Zero = 0,
Quarter = 1,
Half = 2,
ThreeQuarters = 3,
}
impl SubpixelOffset {
// Skia quantizes subpixel offsets into 1/4 increments.
// Given the absolute position, return the quantized increment
fn quantize(pos: f32) -> Self {
// Following the conventions of Gecko and Skia, we want
// to quantize the subpixel position, such that abs(pos) gives:
// [0.0, 0.125) -> Zero
// [0.125, 0.375) -> Quarter
// [0.375, 0.625) -> Half
// [0.625, 0.875) -> ThreeQuarters,
// [0.875, 1.0) -> Zero
// The unit tests below check for this.
let apos = ((pos - pos.floor()) * 8.0) as i32;
match apos {
1..=2 => SubpixelOffset::Quarter,
3..=4 => SubpixelOffset::Half,
5..=6 => SubpixelOffset::ThreeQuarters,
_ => SubpixelOffset::Zero,
}
}
}
impl Into<f64> for SubpixelOffset {
fn into(self) -> f64 {
match self {
SubpixelOffset::Zero => 0.0,
SubpixelOffset::Quarter => 0.25,
SubpixelOffset::Half => 0.5,
SubpixelOffset::ThreeQuarters => 0.75,
}
}
}
#[derive(Clone, Hash, PartialEq, Eq, Debug, Ord, PartialOrd)]
#[cfg_attr(feature = "capture", derive(Serialize))]
#[cfg_attr(feature = "replay", derive(Deserialize))]
pub struct GlyphKey(u32);
impl GlyphKey {
pub fn new(
index: u32,
point: DevicePoint,
subpx_dir: SubpixelDirection,
) -> Self {
let (dx, dy) = match subpx_dir {
SubpixelDirection::None => (0.0, 0.0),
SubpixelDirection::Horizontal => (point.x, 0.0),
SubpixelDirection::Vertical => (0.0, point.y),
SubpixelDirection::Mixed => (point.x, point.y),
};
let sox = SubpixelOffset::quantize(dx);
let soy = SubpixelOffset::quantize(dy);
assert_eq!(0, index & 0xF0000000);
GlyphKey(index | (sox as u32) << 28 | (soy as u32) << 30)
}
pub fn index(&self) -> GlyphIndex {
self.0 & 0x0FFFFFFF
}
fn subpixel_offset(&self) -> (SubpixelOffset, SubpixelOffset) {
let x = (self.0 >> 28) as u8 & 3;
let y = (self.0 >> 30) as u8 & 3;
unsafe {
(mem::transmute(x), mem::transmute(y))
}
}
}
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
#[cfg_attr(feature = "capture", derive(Serialize))]
#[cfg_attr(feature = "replay", derive(Deserialize))]
#[allow(dead_code)]
pub enum GlyphFormat {
Alpha,
TransformedAlpha,
Subpixel,
TransformedSubpixel,
Bitmap,
ColorBitmap,
}
impl GlyphFormat {
pub fn ignore_color(self) -> Self {
match self {
GlyphFormat::ColorBitmap => GlyphFormat::Bitmap,
_ => self,
}
}
}
pub struct RasterizedGlyph {
pub top: f32,
pub left: f32,
pub width: i32,
pub height: i32,
pub scale: f32,
pub format: GlyphFormat,
pub bytes: Vec<u8>,
}
impl RasterizedGlyph {
#[allow(dead_code)]
pub fn downscale_bitmap_if_required(&mut self, font: &FontInstance) {
// Check if the glyph is going to be downscaled in the shader. If the scaling is
// less than 0.5, that means bilinear filtering can't effectively filter the glyph
// without aliasing artifacts.
//
// Instead of fixing this by mipmapping the glyph cache texture, rather manually
// produce the appropriate mip level for individual glyphs where bilinear filtering
// will still produce acceptable results.
match self.format {
GlyphFormat::Bitmap | GlyphFormat::ColorBitmap => {},
_ => return,
}
let (x_scale, y_scale) = font.transform.compute_scale().unwrap_or((1.0, 1.0));
let upscaled = x_scale.max(y_scale) as f32;
let mut new_scale = self.scale;
if new_scale * upscaled <= 0.0 {
return;
}
let mut steps = 0;
while new_scale * upscaled <= 0.5 {
new_scale *= 2.0;
steps += 1;
}
// If no mipping is necessary, just bail.
if steps == 0 {
return;
}
// Calculate the actual size of the mip level.
let new_width = (self.width as usize + (1 << steps) - 1) >> steps;
let new_height = (self.height as usize + (1 << steps) - 1) >> steps;
let mut new_bytes: Vec<u8> = Vec::with_capacity(new_width * new_height * 4);
// Produce destination pixels by applying a box filter to the source pixels.
// The box filter corresponds to how graphics drivers may generate mipmaps.
for y in 0 .. new_height {
for x in 0 .. new_width {
// Calculate the number of source samples that contribute to the destination pixel.
let src_y = y << steps;
let src_x = x << steps;
let y_samples = (1 << steps).min(self.height as usize - src_y);
let x_samples = (1 << steps).min(self.width as usize - src_x);
let num_samples = (x_samples * y_samples) as u32;
let mut src_idx = (src_y * self.width as usize + src_x) * 4;
// Initialize the accumulator with half an increment so that when later divided
// by the sample count, it will effectively round the accumulator to the nearest
// increment.
let mut accum = [num_samples / 2; 4];
// Accumulate all the contributing source sampless.
for _ in 0 .. y_samples {
for _ in 0 .. x_samples {
accum[0] += self.bytes[src_idx + 0] as u32;
accum[1] += self.bytes[src_idx + 1] as u32;
accum[2] += self.bytes[src_idx + 2] as u32;
accum[3] += self.bytes[src_idx + 3] as u32;
src_idx += 4;
}
src_idx += (self.width as usize - x_samples) * 4;
}
// Finally, divide by the sample count to get the mean value for the new pixel.
new_bytes.extend_from_slice(&[
(accum[0] / num_samples) as u8,
(accum[1] / num_samples) as u8,
(accum[2] / num_samples) as u8,
(accum[3] / num_samples) as u8,
]);
}
}
// Fix the bounds for the new glyph data.
self.top /= (1 << steps) as f32;
self.left /= (1 << steps) as f32;
self.width = new_width as i32;
self.height = new_height as i32;
self.scale = new_scale;
self.bytes = new_bytes;
}
}
pub struct FontContexts {
// These worker are mostly accessed from their corresponding worker threads.
// The goal is that there should be no noticeable contention on the mutexes.
worker_contexts: Vec<Mutex<FontContext>>,
// This worker should be accessed by threads that don't belong to the thread pool
// (in theory that's only the render backend thread so no contention expected either).
shared_context: Mutex<FontContext>,
// Stored here as a convenience to get the current thread index.
#[allow(dead_code)]
workers: Arc<ThreadPool>,
locked_mutex: Mutex<bool>,
locked_cond: Condvar,
}
impl FontContexts {
/// Get access to any particular font context.
///
/// The id is ```Some(i)``` where i is an index between 0 and num_worker_contexts
/// for font contexts associated to the thread pool, and None for the shared
/// global font context for use outside of the thread pool.
pub fn lock_context(&self, id: Option<usize>) -> MutexGuard<FontContext> {
match id {
Some(index) => self.worker_contexts[index].lock().unwrap(),
None => self.shared_context.lock().unwrap(),
}
}
/// Get access to the font context usable outside of the thread pool.
pub fn lock_shared_context(&self) -> MutexGuard<FontContext> {
self.shared_context.lock().unwrap()
}
// number of contexts associated to workers
pub fn num_worker_contexts(&self) -> usize {
self.worker_contexts.len()
}
}
pub trait AsyncForEach<T> {
fn async_for_each<F: Fn(MutexGuard<T>) + Send + 'static>(&self, f: F);
}
impl AsyncForEach<FontContext> for Arc<FontContexts> {
fn async_for_each<F: Fn(MutexGuard<FontContext>) + Send + 'static>(&self, f: F) {
// Reset the locked condition.
let mut locked = self.locked_mutex.lock().unwrap();
*locked = false;
// Arc that can be safely moved into a spawn closure.
let font_contexts = self.clone();
// Spawn a new thread on which to run the for-each off the main thread.
self.workers.spawn(move || {
// Lock the shared and worker contexts up front.
let mut locks = Vec::with_capacity(font_contexts.num_worker_contexts() + 1);
locks.push(font_contexts.lock_shared_context());
for i in 0 .. font_contexts.num_worker_contexts() {
locks.push(font_contexts.lock_context(Some(i)));
}
// Signal the locked condition now that all contexts are locked.
*font_contexts.locked_mutex.lock().unwrap() = true;
font_contexts.locked_cond.notify_all();
// Now that everything is locked, proceed to processing each locked context.
for context in locks {
f(context);
}
});
// Wait for locked condition before resuming. Safe to proceed thereafter
// since any other thread that needs to use a FontContext will try to lock
// it first.
while !*locked {
locked = self.locked_cond.wait(locked).unwrap();
}
}
}
pub struct GlyphRasterizer {
#[allow(dead_code)]
workers: Arc<ThreadPool>,
font_contexts: Arc<FontContexts>,
// Maintain a set of glyphs that have been requested this
// frame. This ensures the glyph thread won't rasterize
// the same glyph more than once in a frame. This is required
// because the glyph cache hash table is not updated
// until the end of the frame when we wait for glyph requests
// to be resolved.
#[allow(dead_code)]
pending_glyphs: usize,
// Receives the rendered glyphs.
#[allow(dead_code)]
glyph_rx: Receiver<GlyphRasterJobs>,
#[allow(dead_code)]
glyph_tx: Sender<GlyphRasterJobs>,
// We defer removing fonts to the end of the frame so that:
// - this work is done outside of the critical path,
// - we don't have to worry about the ordering of events if a font is used on
// a frame where it is used (although it seems unlikely).
fonts_to_remove: Vec<FontKey>,
// Defer removal of font instances, as for fonts.
font_instances_to_remove: Vec<FontInstance>,
#[allow(dead_code)]
next_gpu_glyph_cache_key: GpuGlyphCacheKey,
// Whether to parallelize glyph rasterization with rayon.
enable_multithreading: bool,
}
impl GlyphRasterizer {
pub fn new(workers: Arc<ThreadPool>) -> Result<Self, ResourceCacheError> {
let (glyph_tx, glyph_rx) = channel();
let num_workers = workers.current_num_threads();
let mut contexts = Vec::with_capacity(num_workers);
let shared_context = FontContext::new()?;
for _ in 0 .. num_workers {
contexts.push(Mutex::new(FontContext::new()?));
}
let font_context = FontContexts {
worker_contexts: contexts,
shared_context: Mutex::new(shared_context),
workers: Arc::clone(&workers),
locked_mutex: Mutex::new(false),
locked_cond: Condvar::new(),
};
Ok(GlyphRasterizer {
font_contexts: Arc::new(font_context),
pending_glyphs: 0,
glyph_rx,
glyph_tx,
workers,
fonts_to_remove: Vec::new(),
font_instances_to_remove: Vec::new(),
next_gpu_glyph_cache_key: GpuGlyphCacheKey(0),
enable_multithreading: true,
})
}
pub fn add_font(&mut self, font_key: FontKey, template: FontTemplate) {
self.font_contexts.async_for_each(move |mut context| {
context.add_font(&font_key, &template);
});
}
pub fn delete_font(&mut self, font_key: FontKey) {
self.fonts_to_remove.push(font_key);
}
pub fn delete_font_instance(&mut self, instance: &FontInstance) {
self.font_instances_to_remove.push(instance.clone());
}
pub fn prepare_font(&self, font: &mut FontInstance) {
FontContext::prepare_font(font);
// Quantize the transform to minimize thrashing of the glyph cache, but
// only quantize the transform when preparing to access the glyph cache.
// This way, the glyph subpixel positions, which are calculated before
// this, can still use the precise transform which is required to match
// the subpixel positions computed for glyphs in the text run shader.
font.transform = font.transform.quantize();
}
pub fn get_glyph_dimensions(
&mut self,
font: &FontInstance,
glyph_index: GlyphIndex,
) -> Option<GlyphDimensions> {
let glyph_key = GlyphKey::new(
glyph_index,
DevicePoint::zero(),
SubpixelDirection::None,
);
self.font_contexts
.lock_shared_context()
.get_glyph_dimensions(font, &glyph_key)
}
pub fn get_glyph_index(&mut self, font_key: FontKey, ch: char) -> Option<u32> {
self.font_contexts
.lock_shared_context()
.get_glyph_index(font_key, ch)
}
fn remove_dead_fonts(&mut self) {
if self.fonts_to_remove.is_empty() && self.font_instances_to_remove.is_empty() {
return
}
let fonts_to_remove = mem::replace(&mut self.fonts_to_remove, Vec::new());
let font_instances_to_remove = mem::replace(& mut self.font_instances_to_remove, Vec::new());