Greg Pomerantz
2f4768f354
Three root causes, all fixed and verified on the Pixel 9 Pro: 1. Present phase (backend + renderer): VSYNC_LOCKED_RENDER defers the render to the vsync wake; RENDER_AHEAD presents the previous frame at the start of render() (phase = wake + ~1.1 ms) and holds the new frame one slot. Crash fix: a held wgpu frame must be PRESENTED, never merely dropped, before the next acquire (AlreadyAcquired panic at launch otherwise); discard_pending_frame presents too. 2. Full-res prefetch churn (src/lib.rs): the 8-slot full cache cycled through a ~20-cell viewport forever (137 decodes/20 s) and each eviction free()'d a 50 MB Vec on the UI thread (20-52 ms CPU spikes, ~7/s = the residual SLOWEV NonMain jank). Fix: 60 s tombstone cooldown on evicted paths (idle prefetch skips, urgent tap bypasses) + off-thread reaper for the freed blobs (insert: 21 ms -> 4 us). 3. (earlier) Skia final flush + Mailbox present mode (vendor, M3). Instrumentation (all behind --features perf): OTHR/INVK/INVK_TAG/FLCK lines for cross-thread closure timing and push-site tagging. Warm measured swipe, 8580-file grid: cadence median 8.33 ms (exact 120 Hz), p99 15.5 ms, 5/552 gaps >16.7 ms (0.9%, max 28.3 ms, zero >33 ms); PRES phase median ~994 us, zero late frames. Docs updated (docs/BUGS/scroll-jank-120hz.md, full scorecard + line reference). Also: vendored i-slint-core + wgpu-hal (vkshim interposition patch), vkshim profiling tooling, backend made a non-optional dep, debuggable flag for simpleperf (REMOVE before shipping).
77 lines
2.9 KiB
Rust
77 lines
2.9 KiB
Rust
// Copyright © SixtyFPS GmbH <info@slint.dev>
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// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0
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use crate::slice::Slice;
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#[repr(C)]
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#[derive(Debug)]
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/// A pre-rendered glyph with the alpha map and associated metrics
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pub struct BitmapGlyph {
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/// The starting x-coordinate for the glyph, relative to the base line
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/// This is a fixed point number that is shifted by 6 bits
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pub x: i16,
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/// The starting y-coordinate for the glyph, relative to the base line
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/// This is a fixed point number that is shifted by 6 bits
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pub y: i16,
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/// The width of the glyph in pixels
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pub width: i16,
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/// The height of the glyph in pixels
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pub height: i16,
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/// The horizontal distance to the next glyph
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/// This is a fixed point number that is shifted by 6 bits
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pub x_advance: i16,
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/// The 8-bit alpha map that's to be blended with the current text color
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/// or 8-bit signed distance field depending on `BitmapFont::sdf`
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pub data: Slice<'static, u8>,
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}
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#[repr(C)]
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#[derive(Debug)]
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/// A set of pre-rendered bitmap glyphs at a fixed pixel size
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pub struct BitmapGlyphs {
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/// The font size in pixels at which the glyphs were pre-rendered. The boundaries of glyphs may exceed this
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/// size, if the font designer has chosen so. This is only used for matching.
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pub pixel_size: i16,
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/// The data of the pre-rendered glyphs
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pub glyph_data: Slice<'static, BitmapGlyph>,
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}
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#[repr(C)]
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#[derive(Debug)]
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/// An entry in the character map of a [`BitmapFont`].
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pub struct CharacterMapEntry {
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/// The unicode code point for a given glyph
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pub code_point: char,
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/// The corresponding index in the `glyph_data` of [`BitmapGlyphs`]
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pub glyph_index: u16,
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}
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#[repr(C)]
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#[derive(Debug)]
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/// A subset of an originally scalable font that's rendered ahead of time.
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pub struct BitmapFont {
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/// The family name of the font
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pub family_name: Slice<'static, u8>,
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/// A vector of code points and their corresponding glyph index, sorted by code point.
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pub character_map: Slice<'static, CharacterMapEntry>,
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/// The font supplied size of the em square.
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pub units_per_em: f32,
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/// The font ascent in design metrics (typically positive)
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pub ascent: f32,
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/// The font descent in design metrics (typically negative)
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pub descent: f32,
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/// The font's x-height.
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pub x_height: f32,
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/// The font's cap-height.
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pub cap_height: f32,
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/// A vector of pre-rendered glyph sets. Each glyph set must have the same number of glyphs,
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/// which must be at least as big as the largest glyph index in the character map.
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pub glyphs: Slice<'static, BitmapGlyphs>,
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/// The weight of the font in CSS units (400 is normal).
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pub weight: u16,
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/// Whether the type-face is rendered italic.
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pub italic: bool,
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/// Whether the format of the font is a signed distance field
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pub sdf: bool,
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}
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