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dotCooCoo
a262171999
In continuous view the only demand off screen was the pages near the window. A fast wheel spin crosses them faster than a heavy page renders, so pages came into view blank. The view now keeps the direction it last moved and also asks for the next two rows that way (four pages in two-up). A zoom or a layout change clears the direction. Scrolling the other way drops those pages from the queue, which cancels their renders. Pages on screen stay at the head of the queue in their usual order, and the byte and count limits bound the prefetch. The web build renders on the UI thread and does not prefetch. A raster that arrives over the allowance now evicts the cached pages the frame does not ask for first, then those behind the scroll, so it no longer evicts a prefetched page that the next frame asks for again. A prefetched page that is tiled at the current zoom keeps a cached whole-page raster sharper than its backdrop, as a tiled page on screen does. This also applies to the prefetch of single-page and two-page view.
80 lines
3.0 KiB
Rust
80 lines
3.0 KiB
Rust
//! Continuous view renders the pages ahead of the scroll before they come into view.
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use egui_kittest::Harness;
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use pdfcraft_ui_egui::PdfCraftApp;
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const PAGES: usize = 20;
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/// Twenty empty 300×400 pt pages.
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fn pages_pdf() -> Vec<u8> {
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let kids: Vec<String> = (0..PAGES).map(|i| format!("{} 0 R", 3 + i)).collect();
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let mut pdf = format!(
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"%PDF-1.7\n1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj\n2 0 obj << /Type /Pages /Kids [{}] /Count {PAGES} /MediaBox [0 0 300 400] >> endobj\n",
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kids.join(" ")
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);
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for i in 0..PAGES {
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pdf.push_str(&format!("{} 0 obj << /Type /Page /Parent 2 0 R >> endobj\n", 3 + i));
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}
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pdf.push_str("trailer << /Root 1 0 R >>\n%%EOF");
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pdf.into_bytes()
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}
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fn harness() -> Harness<'static, PdfCraftApp> {
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let mut h = Harness::builder().with_size(egui::vec2(1400.0, 900.0)).build_eframe(|_cc| {
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let mut app = PdfCraftApp::new();
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app.set_option("language", "en").unwrap();
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app.open_bytes("pages.pdf", None, pages_pdf()).expect("opens");
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for (k, v) in [("left", "closed"), ("panel", "none"), ("layout", "continuous"), ("zoom", "100")] {
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app.set_option(k, v).unwrap();
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}
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app
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});
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settle(&mut h);
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h
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}
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/// Runs frames until no render is queued.
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fn settle(h: &mut Harness<'static, PdfCraftApp>) {
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h.run_steps(4);
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let deadline = std::time::Instant::now() + std::time::Duration::from_secs(20);
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while h.state().render_pending() {
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assert!(std::time::Instant::now() < deadline, "renders settle");
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h.run_steps(2);
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std::thread::sleep(std::time::Duration::from_millis(5));
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}
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h.run_steps(2);
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}
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/// Goes to a page (1-based, as the page box takes it) and waits for its renders.
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fn go_to(h: &mut Harness<'static, PdfCraftApp>, page: usize) {
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h.state_mut().set_option("page", &page.to_string()).unwrap();
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settle(h);
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}
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fn shown(h: &Harness<'static, PdfCraftApp>) -> Vec<usize> {
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(0..PAGES).filter(|&p| h.state().views[0].page_screen_rect(p).is_some()).collect()
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}
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#[test]
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fn continuous_view_prefetches_the_pages_ahead_of_the_scroll() {
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let mut h = harness();
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go_to(&mut h, 14);
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let shown_down = shown(&h);
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let last = *shown_down.last().expect("pages on screen");
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let cached = h.state().views[0].cached_pages_debug();
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// The page just past the window is within the 400 pt band every frame asks for; the one
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// after it is past the band, and only the prefetch asks for it.
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for page in last + 1..=last + 2 {
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assert!(cached.contains(&page), "page {page} renders ahead of a scroll down: shown {shown_down:?}, cached {cached:?}");
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}
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// Scrolling back up prefetches above the window instead.
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go_to(&mut h, 9);
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let shown_up = shown(&h);
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let first = *shown_up.first().expect("pages on screen");
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let cached = h.state().views[0].cached_pages_debug();
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for page in first.saturating_sub(2)..first {
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assert!(cached.contains(&page), "page {page} renders ahead of a scroll up: shown {shown_up:?}, cached {cached:?}");
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}
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}
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