diff --git a/crates/ui-egui/src/canvas.rs b/crates/ui-egui/src/canvas.rs index dc54d0e245..9a073c4dc4 100644 --- a/crates/ui-egui/src/canvas.rs +++ b/crates/ui-egui/src/canvas.rs @@ -2410,9 +2410,10 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) { // When not scrolling continuously, only one row is shown at a time: the current page, or the // current two-page spread (with the cover rule). These indices drive paging, which pages are // drawn, and the content height (#752). Empty for a document with no pages. - let row: Vec = if rects.is_empty() { - Vec::new() - } else { + let shown_row = |view: &DocView| -> Vec { + if rects.is_empty() { + return Vec::new(); + } let last = rects.len() - 1; let cur = view.current.min(last); match view.layout { @@ -2424,6 +2425,7 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) { } } }; + let row = shown_row(view); let middle_gesture = view.auto_scroll.blocks_input(); // Not scrolling: when the whole page or spread fits, the wheel would do nothing, so it turns // pages instead; zoomed in far enough to pan, it pans, and at the edge it turns the page on @@ -2524,6 +2526,9 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) { if view.fling.gliding() { ui.ctx().request_repaint(); } + // The wheel may have turned the page above: draw the row it turned to. Measured from the old + // row, the jump to the new page scrolled both out of view, a blank frame on every turn forward. + let row = shown_row(view); let visible_pages: Vec = if view.continuous { (0..rects.len()).collect() } else { row.clone() }; let (y_shift, content_h) = if view.continuous { (0.0, rects.iter().map(|r| r.bottom()).reduce(f32::max).map(|bottom| bottom + MARGIN).unwrap_or(0.0)) @@ -2563,9 +2568,6 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) { let r = rects[page.min(rects.len() - 1)]; let point = pos2(r.left() + fx * r.width(), r.top() - y_shift + fy * r.height()); scroll = scroll.scroll_offset(vec2((point.x - rel.x).max(0.0), (point.y - rel.y).max(0.0))); - } else if edge_turned { - // The row above was laid out for the page before the turn: place the new one next frame. - ui.ctx().request_repaint(); } else if let Some((page, frac)) = view.goto.take() { let page = page.min(rects.len() - 1); let r = rects[page]; @@ -3612,6 +3614,26 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) { view.last_scroll = scroll_offset; let pan_held = now_settle < view.pan_hold_until; let (mut wanted, visible_now) = out.inner; + // Single-page and two-page views draw only the current row, so the next one was first asked + // for on the turn and showed blank paper until it rendered. Prefetch the rows either side, + // as continuous scrolling does for the pages just off screen. + if !view.continuous + && let (Some(&first), Some(&last)) = (visible_pages.first(), visible_pages.last()) + { + let n = if view.layout == PageLayout::Single { 1 } else { 2 }; + let max_side = ui.ctx().input(|inp| inp.max_texture_side) as f32; + for i in (last.saturating_add(1)..=last.saturating_add(n)).chain(first.saturating_sub(n)..first) { + let Some(p) = info.pages.get(i).filter(|_| !view.errors.contains_key(&i)) else { continue }; + // As drawn: the whole page at this scale, or the backdrop of a tiled page. + let side = p.width.max(p.height).max(1.0); + wanted.push(if side * scale > TILE_THRESHOLD.min(max_side) { + let bs = BASE_SIDE.min(max_side) / side; + (i, bs, scale_tag(bs), None) + } else { + (i, scale, tag, None) + }); + } + } let cur = view.current; wanted.sort_by_key(|w| (!visible_now.contains(&w.0), w.0.abs_diff(cur), w.3.is_some())); // Tiles of far-away pages are useless: free them. Tiles of an earlier zoom stay for a page diff --git a/crates/ui-egui/tests/view.rs b/crates/ui-egui/tests/view.rs index 3f4420d3b4..372dd9479b 100644 --- a/crates/ui-egui/tests/view.rs +++ b/crates/ui-egui/tests/view.rs @@ -185,6 +185,38 @@ fn single_page_layout_shows_one_page_at_a_time() { assert!(rect(&h, 0).is_none() && rect(&h, 1).is_some(), "only page 2"); } +#[test] +fn single_page_view_prefetches_the_next_page() { + // Only the shown page is drawn, but the next one renders ahead of the turn: otherwise + // turning forward shows blank paper until it arrives. + let mut h = harness(&[("layout", "single"), ("zoom", "50")]); + let deadline = std::time::Instant::now() + std::time::Duration::from_secs(10); + while h.state().render_pending() { + assert!(std::time::Instant::now() < deadline, "renders settle"); + h.run_steps(2); + std::thread::sleep(std::time::Duration::from_millis(5)); + } + assert!(rect(&h, 1).is_none(), "page 2 is not shown"); + assert!(h.state().views[0].raster_memory().page_count >= 2, "page 2 is rendered ahead of the turn"); +} + +#[test] +fn single_page_wheel_turn_draws_the_new_page_at_once() { + // The frame that turns the page draws the new one. Its jump used to be measured from the + // old page's place, which scrolled both out of view: a blank frame on every turn forward. + let mut h = harness_stepping(1.0 / 60.0, &[("layout", "single")]); + h.key_press_modifiers(Modifiers::COMMAND, Key::Num0); // fit page + h.run_steps(4); + let vp = h.state().views[0].viewport_rect(); + h.hover_at(vp.center()); + h.run_steps(2); + h.event(wheel(MouseWheelUnit::Line, -1.0, TouchPhase::Move)); + h.step(); + assert_eq!(h.state().views[0].current, 1, "one notch turns one page"); + let r = rect(&h, 1).expect("page 2 drawn in the frame that turns to it"); + assert!(r.min.y >= vp.min.y && r.max.y <= vp.max.y, "page 2 fits on screen: {r:?} in {vp:?}"); +} + #[test] fn single_page_wheel_pans_instead_when_zoomed_in() { // The zoomed-in guard: with room to pan, the wheel pans and must not turn pages.