makepad/examples/portallist_hit/tests/ui.rs

//! Regression suite for PortalList row geometry.
//!
//! `PortalList` deliberately draws recycled rows past both edges of its
//! viewport and relies on the clip rect to hide them. The widget tree must
//! describe those rows the way a viewer sees them — clipped — or every
//! consumer that turns a reported rect into a click lands somewhere else.
//!
//! Layout under test (`src/main.rs`): a 200px-tall list of 40px rows with a
//! full-width `outside_button` parked directly beneath it. Rows 0..=4 fill the
//! viewport; row 5 is drawn in the band `outside_button` occupies and clipped
//! away. Before the fix, "Play 5" was reported as a visible button at
//! [365, 269, 49, 22] — whose centre lands on `outside_button` — so clicking
//! the row the tree pointed at pressed Outside instead.

use makepad_test::{makepad_test, Selector, TestApp, WidgetSnapshot};

/// Every row button the tree reports must lie inside the list's own viewport.
/// This is the invariant the bug broke: a row drawn past the bottom edge was
/// reported at full size in the band below the list, on top of a different
/// widget that really is drawn there.
fn assert_rows_inside_list(app: &TestApp) {
    let widgets = app.widget_snapshot();
    let list = widgets
        .iter()
        .find(|w| w.id == "list" && w.width > 0 && w.height > 0)
        .cloned()
        .expect("list is drawn");
    let rows: Vec<&WidgetSnapshot> = widgets
        .iter()
        .filter(|w| w.id == "play_button" && w.visible && w.width > 0 && w.height > 0)
        .collect();
    assert!(!rows.is_empty(), "no visible rows reported");
    for row in rows {
        assert!(
            row.y >= list.y && row.y + row.height <= list.y + list.height,
            "row {:?} reported at y {}..{}, outside the list viewport y {}..{}",
            row.text,
            row.y,
            row.y + row.height,
            list.y,
            list.y + list.height,
        );
    }
}

/// Click the bottom-most row the tree reports, at the centre of its reported
/// rect, and check that row is the one that fired. This is the half of the
/// symptom where nothing happens at all: a row straddling the bottom edge is
/// drawn full height, so its *unclipped* rect has its centre below the list —
/// on `outside_button` or on nothing.
fn click_bottom_reported_row(app: &TestApp) {
    let widgets = app.widget_snapshot();
    let bottom = widgets
        .iter()
        .filter(|w| w.id == "play_button" && w.visible && w.width > 0 && w.height > 0)
        .max_by_key(|w| w.y)
        .cloned()
        .expect("a row is reported");
    let label = bottom.text.clone().expect("row button carries its text");
    let index = label
        .strip_prefix("Play ")
        .expect("row button reads 'Play N'")
        .to_string();
    app.locator(Selector::all().text_exact(label.as_str())).click();
    app.locator(Selector::id("last_played"))
        .wait_text(format!("Row {index}"));
}

#[makepad_test]
fn portallist_hides_rows_clipped_past_the_viewport(app: TestApp) {
    app.locator(Selector::all().text_exact("Play 0")).wait_visible();
    app.locator(Selector::all().text_exact("Play 4")).wait_visible();
    app.locator(Selector::id("outside_button")).wait_visible();

    // Row 5 is drawn under `outside_button` and clipped away: it must not be
    // reported as a visible widget sitting on top of the button.
    app.locator(Selector::all().text_exact("Play 5")).wait_count(0);
    app.locator(Selector::all().text_exact("Row 5")).wait_count(0);

    assert_rows_inside_list(&app);
}

#[makepad_test]
fn portallist_rows_click_where_the_tree_reports_them(app: TestApp) {
    app.locator(Selector::all().text_exact("Play 0"))
        .wait_visible()
        .click();
    app.locator(Selector::id("last_played")).wait_text("Row 0");

    // The last row inside the viewport: its reported rect must be the visible
    // one, not the unclipped rect whose centre sits below the list.
    app.locator(Selector::all().text_exact("Play 4"))
        .wait_visible()
        .click();
    app.locator(Selector::id("last_played")).wait_text("Row 4");

    app.locator(Selector::id("outside_button")).click();
    app.locator(Selector::id("last_played")).wait_text("outside");
}

#[makepad_test]
fn portallist_rows_stay_addressable_after_scrolling(app: TestApp) {
    app.locator(Selector::all().text_exact("Play 0")).wait_visible();
    app.locator(Selector::id("list")).scroll(0.0, 160.0);

    // After a scroll the list keeps over-drawing rows past both edges. Every
    // row the tree still reports must be the row a click there actually hits.
    app.locator(Selector::all().text_exact("Play 6"))
        .wait_visible()
        .click();
    app.locator(Selector::id("last_played")).wait_text("Row 6");

    assert_rows_inside_list(&app);

    app.locator(Selector::id("outside_button")).click();
    app.locator(Selector::id("last_played")).wait_text("outside");
}

/// The scroll-gate half of the clipped-rect family: `cropped_scroll` is a
/// 200px ScrollYView inside a 120px clipping view, so its UNCLIPPED rect
/// covers an 80px band below the crop where `under_crop_button` really is.
/// `ScrollBar::handle_scroll_event` gates a wheel by containment in the
/// scroll area's rect — it must use the clipped rect, or a wheel over the
/// invisible band scrolls a view the user cannot see at that spot.
/// (PortalList wheels ride the hit system, which already tests the clipped
/// rect — this covers the ScrollBar path.)
#[makepad_test]
fn wheel_over_a_scrollviews_clipped_away_part_does_not_scroll_it(app: TestApp) {
    app.locator(Selector::all().text_exact("CropRow 0")).wait_visible();
    app.locator(Selector::id("under_crop_button")).wait_visible();

    // Wheel in the clipped-away band: the view must not move.
    app.locator(Selector::id("under_crop_button")).scroll(0.0, 80.0);
    app.locator(Selector::all().text_exact("CropRow 0")).wait_visible();

    // Positive control — the same wheel over the VISIBLE part scrolls it.
    // (If the band wheel above wrongly scrolled the view, "CropRow 0" is
    // already gone and this locator's resolution is the failure.)
    app.locator(Selector::all().text_exact("CropRow 0")).scroll(0.0, 80.0);
    app.locator(Selector::all().text_exact("CropRow 0")).wait_count(0);
}

#[makepad_test]
fn portallist_partially_clipped_row_is_still_clickable(app: TestApp) {
    app.locator(Selector::all().text_exact("Play 0")).wait_visible();

    // Half a row, so the top and bottom rows straddle the viewport edges
    // instead of landing on them. The bottom one (row 5) is drawn full height
    // in the band `outside_button` occupies, with only a sliver on screen: its
    // unclipped rect's centre is outside the list, its clipped rect's centre
    // is on the sliver.
    app.locator(Selector::id("list")).scroll(0.0, 20.0);
    app.locator(Selector::all().text_exact("Play 5")).wait_visible();

    assert_rows_inside_list(&app);
    click_bottom_reported_row(&app);

    app.locator(Selector::id("outside_button")).click();
    app.locator(Selector::id("last_played")).wait_text("outside");
}

/// One huge wheel delta (a fast coast) must land as a first_id jump, not as
/// thousands of pixels of negative-scroll backlog that the draw loop walks
/// row by row: before the renormalisation, dy=4000 here instantiated 106 row
/// widgets in one frame (dy=8000 in the games list drew ~200). The landing
/// position itself must match the height-tree mapping a scroll-bar drag
/// lands by (uniform 40px rows: 4000px = row 100).
#[makepad_test]
fn one_big_wheel_delta_jumps_instead_of_walking_every_row(app: TestApp) {
    app.locator(Selector::all().text_exact("Play 0")).wait_visible();
    app.locator(Selector::id("list")).scroll(0.0, 4000.0);
    app.locator(Selector::all().text_exact("Play 100")).wait_visible();

    let total = app
        .widget_snapshot()
        .iter()
        .filter(|w| w.id == "play_button")
        .count();
    assert!(
        total <= 24,
        "a big wheel delta materialised {total} row widgets — the backlog \
         was walked instead of jumped"
    );
}