Module scrolling 

Scroll behavior primitives: wheel acceleration and middle-click autoscroll.

These are behaviors, not components: they own no rendering and no theme. Applications (or composite components) drive them from ordinary GPUI input events and apply the returned distances to whatever scroll position they manage. This mirrors how Zed’s own editor handles the wheel — discrete line notches are scaled by a sensitivity multiplier while trackpad pixel deltas pass through untouched — and adds Windows-convention cadence acceleration on top for fast successive scrolling.

Wheel acceleration

use gpui_ai::scrolling::{WheelAccelerator, LINE_HEIGHT_PX};
use gpui::{px, Pixels};

let mut wheel = WheelAccelerator::new();
// One notch of a conventional wheel; negative dy scrolls down.
let boost = wheel.line_notch(-1.0, false);
assert!(boost > px(0.) && boost <= px((3.0 - 1.0) * LINE_HEIGHT_PX));

// Trackpad pixel deltas never enter the accelerator: the application
// forwards them straight to its scroll position, unaccelerated.

Middle-click autoscroll

use gpui_ai::scrolling::Autoscroll;
use gpui::{point, px, Pixels};

let mut session = Autoscroll::start(point(px(300.), px(200.)));
session.track(point(px(300.), px(270.)));
// Pointer 70 px below the anchor at ~16 ms/frame:
let distance = session.tick(0.016);
assert!(distance > Pixels::ZERO);

Structs

Autoscroll

Middle-click autoscroll session anchored to a window position.

ScrollRoom

Whether a vertically scrollable region can still absorb wheel motion in the direction the user is scrolling.

ScrollbarTokens

The crate’s scrollbar policy, replaceable before any window renders.

WheelAccelerator

Cadence-based wheel accelerator over discrete line notches.

Enums

ScrollbarPlacement

Where a scrollbar sits relative to the content it scrolls.

ScrollbarVisibility

When a scrollable surface shows its scrollbar.

Constants

AUTOSCROLL_FULL_SPEED_DISTANCE_PX

Pointer distance from the anchor at which autoscroll reaches full speed.

LINE_HEIGHT_PX

Pixels assumed per scroll line when converting line deltas to distances, matching gpui’s List element conversion.

MAX_AUTOSCROLL_SPEED_PX_PER_SEC

Maximum autoscroll speed in pixels per second at or beyond full distance.

WHEEL_ACCEL_DECAY_SECONDS

Seconds without a notch after which cadence decays back to rest.

WHEEL_ACCEL_MAX_MULTIPLIER

Peak wheel acceleration multiplier once cadence saturates.

WHEEL_ACCEL_NOTCHES_TO_FULL

Consecutive same-direction notches before acceleration reaches full strength. Windows conventions ramp over a handful of notches.

WHEEL_FAST_SENSITIVITY

Multiplier applied to wheel line deltas while Alt is held, matching Zed’s editor fast_scroll_sensitivity convention.

WHEEL_SENSITIVITY

Base multiplier applied to wheel line deltas, matching Zed’s editor scroll_sensitivity default of 1.0.