Enum ScrollDelta 

pub enum ScrollDelta {
    Pixels(Point<Pixels>),
    Lines(Point<f32>),
}

The amount a scroll event moves the content.

Trackpads and touch pans report ScrollDelta::Pixels. Line-based mouse wheels report ScrollDelta::Lines. Use ScrollDelta::pixel_delta to get pixels for either.

Variants

Pixels(Point<Pixels>)

An exact amount in logical pixels.

Lines(Point<f32>)

An approximate amount in lines of text. Multiply by the line height to get pixels.

Implementations

impl ScrollDelta

pub fn precise(&self) -> bool

Returns true if this delta is exact, in pixels, rather than in lines.

pub fn pixel_delta(&self, line_height: Pixels) -> Point<Pixels>

Returns this delta in logical pixels.

A pixel delta is returned unchanged. A line delta is multiplied by line_height on each axis, so pass the line height of the text you are scrolling.

Examples

use gpui::{ScrollDelta, point, px};

let lines = ScrollDelta::Lines(point(0., 2.));
assert_eq!(lines.pixel_delta(px(20.)), point(px(0.), px(40.)));

pub fn coalesce(self, other: ScrollDelta) -> ScrollDelta

Merges this delta with a later one, as when two scroll events arrive in the same frame.

Each axis is handled separately. If both deltas move that axis the same way, the amounts add. If they move it in opposite directions, other wins on that axis. Two deltas of different kinds, one in pixels and one in lines, return other unchanged.

A component of zero counts as positive, so a zero in other replaces a negative component of self, and a zero in self is replaced by a negative component of other.

Examples

use gpui::{ScrollDelta, point, px};

// Same direction on x adds (10 + 5); opposite direction on y takes the later 3.
let merged = ScrollDelta::Pixels(point(px(10.), px(-5.)))
    .coalesce(ScrollDelta::Pixels(point(px(5.), px(3.))));
assert_eq!(merged.pixel_delta(px(16.)), point(px(15.), px(3.)));

Trait Implementations

impl Clone for ScrollDelta

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for ScrollDelta

impl Debug for ScrollDelta

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ScrollDelta

fn default() -> Self

Returns the “default value” for a type.