Enum ScrollDelta 

pub enum ScrollDelta {
    Lines(f32, f32),
    PixelDelta(Vec2),
}

Type used by Event::Scroll

Variants

Lines(f32, f32)

Scroll a given number of lines

Positive values indicate that the content that is being scrolled should move right and down (revealing more content left and up). Typically values are integral but this is not guaranteed.

PixelDelta(Vec2)

Scroll a given number of pixels

For a ‘natural scrolling’ touch pad (that acts like a touch screen) this means moving your fingers right and down should give positive values, and move the content right and down (to reveal more things left and up).

Implementations

impl ScrollDelta

pub fn is_vertical(self) -> bool

True if the x-axis delta is zero

pub fn is_horizontal(self) -> bool

True if the y-axis delta is zero

pub fn as_offset(self, cx: &EventState) -> Vec2

Convert to a pan offset

Line deltas are converted to a distance based on scroll_distance configuration.

pub fn as_factor(self, _: &EventState) -> f32

Convert to a zoom factor

pub fn as_offset_or_factor(self, cx: &EventState) -> Result<Vec2, f32>

Convert to a pan offset or zoom factor

This is used for surfaces where panning/scrolling is preferred over zooming, though both are supported (for example, a web page). The Ctrl key is used to select between the two modes.

pub fn as_factor_or_offset(self, cx: &EventState) -> Result<f32, Vec2>

Convert to a zoom factor or pan offset

This is used for surfaces where zooming is preferred over panning, though both are supported (for example, a map view where click-and-drag may also be used to pan). Mouse wheel actions always zoom while the touchpad scrolling may cause either effect.

pub fn as_wheel_action(self, cx: &EventState) -> Option<i32>

Attempt to interpret as a mouse wheel action

Infers the “scroll delta” as an integral step, if appropriate. This may be used e.g. to change the selected value of a ComboBox.

Positive values indicate scrolling up.

Trait Implementations

impl Clone for ScrollDelta

fn clone(&self) -> ScrollDelta

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ScrollDelta

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

Formats the value using the given formatter.

impl PartialEq for ScrollDelta

fn eq(&self, other: &ScrollDelta) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for ScrollDelta

impl StructuralPartialEq for ScrollDelta