Struct titanium::desktop::gui::libdruid::scroll_component::ScrollComponent

pub struct ScrollComponent {
    pub opacity: f64,
    pub timer_id: TimerToken,
    pub hovered: BarHoveredState,
    pub held: BarHeldState,
    pub enabled: ScrollbarsEnabled,
}

Embeddable component exposing reusable scroll handling logic.

In most situations composing Scroll is a better idea for general UI construction. However some cases are not covered by composing those widgets, such as when a widget needs fine grained control over its scrolling state or doesn’t make sense to exist alone without scrolling behavior.

ScrollComponent contains the input-handling and scrollbar-positioning logic used by Scroll. It can be used to add this logic to a custom widget when the need arises.

It can be used like this:

• Store an instance of ScrollComponent in your widget’s struct, and wrap the child widget to be scrolled in a ClipBox.
• Call event and lifecycle with all event and lifecycle events before propagating them to children.
• Call handle_scroll with all events after handling / propagating them.
• Call draw_bars to draw the scrollbars.

Taking a look at the Scroll source code can be helpful. You can also do scrolling without wrapping a child in a ClipBox, but you will need to do certain event and paint transformations yourself; see the ClipBox source code for an example.

Fields

opacity: f64

Current opacity for both scrollbars

timer_id: TimerToken

ID for the timer which schedules scrollbar fade out

hovered: BarHoveredState

Which if any scrollbar is currently hovered by the mouse

held: BarHeldState

Which if any scrollbar is currently being dragged by the mouse

enabled: ScrollbarsEnabled

Which scrollbars are enabled

Implementations

impl ScrollComponent

pub fn new() -> ScrollComponent

Constructs a new ScrollComponent for use.

pub fn are_bars_held(&self) -> bool

true if either scrollbar is currently held down/being dragged

pub fn reset_scrollbar_fade<F>(&mut self, request_timer: F, env: &Env)where F: FnOnce(Duration) -> TimerToken,

Makes the scrollbars visible, and resets the fade timer.

pub fn calc_vertical_bar_bounds(&self, port: &Viewport, env: &Env) -> Option<Rect>

Calculates the paint rect of the vertical scrollbar, or None if the vertical scrollbar is not visible.

pub fn calc_horizontal_bar_bounds( &self, port: &Viewport, env: &Env ) -> Option<Rect>

Calculates the paint rect of the horizontal scrollbar, or None if the horizontal scrollbar is not visible.

pub fn draw_bars(&self, ctx: &mut PaintCtx<'_, '_, '_>, port: &Viewport, env: &Env)

Draw scroll bars.

pub fn point_hits_vertical_bar( &self, port: &Viewport, pos: Point, env: &Env ) -> bool

Tests if the specified point overlaps the vertical scrollbar

Returns false if the vertical scrollbar is not visible

pub fn point_hits_horizontal_bar( &self, port: &Viewport, pos: Point, env: &Env ) -> bool

Tests if the specified point overlaps the horizontal scrollbar

Returns false if the horizontal scrollbar is not visible

pub fn event( &mut self, port: &mut Viewport, ctx: &mut EventCtx<'_, '_>, event: &Event, env: &Env )

Checks if the event applies to the scroll behavior, uses it, and marks it handled

Make sure to call on every event

pub fn handle_scroll( &mut self, port: &mut Viewport, ctx: &mut EventCtx<'_, '_>, event: &Event, env: &Env )

Applies mousewheel scrolling if the event has not already been handled

pub fn lifecycle( &mut self, ctx: &mut LifeCycleCtx<'_, '_>, event: &LifeCycle, env: &Env )

Perform any necessary action prompted by a lifecycle event

Make sure to call on every lifecycle event

Trait Implementations

impl Clone for ScrollComponent

fn clone(&self) -> ScrollComponent

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ScrollComponent

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

Formats the value using the given formatter.

impl Default for ScrollComponent

fn default() -> ScrollComponent

Returns the “default value” for a type.

impl Copy for ScrollComponent