Struct GripPart 

pub struct GripPart { /* private fields */ }

A draggable grip part

Slider, ScrollBar and Splitter all require a component which supports click+drag behaviour. The appearance differs but event handling is the same: this widget is its implementation.

Layout

This widget is unusual in several ways:

Layout::size_rules does not request any size; the parent is expected to determine the grip’s size. (Calling size_rules is still required to comply with widget model.)

Layout::set_rect sets the grip’s rect directly. Self::set_track must be called first.

Often it is preferable to use Self::set_size to set the grip’s size then Self::set_offset to set the position. (Calling set_rect is still required to comply with widget model.)

Layout::draw does nothing. The parent should handle all drawing.

Event handling

This widget handles click/touch events on the widget, pushing a GripMsg to allow the parent to implement further handling.

Optionally, the parent may call GripPart::handle_press_on_track when a Event::PressStart occurs on the track area (which identifies as being the parent widget).

Implementations

impl GripPart

pub fn new() -> GripPart

Construct

pub fn set_track(&mut self, track: Rect)

Set the track

The track is the region within which the grip may be moved.

This method must be called to set the track, presumably from the parent widget’s Layout::set_rect method. It is expected that GripPart::set_offset is called after this.

pub fn track(&self) -> Rect

Get the current track Rect

pub fn set_size(&mut self, size: Size)

Set the grip’s size

It is expected that for each axis the size is no larger than the size of the track (see GripPart::set_track). If equal, then the grip may not be moved on this axis.

This method must be called at least once. It is expected that GripPart::set_offset is called after this.

This size may be read via self.rect().size.

pub fn offset(&self) -> Offset

Get the current grip position

The position returned is relative to self.track().pos and is always between Offset::ZERO and Self::max_offset.

pub fn max_offset(&self) -> Offset

Get the maximum allowed offset

This is the maximum allowed Self::offset, equal to the size of the track minus the size of the grip.

pub fn set_offset(&mut self, cx: &mut EventState, offset: Offset) -> Offset

Set a new grip position

The input offset is clamped between Offset::ZERO and Self::max_offset.

The return value is a tuple of the new offest.

It is expected that Self::set_track and Self::set_size are called before this method.

pub fn handle_press_on_track( &mut self, cx: &mut EventCx<'_>, press: &PressStart, ) -> Offset

Handle an event on the track itself

If it is desired to make the grip move when the track area is clicked, then the parent widget should call this method when receiving Event::PressStart.

Returns the new grip position relative to the track.

The grip position is not adjusted; the caller should also call Self::set_offset to do so. This is separate to allow adjustment of the posision; e.g. Slider pins the position to the nearest detent.

Trait Implementations

impl Clone for GripPart

fn clone(&self) -> GripPart

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for GripPart

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

Formats the value using the given formatter.

impl Default for GripPart

fn default() -> GripPart

Returns the “default value” for a type.

impl Events for GripPart

const REDRAW_ON_MOUSE_OVER: bool = true

Does this widget have a different appearance on mouse over?

fn mouse_over_icon(&self) -> Option<CursorIcon>

The mouse cursor icon to use on mouse over

fn handle_event( &mut self, cx: &mut EventCx<'_>, _: &<GripPart as Widget>::Data, event: Event<'_>, ) -> IsUsed

Handle an Event

fn make_child_id(&mut self, index: usize) -> Id

Make an identifier for a child

fn configure(&mut self, cx: &mut ConfigCx<'_>)

Configure self

fn configure_recurse(&mut self, cx: &mut ConfigCx<'_>, data: &Self::Data)

Configure children

fn update(&mut self, cx: &mut ConfigCx<'_>, data: &Self::Data)

Update self using input data

fn update_recurse(&mut self, cx: &mut ConfigCx<'_>, data: &Self::Data)

Update children

fn handle_mouse_over(&mut self, cx: &mut EventCx<'_>, state: bool)

Mouse focus handler

fn handle_messages(&mut self, cx: &mut EventCx<'_>, data: &Self::Data)

Handler for messages from children/descendants

fn handle_scroll( &mut self, cx: &mut EventCx<'_>, data: &Self::Data, scroll: Scroll, )

Handler for scrolling

impl Layout for GripPart

This implementation is unusual (see GripPart documentation).

fn rect(&self) -> Rect

Get the widget’s region

fn size_rules(&mut self, _: SizeCx<'_>, _axis: AxisInfo) -> SizeRules

Get size rules for the given axis

fn set_rect(&mut self, _: &mut ConfigCx<'_>, rect: Rect, _: AlignHints)

Set size and position

fn draw(&self, _: DrawCx<'_>)

Draw a widget and its children

fn try_probe(&self, coord: Coord) -> Option<Id>

Probe a coordinate for a widget’s Id

impl Tile for GripPart

fn role(&self, _: &mut dyn RoleCx) -> Role<'_>

Describe the widget’s role

fn as_tile(&self) -> &dyn Tile

Get as a dyn Tile

fn id_ref(&self) -> &Id

Get a reference to the widget’s identifier

fn identify(&self) -> IdentifyWidget<'_>

Return a Display-able widget identifier

fn get_child(&self, index: usize) -> Option<&dyn Tile>

Access a child as a dyn Tile, if available

fn child_indices(&self) -> ChildIndices

Get child indices available to recursion

fn nav_next(&self, reverse: bool, from: Option<usize>) -> Option<usize>

Navigation in spatial order

fn probe(&self, coord: Coord) -> Id

Probe a coordinate for a widget’s Id

fn id(&self) -> Id

Get the widget’s identifier

fn navigable(&self) -> bool

Whether this widget supports navigation focus

fn tooltip(&self) -> Option<&str>

Tooltip

fn role_child_properties(&self, cx: &mut dyn RoleCx, index: usize)

Specify additional role properties for child index

fn find_child_index(&self, id: &Id) -> Option<usize>

Find the child which is an ancestor of this id, if any

fn translation(&self, index: usize) -> Offset

Get translation of child index relative to this widget

impl Widget for GripPart

type Data = ()

Input data type

fn as_node<'__a>( &'__a mut self, data: &'__a <GripPart as Widget>::Data, ) -> Node<'__a>

Erase type

fn child_node<'__n>( &'__n mut self, data: &'__n <GripPart as Widget>::Data, index: usize, ) -> Option<Node<'__n>>

Access a child as a Node, if available