Trait conrod::Widget
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pub trait Widget: Sized { type State: Any + PartialEq + Debug; type Style: Any + PartialEq + Debug; fn common(&self) -> &CommonBuilder; fn common_mut(&mut self) -> &mut CommonBuilder; fn unique_kind(&self) -> &'static str; fn init_state(&self) -> Self::State; fn style(&self) -> Self::Style; fn update<C: CharacterCache>(self, args: UpdateArgs<Self, C>); fn draw<C: CharacterCache>(args: DrawArgs<Self, C>) -> Element; fn default_position(&self, _theme: &Theme) -> Position { ... } fn default_h_align(&self, theme: &Theme) -> HorizontalAlign { ... } fn default_v_align(&self, theme: &Theme) -> VerticalAlign { ... } fn default_width<C: CharacterCache>(&self, _theme: &Theme, _: &GlyphCache<C>) -> Scalar { ... } fn default_height(&self, _theme: &Theme) -> Scalar { ... } fn drag_area(&self, _dim: Dimensions, _style: &Self::Style, _theme: &Theme) -> Option<Rect> { ... } fn kid_area<C: CharacterCache>(&self, args: KidAreaArgs<Self, C>) -> KidArea { ... } fn parent<I: Into<Index>>(self, maybe_parent_idx: Option<I>) -> Self { ... } fn floating(self, is_floating: bool) -> Self { ... } fn scrolling(self, scrollable: bool) -> Self { ... } fn vertical_scrolling(self, scrollable: bool) -> Self { ... } fn horizontal_scrolling(self, scrollable: bool) -> Self { ... } fn set<I, U>(self, idx: I, ui: &mut U) where I: Into<Index>, U: UiRefMut { ... } }
A trait to be implemented by all Widget types.
A type that implements Widget can be thought of as a collection of arguments to the Widget's Widget::update method. They type itself is not stored between updates, but rather is used to update an instance of the Widget's Widget::State, which is stored.
Methods that must be overridden: - common - common_mut - unique_kind - init_state - style - update - draw
Methods that can be optionally overridden: - default_position - default_width - default_height - default_h_align - default_v_align
Methods that should not be overridden: - parent - set
Associated Types
type State: Any + PartialEq + Debug
State to be stored within the Ui
s widget cache. Take advantage of this type for any large
allocations that you would like to avoid repeating between updates, or any calculations
that you'd like to avoid repeating between calls to update
and draw
. Conrod will never
clone the state, it will only ever be moved.
type Style: Any + PartialEq + Debug
Styling used by the widget to construct an Element. Styling is useful to have in its own
abstraction in order to making Theme serializing easier. Conrod doesn't yet support
serializing non-internal widget styling with the Theme
type, but we hope to soon.
Required Methods
fn common(&self) -> &CommonBuilder
Return a reference to a CommonBuilder struct owned by the Widget. This method allows us to do a blanket impl of Positionable and Sizeable for T: Widget.
Note: When rust introduces field inheritance, we will move the CommonBuilder accordingly (perhaps under a different name).
fn common_mut(&mut self) -> &mut CommonBuilder
Return a mutable reference to a CommonBuilder struct owned by the Widget. This method allows us to do a blanket impl of Positionable and Sizeable for T: Widget.
Note: When rust introduces field inheritance, we will move the CommonBuilder accordingly (perhaps under a different name).
fn unique_kind(&self) -> &'static str
Return the kind of the widget as a &'static str.
Note that this must be unique from all other widgets' "unique kinds".
This is used by conrod to help avoid WidgetId errors and to provide better messages for those that do occur.
fn init_state(&self) -> Self::State
Return the initial State of the Widget.
The Ui
will only call this once, shortly prior to the first time that Widget::update
is first called.
fn style(&self) -> Self::Style
Return the styling of the widget. The Ui
will call this once prior to each update
. It
does this so that it can check for differences in Style
in case a new Element
needs to
be constructed.
fn update<C: CharacterCache>(self, args: UpdateArgs<Self, C>)
Update our Widget's unique Widget::State via the State wrapper type (the
state
field within the UpdateArgs).
Whenever State::update is called, a has_updated
flag is set within the State, indicating that there has been some change to the unique
Widget::State and that we require re-drawing the Widget's Element (i.e. calling
Widget::draw. As a result, widget designers should only
call State::update when necessary, checking whether or not the state has changed before
invoking the the method. See the custom_widget.rs example for a demonstration
of this.
Arguments
- idx - The
Widget
's unique index (whetherPublic
orInternal
). - prev - The previous common state of the Widget. If this is the first time update is
called,
Widget::init_state
will be used to produce some intial state instead. - state - A wrapper around the
Widget::State
. See the State docs for more details. - rect - The position (centered) and dimensions of the widget.
- style - The style produced by the
Widget::style
method. - ui - A wrapper around the
Ui
, offering restricted access to its functionality. See the docs forUiCell
for more details.
fn draw<C: CharacterCache>(args: DrawArgs<Self, C>) -> Element
Construct a renderable Element from the current styling and new state. This will only be
called on the occasion that the widget's Style
or State
has changed. Keep this in mind
when designing your widget's Style
and State
types.
Arguments
- state - The current Widget::State which should contain all unique state necessary for rendering the Widget.
- style - The current Widget::Style of the Widget.
- theme - The currently active Theme within the
Ui
. - glyph_cache - Used for determining the size of rendered text if necessary.
Provided Methods
fn default_position(&self, _theme: &Theme) -> Position
The default Position for the widget. This is used when no Position is explicitly given when instantiating the Widget.
fn default_h_align(&self, theme: &Theme) -> HorizontalAlign
The default horizontal alignment for the widget. This is used when no HorizontalAlign is explicitly given when instantiating a Widget.
fn default_v_align(&self, theme: &Theme) -> VerticalAlign
The default vertical alignment for the widget. This is used when no VerticalAlign is explicitly given when instantiating a Widget.
fn default_width<C: CharacterCache>(&self, _theme: &Theme, _: &GlyphCache<C>) -> Scalar
The default width of the widget. A reference to the GlyphCache is provided in case the width should adjust to some text len. This method is only used if no width or dimensions are given.
fn default_height(&self, _theme: &Theme) -> Scalar
The default height of the widget. This method is only used if no height or dimensions are given.
fn drag_area(&self, _dim: Dimensions, _style: &Self::Style, _theme: &Theme) -> Option<Rect>
If the widget is draggable, implement this method and return the position an dimensions of the draggable space. The position should be relative to the center of the widget.
fn kid_area<C: CharacterCache>(&self, args: KidAreaArgs<Self, C>) -> KidArea
The area on which child widgets will be placed when using the Place
Position
methods.
fn parent<I: Into<Index>>(self, maybe_parent_idx: Option<I>) -> Self
Set the parent widget for this Widget by passing the WidgetId of the parent. This will attach this Widget to the parent widget.
fn floating(self, is_floating: bool) -> Self
Set whether or not the widget is floating (the default is false
).
A typical example of a floating widget would be a pop-up or alert window.
A "floating" widget will always be rendered after its parent tree and all widgets
connected to its parent tree. If two sibling widgets are both floating, then the one that
was last clicked will be rendered last. If neither are clicked, they will be rendered in
the order in which they were cached into the Ui
.
fn scrolling(self, scrollable: bool) -> Self
Set whether or not the widget's KidArea
is scrollable (the default is false).
If a widget is scrollable and it has children widgets that fall outside of its KidArea
,
the KidArea
will become scrollable.
fn vertical_scrolling(self, scrollable: bool) -> Self
Set whether or not the widget's KidArea
is scrollable (the default is false).
If a widget is scrollable and it has children widgets that fall outside of its KidArea
,
the KidArea
will become scrollable.
fn horizontal_scrolling(self, scrollable: bool) -> Self
Set whether or not the widget's KidArea
is scrollable (the default is false).
If a widget is scrollable and it has children widgets that fall outside of its KidArea
,
the KidArea
will become scrollable.
fn set<I, U>(self, idx: I, ui: &mut U) where I: Into<Index>, U: UiRefMut
Note: There should be no need to override this method.
After building the widget, you call this method to set its current state into the given
Ui
. More precisely, the following will occur when calling this method:
- The widget's previous state and style will be retrieved.
- The widget's current Style
will be retrieved (from the Widget::style
method).
- The widget's state will be updated (using the Widget::udpate
method).
- If the widget's state or style has changed, Widget::draw
will be called to create the
new Element for rendering.
- The new State, Style and Element (if there is one) will be cached within the Ui
.
Implementors
impl<'a, F> Widget for Button<'a, F> where F: FnMut()
impl<'a> Widget for Canvas<'a>
impl<'a, F> Widget for DropDownList<'a, F> where F: FnMut(&mut Option<Idx>, Idx, &str)
impl<'a, E, F> Widget for EnvelopeEditor<'a, E, F> where E: EnvelopePoint, E::X: Any, E::Y: Any, F: FnMut(&mut Vec<E>, usize)
impl<'a> Widget for Label<'a>
impl<'a, F, W> Widget for Matrix<F> where W: Widget, F: FnMut(WidgetNum, ColNum, RowNum) -> W
impl<'a, T, F> Widget for NumberDialer<'a, T, F> where F: FnMut(T), T: Any + Debug + Float + NumCast + ToString
impl<'a, T, F> Widget for Slider<'a, T, F> where F: FnMut(T), T: Any + Debug + Float + NumCast + ToPrimitive
impl<'a> Widget for Tabs<'a>
impl<'a, F> Widget for TextBox<'a, F> where F: FnMut(&mut String)
impl<'a, F> Widget for Toggle<'a, F> where F: FnMut(bool)
impl<'a, X, Y, F> Widget for XYPad<'a, X, Y, F> where X: Float + ToString + Debug + Any, Y: Float + ToString + Debug + Any, F: FnMut(X, Y)