Struct conrod::UiCell

pub struct UiCell<'a> {
    // some fields omitted
}

A wrapper around the Ui that restricts the user from mutating the Ui in certain ways while in the scope of the Ui::set_widgets function and within Widgets' update methods. Using the UiCell, users may access the Ui immutably (via Deref) however they wish, however they may only mutate the Ui via the &mut self methods provided by the UiCell.

The name came from its likening to a "jail cell for the Ui", as it restricts a user's access to it. However, we realise that the name may also cause ambiguity with the std Cell and RefCell types (which UiCell has nothing to do with). Thus, if you have a better name for this type in mind, please let us know at the github repo via an issue or PR sometime before we hit 1.0.0!

Methods

impl<'a> UiCell<'a>

fn theme(&self) -> &Theme

A reference to the Theme that is currently active within the Ui.

fn font(&self, id: Id) -> Option<&Font>

A convenience method for borrowing the Font for the given Id if it exists.

fn window_dim(&self) -> Dimensions

Returns the dimensions of the window

fn global_input(&self) -> &Global

Returns an immutable reference to the input::Global of the Ui.

All coordinates here will be relative to the center of the window.

fn widget_input<I: Into<Index>>(&self, idx: I) -> Widget

Returns a input::Widget with input events for the widget.

All coordinates in the input::Widget will be relative to the widget at the given index.

fn new_unique_node_index(&mut self) -> NodeIndex

Generate a new, unique NodeIndex into a Placeholder node within the Ui's widget graph. This should only be called once for each unique widget needed to avoid unnecessary bloat within the Ui's widget graph.

When using this method in your Widget's update method, be sure to store the returned NodeIndex somewhere within your Widget::State so that it can be re-used on next update.

Panics if adding another node would exceed the maximum capacity for node indices.

fn kids_bounding_box<I: Into<Index>>(&self, idx: I) -> Option<Rect>

The Rect that bounds the kids of the widget with the given index.

Returns None if the widget has no children or if there's is no widget for the given index.

fn scroll_widget<I>(&mut self, widget_idx: I, offset: [Scalar; 2]) where I: Into<Index>

Scroll the widget at the given index by the given offset amount.

The produced Scroll event will be pushed to the pending_scroll_events and will be applied to the widget during the next call to Ui::set_widgets.

Methods from Deref<Target=Ui>

fn widget_input<I: Into<Index>>(&self, widget: I) -> Widget

Returns a input::Widget for the given widget

fn rect_of<I: Into<Index>>(&self, idx: I) -> Option<Rect>

The Rect for the widget at the given index.

Returns None if there is no widget for the given index.

fn w_of<I: Into<Index>>(&self, idx: I) -> Option<Scalar>

The absolute width of the widget at the given index.

Returns None if there is no widget for the given index.

fn h_of<I: Into<Index>>(&self, idx: I) -> Option<Scalar>

The absolute height of the widget at the given index.

Returns None if there is no widget for the given index.

fn wh_of<I: Into<Index>>(&self, idx: I) -> Option<Dimensions>

The absolute dimensions for the widget at the given index.

Returns None if there is no widget for the given index.

fn xy_of<I: Into<Index>>(&self, idx: I) -> Option<Point>

The coordinates for the widget at the given index.

Returns None if there is no widget for the given index.

fn kid_area_of<I: Into<Index>>(&self, idx: I) -> Option<Rect>

The kid_area of the widget at the given index.

Returns None if there is no widget for the given index.

fn maybe_prev_widget(&self) -> Option<Index>

An index to the previously updated widget if there is one.

fn widget_graph(&self) -> &Graph

Borrow the Ui's widget_graph.

fn updated_widgets(&self) -> &HashSet<NodeIndex>

Borrow the Ui's set of updated widgets.

This set indicates which widgets have been instantiated since the beginning of the most recent Ui::set_widgets call.

fn prev_updated_widgets(&self) -> &HashSet<NodeIndex>

Borrow the Ui's set of updated widgets.

This set indicates which widgets have were instantiated during the previous call to Ui::set_widgets.

fn scroll_widget<I>(&mut self, widget_idx: I, offset: [Scalar; 2]) where I: Into<Index>

Scroll the widget at the given index by the given offset amount.

The produced Scroll event will be applied upon the next call to Ui::set_widgets.

fn handle_event<E: Into<Raw>>(&mut self, event: E)

Handle raw window events and update the Ui state accordingly.

This occurs within several stages:

1. Convert the user's given event to a RawEvent so that the Ui may use it.
2. Interpret the RawEvent for higher-level Events such as DoubleClick, WidgetCapturesKeyboard, etc.
3. Update the Ui's global_input State accordingly, depending on the RawEvent.
4. Store newly produced event::Uis within the global_input so that they may be filtered and fed to Widgets next time Ui::set_widget is called.

This method drives the Ui forward, and is what allows for using conrod's Ui with any window event stream.

The given event must implement the ToRawEvent trait so that it can be converted to a RawEvent that can be used by the Ui.

fn calc_xy(&self, maybe_idx: Option<Index>, x_position: Position, y_position: Position, dim: Dimensions, place_on_kid_area: bool) -> Point

Get the centred xy coords for some given Dimensions, Position and alignment.

If getting the xy for a specific widget, its widget::Index should be specified so that we can also consider the scroll offset of the scrollable parent widgets.

The place_on_kid_area argument specifies whether or not Place Position variants should target a Widget's kid_area, or simply the Widget's total area.

fn set_widgets<F>(&mut self, user_widgets_fn: F) where F: FnOnce(UiCell)

A function within which all widgets are instantiated by the user, normally situated within the "update" stage of an event loop.

fn set_num_redraw_frames(&mut self, num_frames: u8)

Set the number of frames that the Ui should draw in the case that needs_redraw is called. The default is 3 (see the SAFE_REDRAW_COUNT docs for details).

fn needs_redraw(&mut self)

Tells the Ui that it needs to be re-draw everything. It does this by setting the redraw count to num_redraw_frames. See the docs for set_num_redraw_frames, SAFE_REDRAW_COUNT or draw_if_changed for more info on how/why the redraw count is used.

fn clear_with(&mut self, color: Color)

The first of the Primitivees yielded by Ui::draw or Ui::draw_if_changed will always be a Rectangle the size of the window in which conrod is hosted.

This method sets the colour with which this Rectangle is drawn (the default being conrod::color::TRANSPARENT.

fn draw<'a, Img>(&'a mut self, image_map: &'a Map<Img>) -> Primitives<'a, Img>

Draw the Ui in it's current state.

NOTE: If you don't need to redraw your conrod GUI every frame, it is recommended to use the Ui::draw_if_changed method instead.

fn draw_if_changed<'a, Img>(&'a mut self, image_map: &'a Map<Img>) -> Option<Primitives<'a, Img>>

Same as the Ui::draw method, but only draws if the redraw_count is greater than 0.

The redraw_count is set to SAFE_REDRAW_COUNT whenever a Widget indicates that it needs to be re-drawn.

It can also be triggered manually by the user using the Ui::needs_redraw method.

This method is generally preferred over Ui::draw as it requires far less CPU usage, only redrawing to the screen if necessary.

Note that when Ui::needs_redraw is triggered, it sets the redraw_count to 3 by default. This ensures that conrod is drawn to each buffer in the case that there is buffer swapping happening. Let us know if you need finer control over this and we'll expose a way for you to set the redraw count manually.

fn kids_bounding_box<I: Into<Index>>(&self, idx: I) -> Option<Rect>

The Rect that bounds the kids of the widget with the given index.

fn visible_area<I: Into<Index>>(&self, idx: I) -> Option<Rect>

The Rect that represents the maximum fully visible area for the widget with the given index, including consideration of cropped scroll area.

Otherwise, return None if the widget is not visible.

Trait Implementations

impl<'a> Deref for UiCell<'a>

type Target = Ui

The resulting type after dereferencing

fn deref(&self) -> &Ui

The method called to dereference a value

impl<'a> AsRef<Ui> for UiCell<'a>

fn as_ref(&self) -> &Ui

Performs the conversion.