Struct UiMessage

pub struct UiMessage {
    pub handled: Cell<bool>,
    pub data: Rc<dyn MessageData>,
    pub destination: Handle<UiNode>,
    pub direction: MessageDirection,
    pub perform_layout: Cell<bool>,
    pub flags: u64,
}

Message is basic communication element that is used to deliver information to UI nodes or to user code.

Threading

UiMessage is nor Send or Sync. User interface is a single-thread thing, as well as its messages.

Fields

handled: Cell<bool>

Useful flag to check if a message was already handled.

data: Rc<dyn MessageData>

Actual message data.

destination: Handle<UiNode>

Handle of node that will receive message. Please note that all nodes in hierarchy will also receive this message, order is “up-on-tree”.

direction: MessageDirection

Indicates the direction of the message.

See MessageDirection for details.

perform_layout: Cell<bool>

Whether or not message requires layout to be calculated first.

Some of message handling routines uses layout info, but message loop performed right after layout pass, but some of messages may change layout and this flag tells UI to perform layout before passing message further. In ideal case we’d perform layout after each message, but since layout pass is super heavy we should do it only when it is actually needed.

flags: u64

A custom user flags.

Implementations

impl UiMessage

pub fn with_data<T>(data: T) -> UiMessage

where T: MessageData,

pub fn with_destination(self, destination: Handle<UiNode>) -> UiMessage

pub fn with_direction(self, direction: MessageDirection) -> UiMessage

pub fn with_perform_layout(self, perform_layout: bool) -> UiMessage

pub fn reverse(&self) -> UiMessage

Creates a new copy of the message with reversed direction. Typical use case is to re-send messages to create “response” in widget. For example you have a float input field and it has Value message. When the input field receives Value message with MessageDirection::ToWidget it checks if value needs to be changed and if it does, it re-sends same message but with reversed direction back to message queue so every “listener” can reach properly. The input field won’t react at MessageDirection::FromWidget message so there will be no infinite message loop.

pub fn destination(&self) -> Handle<UiNode>

pub fn data<T>(&self) -> Option<&T>

where T: MessageData,

pub fn set_handled(&self, handled: bool)

pub fn handled(&self) -> bool

pub fn direction(&self) -> MessageDirection

pub fn set_perform_layout(&self, value: bool)

pub fn need_perform_layout(&self) -> bool

pub fn has_flags(&self, flags: u64) -> bool

Trait Implementations

impl Clone for UiMessage

fn clone(&self) -> UiMessage

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for UiMessage

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

Formats the value using the given formatter.

impl PartialEq for UiMessage

fn eq(&self, other: &UiMessage) -> 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.