Struct Alert 

pub struct Alert { /* private fields */ }

An inline banner: Info, Success, Warning or Error, with a message.

Not interactive, not focusable, not a tab stop. It sits in the layout, in the place the thing it is about would be.

Alert::new(Role::Success, "Lagret").with_icon('✓');
Alert::new(Role::Error, "Kunne ikke lagre: disken er full");

This is a banner, not a dialog

Worth being explicit, because the word covers both. A dialog — something that takes over, dims what is behind it and demands an answer — is Ui::push_scene, which already exists and already dims and captures input. This is the strip of colour that reports something happened.

Neither one opens a window. Denise is a single Surface: on denise-drm there is no window system to open one in, and denise-win32, denise-macos and denise-activex are embedded — the host owns the window and Denise owns one rectangle inside it, so a control that spawned a top-level window would escape its host’s modality and outlive the dialog that owns it.

An application that wants a native message box on a desktop build should call the platform for one. It knows which build it is; the toolkit would have to guess. That is the same conclusion the backend choice reached.

Sizing

preferred_height reports what the message needs once wrapped to a width — the query convention every sizable widget here uses, called by the application and never by the tree.

Implementations

impl Alert

pub fn new(role: Role, text: impl Into<String>) -> Self

A banner in role carrying text.

text may contain \n, and is wrapped to the width it is given.

pub fn with_icon(self, icon: char) -> Self

Puts a character in front of the message.

A char, not an icon set. There is no icon story in this toolkit and inventing one inside a banner would be the wrong place to start; whether ✓ or ⚠ actually draws depends on the font in use, and the built-in bitmap font has Latin and æøå and nothing else. ! and i always work.

pub fn with_style(self, style: TextStyle) -> Self

Sets the message’s font and size.

pub fn text(&self) -> &str

The current message.

pub fn set_text(&mut self, text: impl Into<String>)

Replaces the message.

pub fn update(&mut self, text: &str) -> bool

Replaces the message, reporting whether it actually changed.

pub fn set_role(&mut self, role: Role)

Replaces the role.

pub const fn role(&self) -> Role

The current role.

pub fn set_icon(&mut self, icon: Option<char>)

Replaces the leading character, or removes it.

pub fn preferred_height(&self, engine: &mut TextEngine, width: i32) -> i32

Height this banner needs for its message wrapped to width.

Trait Implementations

impl Clone for Alert

fn clone(&self) -> Alert

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Alert

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

Formats the value using the given formatter.

impl Describe for Alert

const KIND: &'static str = "alert"

The name a form file uses for this widget. Kebab-case.

const DOC: &'static str = "A coloured banner saying something happened, in the place it happened."

One line saying what this widget is, for somebody choosing one.

const GROUP: Group = Group::Display

Which shelf of the catalogue this belongs on.

const ICON: &'static Icon

The widget’s glyph: a small portrait of the thing, for a palette to draw beside — or instead of — its name.

const PROPERTIES: &'static [Property]

Every property, in the order an inspector should show them.

fn get(&self, name: &str) -> Option<Value>

The current value.

fn apply(&mut self, name: &str, value: Value) -> Result<(), Mismatch>

Applies a value, reporting only what went wrong.

fn set(&mut self, name: &str, value: Value) -> Result<(), PropertyError>

Applies a value, reporting what went wrong and where.

impl<M: 'static> Widget<M> for Alert

fn describe(&self) -> Option<&dyn DynDescribe>

This widget’s property description, if it has one.

fn describe_mut(&mut self) -> Option<&mut dyn DynDescribe>

The mutable half of describe.

fn measure(&self, ctx: &mut MeasureCtx<'_>, offered: Offer) -> Measured

How big this widget would like to be, given what the caller can promise.

fn paint(&self, ctx: &mut PaintCtx<'_>, canvas: &mut Pen<'_>)

Draws into canvas, which is already clipped to this widget’s bounds intersected with the damage region being repainted.

fn on_event(&mut self, event: &Event<'_>, ctx: &mut EventCtx<'_, M>) -> Handled

Reacts to an event routed to this widget.

fn accepts_pointer(&self) -> bool

Returns true if the pointer can hit this widget.

fn focusable(&self) -> bool

Returns true if this widget can take keyboard focus.

fn preserves_focus(&self) -> bool

Returns true if a press on this widget should leave focus exactly where it is.

fn animate(&mut self, now_ms: u64) -> Animation

Advances time-based state. Called only while this widget has asked to animate — see EventCtx::request_animation — and stops being called the moment it answers Wake::Never.

fn snap(&mut self, now_ms: u64) -> Animation

Lands whatever is in flight at its end state, without animating it.