Struct ImageWidget 

pub struct ImageWidget { /* private fields */ }

A widget that displays a raster image (PNG, WebP, or raw RGBA pixels) with configurable fit and alignment.

Implementations

impl ImageWidget

pub fn new(icon: &RasterIcon) -> Self

Create from a decoded [RasterIcon] (e.g., from res!()).

The texture is named after the icon’s identity, so every ImageWidget showing this icon (or a clone of it) in a window shares one texture, uploaded once.

That texture, with its mip chain, stays on the GPU for the life of the window and is never freed, even once no widget shows the icon. Each distinct identity keeps one: a clone of the icon is the same identity, but the same bytes decoded again are a new one. Keep decoded images in an application cache and clone them, rather than decoding per widget or per realization: in a virtualized grid of runtime images such as album covers, a cover decoded each time its tile scrolls into view leaves one more texture behind each time. Pixels shown once, or that change, belong on from_raw, whose texture goes with the widget; a mask takes that path too.

pub fn from_raw(pixels: Vec<u8>, width: u32, height: u32) -> Self

Create from raw RGBA pixel data, width × height, tightly packed.

The pixels are written once into a live source when the widget is first built, without a copy. The window’s texture for them goes with the first frame that does not draw the widget (it was destroyed, scrolled out or parked), so GPU memory follows what is on screen, and comes back with one upload. Input the source refuses (a zero side, a buffer shorter than width × height × 4, a side over LiveImageSource::MAX_DIMENSION) draws nothing, and says so once on standard error.

pub fn mask(self, shape: ImageMaskShape) -> Self

Apply an anti-aliased alpha mask to the image at construction time. The pixels are first centre-cropped to the shorter side (so the mask shape is geometrically consistent regardless of the source aspect ratio), then their alpha channel is modulated by the mask coverage. RGB is preserved.

Cover fit is the natural pairing — the masked square fills the avatar/thumbnail bounds and the masked-out corners stay transparent. Contain works but may letterbox. The default fit (Contain) is left unchanged so callers explicitly pick a fit when they apply a mask.

The masked picture is the widget’s own, written once into a live source as from_raw’s is: the icon’s shared texture is left alone. ImageMaskShape::None is a no-op.

pub fn fit(self, fit: ImageFit) -> Self

Set the content-fit mode — how the image pixels map into the box. See ImageFit.

pub fn alignment(self, alignment: Alignment) -> Self

Set where the fitted image sits within the box when the active fit leaves slack or crops (the CSS object-position analogue). Defaults to [Alignment::CENTER]. Leading/Trailing resolve against the active layout direction (RTL-aware).

pub fn width(self, w: f32) -> Self

Pin a fixed display width (in logical pixels). The width axis becomes rigid — reported as-is and never scaled to a parent proposal. With no height pinned, the height derives from the image’s aspect ratio (CSS width: Npx; height: auto).

pub fn height(self, h: f32) -> Self

Pin a fixed display height (in logical pixels). The height axis becomes rigid. With no width pinned, the width derives from the image’s aspect ratio.

pub fn size(self, w: f32, h: f32) -> Self

Pin both display width and height (in logical pixels). The box is exactly this size, rigid on both axes; the image content is fitted inside it via the fit mode. This is the fixed-size-logo case — .size(32.0, 32.0).

pub fn resizable(self, resizable: bool) -> Self

Control whether, with no axis pinned, a constraining parent proposal scales the natural pixel size (true, the default) or the box stays locked to the raw pixel dimensions (false). Equivalent to opting out of SwiftUI’s .resizable(). No effect once a dimension is pinned via width / height / size.

pub fn alt(self, text: impl Into<String>) -> Self

Set the accessibility alt text.

pub fn a11y_hidden(self) -> Self

Mark this image as decorative — hidden from the accessibility tree. Use when the image’s semantic content is already conveyed by adjacent text (e.g. a hero image next to its caption). ARIA equivalent of alt="" / role="presentation".

Trait Implementations

impl Debug for ImageWidget

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

Formats the value using the given formatter.

impl Widget for ImageWidget

fn build(&mut self, ctx: &mut BuildContext<'_>) -> Vec<WidgetId>

An owned picture is committed to its source at the first build, and every build attaches it in the widget’s window.

fn layout_response( &self, proposal: SizeProposal, _ctx: &LayoutContext<'_>, ) -> LayoutResponse

Respond to the parent’s size proposal with this widget’s wanted size, grow/shrink weights, and compression floor (see [LayoutResponse]).

fn paint(&self, bounds: Rect, canvas: &mut Canvas, ctx: &PaintContext<'_>)

Draw the widget’s visual representation.

fn accessibility(&self, builder: &mut AccessNodeBuilder)

Declare this widget’s accessibility identity.

fn type_name(&self) -> &'static str

Concrete type name of this widget (e.g. "teksilo_widgets::button::Button"). The default implementation resolves at the impl site via std::any::type_name::<Self>(), so calls through &dyn Widget correctly dispatch to the monomorphized fn for the concrete type — getting the concrete name through the vtable without per-impl boilerplate.

fn cacheable_layout(&self) -> bool

Whether this widget’s layout_response may be memoized by the per-pass layout cache. Defaults to true.

fn place_children( &self, _bounds: Rect, _proposal: SizeProposal, _children: &mut [WidgetPlacement], _ctx: &LayoutContext<'_>, )

Position children within the allocated bounds.

fn wants_after_paint(&self) -> bool

Whether this widget wants its after_paint hook to fire each frame. Returning false (the default) saves a virtual call per widget per frame for the vast majority of widgets that don’t aggregate descendant geometry.

fn after_paint(&self, _view: &WidgetTreeView<'_>, _ctx: &PaintContext<'_>)

Called once per frame after this widget’s subtree has finished painting. Receives a read-only view of the layout-resolved arena so a parent can read its descendants’ final bounds — e.g. TitleBar aggregates its drag region and control-button rects into a single HitRegions payload for the Windows backend’s WM_NCHITTEST.

fn wants_post_paint(&self) -> bool

Whether this widget wants its post_paint hook to fire each frame. Returning false (the default) saves a virtual call per widget per frame for the vast majority of widgets that don’t draw a foreground over their children.

fn post_paint( &self, _bounds: Rect, _canvas: &mut Canvas, _ctx: &PaintContext<'_>, )

Draw a foreground layer over this widget’s children.

fn wants_descendant_redirects(&self) -> bool

Whether this widget wants the AT walker to consult its a11y_redirect_descendant hook for every descendant during AT tree emission, not just its direct arena children.

fn culls_children(&self) -> bool

Whether this widget decides, on every layout pass, which of its children exist at all.

fn a11y_redirect_descendant( &self, _self_id: WidgetId, _descendant: WidgetId, ) -> Option<NodeId>

Optional redirection hook for AT-tree placement of a child.

fn accessible_title_hint(&self) -> Option<String>

Suggest an accessible title to an enclosing container that wraps this widget as content — typically a modal / dialog shell that wants to propagate the inner content’s visible title as the shell’s own accessible name.

fn accessible_title_node(&self) -> Option<WidgetId>

The widget that paints this one’s title, when it has one.

fn initial_focus_hint(&self) -> Option<WidgetId>

Optional hint that directs initial focus to a specific descendant when this widget is the root of a deferred-built modal surface.

fn accessibility_proxy(&self) -> Option<WidgetId>

The descendant whose accessibility node stands for this widget.

fn context_menu_key_target(&self) -> Option<WidgetId>

Which descendant a keyboard request for a context menu should target.

fn children(&self) -> Vec<WidgetId>

Return the child widget IDs that this widget manages.

fn accessibility_children(&self) -> Option<Vec<WidgetId>>

Optional override for the child ORDER presented to assistive technology, when it must differ from the paint / z-order child order returned by children.

fn as_any(&self) -> Option<&(dyn Any + 'static)>

Downcast hook. Default implementation returns None; concrete widgets override with Some(self) when they want to expose their concrete type to test-level introspection or reflection. The trait already bounds on std::any::Any so concrete types satisfy the 'static requirement.

fn as_any_mut(&mut self) -> Option<&mut (dyn Any + 'static)>

Mutable counterpart of as_any. Default returns None; widgets that want to expose mutable state to tests (e.g. so a test can mutate a Scene inside a SceneView post-layout) override with Some(self). Should follow the same opt-in pattern as as_any: only widgets that opt into & introspection should opt into &mut.

fn clips_children(&self) -> bool

Whether this widget clips its children to its bounds.

fn focus_reveal_rect(&self, _bounds: Rect) -> Option<Rect>

The rectangle (in absolute tree coordinates) that best represents this widget when the framework reveals it into an ancestor scroll area on focus gain. Returning None (the default) reveals the widget’s whole bounds — correct for most controls.

fn hit_shape(&self, _local_point: Point, _bounds: Rect) -> bool

Whether the point lies inside this widget’s actual shape, not just its rectangular bounds. Consulted by hit-testing right after the bounds check: returning false for a point that is inside the bounding box makes the widget transparent to the click there, so it falls through to whatever sibling is painted underneath (the same machinery as a fully pass-through node, but shape-aware).

fn accepts_child_hit(&self, _child: WidgetId, _point: Point) -> bool

Veto a hit on one of this widget’s direct children, per point.

fn hit_outset(&self, _kind: PointerKind, _tokens: &InputTokens) -> EdgeInsets

How far outside its own bounds this widget still absorbs a press, per edge, for the pointer that is asking.

fn hit_slop(&self, _kind: PointerKind, _tokens: &InputTokens) -> Option<HitSlop>

This widget’s own say in the miss-only slop pass, overriding the density default for its node.

fn hit_distance(&self, local_point: Point, bounds: Rect) -> Option<f32>

How far a missed press is from this widget’s actual silhouette, in the widget’s own bounds space.

fn target_regions(&self, _bounds: Rect) -> Vec<TargetRegion>

The interactive sub-regions this widget paints inside its own single node — a scroll bar’s thumb, a slider’s knob, a header cell’s filter affordance.

fn preserves_children_on_rebuild(&self) -> bool

How rebuild_single_widget treats this widget’s existing children when re-running its build().

fn tooltip_has_content(&self) -> bool

Whether this widget, used as tooltip content, currently has anything worth showing.

fn declare_shortcuts(&self) -> Vec<Shortcut>

Declare the rebindable keyboard shortcuts this widget exposes, without installing handlers. The framework calls this at arena insertion time (before build()) and at certain lazy boundaries (e.g. Switcher walks declarations on its not-yet-mounted Pending slots), so settings UIs and the ShortcutRegistry see the keystrokes the moment the owning container mounts — even if build() hasn’t run.

fn take_handler_set(&mut self) -> Option<HandlerSet>

Extract attached handler set from a WidgetWithHandlers wrapper. Called during arena insertion to transfer handlers to the WidgetNode. Default: returns None (no attached handlers).