Struct Extent 

pub struct Extent<'r, R: Renderer> {
    inner: &'r R,
    bounds: Bounds,
}

A Renderer that draws nothing and only measures: hand it the same draw passes the canvas runs and Extent::finish is the world-space rect they covered. Text and image sizes come from inner, the backend that would have drawn them.

Fields

inner: &'r R

bounds: Bounds

Implementations

impl<'r, R: Renderer> Extent<'r, R>

pub fn measuring_through(inner: &'r R) -> Self

pub fn finish(self) -> Option<Rect>

The union of everything the passes drew, or None if they drew nothing.

Trait Implementations

impl<R: Renderer> Renderer for Extent<'_, R>

fn rect( &self, rect: Rect, _rounding: WorldPx, _fill: impl Into<Swatch>, stroke: impl Into<PaletteStroke>, )

fn line_segment(&self, points: [Pos2; 2], _stroke: impl Into<PaletteStroke>)

fn line(&self, points: Vec<Pos2>, _stroke: impl Into<PaletteStroke>)

fn circle( &self, center: Pos2, radius: WorldPx, _fill: impl Into<Swatch>, stroke: impl Into<PaletteStroke>, )

fn add_convex_polygon( &self, points: Vec<Pos2>, _fill: impl Into<Swatch>, _stroke: impl Into<PaletteStroke>, )

fn text( &self, pos: Pos2, anchor: Align2, text: impl ToString, font: &Font, _color: impl Into<Swatch>, ) -> Rect

fn text_wrapped( &self, pos: Pos2, anchor: Align2, text: impl ToString, font: &Font, _color: impl Into<Swatch>, max_width: WorldPx, ) -> Rect

Like Renderer::text but wraps to max_width (word wrap); WorldPx::UNBOUNDED draws unwrapped. The default ignores max_width and draws unwrapped; backends that lay text out override it. Both the on-screen and the SVG backend break the text with the same layout engine, so they agree on the break points.

fn rotated_text( &self, pos: Pos2, anchor: Align2, text: impl ToString, font: &Font, _color: impl Into<Swatch>, _angle: Angle, )

fn text_size(&self, text: impl ToString, font: &Font) -> Vec2

fn text_size_wrapped( &self, text: impl ToString, font: &Font, max_width: WorldPx, ) -> Vec2

Like Renderer::text_size but measured with word wrap at max_width. The default ignores max_width.

fn text_layout(&self, text: &str, font: &Font, max_width: WorldPx) -> Layout

text laid out in font and word-wrapped at max_width, in world units: the rows Self::text_size_wrapped measures.

fn draw_image(&self, rect: Rect, _image: &Asset)

Draw image (an SVG or PNG payload) filling the world-space rect. The caller sizes rect to honor the image’s aspect ratio (see Renderer::image_intrinsic_size), so each backend simply fills rect: the on-screen painter caches the bytes in its own hash → handle table and polls the toolkit’s loader, while the SVG exporter embeds the bytes as a base64 data URI.

fn image_intrinsic_size(&self, image: &Asset) -> Option<Vec2>

The intrinsic point size of image (always strictly positive), used by the caller for aspect-fit and the resize-ring geometry. None if the bytes are not a valid SVG/PNG.

fn animator(&self) -> Option<&dyn Animator>

The frame animation this backend drives, for interactive overlays drawn on the generic render path. The on-screen canvas supplies itself; offline backends (the SVG exporter) return None, so those overlays fall back to a static draw.

fn visible_world_bounds(&self) -> Option<Rect>

The world-space rect currently visible on screen, if this backend paints into a bounded viewport. The render path uses it to viewport-cull the scene: shapes outside it are skipped. None (the default) means “no viewport — draw everything”, which is what offline backends (the SVG exporter) want, so an export is never culled.