Struct BlockLayouts 

pub struct BlockLayouts(/* private fields */);

Where each block’s text landed, recorded as it painted.

A caret has to be placeable by pointer, and only paint knows where a glyph ended up. An editor hands one of these in, the renderer fills it, and the next click resolves against it. Read-only callers pass nothing and pay nothing.

Implementations

impl BlockLayouts

pub fn hit(&self, point: Point<Pixels>) -> Option<Cursor>

The position under point.

Falls back to the nearest text vertically, so clicking the margin beside a line — or below the last one — still lands somewhere useful rather than doing nothing.

pub fn position(&self, at: Cursor) -> Option<(Point<Pixels>, Pixels)>

Where a position painted last frame, and how tall its line is.

Vertical motion is geometry rather than arithmetic on line numbers, so a wrapped row and a hard newline are the same case and neither needs counting — the rule ui::TextField arrived at.

pub fn rects(&self, selection: Selection) -> Vec<Bounds<Pixels>>

The painted rows of a range, in document order — what a bar centred over a selection is placed against, and what a highlight of a caller’s own is drawn from.

One rect per visual row rather than one box: a selection that wraps or crosses blocks has no single box, and a caller given one would paint over the gaps.

pub fn step_row( &self, at: Cursor, from: Point<Pixels>, down: bool, ) -> Option<(Cursor, Pixels)>

The position one painted row above or below at, and the row it landed on. Walks the recorded runs in paint order — which is document order.

Two things make this refuse to be a hit test. The gap between blocks belongs to no run, so a probe there answers with whichever run is nearest — and at a boundary that is the block being left, whose bottom edge is zero pixels away while the next block’s top is a whole gap. And from is passed in rather than derived from at, because an offset at a soft wrap belongs to two rows and position_for_index always answers with the first: derive it and every step down recomputes the same row.

pub fn over_text(&self, point: Point<Pixels>) -> bool

Whether point is inside painted text.

Self::hit answers with the nearest run wherever it is asked, which is what a click wants and what a pointer must not have: an I-beam belongs where a caret would land, not everywhere an editor’s box reaches.

pub fn block_at(&self, point: Point<Pixels>) -> Option<usize>

The block under point, for a gutter handle and a drop target.

pub fn first_row(&self, ix: usize) -> Option<(Pixels, Pixels)>

Where a block’s first painted row sits, and how tall that row is — what a mark in the gutter has to line up with.

Self::block_bounds is not that: it spans every row the block holds, and a heading’s single row is taller than a paragraph’s, so anything placed from the top of the box rides above the text it points at. None for a block that paints no text at all, a rule being the one that does.

pub fn block_bounds(&self, ix: usize) -> Option<Bounds<Pixels>>

Where a block painted last frame, in window coordinates.

pub fn language_bounds(&self, ix: usize) -> Option<Bounds<Pixels>>

Where a fenced block’s language label painted — the box a host hangs its picker on. Recorded rather than derived: the word’s width is the text system’s answer, and padding arithmetic would be wrong the first time any of it changed.

pub fn picture_bounds(&self, ix: usize) -> Option<Bounds<Pixels>>

Where an image block’s picture painted, which BlockLayouts::block_bounds does not give: that box spans the column and takes in the caption, so a handle placed from it sits off the edge of any picture narrower than the page.

pub fn checkbox_bounds(&self, ix: usize) -> Option<Bounds<Pixels>>

Where a task block’s checkbox painted, which is the box itself and not the marker column it sits in — a press outside it is a press on the gutter, and belongs to whatever handles one.

Trait Implementations

impl Clone for BlockLayouts

fn clone(&self) -> BlockLayouts

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Default for BlockLayouts

fn default() -> BlockLayouts

Returns the “default value” for a type.