Crate egui_richedit 

Rich-text editing for egui, over paragraphs the application lays out and owns itself.

egui’s TextEdit edits one string drawn in one format. A document editor draws paragraphs of styled runs among lists, tables and pictures of its own, and wants a caret that moves through all of them as if the page were one surface. This crate is that caret. The application keeps its document and its layout; it describes each paragraph’s text as a ParagraphJob and implements Model so that an edit lands in its own document. A RichEdit turns keys, the pointer and the clipboard into Edits, and paints the selection and the caret over the application’s galleys.

A frame

1. RichEdit::input, before anything is laid out, takes this frame’s events and applies them to the model, so the layout that follows already shows what was typed.
2. Then, for every editable paragraph in document order, whether or not it is on screen: build its ParagraphJob, lay it out, allocate a response that senses clicks and drags, and hand all of it to RichEdit::paragraph, which paints it.

Offsets

A Position is a paragraph and a character offset (characters, not bytes) into the model’s text of that paragraph. What is drawn need not be that text: a tab drawn as spaces, a footnote’s citation that the model does not count, a field’s current value. ParagraphJob::atom records each such piece, and the caret steps over it whole.

Structs

Laid

A paragraph as the application laid it out and where it is on screen.

OffsetMap

Which drawn characters of a paragraph stand for which of the model’s.

ParagraphJob

A paragraph’s text as it is drawn, built piece by piece so that every drawn character is known to stand for some part of the model’s text.

Position

Where a caret can stand: a paragraph, and a character offset into the model’s text of it.

RichEdit

The editor’s state, kept by the application from one frame to the next.

Selection

A selection: where it began and where it has been taken to. The two are the same position when the selection is a caret.

Enums

Edit

A change the editor asks the model to make.

Mark

Formatting a range of text is given or has taken off. The set is fixed, so that neither the editor nor the model needs a style system to agree on.

Traits

Model

The document, as the editor sees it. The application implements this over whatever it keeps its document in.