Using a Highlighter

A highlighter is a component (derived from TSynCustomHighlighter) that splits the text in tokens (keywords, comments, strings, numbers...) and gives each kind of token a set of attributes (foreground color, background color, font style).

At design time

1. Drop a TSynEdit on the form.
2. Drop a highlighter from the SynEdit Highlighters page, for example TSynPasSyn.
3. Assign it to the Highlighter property of the editor.

At run time

uses
  SynEdit.Core, SynEdit.Highlighter.Pas;

SynEdit1.Highlighter := TSynPasSyn.Create(Self);

The same highlighter can be assigned to more editors. A highlighter must live at least as long as the editors that use it.

Choosing the highlighter from the file name

Every highlighter has a DefaultFilter (for example Pascal Files (*.pas;*.pp;*.dpr;*.dpk;*.inc)|*.pas;*.pp;*.dpr;*.dpk;*.inc). The demos use it to pick the highlighter of a file from its extension: see the unit uHighlighterProcs in the Demos folder, that also builds the filter of the open and save dialogs.

Attributes

Each highlighter publishes its attributes as properties: CommentAttri, KeyAttri, StringAttri, NumberAttri, IdentifierAttri, SpaceAttri, SymbolAttri and the specific ones of the language. Each attribute has Foreground, Background and Style (a set of fsBold, fsItalic, fsUnderline, fsStrikeOut):

SynPasSyn1.KeyAttri.Foreground := clNavy;
SynPasSyn1.KeyAttri.Style := [fsBold];
SynPasSyn1.CommentAttri.Style := [fsItalic];

The dialog of the unit SynEdit.FHighlightProp lets the user edit the attributes of a highlighter with a preview: see Options Dialog.

Highlighter options

TSynEditHighlighterOptions (unit SynEdit.HighlighterOptions, Options property of the highlighters) describes the language: Title, DefaultExtension, LineCommentarStart, LineCommentarEnd, Visible and the auto-detection of the language from the content (AutoDetectEnabled, AutoDetectLineLimit, AutoDetectMatchExpression). It is useful to build a menu of the languages or to comment and uncomment the lines.

Highlighters and code folding

The highlighters derived from TSynCustomCodeFoldingHighlighter provide the ranges of the code folding.

Available highlighters

See Available Highlighters.