Author: Jonas Bilinkevicius

How to do syntax highlighting in a TRichEdit

Answer:

1   {Content of the TRichEdit for example:
2   
3   This is a test to show how to find the @ character in a rich text.
4   The @ character occurs twice in the text.
5   }
6   
7   procedure MarkFirstWord(RE: TRichEdit; TheWord: string; Color: TColor; Style:
8     TFontStyles);
9   var
10    i, CharPos, noChars: Integer;
11  begin
12    CharPos := 0;
13    noChars := 0;
14    for i := 0 to Pred(RE.Lines.Count) do
15      noChars := noChars + Length(RE.Lines[i]);
16    CharPos := RE.FindText(TheWord, CharPos, noChars, [stWholeWord]);
17    RE.SelStart := CharPos;
18    RE.SelLength := Length(TheWord);
19    RE.SelAttributes.Color := Color;
20    RE.SelAttributes.Style := Style;
21    RE.SelLength := 0;
22  end;
23  
24  procedure MarkAllWords(RE: TRichEdit; TheWord: string; Color: TColor; Style:
25    TFontStyles);
26  var
27    i, CharPos, CharPos2, noChars: Integer;
28  begin
29    CharPos := 0;
30    noChars := 0;
31    for i := 0 to Pred(RE.Lines.Count) do
32      noChars := noChars + Length(RE.Lines[i]);
33    repeat
34      CharPos2 := RE.FindText(TheWord, CharPos, noChars, [stWholeWord]);
35      CharPos := CharPos2 + 1;
36      RE.SelStart := CharPos2;
37      RE.SelLength := Length(TheWord);
38      RE.SelAttributes.Color := Color;
39      RE.SelAttributes.Style := Style;
40    until
41      charpos = 0;
42    RE.SelLength := 0;
43  end;
44  
45  procedure TForm1.Button2Click(Sender: TObject);
46  begin
47    {Will mark only the first occurance of '@' in Red}
48    MarkFirstWord(RichEdit1, '@', clRed, [fsBold]);
49    {Will mark all occurances of @ in Teal and italic}
50    MarkAllWords(RichEdit1, '@', clTeal, [fsItalic, fsBold]);
51  end;