讲述如何开发一个控件,很有价值(七)

MyRun := PasCon.GetToken(MyRun,MyTokenState,MyTokenStr);

MyRE.SelStart := MySelStart;
MyRE.SelLength := Length(MyTokenStr);

If MyRE.SelAttributes.Name <> PasCon.FParseFont[MyTokenState].Name then MyRE.SelAttributes.Name := PasCon.FParseFont[MyTokenState].Name;

If MyRE.SelAttributes.Color <> PasCon.FParseFont[MyTokenState].Color then MyRE.SelAttributes.Color := PasCon.FParseFont[MyTokenState].Color;

if MyRE.SelAttributes.Style <> PasCon.FParseFont[MyTokenState].Style then MyRE.SelAttributes.Style := PasCon.FParseFont[MyTokenState].Style;

MySelStart := MySelStart Length(MyTokenStr);

end;

MyRE.SelStart := WasSelStart;
MyRE.SelLength := 0;
MyRe.OnChange := SaveOnChangeIn;
MyRe.Enabled := True;

MyRe.SetFocus;

end;

Towards - ASH Version 1.0b

Couple of problems with the last version if you try it out for size:

1. Its slightly inefficient in that everytime SelAttributes is changed it forces a repaint of the same token in the control. We should instead use some variable (e.g var DoFormat:Boolean) to decided if we need to reformat, and then check the value of DoFormat at the end of this checking, and do it all then by a simple SelAttribute.Assign(FParseFont[MyTokenState]). This means we can also change the seperate "if" statements to a single if ... then .. else .. if ... then .. else which should code faster - especially if you put the various test situations in the order of likeliness to occur (e.g font changes less frequently than the color, so should be further down the if..else..if)
2. 
   
3. For some reason if you type a {style comment} on a line, after about 4-7 characters it reverts to different colours. I can''''t seem to work out yet why this happens - but I understand why its not being picked up. SelAttributes returns the value of the "initial" styling of the entire selected block. So if you select text which starts off black and then becomes blue, SelAttributes.Color will equal clBlack. We must also examine SelAttributes.ConsistentAttributes to ensure that the entire selection is consistent in the way it is highlighted. If it isn''''t - then we want to force it to be rehighlighted - its obviously not in the correct format.
4. 
   
5. Multi-line comments are a big pain e.g { words <CR> word <CR> words }. I don''''t have them in my 4GL so I didn''''t need to fix this sort of problem. However I do have muti-line strings - so I need to be able to string strings across many lines. The trouble is we have to code to program over a number of lines - but have a look at what happens in Delphi when you place a "{" anywhere in the code. The highlighting can force a repaint of the entire 2,000,000 lines of text in the control. We could catch that situation - ie if the last token on the line is a tsComment and it doesn''''t end in ''''}'''' we could increase SelLength until it did or we reach the end of the RichEdit.Lines. (That basically what the tokeniser does anyway with all that inc(Run).)
6. 
   

   
   
   

   That easy. But what happens if you then delete the "{"? You need to go forward 2,000,000 lines and put the highlighting back again? We could decide to keep going until the if...then..else..list didn''''t set DoFormat := True. But what happens if we''''re in a colour mode were Comment highlighting style = KeyWord highlighting style. We would stop prematurely. So this "logic" wont help in all situations.
   

7. You can still get the "someone is chasing you effect" - except now its "someone is fleeing from you" effect. It happens when you have (* This is a comment *) and delete the first *-character. The control takes an appreciable time to rehighlight the text.
8. 
   
9. While looking for a fix for the last problem, I remembered the Richedit.Lines.BeginUpdate function. But that didn''''t help either. What we need is a

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