讲述如何开发一个控件,很有价值(二)
来源：岁月联盟
编辑：exp
时间：2009-05-20
would be divided up into:
| procedure | tsKeyWord | | tsSpace | TForm1 | tsIdentifier | . | tsSymbol | FormCreate | tsIdentifier | ( | tsSymbol | Sender | tsIdentifier | : | tsSymbol | TObject | tsIdentifier | ); | tsSymbol | | tsSpace | {Create Form} | tsComment | <CR><LF> | tsCRLFHow is it Done?The RichEdit control normally loads preformatted text from .RTF files by way of by of the RichEdit.Lines.LoadFromFile() function. YourPasEdit uses the RichEdit.Lines.LoadFromStream() function to load the file from a TPasConversion - a custom TMemoryStream descendant. This stream takes the plaint text Pascal source file, loads it into its internal memory buffe, and then converts it from plain text to a text impregnated with RTF codes. This way when it is loaded into the RichEdit control via RichEdit.Lines.LoadFromStream the Pascal source file appears in the control color-syntax highlighted. To the main Editor, this process is transparent - the code looks something like this:
| begin NewRichEdit := TRichEdit.Create; PasCon.Clear; // Prepare the TPasConversion
PasCon.LoadFromFile(FName); // Load the File into the Memory Stream
PasCon.ConvertReadStream; // Convert the stream to RTF format NewRichEdit.Lines.BeginUpdate;
NewRichEdit.Lines.LoadFromStream(PasCon); // Read from the TPasConversion
NewRichEdit.Lines.EndUpdate NewRichEdit.Show; Result := NewRichEdit; end | EXAMPLE - snippet of code from the NewRichEditCreate(Fname) routine As I said, it is the TMemoryStream derived TPasConversion which does all the hard work:
<SOURCE PASCAL FILE>
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V
Plain source loaded into memory
(TPasConversion.LoadFromFile)
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V
Converted internally by parsing the source file
(ConvertReadStream)
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V
Result made available
(SetMemoryPointer)
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V
RichEdit.LoadFromStream Most of the work in TPasConversion is done by the ConvertReadStream procedure. Its purpose is to split up each line of source code into tokens (as showed previously) and then depending on its TokenType, load it into the outbuffer preceded by RTF codes to make it a particular Color, Bold, Italics etc. Here what it looks like:
| // prepare the Outbuf to a certain default size FOutBuffSize:= size+3;
ReAllocMem(FOutBuff, FOutBuffSize); // Initialise the parser to its begining state FTokenState := tsUnknown;
FComment := csNo;
FBuffPos := 0;
FReadBuff := Memory; // Write leading RTF Header WriteToBuffer({tf1ansideff0deftab720{fonttbl{f0fswiss MS SansSerif;}
{f1fromanfcharset2 Symbol;}{f2fmodern Courier New;}}+#13+#10);
WriteToBuffer({colortbled0green0lue0;}+#13+#10);
WriteToBuffer(deflang1033pardplainf2fs20 ); // Create the INSTREAM (FReadBuff) and tokenize it Result:= Read(FReadBuff^, Size);
FReadBuff[Result] := #0; if Result > 0 then
begin Run:= FReadBuff;
TokenPtr:= Run; while Run^ <> #0 do
begin Case Run^ of #13: // Deal with CRLFs
begin
FComment:= csNo;
HandleCRLF;
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