The package consists of three main classes:

• CCrystalTextBuffer class is responsible for storing lines, loading and saving text to a file. To simplify Undo/Redo command implementations, every editing operation is split into a sequence of 'insert text' and 'delete text' actions. Accordingly, CView-derived classes are only intended to react only on this primitive operations.
• CCrystalTextView class is the framework for text viewing window. It derives from CView, and it provides text painting code, overridable functions for syntax highlighting, different kinds of text selections, cursor movements, Find common dialog etc. However, it's not allowed to perform any changes to the text.
  CCrystalTextView-derived views are usually used with CCrystalTextBuffer object. Once such a view is connected to the CCrystalTextBuffer object, it is capable to track changes made to the text. (Obviously, any number of views can be connected to a single CCrystalTextBuffer object at the same time. This is useful, when we need to use the editor in the dynamic splitter as shown on the figure above).
• CCrystalEditView class is derived from CCrystalTextView class. Unlike its ansector, which is only able to display a text and update the view when it is needed, it has functions to perform all sorts of editing, including drag-and-drop and Replace dialog. Note, that the view does not make the changes in the text directly, instead, it transforms the command into a sequence of primitive operations described above, and delegates them to the CCrystalTextBuffer object. Once the changes are made, the CCrystalTextBuffer object updates all views connected to it.

class CSampleDoc : public CDocument
{
// code omitted

// Attributes
public:
    class CSampleTextBuffer : public CCrystalTextBuffer
    {
    private:
        CSampleDoc *m_pOwnerDoc;
    public:
        CSampleTextBuffer(CSampleDoc *pDoc) { m_pOwnerDoc = pDoc; };

        virtual void SetModified(BOOL bModified = TRUE)
            { m_pOwnerDoc->SetModifiedFlag(bModified); };
    };

    CSampleTextBuffer m_xTextBuffer;
};

1. Derive your class from CCrystalEditView (or CCrystalTextView).
2. Override LocateTextBuffer member function. After that, your view class declaration will look like this:

   class CSampleView : public CCrystalEditView
   {
       // code omitted
   
   protected:
       virtual CCrystalTextBuffer *LocateTextBuffer();
   }

   and the implementation will look like this:

   CCrystalTextBuffer *CSampleView::LocateTextBuffer()
   {
       CSampleDoc *pDoc = (CSampleDoc *) GetDocument();
       return &pDoc->m_xTextBuffer;
   }
   

virtual DWORD ParseLine(DWORD dwCookie, int nLineIndex,
                        TEXTBLOCK *pBuf, int &nActualItems);

struct TEXTBLOCK
{
    int  m_nCharPos;      // Offset from beginning of the line
    int  m_nColorIndex;   // Type of the block being defined: COLORINDEX_NORMALTEXT,
                          //  COLORINDEX_KEYWORD, COLORINDEX_COMMENT, etc.
};

• Extended comment (/* */) flag. This is absolutely needed because C++ has multiple-line comments.
• Continuous double-slash comment;
• Continuous preprocessor directive;
• Continuous string constant;
• Continuous character constant.

// This is the continuous double-slash comment.\
    you see, it is really continuous !
#define MESSAGE "And this is continuous preprocessor directive.\n"\
    "And this is its second line."

protected:
    virtual int GetLineCount();
    virtual int GetLineLength(int nLineIndex);
    virtual LPCTSTR GetLineChars(int nLineIndex);

int CSampleView::GetLineCount()
{
    // Please note that we must always return at least 1 line.
    // Even empty text has a single *empty* line!
    CSampleDoc *pDoc = (CSampleDoc *) GetDocument();
    return pDoc->m_strarrLines.GetSize();
}

int CSampleView::GetLineLength(int nLineIndex)
{
    CSampleDoc *pDoc = (CSampleDoc *) GetDocument();
    return pDoc->m_strarrLines[nLineIndex].GetLength();
}

LPCTSTR CSampleView::GetLineChars(int nLineIndex)
{
    CSampleDoc *pDoc = (CSampleDoc *) GetDocument();
    return pDoc->m_strarrLines[nLineIndex];
}

• Only fixed fonts are supported.
• No support for bold/italic on syntax elements (Delphi style)
• No 'word wrap'. (Since the editor was primarily designed as a code editor, is this feature really needed?)
• No support for column selection.