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We needed a mathematical formula editor that was able to export the content of the formulas into a programming language (FORTRAN 77 in our case). Therefore we developed a set of classes described below.

Parts of the code are based on the work of

• Chris Maunder (CGridCtrl, CColourPopup),
• Alexander Bischofberger (CColourPopup),
• Matt Weagle (CFormulaInplaceEdit),
• Norm Almond (CFontCombo),
• Shekar Narayanan and S. D. Rajan (CToolBarBtn),
• Keith Rule (CUndo)

Thanks to you for your excellent work.

General appearance

The following files and classes are included into the source code :

Core Data Structure

bintree.cpp, bintree.h	CBinTree	The binary-tree datastructure.
node.cpp, node.h	CNode	The core node datastructure.
nodeentities.cpp, nodeentities.h	see table 1)	The special node entities.
bintreeformat.cpp, bintreeformat.h	CBinTreeFormat, CFormatInfoOb	Formatting information
undo.h	CUndo	Undo/Redo functions

 

Editing and Visualizing

formuladlg.cpp, formuladlg.h, formuladlg_toolbar.cpp	CFormulaDlg	A Dialog that holds a CFormulaCtrl and toolbar-buttons supporting formula-editing. The dialog provides Callback-functions which handle the CToolBarBtn notifications
formulactrl.cpp, formulactrl.h	CFormulaCtrl	Custom control that handles keyboard- and mouse-input.
formulainplaceedit.cpp, formulainplaceedit.h	CFormulaInPlaceEdit	Inplace Edit-Control. Behaves like inplace-edit control in CGridCtrl
formuladroptarget.cpp, formuladroptarget.h	CFormulaDropTarget	The drop target for the formula-control
matrixdlg.cpp, matrixdlg.h	CMatrixDlg	A Subdialog for parametrizing matrix dimensions.
formulasettingsdialog.cpp, formulasettingsdialog.h	CFormulaSettingsDlg	Sub dialog supporting the customizing of the formula settings (eg. colours, fonts ...)

Helper classes

fontcombobox.cpp, fontcombobox.h	CFontCombo	A CComboBox derived control supporting fontselection.
colourpicker.cpp, colourpicker.h	CColourPicker	A CButton derived control supporting colour-selection.
colourpopup.cpp, colourpopup.h	CColourPopup	A CWnd derived control supporting colour-selection (used by CColourPicker).
toolbarbtn.cpp, toolbarbtn.h	CToolBarBtn	A CButton derived control supporting the bitmap-based node-entity selections.
toolbarbtnctrl.cpp, toolbarbtnctrl.h, toolbardlg.cpp, toolbardlg.h	CToolBarBtnCtrl, CToolBarDlg	used by CToolBarBtn

The basic approach of the formula-editor is the representation of mathematical content in a binary-tree data-structure. the extraction of the content is performed by an inorder-traversal through the binary tree.

Algorithm	Binary tree	Output
inorder traversal through a binary tree inorder (node) { inorder (left_child); process (this); inorder (right_child); }

The base class CNode was originally designed as an abstract base class, but it currently provides the standard behaviour of a node. (draw my left child on the left, draw my right child on the right and draw my own content into the middle). If you want to integrate a new node you have to do the following steps:

1. Define a new node-type (insert a new unique NT_* define into the node.h)
2. Declare a new node-entity in the nodeentities.h (derive it public from CNode)
class CMyNode : public CNode
3. Implement the methods
   virtual void Serialize(CArchive& ar, CBinTree* pTree);
virtual void TransformRects(CRect& ,CRect& ,CRect& ,CRect& );
virtual CRect GetContentRect(CDC* pDC);
virtual void DrawContent(CDC* pDC, CRect rect, DWORD dwSelect);
4. Insert a new button into a already present ToolbarBtn or build a new ToolbarBtn with your own node
5. Handle the ToolBarCtrlSelected Event for your node (in the FormulaDlg_ToolBar.cpp file)

Please have a look on the implementation of the already integrated nodes for further details. Here is a list of them and ther interdependencies:

 

Node class	Type	Left Child	Right Child
CNode	NT_STANDARD
CNablaNode	NT_NABLA	NULL	CIndexNode
CIndexNode	NT_INDEX	Superscript	Subscript
CPartialDerivativeNode	NT_PARTDERIVE	Derivation variable	Content of the derivation
CDerivativeNode	NT_DERIVE	Derivation variable	Content of the derivation
CPlaceHolderNode	NT_PLACEHOLDER	NULL	CIndexNode
CNthRootNode	NT_NTHROOT, NT_ROOT	Content of the root	Basis
CPowerToNode	NT_POWERTO	Basis	Exponent
CSumNode	NT_SUM	CRangeNode	Content of the Sum
CProdNode	NT_PROD	CRangeNode	Content of the Product
CRangeNode	NT_RANGE	Upper Range	Lower Range
CIntegrandNode	NT_INTEGRAND	Content of the integral	Integration variable
CLimesNode	NT_LIMES	COperatorNode	Content of the limes
CBinomialNode	NT_BINOMIAL	Upper	Lower
CMatrixNode	NT_MATRIX	CLineNode	NULL
CLineNode	NT_LINE	CLineNode	CElementNode
CElementNode	NT_ELEMENT	Content of the Matrixelement	CElementNode
CValueNode
CVariableNode	NT_VARIABLE	NULL	CIndexNode
CConstantNode	NT_CONSTANT	NULL	CIndexNode
CInfinityNode	NT_INFINITY	NULL	CIndexNode
CPlanckNode	NT_PLANCK	NULL	CIndexNode
CLambdaNode	NT_LAMBDA	NULL	CIndexNode
CNumberNode	NT_NUMBER	NULL	CIndexNode
CTypedNode
CFunctionNode
CUserFuncNode	NT_USERFUNCTION	CBraceNode	NULL
CFuncNode	NT_FUNC	CBraceNode	NULL
CExtFuncNode	NT_EXTFUNC	CBraceNode	NULL
COpNode
CDivisionNode	NT_DIVISION	Left hand side	Right hand side
CEquationNode	NT_EQUATION	Left hand side	Right hand side
COperatorNode	NT_OPERATOR	Left hand side	Right hand side
CBraceNode	NT_BRACE	Content of the brace	NULL
CPoisonNode	NT_POISON	*	*
CVectorNode	NT_VECTOR	Content of the Vector	NULL
CIntegralNode	NT_INTEGRAL	CRangeNode	CIntegrandNode
COverlineNode	NT_OVERLINE	*	*
CArrowNode	NT_ARROWS	Left hand side	Right hand side
CPlusNode	NT_PLUS	Left hand side	Right hand side
CMinusNode	NT_MINUS	Left hand side	Right hand side
CTimesNode	NT_TIMES	Left hand side	Right hand side
CCrossNode	NT_CROSS	Left hand side	Right hand side

table 1) List of already integrated nodes and their dependecies

Please see the implemented TransformRect and DrawContent methods as an example! There are a lot of ways to code them much better. Any suggestions and refinements are welcome.

If you want to use this code in your project you only have to import the classes and to call the DoModal-method of the FormulaDlg.Please be careful with the resources. The resources for the toolbar of the formula-dialog are included via compiletime-directives (resource includes-submenu in the view -menu of the developer-studio)

#include "mathsym.h"
#include "mathsym.rc"

#include "FormulaDlg.h"

void CMainFrame::OnFormula() 
{
    CFormulaDlg FormulaDlg;
    FormulaDlg.DoModal();
}

The core-classes with there attributes and methods look as follow:

CBinTree

CNode* m_pRootNode	The rootnode of the tree.
CNode* m_pSelectNode	The selected node.
DWORD m_dwSelectType	The node-selection type (one of NS_*, see node.h).
CString m_strName	The name of the tree.
CNode* CreateTree(CString strType)	Creates a tree with a root node of type strType.
CNode* GetRootNode()	Returns the root node.
void SetRootNode(CNode* pNode)	Sets the root node.
void SetName(CString)	Sets the Name of the Bintree.
CString GetName()	Returns the name of the Bintree.
void SelectNode(CNode* pNode, DWORD dwSelectType)	Selects the node pNode with nodeselectiontype dwSelectType.
CNode* GetSelectedNode()	Returns the selected node.
void SetNodeSelectionType(DWORD dwSelectType)	Sets the nodeselectiontype for the tree.
void GetNodeSelectionType(DWORD dwSelectType)	Returns the nodeselectiontype for the tree.
void ResetTree()	Resets the tree and delete all nodes.
CNode* GetParent(CNode* pNode)	Returns the parent of node pNode.
CNode* CreateNode(CString strType)	Creates a node of type strType.
CNode* ReplaceNode(CNode*, CString) void ReplaceNode(CNode*, CNode*) CNode* ReplaceSubTree(CNode*, CString) CNode* InsertNode(CNode*, CNode*, CString, DWORD )	Some handy functions for rearrangement of the tree.
void DrawTree(CDC* pDC, CRect rect)	Draws the tree on a dc.
CRect GetRect(CDC* pDC)	Returns the destination-rect of the tree.
CNode* GetNodeFromPoint(CDC*, CRect&, CPoint)	Returns a node that draws itself into a rect (resultRect) that contains point.
void ReformatNodes(CBinTreeFormat* pFormat=NULL)	Reformat the tree with a special formatter.
void SortPreOrder(CNode* pOldNode) CNode* SwapLeftChildNode(CNode*, CNode*) CNode* SwapRightChildNode(CNode*, CNode*)	Sorting the tree in associative order (currently not used).
BOOL WriteDIB(CString strFile)	Writes the binary-tree content into a dib.
BOOL PrintDDB(CDC* pDC)	Prints the binary-tree content into a DC.
CString CBinTree::WriteFormula(int nLanguageType)	Write the binary-tree content into a CString.
virtual void DeleteContents()	Resets the tree and delete all nodes (from CUndo).
void DeleteNode(CNode* pNode)	Deletes a node.
CNode* CloneNode(CNode* pNode, BOOLbCloneSubTree)	Clones a node with or without its subtree.

 

CNode

CNode* m_pParent	Pointer to parent.
CNode* m_pLeftChild	Pointer to left child.
CNode* m_pRightChild	Pointer to right child.
int m_nAssociativityLevel	assoicativity level for mathematical analysis
DWORD m_dwEditMode	edit mode of the node (one of the NE_* defines)
int m_nSubLevel	sublevel (subscript, sub-subscript ...)
int m_nSubLevelLeftInc int m_nSubLevelRightInc	the increments of the sublevel for the children
CString m_strNodeType	node type (one of the NT_* defines)
CString m_strShortCut	the shortcut of the node (sin for sinus)
CString m_strName	the name of the node (sinus for sinus)
COLORREF m_crColor	color of the node (modified by the formatter class)
LOGFONT m_lf	LOGFONT node (modified by the formatter class)
CStringArray m_saKeyWord	Keywords are stored in a Stringarray (Use the define LT_* to access)
CRect m_NodeRect	the destination rectangle for the ouput
int m_nBaseLine	the baseline of the node (with childs ) // e.g. the division line for the CDivisionNode
CString GetNodeType()	Returns the node type
void SetParentDirect(CNode* pNode)	Sets the parent node directly
CNode* GetParentDirect()	Returns the parent node
void SetLeftChild(CNode* pNode)	Sets the left child (and sets left child's new parent as this)
CNode* GetLeftChild()	Returns the left child
void SetRightChild(CNode* pNode)	Sets the right child (and sets right child's new parent as this)
CNode* GetRightChild()	Returns the right child
void SetName(CString strName)	Sets the name of the node
CString GetName()	Returns the name of the node
void SetShortCut(CString strShortCut)	Sets the shortcut of the node (used for rendering)
<CODE><CODE>CString GetShortCut()	Returns the shortcut of the node
void SetEditMode(DWORD dwEditMode)	Sets the edit mode of the node (Combination of NE_ defines)
DWORD GetEditMode()	Returns the edit mode of the node
void SetItalic(BOOL bItalic)	Sets the italic attribute in the LOGFONT structure
BOOL GetItalic()	Returns the italic attribute in the LOGFONT structure
void SetBold(BOOL bBold)	Sets the lfWeight-value of the LOGFONT structure (FW_BOLD for bBold==TRUE and FW_NORMAL for bBold==FALSE)
BOOL GetBold()	Returns the weight of LOGFONT structure (TRUE for lfWeight==FW_BOLD and FALSE for bBold==FW_NORMAL)
void SetColor(COLORREF crColor)	Sets the RGB colour of the node
COLORREF GetColor()	Returns the RGB colour of the node
void SetSubLevel(int nSubLevel)	Sets the sublevel of the node
int GetSubLevel()	Returns the sublevel of the node
int GetSubLevelLeftInc()	Returns the sublevel-increment of the left children
int GetSubLevelRightInc()	Returns the sublevel-increment of the right children
void SetFaceName(CString strFaceName)	Sets the facename in the LOGFONT structure
CString GetFaceName()	Returns the facename of the LOGFONT structure as a CString
virtual int GetAssociativityLevel()	Returns the Associativity Level of the node (for symbolical postprocessing, currently not used)
virtual BOOL IsNodeLeaf()	Returns TRUE if the node has no valid left and right child
virtual void DrawNode(CDC*, CRect&,                       CNode*, DWORD) virtual CNode* GetNodeFromPoint(CDC*, CRect&,                                  CPoint) virtual void FormatNode(                     CBinTreeFormat* pFormat=NULL) virtual CRect GetRect(CDC* pDC)	drawing functions
CNode* FindParentPraeorder(CNode* pSearchNode)	searching praeorder for the parent of a given node
virtual void Serialize(CArchive& ar,                        CBinTree* pTree)	function to overload by subentities
virtual void TransformRects(CRect&, CRect&,                             CRect&, CRect&) virtual CRect GetContentRect(CDC* pDC) virtual void DrawContent(CDC*, CRect, DWORD)	standardimplementation (default behaviour)
virtual CString WriteNode(int nLanguageType)	Output of the formula in the language LT_*
LOGFONT* GetLogFont()	Returns a pointer to the LOGFONT structure m_lf

 

Features

The formula-control has got the following additional features:

• Copy, cut and paste (currently you are allowed to paste into placeholder-nodes only )
• Drag & Drop (currently you are allowed to drop onto placeholder-nodes only)
• Export into a Bitmap
• Printing and Print-Preview is realized via DDB
• Source code export (currently only FORTRAN 77 is implemented)

How to use...

Select an equation-node from the equation-toolbar-button. Then you get an equation with placeholders on the left and on the right side. By moving the mouse over the equation the nodes are highlited. Select a placeholder with a single left-mouseclick. Now you can overwrite the placeholder with any node you want. By selecting a node with a double-click, the whole subtree of the node is selcted (e.g select the = from an equation with a doubleclick and either the left and the right side of the equation are selected). If you select a variable-node, a constant-node, a number-node or a userfunction-node you get into the editing by another left-mouseclick.

History

for detailed information please have a look on the file-header-comments
Version 1.0.0.1 - 15-Apr-2003

• Reduced Flickering (Scrolling and Updating)
• Drag&Drop refined
• Modified FormulaInPlaceEdit
• Added WMF export
• CRangeNode refined

Version 1.0.0.0 - 09-Apr-2003
First Version

Environment:
Windows NT 4.0 Service Pack 6
MFC Version: 6.0
Service Pack: 5