Autocomplection in RichEdit Control

• Download source files - 6 Kb
• Download demo project - 26 Kb

CAutocomplectionCtrl is a control designed to add the auto completion feature in a CRichEditCtrl. You can easily modify the code to add the auto completion feature in a CRichEditView.

You can specify options such as displaying all known words or only the matching ones.

User can start the auto completion feature pressing Ctrl+space; he can confirm the selected word pressing space, Enter or a non-alpha char; he can use up, down, pgUp, pgDown, home, end, Ctrl+Space or mouse-wheel to switch between the words in the list; he can use left, right to modify the matching part of the word.

Using the control

Using ClassWizard add a variable in your dialog class; the variable must be a CAutocomplectionCtrl control; if the ClassWizard displays only CRichEdit select it, and change it to CAutocomplectionCtrl in the .h file.

Remember to include "Autocomplection.h" in your .h file and to insert the line

AfxInitRichEdit();

in the Initinstance() function of your application.

Then you must define your dictionary using the AddKeyword() funcion; usually you'll do that in the OnInitDialog function. In the sample application I read the words from a file, so resulting code is:

while (file.ReadString(keyword))
	m_edit.AddKeyword(keyword);

Well, your work is done :)

If you like you can specify some options...

Option functions

void Enable(BOOL);

You can enable or disable the auto completion feature; by default it's enabled.

void ShowListBox(BOOL);

You can select if to display the listbox or not

void ListAllWords(BOOL);

You can select if to display in the listbox all known words, or only the matching ones

void TrapEnter(BOOL);

Pressing Enter, the selected word is confirmed.

If TrapEnter is set to FALSE, when pressing Enter, the control will add a new line char, if TrapEnter is set to TRUE, the new line char will not be displayed

void CaseSensitive(BOOL);

You can select if the matching function must be case sensitive or not.

void AutoLearn(BOOL);

That feature isn't very useful; if enabled, when the user types an unknown word, the control will add it to the dictionary; that could be nice if the user never mistakes typing words...

void LearnOnDblClick(BOOL);

If this feature is enabled, when the user double-clicks over a word, the control learns it.

Dictionary functions

void GetDictionary(CStringArray& dictionary);

This function fills the given CStringArray with all known words.

void ResetDictionary();

This function empties the dictionary.

BOOL AddKeyword(const CString& str);

This function adds the specified word in the dictionary.

BOOL IsKeyword(const CString& str);

This function checks if the specified word is in the dictionary.

Developing notes

Search

I chose to insert word in alphabetic order and to find them using a binary search, so the search function is O(log(n)).

Case sense

Word matching can be case sensitive or not case sensitive. Instead of checking anytime or duplicate the code I decided to use function pointers...

Word recognition

Word recognition is done looking for the left-nearest "space" character. You can easily change your word recognition modifying the line

while (from && buffer[from]!=' ')

while (from && buffer[from]!=' ' && buffer[from]!='(' && buffer[from]!='=')

Further improvements (aka TODO)

You could like to display an icon near the word (yes, like Visual Studio)... so you should replace the CArrayString with an array class and a class containing the string and an ID specifying the icon.

Sometimes (when there are many matching words) filling CListBox is slow. It could be useful to replace the CListBox with a faster one (maybe a owner data listbox...)

History

12 July 2002 - First public release

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here