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Simple keyboard string editing         A small class to take key presses and edit a string

This code snippet was originally created as a part of an in-game console. All it does is take key press events and either adds them to a string or otherwise manipulates it. This string can be retrieved at any time. It is currently setup for the use with OIS, however this could be easily changed.

Usage:

Define an instance any way you like:

EditString myEdit;

In an OIS keyboard listener:

if( myEdit.injectKeyPress( arg ) == false )
{
  // Did not use the key.
  ...
}
else
{
  // Used the key so the string has possibly changed.
  myTextBoxOverlayElement->SetCaption( myEdit.getText() );
  ...
  // Display cursor somehow.  Left as an exercise for the reader as 
  // I havn't figured out how I'm going to do it yet. :)
}

The Code


EditString.h

#pragma once
 
#include <string>
 
#define OIS_DYNAMIC_LIB
#include <OIS/OIS.h>
 
class EditString
{
public:
  EditString(void) : mInsert(true), mPosition(mText.begin()), mCaret(0)
  {}
     
  EditString( std::string newText )
  {
    setText( newText );
  }
     
  ~EditString(void)
  {}
 
protected:
  // The text for editing
  std::string mText;
     
  // Overwrite or insert
  bool mInsert;
 
  // Position for insert / overwrite
  std::string::iterator mPosition;
 
  // Caret Position - for positioning the cursor.
  int mCaret;
 
public:
  void setText( std::string & newText ) 
  { 
    mText = newText;
    mPosition = mText.end();
    mCaret = (int)mText.length();
  }

  std::string & getText() { return mText; }
 
  void clear()
  {
    mText.clear()
    mPosition = mText.end();
    mCaret = 0;
  }
 
  bool inserting() { return mInsert; }
 
  bool injectKeyPress( const OIS::KeyEvent );
 
  // gets the current position in the text for cursor placement
  int getPosition(void) { return mCaret; }
};

EditString.cpp


#include "editstring.h"
 
// Process a key press.  Return true if it was used.
 
bool EditString::injectKeyPress( const OIS::KeyEvent arg )
{
  bool keyUsed = true;
 
  if( isgraph( arg.text ) || isspace( arg.text ) )
  {
    if( mInsert || mPosition == mText.end() )
    {
      mPosition = mText.insert( mPosition, arg.text );
    }
    else
    {
      *mPosition = arg.text;
    }
    mPosition++;
    mCaret++;        
  }
  else
  {
    switch( arg.key )
    {
      case OIS::KC_BACK:
        if( mPosition != mText.begin() )
        {
          mPosition = mText.erase( --mPosition );
          --mCaret;
        }
        break;
 
      case OIS::KC_INSERT:
        mInsert = ! mInsert;
        break;
 
      case OIS::KC_HOME:
        mPosition = mText.begin();
        mCaret = 0;
        break;
 
      case OIS::KC_END:
        mPosition = mText.end();
        mCaret = (int)mText.length();
        break;
 
      case OIS::KC_LEFT:
        if( mPosition != mText.begin() )
        {
          mPosition--;
          mCaret--;
        }
        break;
 
      case OIS::KC_RIGHT:
        if( mPosition != mText.end() )
        {
          mPosition++;
          mCaret++;
        }
        break;
 
      case OIS::KC_DELETE:
        if( mPosition != mText.end() )
          mPosition = mText.erase( mPosition );
        break;
 
      default:
        keyUsed = false;
        break;
    }
  }
 
  return keyUsed;
}