editable_combo_box.cpp

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/*
 * Copyright (c) 2012, Willow Garage, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Willow Garage, Inc. nor the names of its
 *       contributors may be used to endorse or promote products derived from
 *       this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 */

#include <stdio.h>

#include <QCompleter>
#include <QKeyEvent>
#include <QLineEdit>

#include "rviz/properties/editable_combo_box.h"

namespace rviz
{

EditableComboBox::EditableComboBox( QWidget* parent )
  : ComboBox( parent )
{
  setEditable( true );
  completer()->setCompletionMode( QCompleter::PopupCompletion );
  completer()->setCaseSensitivity( Qt::CaseInsensitive );
}

QString findMaxCommonPrefix( const QStringList& strings )
{
  if( strings.size() == 0 )
  {
    return "";
  }
  if( strings.size() == 1 )
  {
    return strings[ 0 ];
  }
  QString common_prefix;
  int char_index = 0;

  // loop over character index
  while( true )
  {
    if( char_index >= strings[ 0 ].size() )
    {
      return common_prefix;
    }
    const QChar c = strings[ 0 ][ char_index ];

    // loop over strings
    for( int string_index = 1; string_index < strings.size(); string_index++ )
    {
      const QString& str = strings[ string_index ];
      if( char_index >= str.size() ||
          str[ char_index ] != c )
      {
        return common_prefix;
      }
    }
    common_prefix += c;
    char_index++;
  }
  return ""; // just to satisfy compiler... I know it will never reach this.
}

bool EditableComboBox::event( QEvent* event )
{
  if( event->type() == QEvent::KeyPress )
  {                                                                                                          
    QKeyEvent* k = (QKeyEvent*) event;
    if( k->key() == Qt::Key_Tab && k->modifiers() == Qt::NoModifier )
    {
      QCompleter* comp = completer();

      QStringList completions;
      for( int i = 0; comp->setCurrentRow( i ); i++ )
      {
        completions.push_back( comp->currentCompletion() );
      }
      QString max_common_prefix = findMaxCommonPrefix( completions );
      if( max_common_prefix.size() > currentText().size() )
      {
        setEditText( max_common_prefix );
        lineEdit()->setCursorPosition( max_common_prefix.size() );
      }

      event->accept();
      return true;
    }
  }
  return ComboBox::event( event );
}

} // end namespace rviz