Qt 5.6 | Qt Widgets | Custom Completer Example | textedit.cpp Example File

Qt 5.6.2 Reference Documentation

# textedit.cpp Example File

tools/customcompleter/textedit.cpp

      /****************************************************************************
      **
      ** Copyright (C) 2015 The Qt Company Ltd.
      ** Contact: http://www.qt.io/licensing/
      **
      ** This file is part of the examples of the Qt Toolkit.
      **
      ** $QT_BEGIN_LICENSE:BSD$
      ** You may use this file under the terms of the BSD license as follows:
      **
      ** "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 Qt Company Ltd 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 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
      ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
      ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
      ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
      ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
      **
      ** $QT_END_LICENSE$
      **
      ****************************************************************************/

      #include "textedit.h"
      #include <QCompleter>
      #include <QKeyEvent>
      #include <QAbstractItemView>
      #include <QtDebug>
      #include <QApplication>
      #include <QModelIndex>
      #include <QAbstractItemModel>
      #include <QScrollBar>

      TextEdit::TextEdit(QWidget *parent)
      : QTextEdit(parent), c(0)
      {
          setPlainText(tr("This TextEdit provides autocompletions for words that have more than"
                          " 3 characters. You can trigger autocompletion using ") +
                          QKeySequence("Ctrl+E").toString(QKeySequence::NativeText));
      }

      TextEdit::~TextEdit()
      {
      }

      void TextEdit::setCompleter(QCompleter *completer)
      {
          if (c)
              QObject::disconnect(c, 0, this, 0);

          c = completer;

          if (!c)
              return;

          c->setWidget(this);
          c->setCompletionMode(QCompleter::PopupCompletion);
          c->setCaseSensitivity(Qt::CaseInsensitive);
          QObject::connect(c, SIGNAL(activated(QString)),
                           this, SLOT(insertCompletion(QString)));
      }

      QCompleter *TextEdit::completer() const
      {
          return c;
      }

      void TextEdit::insertCompletion(const QString& completion)
      {
          if (c->widget() != this)
              return;
          QTextCursor tc = textCursor();
          int extra = completion.length() - c->completionPrefix().length();
          tc.movePosition(QTextCursor::Left);
          tc.movePosition(QTextCursor::EndOfWord);
          tc.insertText(completion.right(extra));
          setTextCursor(tc);
      }

      QString TextEdit::textUnderCursor() const
      {
          QTextCursor tc = textCursor();
          tc.select(QTextCursor::WordUnderCursor);
          return tc.selectedText();
      }

      void TextEdit::focusInEvent(QFocusEvent *e)
      {
          if (c)
              c->setWidget(this);
          QTextEdit::focusInEvent(e);
      }

      void TextEdit::keyPressEvent(QKeyEvent *e)
      {
          if (c && c->popup()->isVisible()) {
              // The following keys are forwarded by the completer to the widget
             switch (e->key()) {
             case Qt::Key_Enter:
             case Qt::Key_Return:
             case Qt::Key_Escape:
             case Qt::Key_Tab:
             case Qt::Key_Backtab:
                  e->ignore();
                  return; // let the completer do default behavior
             default:
                 break;
             }
          }

          bool isShortcut = ((e->modifiers() & Qt::ControlModifier) && e->key() == Qt::Key_E); // CTRL+E
          if (!c || !isShortcut) // do not process the shortcut when we have a completer
              QTextEdit::keyPressEvent(e);

          const bool ctrlOrShift = e->modifiers() & (Qt::ControlModifier | Qt::ShiftModifier);
          if (!c || (ctrlOrShift && e->text().isEmpty()))
              return;

          static QString eow("~!@#$%^&*()_+{}|:\"<>?,./;'[]\\-="); // end of word
          bool hasModifier = (e->modifiers() != Qt::NoModifier) && !ctrlOrShift;
          QString completionPrefix = textUnderCursor();

          if (!isShortcut && (hasModifier || e->text().isEmpty()|| completionPrefix.length() < 3
                            || eow.contains(e->text().right(1)))) {
              c->popup()->hide();
              return;
          }

          if (completionPrefix != c->completionPrefix()) {
              c->setCompletionPrefix(completionPrefix);
              c->popup()->setCurrentIndex(c->completionModel()->index(0, 0));
          }
          QRect cr = cursorRect();
          cr.setWidth(c->popup()->sizeHintForColumn(0)
                      + c->popup()->verticalScrollBar()->sizeHint().width());
          c->complete(cr); // popup it up!
      }