textfinder.cpp Example File

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 #include <QtUiTools>
 #include <QtGui>
 #include "textfinder.h"

 TextFinder::TextFinder(QWidget *parent)
     : QWidget(parent)
 {
     QWidget *formWidget = loadUiFile();

     ui_findButton = findChild<QPushButton*>("findButton");
     ui_textEdit = findChild<QTextEdit*>("textEdit");
     ui_lineEdit = findChild<QLineEdit*>("lineEdit");

     QMetaObject::connectSlotsByName(this);

     loadTextFile();

     QVBoxLayout *layout = new QVBoxLayout;
     layout->addWidget(formWidget);
     setLayout(layout);

     setWindowTitle(tr("Text Finder"));
     isFirstTime = true;
 }

 QWidget* TextFinder::loadUiFile()
 {
     QUiLoader loader;

     QFile file(":/forms/textfinder.ui");
     file.open(QFile::ReadOnly);

     QWidget *formWidget = loader.load(&file, this);
     file.close();

     return formWidget;
 }

 void TextFinder::loadTextFile()
 {
     QFile inputFile(":/forms/input.txt");
     inputFile.open(QIODevice::ReadOnly);
     QTextStream in(&inputFile);
     QString line = in.readAll();
     inputFile.close();

     ui_textEdit->append(line);
     ui_textEdit->setUndoRedoEnabled(false);
     ui_textEdit->setUndoRedoEnabled(true);
 }

 void TextFinder::on_findButton_clicked()
 {
     QString searchString = ui_lineEdit->text();
     QTextDocument *document = ui_textEdit->document();

     bool found = false;

     if (isFirstTime == false)
         document->undo();

     if (searchString.isEmpty()) {
         QMessageBox::information(this, tr("Empty Search Field"),
                 "The search field is empty. Please enter a word and click Find.");
     } else {

         QTextCursor highlightCursor(document);
         QTextCursor cursor(document);

         cursor.beginEditBlock();

         QTextCharFormat plainFormat(highlightCursor.charFormat());
         QTextCharFormat colorFormat = plainFormat;
         colorFormat.setForeground(Qt::red);

         while (!highlightCursor.isNull() && !highlightCursor.atEnd()) {
             highlightCursor = document->find(searchString, highlightCursor, QTextDocument::FindWholeWords);

             if (!highlightCursor.isNull()) {
                 found = true;
                 highlightCursor.movePosition(QTextCursor::WordRight,
                                        QTextCursor::KeepAnchor);
                 highlightCursor.mergeCharFormat(colorFormat);
             }
         }

         cursor.endEditBlock();
         isFirstTime = false;

         if (found == false) {
             QMessageBox::information(this, tr("Word Not Found"),
                 "Sorry, the word cannot be found.");
         }
     }
 }