textfinder.cpp Example File

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 #include "textfinder.h"
 #include <QFile>
 #include <QLineEdit>
 #include <QMessageBox>
 #include <QPushButton>
 #include <QTextEdit>
 #include <QTextStream>
 #include <QUiLoader>
 #include <QVBoxLayout>

 static QWidget *loadUiFile(QWidget *parent)
 {
     QFile file(":/forms/textfinder.ui");
     file.open(QIODevice::ReadOnly);

     QUiLoader loader;
     return loader.load(&file, parent);
 }

 static QString loadTextFile()
 {
     QFile inputFile(":/forms/input.txt");
     inputFile.open(QIODevice::ReadOnly);
     QTextStream in(&inputFile);
     in.setCodec("UTF-8");
     return in.readAll();
 }

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

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

     QMetaObject::connectSlotsByName(this);

     ui_textEdit->setText(loadTextFile());

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

     setWindowTitle(tr("Text Finder"));
 }

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

     bool found = false;

     // undo previous change (if any)
     document->undo();

     if (searchString.isEmpty()) {
         QMessageBox::information(this, tr("Empty Search Field"),
                                  tr("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();

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