chatdialog.cpp Example File

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 #include <QtWidgets>

 #include "chatdialog.h"

 ChatDialog::ChatDialog(QWidget *parent)
     : QDialog(parent)
 {
     setupUi(this);

     lineEdit->setFocusPolicy(Qt::StrongFocus);
     textEdit->setFocusPolicy(Qt::NoFocus);
     textEdit->setReadOnly(true);
     listWidget->setFocusPolicy(Qt::NoFocus);

     connect(lineEdit, SIGNAL(returnPressed()), this, SLOT(returnPressed()));
     connect(lineEdit, SIGNAL(returnPressed()), this, SLOT(returnPressed()));
     connect(&client, SIGNAL(newMessage(QString,QString)),
             this, SLOT(appendMessage(QString,QString)));
     connect(&client, SIGNAL(newParticipant(QString)),
             this, SLOT(newParticipant(QString)));
     connect(&client, SIGNAL(participantLeft(QString)),
             this, SLOT(participantLeft(QString)));

     myNickName = client.nickName();
     newParticipant(myNickName);
     tableFormat.setBorder(0);
     QTimer::singleShot(10 * 1000, this, SLOT(showInformation()));
 }

 void ChatDialog::appendMessage(const QString &from, const QString &message)
 {
     if (from.isEmpty() || message.isEmpty())
         return;

     QTextCursor cursor(textEdit->textCursor());
     cursor.movePosition(QTextCursor::End);
     QTextTable *table = cursor.insertTable(1, 2, tableFormat);
     table->cellAt(0, 0).firstCursorPosition().insertText('<' + from + "> ");
     table->cellAt(0, 1).firstCursorPosition().insertText(message);
     QScrollBar *bar = textEdit->verticalScrollBar();
     bar->setValue(bar->maximum());
 }

 void ChatDialog::returnPressed()
 {
     QString text = lineEdit->text();
     if (text.isEmpty())
         return;

     if (text.startsWith(QChar('/'))) {
         QColor color = textEdit->textColor();
         textEdit->setTextColor(Qt::red);
         textEdit->append(tr("! Unknown command: %1")
                          .arg(text.left(text.indexOf(' '))));
         textEdit->setTextColor(color);
     } else {
         client.sendMessage(text);
         appendMessage(myNickName, text);
     }

     lineEdit->clear();
 }

 void ChatDialog::newParticipant(const QString &nick)
 {
     if (nick.isEmpty())
         return;

     QColor color = textEdit->textColor();
     textEdit->setTextColor(Qt::gray);
     textEdit->append(tr("* %1 has joined").arg(nick));
     textEdit->setTextColor(color);
     listWidget->addItem(nick);
 }

 void ChatDialog::participantLeft(const QString &nick)
 {
     if (nick.isEmpty())
         return;

     QList<QListWidgetItem *> items = listWidget->findItems(nick,
                                                            Qt::MatchExactly);
     if (items.isEmpty())
         return;

     delete items.at(0);
     QColor color = textEdit->textColor();
     textEdit->setTextColor(Qt::gray);
     textEdit->append(tr("* %1 has left").arg(nick));
     textEdit->setTextColor(color);
 }

 void ChatDialog::showInformation()
 {
     if (listWidget->count() == 1) {
         QMessageBox::information(this, tr("Chat"),
                                  tr("Launch several instances of this "
                                     "program on your local network and "
                                     "start chatting!"));
     }
 }