qtbase-opensource-src/examples/network/network-chat/chatdialog.cpp

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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, &QLineEdit::returnPressed,
            this, &ChatDialog::returnPressed);
    connect(&client, &Client::newMessage,
            this, &ChatDialog::appendMessage);
    connect(&client, &Client::newParticipant,
            this, &ChatDialog::newParticipant);
    connect(&client, &Client::participantLeft,
            this, &ChatDialog::participantLeft);

    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!"));
    }
}