DownloaderGui.cpp

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// ======================================================================
//  DownloaderGui.cpp
// ======================================================================
//                   This file is a part of the book 
//             "Qt 5.10 Professional programming with C++"
//                       http://qt-book.com
// ======================================================================
//  Copyright (c) 2017 by Max Schlee
// ======================================================================

#include <QtWidgets>
#include "Downloader.h"
#include "DownloaderGui.h"

// ----------------------------------------------------------------------
DownloaderGui::DownloaderGui(QWidget* pwgt /*=0*/) : QWidget(pwgt)
{ 
    m_pdl  = new Downloader(this);
    m_ppb  = new QProgressBar;
    m_ptxt = new QLineEdit;
    m_pcmd = new QPushButton(tr("&Go"));

    QString strDownloadLink = "http://qt-book.com/pic.jpg";
    m_ptxt->setText(strDownloadLink);
    
    connect(m_pcmd, SIGNAL(clicked()), SLOT(slotGo()));
    connect(m_pdl, SIGNAL(downloadProgress(qint64, qint64)),  
            this,  SLOT(slotDownloadProgress(qint64, qint64)) 
           );
    connect(m_pdl, SIGNAL(done(const QUrl&, const QByteArray&)),  
            this,  SLOT(slotDone(const QUrl&, const QByteArray&)) 
           );

    QGridLayout* pLayout = new QGridLayout;
    pLayout->addWidget(m_ptxt, 0, 0);
    pLayout->addWidget(m_pcmd, 0, 1);
    pLayout->addWidget(m_ppb, 1, 0, 1, 1);
    setLayout(pLayout);
}

// ----------------------------------------------------------------------
void DownloaderGui::slotGo()
{
    m_pdl->download(QUrl(m_ptxt->text()));
}

// ----------------------------------------------------------------------
void DownloaderGui::slotDownloadProgress(qint64 nReceived, qint64 nTotal)
{
    if (nTotal <= 0) {
        slotError();
        return;
    }
    m_ppb->setValue(100 * nReceived / nTotal);
}

// ----------------------------------------------------------------------
void DownloaderGui::slotDone(const QUrl& url, const QByteArray& ba)
{
    QString strFileName = 
      QStandardPaths::writableLocation(QStandardPaths::PicturesLocation)
      + "/" + url.path().section('/', -1);
    QFile file(strFileName);
    if (file.open(QIODevice::WriteOnly)) {
        file.write(ba);
        file.close();

        if (strFileName.endsWith(".jpg") 
            || strFileName.endsWith(".png") 
           ) {
            showPic(strFileName);
        }
    }
}

// ----------------------------------------------------------------------
void DownloaderGui::showPic(const QString& strFileName)
{
    QPixmap pix(strFileName);
    pix = pix.scaled(pix.size() / 2, 
                     Qt::IgnoreAspectRatio, 
                     Qt::SmoothTransformation
                    );
    QLabel* plbl = new QLabel;
    plbl->setPixmap(pix);
    plbl->setFixedSize(pix.size());
    plbl->show();
}

// ----------------------------------------------------------------------
void DownloaderGui::slotError()
{
    QMessageBox::critical(0, 
                          tr("Error"), 
                          tr("An error while download is occured")
                         );
}