Improve QtConcurrent ImageScaling example to demo new features

In order to demonstrate the new functionality, changed the example to
download the images from the network, scale and show them by attaching
different continuations to QFuture. Because QtConcurrent::map is not
used anymore, removed the suspension functionality (supporting
suspension of download would complicate the logic).

Task-number: QTBUG-87205
Change-Id: I5a48b63195d28025ae8c5de28bc6d6178dad03db
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

1 files changed, 87 insertions, 0 deletions

diff --git a/examples/qtconcurrent/imagescaling/downloaddialog.cpp b/examples/qtconcurrent/imagescaling/downloaddialog.cpp
new file mode 100644
index 0000000000..2f2f901b0e
--- /dev/null
+++ b/examples/qtconcurrent/imagescaling/downloaddialog.cpp
@@ -0,0 +1,87 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#include "downloaddialog.h"
+#include "ui_downloaddialog.h"
+
+#include <QUrl>
+
+DownloadDialog::DownloadDialog(QWidget *parent) : QDialog(parent), ui(new Ui::DownloadDialog)
+{
+    ui->setupUi(this);
+
+    ui->urlLineEdit->setPlaceholderText(tr("Enter the URL of an image to download"));
+
+    connect(ui->addUrlButton, &QPushButton::clicked, this, [this] {
+        const auto text = ui->urlLineEdit->text();
+        if (!text.isEmpty()) {
+            ui->urlListWidget->addItem(text);
+            ui->urlLineEdit->clear();
+        }
+    });
+    connect(ui->urlListWidget, &QListWidget::itemSelectionChanged, this, [this] {
+        ui->removeUrlButton->setEnabled(!ui->urlListWidget->selectedItems().empty());
+    });
+    connect(ui->clearUrlsButton, &QPushButton::clicked, ui->urlListWidget, &QListWidget::clear);
+    connect(ui->removeUrlButton, &QPushButton::clicked, this,
+            [this] { qDeleteAll(ui->urlListWidget->selectedItems()); });
+}
+
+DownloadDialog::~DownloadDialog()
+{
+    delete ui;
+}
+
+QList<QUrl> DownloadDialog::getUrls() const
+{
+    QList<QUrl> urls;
+    for (auto row = 0; row < ui->urlListWidget->count(); ++row)
+        urls.push_back(QUrl(ui->urlListWidget->item(row)->text()));
+    return urls;
+}