Polish DnD Examples.

- Remove class DragLabel in draggabletext and add a static creation
  function instead since it only has a constructor setting some
  properties.
- Use QRegularExpression instead of QRegExp
- Use new connection syntax.
- Ensure compilation with
  DEFINES += QT_NO_CAST_TO_ASCII QT_NO_CAST_FROM_ASCII
  demonstrating use of QLatin1String vs QStringLiteral.
- Streamline code.

Change-Id: I2e2ddeb40837dba379990836c77fb72ad7263e2d
Reviewed-by: Oliver Wolff <oliver.wolff@theqtcompany.com>

4 files changed, 25 insertions, 133 deletions

diff --git a/examples/widgets/draganddrop/draggabletext/draggabletext.pro b/examples/widgets/draganddrop/draggabletext/draggabletext.pro
index 2815be1613..1add2a270e 100644
--- a/examples/widgets/draganddrop/draggabletext/draggabletext.pro
+++ b/examples/widgets/draganddrop/draggabletext/draggabletext.pro
@@ -1,10 +1,8 @@
 QT += widgets
 
-HEADERS     = draglabel.h \
-              dragwidget.h
+HEADERS     = dragwidget.h
 RESOURCES   = draggabletext.qrc
-SOURCES     = draglabel.cpp \
-              dragwidget.cpp \
+SOURCES     = dragwidget.cpp \
               main.cpp
 
 # install
diff --git a/examples/widgets/draganddrop/draggabletext/draglabel.cpp b/examples/widgets/draganddrop/draggabletext/draglabel.cpp
deleted file mode 100644
index 4e741fb6c8..0000000000
--- a/examples/widgets/draganddrop/draggabletext/draglabel.cpp
+++ /dev/null
@@ -1,49 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2015 The Qt Company Ltd.
-** Contact: http://www.qt.io/licensing/
-**
-** This file is part of the examples of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:BSD$
-** 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 "draglabel.h"
-
-DragLabel::DragLabel(const QString &text, QWidget *parent)
-    : QLabel(text, parent)
-{
-    setAutoFillBackground(true);
-    setFrameShape(QFrame::Panel);
-    setFrameShadow(QFrame::Raised);
-}
diff --git a/examples/widgets/draganddrop/draggabletext/draglabel.h b/examples/widgets/draganddrop/draggabletext/draglabel.h
deleted file mode 100644
index 8d2c31aa1d..0000000000
--- a/examples/widgets/draganddrop/draggabletext/draglabel.h
+++ /dev/null
@@ -1,58 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2015 The Qt Company Ltd.
-** Contact: http://www.qt.io/licensing/
-**
-** This file is part of the examples of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:BSD$
-** 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."
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef DRAGLABEL_H
-#define DRAGLABEL_H
-
-#include <QLabel>
-
-QT_BEGIN_NAMESPACE
-class QDragEnterEvent;
-class QDragMoveEvent;
-class QFrame;
-QT_END_NAMESPACE
-
-class DragLabel : public QLabel
-{
-public:
-    DragLabel(const QString &text, QWidget *parent);
-};
-
-#endif // DRAGLABEL_H
diff --git a/examples/widgets/draganddrop/draggabletext/dragwidget.cpp b/examples/widgets/draganddrop/draggabletext/dragwidget.cpp
index 3b8bca3277..36c4df2e43 100644
--- a/examples/widgets/draganddrop/draggabletext/dragwidget.cpp
+++ b/examples/widgets/draganddrop/draggabletext/dragwidget.cpp
@@ -40,13 +40,23 @@
 
 #include <QtWidgets>
 
-#include "draglabel.h"
 #include "dragwidget.h"
 
+static QLabel *createDragLabel(const QString &text, QWidget *parent)
+{
+    QLabel *label = new QLabel(text, parent);
+    label->setAutoFillBackground(true);
+    label->setFrameShape(QFrame::Panel);
+    label->setFrameShadow(QFrame::Raised);
+    return label;
+}
+
+static QString hotSpotMimeDataKey() { return QStringLiteral("application/x-hotspot"); }
+
 DragWidget::DragWidget(QWidget *parent)
     : QWidget(parent)
 {
-    QFile dictionaryFile(":/dictionary/words.txt");
+    QFile dictionaryFile(QStringLiteral(":/dictionary/words.txt"));
     dictionaryFile.open(QIODevice::ReadOnly);
     QTextStream inputStream(&dictionaryFile);
 
@@ -57,7 +67,7 @@ DragWidget::DragWidget(QWidget *parent)
         QString word;
         inputStream >> word;
         if (!word.isEmpty()) {
-            DragLabel *wordLabel = new DragLabel(word, this);
+            QLabel *wordLabel = createDragLabel(word, this);
             wordLabel->move(x, y);
             wordLabel->show();
             wordLabel->setAttribute(Qt::WA_DeleteOnClose);
@@ -69,12 +79,6 @@ DragWidget::DragWidget(QWidget *parent)
         }
     }
 
-    /*
-    QPalette newPalette = palette();
-    newPalette.setColor(QPalette::Window, Qt::white);
-    setPalette(newPalette);
-    */
-
     setAcceptDrops(true);
     setMinimumSize(400, qMax(200, y));
     setWindowTitle(tr("Draggable Text"));
@@ -98,19 +102,19 @@ void DragWidget::dropEvent(QDropEvent *event)
 {
     if (event->mimeData()->hasText()) {
         const QMimeData *mime = event->mimeData();
-        QStringList pieces = mime->text().split(QRegExp("\\s+"),
+        QStringList pieces = mime->text().split(QRegularExpression(QStringLiteral("\\s+")),
                              QString::SkipEmptyParts);
         QPoint position = event->pos();
         QPoint hotSpot;
 
-        QList<QByteArray> hotSpotPos = mime->data("application/x-hotspot").split(' ');
+        QByteArrayList hotSpotPos = mime->data(hotSpotMimeDataKey()).split(' ');
         if (hotSpotPos.size() == 2) {
             hotSpot.setX(hotSpotPos.first().toInt());
             hotSpot.setY(hotSpotPos.last().toInt());
         }
 
-        foreach (QString piece, pieces) {
-            DragLabel *newLabel = new DragLabel(piece, this);
+        foreach (const QString &piece, pieces) {
+            QLabel *newLabel = createDragLabel(piece, this);
             newLabel->move(position - hotSpot);
             newLabel->show();
             newLabel->setAttribute(Qt::WA_DeleteOnClose);
@@ -127,18 +131,15 @@ void DragWidget::dropEvent(QDropEvent *event)
     } else {
         event->ignore();
     }
-    foreach (QObject *child, children()) {
-        if (child->inherits("QWidget")) {
-            QWidget *widget = static_cast<QWidget *>(child);
-            if (!widget->isVisible())
-                widget->deleteLater();
-        }
+    foreach (QWidget *widget, findChildren<QWidget *>()) {
+        if (!widget->isVisible())
+            widget->deleteLater();
     }
 }
 
 void DragWidget::mousePressEvent(QMouseEvent *event)
 {
-    QLabel *child = static_cast<QLabel*>(childAt(event->pos()));
+    QLabel *child = qobject_cast<QLabel*>(childAt(event->pos()));
     if (!child)
         return;
 
@@ -146,8 +147,8 @@ void DragWidget::mousePressEvent(QMouseEvent *event)
 
     QMimeData *mimeData = new QMimeData;
     mimeData->setText(child->text());
-    mimeData->setData("application/x-hotspot",
-                      QByteArray::number(hotSpot.x()) + " " + QByteArray::number(hotSpot.y()));
+    mimeData->setData(hotSpotMimeDataKey(),
+                      QByteArray::number(hotSpot.x()) + ' ' + QByteArray::number(hotSpot.y()));
 
     QPixmap pixmap(child->size());
     child->render(&pixmap);