Move scroller/graphicsview example into tests/manual

The example seems incomplete, is undocumented (and unused in shippets,
in spite of tags being present), and generally full of comments that
give the impression that this is for manual testing rather than showing
best practices.

Pick-to: 6.5 6.6
Change-Id: Ie615420e493cc6bb461c5d9ff8d4ae82bb3591db
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 255 insertions, 0 deletions

diff --git a/tests/manual/examples/widgets/scroller/graphicsview/main.cpp b/tests/manual/examples/widgets/scroller/graphicsview/main.cpp
new file mode 100644
index 0000000000..b8df2b1b2e
--- /dev/null
+++ b/tests/manual/examples/widgets/scroller/graphicsview/main.cpp
@@ -0,0 +1,255 @@
+// Copyright (C) 2016 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include <QtCore>
+#include <QtWidgets>
+
+#define NUM_ITEMS 100
+#define NUM_LISTS 10
+
+/*!
+    \class RectObject
+    Note that it needs to be a QGraphicsObject or else the gestures will not work correctly.
+*/
+class RectObject : public QGraphicsObject
+{
+    Q_OBJECT
+
+public:
+
+    RectObject(const QString &text, qreal x, qreal y, qreal width, qreal height, QBrush brush, QGraphicsItem *parent = nullptr)
+        : QGraphicsObject(parent)
+        , m_text(text)
+        , m_rect(x, y, width, height)
+        , m_pen(brush.color().lighter(), 3.0)
+        , m_brush(brush)
+    {
+        setFlag(QGraphicsItem::ItemClipsToShape, true);
+    }
+
+    QRectF boundingRect() const override
+    {
+        // here we only want the size of the children and not the size of the children of the children...
+        qreal halfpw = m_pen.widthF() / 2;
+        QRectF rect = m_rect;
+        if (halfpw > 0.0)
+            rect.adjust(-halfpw, -halfpw, halfpw, halfpw);
+
+        return rect;
+    }
+
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override
+    {
+        Q_UNUSED(option);
+        Q_UNUSED(widget);
+        painter->setPen(m_pen);
+        painter->setBrush(m_brush);
+        painter->drawRect(m_rect);
+
+        painter->setPen(Qt::black);
+        QFont f;
+        f.setPixelSize(m_rect.height());
+        painter->setFont(f);
+        painter->drawText(m_rect, Qt::AlignCenter, m_text);
+    }
+
+    QString m_text;
+    QRectF m_rect;
+    QPen m_pen;
+    QBrush m_brush;
+};
+
+class ViewObject : public QGraphicsObject
+{
+    Q_OBJECT
+public:
+    ViewObject(QGraphicsObject *parent)
+        : QGraphicsObject(parent)
+    { }
+
+    QRectF boundingRect() const override
+    {
+        QRectF rect;
+        const auto items = childItems();
+        for (const QGraphicsItem *item : items)
+            rect |= item->boundingRect().translated(item->pos());
+        return rect;
+    }
+
+    void paint(QPainter *, const QStyleOptionGraphicsItem *, QWidget *) override
+    { }
+};
+
+class ListObject : public QGraphicsObject
+{
+    Q_OBJECT
+
+public:
+    ListObject(const QSizeF &size, bool useTouch)
+    {
+        m_size = size;
+        setFlag(QGraphicsItem::ItemClipsChildrenToShape, true);
+        // grab gesture via Touch or Mouse events
+        QScroller::grabGesture(this, useTouch ? QScroller::TouchGesture : QScroller::LeftMouseButtonGesture);
+
+        // this needs to be QGraphicsOBJECT - otherwise gesture recognition
+        // will not work for the parent of the viewport (in this case the
+        // list)
+        m_viewport = new ViewObject(this);
+
+    }
+
+    QGraphicsObject *viewport() const
+    {
+        return m_viewport;
+    }
+
+    bool event(QEvent *e) override
+    {
+        switch (e->type()) {
+// ![2]
+        case QEvent::ScrollPrepare: {
+            QScrollPrepareEvent *se = static_cast<QScrollPrepareEvent *>(e);
+            se->setViewportSize(m_size);
+            QRectF br = m_viewport->boundingRect();
+            se->setContentPosRange(QRectF(0, 0,
+                                          qMax(qreal(0), br.width() - m_size.width()),
+                                          qMax(qreal(0), br.height() - m_size.height())));
+            se->setContentPos(-m_viewport->pos());
+            se->accept();
+            return true;
+        }
+// ![1]
+// ![2]
+        case QEvent::Scroll: {
+            QScrollEvent *se = static_cast<QScrollEvent *>(e);
+            m_viewport->setPos(-se->contentPos() - se->overshootDistance());
+            return true;
+        }
+// ![2]
+        default:
+            break;
+        }
+        return QGraphicsObject::event(e);
+    }
+
+    bool sceneEvent(QEvent *e) override
+    {
+        switch (e->type()) {
+        case QEvent::TouchBegin: {
+            // We need to return true for the TouchBegin here in the
+            // top-most graphics object - otherwise gestures in our parent
+            // objects will NOT work at all (the accept() flag is already
+            // set due to our setAcceptTouchEvents(true) call in the c'tor
+            return true;
+
+        }
+        case QEvent::GraphicsSceneMousePress: {
+            // We need to return true for the MousePress here in the
+            // top-most graphics object - otherwise gestures in our parent
+            // objects will NOT work at all (the accept() flag is already
+            // set to true by Qt)
+            return true;
+
+        }
+        default:
+            break;
+        }
+        return QGraphicsObject::sceneEvent(e);
+    }
+
+    QRectF boundingRect() const override
+    {
+        return QRectF(0, 0, m_size.width() + 3, m_size.height());
+    }
+
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override
+    {
+        Q_UNUSED(option);
+        Q_UNUSED(widget);
+        painter->setPen(QPen(QColor(100, 100, 100), 3.0));
+        painter->drawRect(QRectF(1.5, 1.5, m_size.width() - 3, m_size.height() - 3));
+    }
+
+    QSizeF m_size;
+    ViewObject *m_viewport;
+};
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    MainWindow(bool useTouch)
+    {
+        m_scene = new QGraphicsScene();
+
+        // -- make the main list
+        ListObject *mainList = new ListObject(QSizeF(780, 400), useTouch);
+        mainList->setObjectName(QLatin1String("MainList"));
+        m_scene->addItem(mainList);
+// ![3]
+        for (int i=0; i<NUM_LISTS; i++) {
+            ListObject *childList = new ListObject(QSizeF(mainList->m_size.width()/3, mainList->m_size.height()), useTouch);
+            childList->setObjectName(QString("ChildList %1").arg(i));
+            fillList(childList);
+            childList->setParentItem(mainList->viewport());
+            childList->setPos(i*mainList->m_size.width()/3, 0);
+        }
+        mainList->viewport()->setPos(0, 0);
+
+
+        /*
+        list1->setTransformOriginPoint(200, 200);
+        list1->setRotation(135);
+        list1->setPos(20 + 200 * .41, 20 + 200 * .41);
+        */
+// ![3]
+
+        m_view = new QGraphicsView(m_scene);
+        setCentralWidget(m_view);
+        setWindowTitle(tr("Gesture example"));
+        m_scene->setSceneRect(0, 0, m_view->viewport()->width(), m_view->viewport()->height());
+    }
+
+    /**
+     *  Fills the list object \a list with RectObjects.
+     */
+    void fillList(ListObject *list)
+    {
+        qreal h = list->m_size.height() / 10;
+        for (int i=0; i<NUM_ITEMS; i++) {
+            QColor color =  QColor(255*i/NUM_ITEMS, 255*(NUM_ITEMS-i)/NUM_ITEMS, 127*(i%2)+64*(i/2%2));
+            QString text = QLatin1String("Item #") + QString::number(i);
+            QGraphicsItem *rect = new RectObject(text, 0, 0, list->m_size.width() - 6, h - 3, QBrush(color), list->viewport());
+            rect->setPos(3, h*i+3);
+        }
+        list->viewport()->setPos(0, 0);
+    }
+
+
+protected:
+    void resizeEvent(QResizeEvent *e) override
+    {
+        // resize the scene according to our own size to prevent scrolling
+        m_scene->setSceneRect(0, 0, m_view->viewport()->width(), m_view->viewport()->height());
+        QMainWindow::resizeEvent(e);
+    }
+
+    QGraphicsScene *m_scene;
+    QGraphicsView *m_view;
+};
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    bool touch = (a.arguments().contains(QLatin1String("--touch")));
+    MainWindow mw(touch);
+    mw.show();
+#ifdef Q_OS_MAC
+    mw.raise();
+#endif
+    return a.exec();
+}
+
+#include "main.moc"