graphwidget.cpp

Go to the documentation of this file.

/****************************************************************************
**
** Copyright (C) 2016 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 "graphwidget.h"
#include "edge.h"
#include "node.h"
 
#include <math.h>
 
#include <QKeyEvent>
#include <QRandomGenerator>
 
GraphWidget::GraphWidget(QWidget *parent)
    : QGraphicsView(parent) 
{
    QGraphicsScene *scene = new QGraphicsScene(this);
    scene->setItemIndexMethod(QGraphicsScene::NoIndex);
    scene->setSceneRect(-200, -200, 400, 400);
    setScene(scene);
    setCacheMode(CacheBackground);
    setViewportUpdateMode(BoundingRectViewportUpdate);
    setRenderHint(QPainter::Antialiasing);
    setTransformationAnchor(AnchorUnderMouse);
    scale(qreal(0.8), qreal(0.8));
    setMinimumSize(400, 400);
    setWindowTitle(tr("Elastic Nodes"));
 
    Node *node1 = new Node(this);
    Node *node2 = new Node(this);
    Node *node3 = new Node(this);
    Node *node4 = new Node(this);
    centerNode = new Node(this);
    Node *node6 = new Node(this);
    Node *node7 = new Node(this);
    Node *node8 = new Node(this);
    Node *node9 = new Node(this);
    scene->addItem(node1);
    scene->addItem(node2);
    scene->addItem(node3);
    scene->addItem(node4);
    scene->addItem(centerNode);
    scene->addItem(node6);
    scene->addItem(node7);
    scene->addItem(node8);
    scene->addItem(node9);
    scene->addItem(new Edge(node1, node2));
    scene->addItem(new Edge(node2, node3));
    scene->addItem(new Edge(node2, centerNode));
    scene->addItem(new Edge(node3, node6));
    scene->addItem(new Edge(node4, node1));
    scene->addItem(new Edge(node4, centerNode));
    scene->addItem(new Edge(centerNode, node6));
    scene->addItem(new Edge(centerNode, node8));
    scene->addItem(new Edge(node6, node9));
    scene->addItem(new Edge(node7, node4));
    scene->addItem(new Edge(node8, node7));
    scene->addItem(new Edge(node9, node8));
 
    node1->setPos(-50, -50);
    node2->setPos(0, -50);
    node3->setPos(50, -50);
    node4->setPos(-50, 0);
    centerNode->setPos(0, 0);
    node6->setPos(50, 0);
    node7->setPos(-50, 50);
    node8->setPos(0, 50);
    node9->setPos(50, 50);
}
 
void GraphWidget::itemMoved()
{
    if (!timerId)
        timerId = startTimer(1000 / 25);
}
 
void GraphWidget::keyPressEvent(QKeyEvent *event)
{
    switch (event->key()) {
    case Qt::Key_Up:
        centerNode->moveBy(0, -20);
        break;
    case Qt::Key_Down:
        centerNode->moveBy(0, 20);
        break;
    case Qt::Key_Left:
        centerNode->moveBy(-20, 0);
        break;
    case Qt::Key_Right:
        centerNode->moveBy(20, 0);
        break;
    case Qt::Key_Plus:
        zoomIn();
        break;
    case Qt::Key_Minus:
        zoomOut();
        break;
    case Qt::Key_Space:
    case Qt::Key_Enter:
        shuffle();
        break;
    default:
        QGraphicsView::keyPressEvent(event);
    }
}
 
void GraphWidget::timerEvent(QTimerEvent *event)
{
    Q_UNUSED(event);
 
    QList<Node *> nodes;
    const QList<QGraphicsItem *> items = scene()->items();
    for (QGraphicsItem *item : items) {
        if (Node *node = qgraphicsitem_cast<Node *>(item))
            nodes << node;
    }
 
    for (Node *node : qAsConst(nodes))
        node->calculateForces();
 
    bool itemsMoved = false;
    for (Node *node : qAsConst(nodes)) {
        if (node->advancePosition())
            itemsMoved = true;
    }
 
    if (!itemsMoved) {
        killTimer(timerId);
        timerId = 0;
    }
}
 
#if QT_CONFIG(wheelevent)
void GraphWidget::wheelEvent(QWheelEvent *event)
{
    scaleView(pow(2., -event->angleDelta().y() / 240.0));
}
#endif
 
void GraphWidget::drawBackground(QPainter *painter, const QRectF &rect)
{
    Q_UNUSED(rect);
 
    // Shadow
    QRectF sceneRect = this->sceneRect();
    QRectF rightShadow(sceneRect.right(), sceneRect.top() + 5, 5, sceneRect.height());
    QRectF bottomShadow(sceneRect.left() + 5, sceneRect.bottom(), sceneRect.width(), 5);
    if (rightShadow.intersects(rect) || rightShadow.contains(rect))
        painter->fillRect(rightShadow, Qt::darkGray);
    if (bottomShadow.intersects(rect) || bottomShadow.contains(rect))
        painter->fillRect(bottomShadow, Qt::darkGray);
 
    // Fill
    QLinearGradient gradient(sceneRect.topLeft(), sceneRect.bottomRight());
    gradient.setColorAt(0, Qt::white);
    gradient.setColorAt(1, Qt::lightGray);
    painter->fillRect(rect.intersected(sceneRect), gradient);
    painter->setBrush(Qt::NoBrush);
    painter->drawRect(sceneRect);
 
    // Text
    QRectF textRect(sceneRect.left() + 4, sceneRect.top() + 4,
                    sceneRect.width() - 4, sceneRect.height() - 4);
    QString message(tr("Click and drag the nodes around, and zoom with the mouse "
                       "wheel or the '+' and '-' keys"));
 
    QFont font = painter->font();
    font.setBold(true);
    font.setPointSize(14);
    painter->setFont(font);
    painter->setPen(Qt::lightGray);
    painter->drawText(textRect.translated(2, 2), message);
    painter->setPen(Qt::black);
    painter->drawText(textRect, message);
}
 
void GraphWidget::scaleView(qreal scaleFactor)
{
    qreal factor = transform().scale(scaleFactor, scaleFactor).mapRect(QRectF(0, 0, 1, 1)).width();
    if (factor < 0.07 || factor > 100)
        return;
 
    scale(scaleFactor, scaleFactor);
}
 
void GraphWidget::shuffle()
{
    const QList<QGraphicsItem *> items = scene()->items();
    for (QGraphicsItem *item : items) {
        if (qgraphicsitem_cast<Node *>(item))
            item->setPos(-150 + QRandomGenerator::global()->bounded(300), -150 + QRandomGenerator::global()->bounded(300));
    }
}
 
void GraphWidget::zoomIn()
{
    scaleView(qreal(1.2));
}
 
void GraphWidget::zoomOut()
{
    scaleView(1 / qreal(1.2));
}